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	<title>Library &#8211; Center for Climate and Resilience Research &#8211; CR2</title>
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	<description>Chilean research center on climate, climate change and resilience</description>
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		<title>Policy Brief: Hydrogen&#8217;s Impacts on the Climate System</title>
		<link>https://www.cr2.cl/eng/policy-brief-hydrogens-impacts-on-the-climate-system/</link>
		
		<dc:creator><![CDATA[Giselle Ogaz]]></dc:creator>
		<pubDate>Sat, 16 Nov 2024 20:52:55 +0000</pubDate>
				<category><![CDATA[Featured]]></category>
		<category><![CDATA[Policy Briefs]]></category>
		<guid isPermaLink="false">https://www.cr2.cl/eng/?p=20732</guid>

					<description><![CDATA[Rodrigo Seguel, Charlie Opazo y Lucas Castillo, researchers CR2 Edtor: José Barraza, CR2 Science Communicator Hydrogen causes methane, a greenhouse gas (GHG), to persist longer in the atmosphere, thereby contributing to enhanced global warming. The chemical transformation of hydrogen generates increased quantities of ozone, another GHG significant to climate change. Hydrogen degradation also produces water [&#8230;]]]></description>
										<content:encoded><![CDATA[<p><em>Rodrigo Seguel, Charlie Opazo y Lucas Castillo, researchers CR2</em></p>
<p style="text-align: right;"><strong>Edtor: </strong>José Barraza, CR2 Science Communicator</p>
<ul>
<li>Hydrogen causes methane, a greenhouse gas (GHG), to persist longer in the atmosphere, thereby contributing to enhanced global warming.</li>
<li>The chemical transformation of hydrogen generates increased quantities of ozone, another GHG significant to climate change.</li>
<li>Hydrogen degradation also produces water vapor in the lower stratosphere, resulting in surface-level warming.</li>
</ul>
<p>Molecular hydrogen (H<sub>2</sub>) possesses high energy content compared to fossil fuels and can be utilized in modified internal combustion engines or through fuel cells (Staffell et al., 2019).(<a href="https://doi.org/10.1039/c8ee01157e" target="_blank" rel="noopener">Staffell et al., 2019</a>). H<sub>2</sub> is obtained through electrolysis, a process where water molecules are split using electricity to produce hydrogen and oxygen gas..</p>
<p>Since 2020, interest in H₂ has increased significantly, particularly because its industrial production through electrolysis can be powered by renewable energy sources (<a href="https://doi.org/10.5194/amt-2024-4" target="_blank" rel="noopener">Pétron et al., 2024</a>). In northern Chile, this would primarily rely on solar panels, while in the south, wind turbines would be the main source. Thus, hydrogen emerges as a significant alternative for achieving national decarbonization and facilitating the global energy transition toward low-carbon consumption.</p>
<p>It should be noted that no known energy generation process is entirely environmentally benign. In the case of molecular hydrogen, the primary environmental impact from production, transport, and storage is associated with leaks, venting, and purging, with atmospheric emissions estimated to range between 1% and 12% (<a href="https://doi.org/10.1073/pnas.2103335118" target="_blank" rel="noopener">Patterson et al., 2021</a>). Given that the hydrogen market is nascent in Chile, anticipating its impacts on the climate system is crucial to ensure its benefits outweigh potential negative effects.</p>
<h5><strong>Current State of Knowledge</strong></h5>
<p>Atmospheric molecular hydrogen can originate from both natural and anthropogenic sources. It can be produced through photochemical formation from methane and biogenic volatile organic compounds<a href="#_ftn1" name="_ftnref1"> [1] </a>biomass burning, and fossil fuel combustion, respectively (<a href="https://doi.org/10.5194/acp-24-4217-2024" target="_blank" rel="noopener">Paulot et al., 2024</a>). The primary hydrogen sinks are microbial activity in soils and photochemical reactions involving the primary atmospheric cleaning agent (technically known as the hydroxyl radical). The atmospheric residence time of molecular hydrogen has been estimated at two years (<a href="https://doi.org/10.1021/es803180g" target="_blank" rel="noopener">Novelli et al., 2009</a>).</p>
<p>Hydrogen is considered an indirect greenhouse gas with high global warming potential. The emission of 1 kg of hydrogen into the atmosphere will produce global warming equivalent to 11.6 kg of carbon dioxide (CO<sub>2</sub>) over a 100-year period (<a href="https://doi.org/10.1038/s43247-023-00857-8" target="_blank" rel="noopener">Sand et al., 2023</a>). This climate system impact can be explained through three mechanisms:</p>
<ol>
<li>Molecular hydrogen and methane (the second most potent greenhouse gas) compete for the same atmospheric removal agent. Therefore, increased hydrogen abundance leads to longer atmospheric residence time for methane, resulting in enhanced global warming.</li>
<li>The chemical destruction of hydrogen produces a highly reactive agent (technically known as the hydroperoxyl radical), whose subsequent reactions increase tropospheric ozone formation (the third most important greenhouse gas for climate change). This process is particularly significant in atmospheres with elevated nitric oxide levels, such as those found in South American megacities.</li>
<li>Finally, molecular hydrogen degradation also produces water, whose impact in the troposphere is considered negligible. However, small changes in stratospheric water vapor, characterized by extreme dryness, affect atmospheric circulation patterns, resulting in surface-level warming.</li>
</ol>
<p>Recent estimates indicate that atmospheric hydrogen abundance has increased by 70% compared to preindustrial levels due to anthropogenic activities (<a href="https://doi.org/10.1073/pnas.2103335118" target="_blank" rel="noopener">Patterson et al., 2021</a>). Global observations also show hydrogen increases during the 2010-2019 period (<a href="https://doi.org/10.5194/acp-24-4217-2024" target="_blank" rel="noopener">Paulot et al., 2024</a>). Furthermore, Figure 1 demonstrates an upward trend for hydrogen in remote areas of Chile (Rapa Nui) and Argentina (Ushuaia).</p>
<p><a href="https://www.cr2.cl/wp-content/uploads/2024/08/Figura-1.1.png"><img fetchpriority="high" decoding="async" class="alignnone size-medium wp-image-45865" src="https://www.cr2.cl/wp-content/uploads/2024/08/Figura-1.1-300x193.png" alt="" width="300" height="193" /></a> <a href="https://www.cr2.cl/wp-content/uploads/2024/08/Figura-1.png"><img decoding="async" class="alignnone size-medium wp-image-45866" src="https://www.cr2.cl/wp-content/uploads/2024/08/Figura-1-300x193.png" alt="" width="300" height="193" /></a></p>
<p style="text-align: center;"><em><strong>Figure 1.</strong></em> Molecular hydrogen trend in remote regions of the South Pacific (left) and Patagonia (right) based on monthly averages. In Rapa Nui and Ushuaia, an annual increase of approximately 2 nmol mol-1 is observed, representing a total accumulated increase of 18 nmol mol-1 over a decade. Measurements conducted by NOAA&#8217;s Global Monitoring Laboratory (USA).</p>
<h5><strong>Scientific and Technological Challenges</strong></h5>
<p>These findings initially suggest a potential underestimation of hydrogen emissions and the difficulties in estimating its global balance. They also highlight the scientific and technological challenges of this promising alternative to fossil fuels, whose climate benefits will depend on emission rates established as targets by industry, regulatory agencies, and society.</p>
<h5 id="recomendaciones"><strong>Recommendations</strong></h5>
<ol>
<li style="list-style-type: none;">
<ol>
<li>Promote the development of new measurement technologies in the country to establish baselines and detect molecular hydrogen leaks.</li>
<li>Anticipate hydrogen emission mitigation strategies throughout the entire value chain.</li>
<li>Develop adaptation plans emphasizing molecular hydrogen&#8217;s feedback mechanisms with other gases and the geographical (physical) particularities of areas where new infrastructure will be located.</li>
<li>Reduce information gaps related to global hydrogen balance and its indirect effects on the climate system to project the real impact associated with its mass adoption.</li>
<li>Reduce emissions of methane, volatile organic compounds, and nitrogen oxides to maximize the benefits of hydrogen use.</li>
<li>Improve hydrogen monitoring coverage in remote locations to decouple the upward trend from local impacts.</li>
</ol>
</li>
</ol>
<h5><strong>References</strong></h5>
<p>Novelli, P. C., Crotwell, A. M., &amp; Hall, B. D. (2009). Application of gas chromatography with a pulsed discharge helium ionization detector for measurements of molecular hydrogen in the atmosphere. <em>Environ Sci Technol, 43</em>, <a href="https://doi.org/10.1021/es803180g" target="_blank" rel="noopener">https://doi.org/10.1021/es803180g</a>.</p>
<p>Patterson, J. D., Aydin, M., Crotwell, A. M., Pétron, G., Severinghaus, J. P., Krummel, P. B., Langenfelds, R. L., &amp; Saltzman, E. S. (2021). H<sub>2</sub> in Antarctic firn air: Atmospheric reconstructions and implications for anthropogenic emissions. <em>Proc Natl Acad Sci U S A, 118</em>, <a href="https://doi.org/10.1073/pnas.2103335118" target="_blank" rel="noopener">https://doi.org/10.1073/pnas.2103335118</a>.</p>
<p>Paulot, F., Pétron, G., Crotwell, A. M., &amp; Bertagni, M. B. (2024). Reanalysis of NOAA H<sub>2</sub> observations: implications for the H<sub>2 </sub>budget. <em>Atmos. Chem. Phys., 24</em>, 4217–4229, <a href="https://doi.org/10.5194/acp-24-4217-2024" target="_blank" rel="noopener">https://doi.org/10.5194/acp-24-4217-2024</a>.</p>
<p>Pétron, G. B., Crotwell, A. M., Mund, J., Crotwell, M., Mefford, T., Thoning, K., Hall, B. D., Kitzis, D. R., Madronich, M., Moglia, E., Neff, D., Wolter, S., Jordan, A., Krummel, P., Langenfelds, R., and Patterson, J. D. (2024). Atmospheric H<sub>2</sub> observations from the NOAA Global Cooperative Air Sampling Network, Atmos. Meas. Tech. Discuss. [preprint], <a href="https://doi.org/10.5194/amt-2024-4" target="_blank" rel="noopener">https://doi.org/10.5194/amt-2024-4</a>, in review.</p>
<p>Sand, M., Skeie, R. B., Sandstad, M., Krishnan, S., Myhre, G., Bryant, H., Derwent, R., Hauglustaine, D., Paulot, F., Prather, M., &amp; Stevenson, D. (2023) A multi-model assessment of the Global Warming Potential of hydrogen. <em>Commun Earth Environ, 4</em>, <a href="https://doi.org/10.1038/s43247-023-00857-8" target="_blank" rel="noopener">https://doi.org/10.1038/s43247-023-00857-8</a>.</p>
<p>Staffell, I., Scamman, D., Velazquez Abad, A., Balcombe, P., Dodds, P. E., Ekins, P., Shah, N., &amp; Ward, K. R. (2019). The role of hydrogen and fuel cells in the global energy system, <a href="https://doi.org/10.1039/c8ee01157e" target="_blank" rel="noopener">https://doi.org/10.1039/c8ee01157e</a></p>
<h5><strong>Notas</strong></h5>
<p><a href="#_ftnref1" name="_ftn1">[1]</a> Reacciones químicas en la atmósfera que incluyen absorción de radiación solar.</p>
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		<title>Analysis CR2 &#124; Scope and Perspectives Associated with the Ozone Evaluation Report in South America</title>
		<link>https://www.cr2.cl/eng/cr2-analysis-scope-and-perspectives-associated-with-the-ozone-evaluation-report-in-south-america/</link>
		
		<dc:creator><![CDATA[Giselle Ogaz]]></dc:creator>
		<pubDate>Thu, 08 Aug 2024 14:11:35 +0000</pubDate>
				<category><![CDATA[Analysis]]></category>
		<category><![CDATA[Featured]]></category>
		<category><![CDATA[Resilient cities]]></category>
		<guid isPermaLink="false">https://www.cr2.cl/eng/?p=20715</guid>

					<description><![CDATA[Rodrigo Seguel a, b, Charlie Opazo a, b y Lucas Castillo a, b a Center for Climate Science and Resilience Research b Department of Geophysics, Faculty of Physical and Mathematical Sciences, University of Chile Edited by: José Barraza, CR2 Science Communicator Trends in Surface Ozone in Major South American Cities Over the past decade, surface [&#8230;]]]></description>
										<content:encoded><![CDATA[<p><em>Rodrigo Seguel <sup>a, b</sup>, Charlie Opazo <sup>a, b</sup> y Lucas Castillo <sup>a, b</sup></em><br />
<em><sup>a</sup> Center for Climate Science and Resilience Research</em><br />
<em><sup>b</sup> Department of Geophysics, Faculty of Physical and Mathematical Sciences, University of Chile</em></p>
<p style="text-align: right;"><strong>Edited by</strong>: José Barraza, CR2 Science Communicator</p>
<ul>
<li>
<h5><strong>Trends in Surface Ozone in Major South American Cities<br />
</strong>Over the past decade, surface ozone levels in major cities of South America have increased or remained stable. In the Metropolitan Region, surface-level ozone has shown an upward trend since 2017.</h5>
</li>
</ul>
<h5><strong>Context</strong></h5>
<p>The Tropospheric Ozone Assessment Report (<a href="https://igacproject.org/activities/TOAR" target="_blank" rel="noopener">TOAR</a>), developed by the International Global Atmospheric Chemistry (<a href="https://igacproject.org/" target="_blank" rel="noopener">IGAC</a>),project, provides an up-to-date scientific assessment of the global distribution and trends in tropospheric ozone, which spans from the Earth&#8217;s surface to approximately 10 to 15 kilometers in altitude.</p>
<p>The first phase of TOAR (<a href="https://igacproject.org/activities/TOAR/TOAR-I" target="_blank" rel="noopener">2014-2019</a>) produced an open-access database with easily accessible web services for evaluating ozone metrics at all available monitoring sites worldwide. This database offers the scientific community a global view of surface ozone based on observational data.</p>
<p>TOAR is currently in its second phase (<a href="https://igacproject.org/activities/TOAR/TOAR-II" target="_blank" rel="noopener">TOAR-II, 2020-2025</a>). involving more than 150 researchers from 31 countries, organized into 16 working groups <a href="#_ftn1" name="_ftnref1">[1]</a>. This phase aims to update the global distribution and trends in tropospheric ozone, including its precursors (gases that, through chemical reactions, produce ozone). Like the first phase, TOAR-II aims to quantify the impacts of tropospheric ozone on climate, human health, and vegetation.</p>
<h5><strong>State of Knowledge </strong></h5>
<p>Recent research shows that global tropospheric ozone levels have increased by approximately 45% since 1850 due to emissions of anthropogenic precursors (<a href="https://dx.doi.org/10.1017/9781009157896.008" target="_blank" rel="noopener">Szopa et al., 2021</a>). Additionally, surface ozone has increased by 32% to 71% (with significant uncertainty) in the atmosphere over rural areas in the Northern Hemisphere compared to historical observations (1896-1975) (<a href="https://doi.org/10.1525/elementa.376" target="_blank" rel="noopener">Tarasick et al., 2019</a>). Since the mid-1990s, free tropospheric ozone (at altitudes of approximately 3 to 12 kilometers) <a href="#_ftn2" name="_ftnref2">[2]</a> has increased by 1 to 4 nmol mol<sup>-1</sup> per decade across most mid-latitude regions in the Northern Hemisphere and by 1 to 5 nmol mol<sup>-1</sup> per decade in tropical areas (high-confidence data) (<a href="https://doi.org/10.1017/9781009157896.004" target="_blank" rel="noopener">Gulev et al., 2021</a>).</p>
<p>In the Southern Hemisphere, limited monitoring station coverage has hindered estimating ozone trends. However, tropospheric ozone column observations since the mid-1990s suggest an increase of less than 1 nmol mol-1 per decade in mid-latitudes, with medium confidence (<a href="https://doi.org/10.1525/elementa.420" target="_blank" rel="noopener">Cooper et al., 2020</a>; <a href="https://doi.org/10.1017/9781009157896.004" target="_blank" rel="noopener">Gulev et al., 2021</a>).</p>
<h5><strong>South America</strong></h5>
<p>From a global perspective, South America is considered by the scientific community as an under-studied region where ozone trend estimates have rarely been addressed comprehensively. For this reason, the <a href="https://igacproject.org/top-focus-working-group">Tropospheric Ozone Precursors Working Group</a> has focused part of its efforts on estimating trends in surface ozone and its precursors in South America since the early 21st century. Results published in the 2024 special issue of <a href="https://acp.copernicus.org/articles/24/8225/2024/">Copernicus</a> yield the following conclusions:</p>
<ol>
<li>Trends in surface ozone in monitored major South American cities have either increased or remained stable, with no evidence of reduction in the past decade.</li>
<li>Rising trends can be attributed to photochemical regimes that efficiently transform anthropogenic precursors into chemical products favoring ozone accumulation.</li>
<li>These results suggest a phenomenon termed &#8220;climate penalty&#8221; for ozone, whereby extreme events tend to increase ozone levels, worsening air quality. In Chile, meteorological conditions favoring forest fires led to the emission of ozone precursors. In southern Brazil, this penalty is associated with extended heatwaves capable of increasing tropospheric ozone formation.</li>
</ol>
<h5><strong>Relevant Findings for Chile</strong></h5>
<ul>
<li>In the Metropolitan Region, surface ozone levels decreased by 2 nmol mol<sup>-1 </sup> per decade from 1997 to 2017 (with very high confidence). However, from 2017 onwards, ozone trends increased by 0.6 nmol mol-1 per year (with high confidence), representing a cumulative increase of 3 nmol mol-1 over five years. Thus, the past five years have seen a reversal equivalent to 20 years of progress in ozone reduction (<strong>Figure 1</strong>). This increase over five years is partly explained by warmer summers, ozone precursors emitted in forest fires, the <a href="https://online.ucpress.edu/elementa/article/10/1/00044/169476/Photochemical-sensitivity-to-emissions-and-local">pandemic&#8217;s effects</a> on anthropogenic emissions, and inconsistent control of nitrogen oxides and volatile organic compounds (represented by carbon monoxide in Figure 1), among other variables.</li>
<li>In Los Andes, the highest short- and long-term ozone exposure risk levels were recorded at 88 and 58 nmol mol<sup>-1 </sup>, respectively. These values far exceed the World Health Organization&#8217;s recommended short- and long-term metrics of 51 and 31 nmol mol<sup>-1</sup>, respectively (<a href="https://www.who.int/publications/i/item/9789240034228">WHO, 2021</a>).</li>
<li>The Tololo station, located in the Coquimbo region at an altitude of 2.2 km, is one of the few South American stations with a long enough time series to evaluate changes in the baseline ozone level. Between 2006 and 2014, a cumulative increase of 2 nmol mol<sup>-1</sup> was observed, signaling regional and hemispheric changes in the baseline ozone level in the Southern Hemisphere’s troposphere.</li>
</ul>
<p style="text-align: center;"><a href="https://www.cr2.cl/wp-content/uploads/2024/08/Figura-1-Ozono.png"><img decoding="async" class="aligncenter wp-image-45651 size-large" src="https://www.cr2.cl/wp-content/uploads/2024/08/Figura-1-Ozono-1920x1024.png" alt="" width="696" height="371" /></a></p>
<p style="text-align: center;"><em><strong>Figure 1 </strong>shows surface ozone trends (Panel A), carbon monoxide (Panel D), and nitrogen oxides (Panel E) based on monthly anomalies in Santiago. In these panels, orange points indicate the first three months of each year, the red line corresponds to the 50th percentile (or median), and the blue lines represent the remaining percentiles. A shaded vertical red line represents the trend change point (November 2017 for ozone) and its 95% confidence interval. Notably, Panel A shows that nearly all ozone reductions achieved over the past 20 years were reversed from 2017 onwards. Panels b and c show the trend of each percentile (in intervals of 5) before and after 2017. Up until 2017, the highest percentiles (above 80) showed the most significant decreasing trends (panel b). In contrast, following the change in the 2017 trend, these percentiles demonstrated significant increasing trends (panel c).<br />
Adapted from Seguel et al. (2024): <a href="https://doi.org/10.5194/egusphere-2024-328">https://doi.org/10.5194/egusphere-2024-328</a></em></p>
<h5><strong>Ongoing Activities: Regional Tropospheric Ozone Assessment in South America</strong></h5>
<p>To continue improving knowledge and confidence in information for South America, the TOAR-II Steering Committee approved a specific assessment for this region <a href="#_ftn3" name="_ftnref3">[3]</a>, this assessment aims to bridge information gaps caused by the limited surface monitoring coverage by using satellite observations and regional models and reporting key risks and findings with corresponding uncertainty estimates.</p>
<h5><strong>References</strong></h5>
<p>Cooper, O. R., Schultz, M. G., Schröder, S., Chang, K. L., Gaudel, A., Benítez, G. C., Cuevas, E., Fröhlich, M., Galbally, I. E., Molloy, S., Kubistin, D., Lu, X., McClure-Begley, A., Nédélec, P., O’Brien, J., Oltmans, S. J., Petropavlovskikh, I., Ries, L., Senik, I., Sjöberg, K., Solberg, S., Spain, G. T., Spangl, W., Steinbacher, M., Tarasick, D., Thouret, V., &amp; Xu, X. (2020). Multi-decadal surface ozone trends at globally distributed remote locations. <em>Elementa</em>, <em>8</em>, 23. <a href="https://doi.org/10.1525/elementa.420" target="_blank" rel="noopener">https://doi.org/10.1525/elementa.420</a>.</p>
<p>Gulev, S.K., P.W. Thorne, J. Ahn, F.J. Dentener, C.M. Domingues, S. Gerland, D. Gong, D.S. Kaufman, H.C. Nnamchi, J. Quaas, J.A. Rivera, S. Sathyendranath, S.L. Smith, B. Trewin, K. von Schuckmann, &amp; R.S. Vose. (2021). Changing State of the Climate System. In <em>Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change</em> [Masson-Delmotte, V., P. Zhai, A. Pirani, S.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M.I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R. Matthews, T.K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 287–422, doi: <a href="https://doi.org/10.1017/9781009157896.004" target="_blank" rel="noopener">10.1017/9781009157896.004</a>.</p>
<p>Organización Mundial de la Salud (OMS). 2021. <a href="https://www.who.int/publications/i/item/9789240034228" target="_blank" rel="noopener"><em>Global air quality guidelines. Particulate matter (PM<sub>2.5</sub> and PM<sub>10</sub>), ozone, nitrogen dioxide, sulfur dioxide and carbon monoxide</em></a>. World Health Organization, Geneva, ISBN 978-92-4- 003422-8, ISBN 978-92-4-003421-1.</p>
<p>Seguel, R.J., Castillo, L., Opazo, C., Rojas, N., Nogueira, T., Cazorla, M., Gavidia-Calderón, M., Gallardo, L., Garreaud, R., Carrasco-Escaff, T., &amp; Elshorbany, Y. (2024). Changes in South American Surface Ozone Trends: Exploring the Influences of Precursors and Extreme Events. Aceptado en: <em>Atmospheric Chemistry and Physics</em>. DOI: <a href="https://doi.org/10.5194/egusphere-2024-328" target="_blank" rel="noopener">https://doi.org/10.5194/egusphere-2024-328</a>.</p>
<p>Szopa, S., Naik, V., Adhikary, B.,  Artaxo, P.,  Berntsen, T.,  Collins, W.D.,  Fuzzi, S., Gallardo, L., Kiendler-Scharr, A., Klimont, Z., Liao, H., Unger, N.,  &amp; Zanis, P. (2021). Short-Lived Climate Forcers. In <em>Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change </em>[Masson-Delmotte, V., P. Zhai, A. Pirani, S.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M.I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R. Matthews, T.K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 817–922, doi:<a href="https://dx.doi.org/10.1017/9781009157896.008" target="_blank" rel="noopener">10.1017/9781009157896.008</a>.</p>
<p>Tarasick, D., Galbally, I. E., Cooper, O. R., Schultz, M. G., Ancellet, G., Leblanc, T., Wallington, T. J., Ziemke, J., Liu, X., Steinbacher, M., Staehelin, J., Vigouroux, C., Hannigan, J. W., García, O., Foret, G., Zanis, P., Weatherhead, E., Petropavlovskikh, I., Worden, H., Osman, M., Liu, J., Chang, K. L., Gaudel, A., Lin, M., Granados-Muñoz, M., Thompson, A. M., Oltmans, S. J., Cuesta, J., Dufour, G., Thouret, V., Hassler, B., Trickl, T., &amp; Neu, J. L. (2019). Tropospheric ozone assessment report: Tropospheric ozone from 1877 to 2016, observed levels, trends and uncertainties.  <em>Elem Sci Anth</em>, <em>7</em>, 39. <a href="https://doi.org/10.1525/elementa.376" target="_blank" rel="noopener">https://doi.org/10.1525/elementa.376</a>.</p>
<h5><strong>Notes</strong></h5>
<p><a href="#_ftnref1" name="_ftn1">[1]</a>  Current Working Groups: Chemical Reanalysis Focus Working Group, East Asia Focus Working Group, Global and Regional Models Focus Working Group, HEGIFTOM Focus Working Group, Human Health Impacts of Ozone Focus Working Group, Machine Learning for Tropospheric Ozone Focus Working Group, Ozone Deposition Focus Working Group, Ozone over the Oceans Focus Working Group, Ozone and Precursors in the Tropics (OPT) Focus Working Group, Radiative Forcing Focus Working Group, ROSTEES Focus Working Group, Satellite Ozone Focus Working Group, South Asia Focus Working Group, Statistics Focus Working Group, Tropospheric Ozone Precursors (TOP) Focus Working Group, Urban Ozone Focus Working Group.</p>
<p><a href="#_ftnref2" name="_ftn2">[2]</a> Expressed in a molar fraction of ozone in the air.</p>
<p><a href="#_ftnref3" name="_ftn3">[3]</a> Assessments focused on Health, vegetation, climate, South America, Africa, stratosphere-troposphere exchange, and satellite observations.</p>
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		<title>Climate Capsule: What is carbon neutrality?</title>
		<link>https://www.cr2.cl/eng/climate-capsule-what-is-carbon-neutrality/</link>
		
		<dc:creator><![CDATA[Giselle Ogaz]]></dc:creator>
		<pubDate>Tue, 23 Jul 2024 19:26:36 +0000</pubDate>
				<category><![CDATA[Climate Capsules]]></category>
		<category><![CDATA[Featured]]></category>
		<guid isPermaLink="false">https://www.cr2.cl/eng/?p=20728</guid>

					<description><![CDATA[Greenhouse gases [1] (GHG) are naturally found in the Earth&#8217;s atmosphere and absorb thermal energy emitted by the sun and the planet&#8217;s surface. GHGs radiate this energy, producing what is known as the greenhouse effect, which has generated an ideal temperature to allow the evolution of life on Earth. However, this natural process has been [&#8230;]]]></description>
										<content:encoded><![CDATA[<p><a href="https://www.cr2.cl/eng/wp-content/uploads/2024/11/CarbonoN_ingles.jpg"><img loading="lazy" decoding="async" class="aligncenter size-large wp-image-20729" src="https://www.cr2.cl/eng/wp-content/uploads/2024/11/CarbonoN_ingles-1024x1024.jpg" alt="" width="696" height="696" srcset="https://www.cr2.cl/eng/wp-content/uploads/2024/11/CarbonoN_ingles-1024x1024.jpg 1024w, https://www.cr2.cl/eng/wp-content/uploads/2024/11/CarbonoN_ingles-300x300.jpg 300w, https://www.cr2.cl/eng/wp-content/uploads/2024/11/CarbonoN_ingles-150x150.jpg 150w, https://www.cr2.cl/eng/wp-content/uploads/2024/11/CarbonoN_ingles-768x768.jpg 768w, https://www.cr2.cl/eng/wp-content/uploads/2024/11/CarbonoN_ingles-228x228.jpg 228w, https://www.cr2.cl/eng/wp-content/uploads/2024/11/CarbonoN_ingles-696x696.jpg 696w, https://www.cr2.cl/eng/wp-content/uploads/2024/11/CarbonoN_ingles-1068x1068.jpg 1068w, https://www.cr2.cl/eng/wp-content/uploads/2024/11/CarbonoN_ingles-420x420.jpg 420w, https://www.cr2.cl/eng/wp-content/uploads/2024/11/CarbonoN_ingles.jpg 1080w" sizes="(max-width: 696px) 100vw, 696px" /></a>Greenhouse gases <a href="#_ftn1" name="_ftnref1">[1]</a> (GHG) are naturally found in the Earth&#8217;s atmosphere and absorb thermal energy emitted by the sun and the planet&#8217;s surface. GHGs radiate this energy, producing what is known as the greenhouse effect, which has generated an ideal temperature to allow the evolution of life on Earth.</p>
<p>However, this natural process has been disturbed by human action. Social and productive activities have caused a higher concentration of GHGs in the atmosphere, increasing the planet&#8217;s surface temperature. The most abundant emissions are carbon dioxide (CO<sub>2</sub>), which remains in the atmosphere for decades to centuries.</p>
<p>The 2015 Paris Agreement established international objectives and guidelines for mitigating GHG emissions and adapting to the effects of climate change. Chile ratified this Agreement in 2017 and has set a goal to achieve carbon neutrality by 2050 at the latest, which has been established in the Climate Change Framework Law and in commitments to international organizations, mainly in the Nationally Determined Contributions (NDCs).</p>
<p>Carbon neutrality <a href="#_ftn2" name="_ftnref2"><sup>[2] </sup></a>is a goal that can be defined at different levels (international, national, etc.). It involves reaching a point of equilibrium between GHG emissions produced by human activities and the capture carried out by ecosystems, such as native forests, wetlands, peatlands, and macroalgae forests. By achieving this balance between emissions and captures, increasing the concentration of GHGs in the atmosphere is avoided, which slows global warming.</p>
<p>The GHG emissions considered in these agreements are those directly related to human activities and accounted for in National Inventories (INGEI), such as the generation of electricity we use domestically and industrially, and the refined fossil fuels used for transportation. Additionally, waste and those produced by industrial processes, agriculture, forestry, and other land uses are included.</p>
<p>The component that counteracts these emissions is to capture. The INGEI accounts for captures made by ecosystems managed by humans, such as protected or restored areas and forest plantations. Natural ecosystems can largely buffer emissions from the energy and industrial sectors, representing an advantage for Chile, which has vast vegetated areas.</p>
<p>Accurate estimation of ecosystems&#8217; carbon capture and retention capacity is essential to defining and implementing actions to achieve the carbon neutrality goal. In this sense, Chile faces a challenge associated with quantifying the carbon capture potential of ecosystems, especially those less studied, such as coastal and marine ecosystems, coastal wetlands, and macroalgae forests <a href="#_ftn3" name="_ftnref3"><sup>[3]</sup></a>.</p>
<h5><strong>Notes</strong></h5>
<p><a href="#_ftnref1" name="_ftn1"><sup>[1]</sup></a> Among the main GHGs are water vapor (H<sub>2</sub>O), carbon dioxide (CO<sub>2</sub>), nitrous oxide (N<sub>2</sub>O), methane (CH<sub>4</sub>), ozone (O<sub>3</sub>) and chlorofluorocarbons 11 and 12.</p>
<p><a href="#_ftnref2" name="_ftn2"><sup>[2]</sup></a> We use carbon neutrality as two separate words since it is written this way in Chile&#8217;s Nationally Determined Contribution<br />
(<a href="https://mma.gob.cl/wp-content/uploads/2020/04/NDC_Chile_2020_español-1.pdf" target="_blank" rel="noopener">https://mma.gob.cl/wp-content/uploads/2020/04/NDC_Chile_2020_español-1.pdf</a>), however, the RAE&#8217;s recommendation is to use carbononeutrality  (<a href="https://www.fundeu.es/recomendacion/neutralidad-en-carbono-o-carbononeutralidad-no-carbono-neutralidad/" target="_blank" rel="noopener">https://www.fundeu.es/recomendacion/neutralidad-en-carbono-o-carbononeutralidad-no-carbono-neutralidad/</a>).</p>
<p><a href="#_ftnref3" name="_ftn3"><sup>[3]</sup></a> Farías, L., K. Ubilla, C. Aguirre, L. Bedriñana, R. Cienfuegos, V. Delgado, C. Fernández, M. Fernández, A. Gaxiola, H. González, R. Hucke-Gaete, P. Marquet, V. Montecino, C. Morales, D. Narváez, M. Osses, B. Peceño, E. Quiroga, L. Ramajo, H. Sepúlveda, D. Soto, J. Valencia, E. Vargas, F. Viddi. (2019). Nine ocean-based measures for Chile&#8217;s Nationally Determined Contributions. Report of the Oceans table. Santiago: COP25 Scientific Committee; Ministry of Science, Technology, Knowledge and Innovation. <a href="https://cdn.digital.gob.cl/filer_public/f8/68/f8681032-771f-4666-b745-5c41552de2d8/16oceanos-nueve-soluciones-para-las-ndc.pdf" target="_blank" rel="noopener">https://cdn.digital.gob.cl/filer_public/f8/68/f8681032-771f-4666-b745-5c41552de2d8/16oceanos-nueve-soluciones-para-las-ndc.pdf</a></p>
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		<title>Policy Brief CR2 &#124; What is happening to the native forests of south-central Chile after the wildfires?</title>
		<link>https://www.cr2.cl/eng/policy-brief-cr2-what-is-happening-to-the-native-forests-of-south-central-chile-after-the-wildfires/</link>
		
		<dc:creator><![CDATA[Nicole Tondreau]]></dc:creator>
		<pubDate>Tue, 23 Jul 2024 13:19:35 +0000</pubDate>
				<category><![CDATA[Featured]]></category>
		<category><![CDATA[Land use change]]></category>
		<category><![CDATA[Library]]></category>
		<category><![CDATA[Policy Briefs]]></category>
		<category><![CDATA[biological invasions]]></category>
		<category><![CDATA[forest fires]]></category>
		<category><![CDATA[native forest]]></category>
		<category><![CDATA[wildfires]]></category>
		<guid isPermaLink="false">https://www.cr2.cl/eng/?p=20643</guid>

					<description><![CDATA[Authors: Claudia Leal Medina, master’s in sciences on Forests and Environment; Mauro E. González, Mauricio Galleguillos, and Javier Lopatín, CR2 researchers Edited by: José Barraza, CR2 science disseminator Pine trees are highly adapted to fire, effectively reproducing and colonizing native forests after fire events. A significant invasion of this exotic species was identified in the [&#8230;]]]></description>
										<content:encoded><![CDATA[<p style="text-align: left;"><em>Authors: Claudia Leal Medina, master’s in sciences on Forests and Environment; Mauro E. González, Mauricio Galleguillos, and Javier Lopatín, CR2 researchers</em></p>
<p style="text-align: left;">Edited by: José Barraza, CR2 science disseminator</p>
<ul>
<li>Pine trees are highly adapted to fire, effectively reproducing and colonizing native forests after fire events.</li>
<li>A significant invasion of this exotic species was identified in the remaining native forest fragments following the 2017 wildfire.</li>
<li>Pine invasion is an emerging pressure due to the positive feedback associated with future fires and the competition it generates with native species in conservation categories.</li>
</ul>
<p>Pine (<em>Pinus radiata</em>) is a fast-growing tree with high-quality wood. Due to these qualities, the forestry industry has promoted its use in Chile for years. However, it has been demonstrated that the homogeneity of forest plantations of this species facilitates the propagation of fires (McWethy et al., 2018; Bowman et al., 2019).</p>
<p>This last point is of utmost importance since pines are highly adapted to fire, having a mechanism for the rapid establishment of seedlings after a fire (Turner, 2010), while native forests must resprout and re-establish from scarce and dispersed seeds or regrow through vegetative regeneration strategies (Montenegro et al., 2004; Gómez-González &amp; Cavieres, 2009; Keeley, 2012; Gómez-González et al., 2017). Consequently, pines&#8217; rapid regeneration and dispersal exacerbate the threat condition under which native forest patches find themselves after a fire (Kay, 1994; Despain, 2001; Peterken, 2001; Brooker et al., 2008).</p>
<p>To evaluate the impacts of this <em>Pinus radiata</em> invasion on national forest ecosystems damaged by fire, a study used a combination of remote sensing and field data, with the results published in the journal Forest Ecology and Management.</p>
<p>The study area focused on the coastal forest of the Maule region (Figure 1), chosen due to: 1) It is a global biodiversity hotspot with many endemic species, 2) the occurrence of the Las Máquinas wildfire, which burned more than 160,000 hectares in 2017, is the largest in the last fifty years (CONAF, 2017; Lara et al., 2023), and 3. the historical substitution of native forest in this area, initially replaced by agricultural lands and later by forest monocultures, generating deforestation and fragmentation of native forests, leaving only 20% of the original vegetation dispersed in small patches (Bowman et al., 2019).</p>
<p><strong><em><a href="https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-1-scaled-1.jpg"><img loading="lazy" decoding="async" class="aligncenter size-large wp-image-20644" src="https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-1-scaled-1-710x1024.jpg" alt="" width="696" height="1004" srcset="https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-1-scaled-1-710x1024.jpg 710w, https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-1-scaled-1-208x300.jpg 208w, https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-1-scaled-1-768x1107.jpg 768w, https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-1-scaled-1-158x228.jpg 158w, https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-1-scaled-1-1066x1536.jpg 1066w, https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-1-scaled-1-1421x2048.jpg 1421w, https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-1-scaled-1-696x1003.jpg 696w, https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-1-scaled-1-1068x1539.jpg 1068w, https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-1-scaled-1-291x420.jpg 291w, https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-1-scaled-1.jpg 1776w" sizes="(max-width: 696px) 100vw, 696px" /></a>Figure 1.</em></strong><em> A. Study region, B. map of the Las Máquinas wildfire (pink) and native forest patches (green), and C. fire severity (from yellow to red) and sampling areas (blue dots).</em></p>
<h4><strong>Results</strong></h4>
<p>The abundance of species before the fire was dominated by Hualo (<em>Nothofagus glauca</em>), a native species with 52% presence, followed by other native species such as Peumo (<em>Cryptocarya alba</em>) with 16%, and 27 others with very low representation. However, two years after the fire, both native species presented a relative abundance of barely 5%. In contrast, the most abundant species was pine, with an approximate abundance of 60% and a density that varied between 36,000 and 57,000 individuals per hectare (Figure 2), which far exceeds the density used in commercial plantations.</p>
<p><strong><em><a href="https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-2-1-scaled-1.jpg"><img loading="lazy" decoding="async" class="aligncenter size-large wp-image-20645" src="https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-2-1-scaled-1-1200x900.jpg" alt="" width="696" height="522" srcset="https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-2-1-scaled-1-1200x900.jpg 1200w, https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-2-1-scaled-1-300x225.jpg 300w, https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-2-1-scaled-1-768x576.jpg 768w, https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-2-1-scaled-1-304x228.jpg 304w, https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-2-1-scaled-1-1536x1152.jpg 1536w, https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-2-1-scaled-1-2048x1536.jpg 2048w, https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-2-1-scaled-1-80x60.jpg 80w, https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-2-1-scaled-1-265x198.jpg 265w, https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-2-1-scaled-1-696x522.jpg 696w, https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-2-1-scaled-1-1068x801.jpg 1068w, https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-2-1-scaled-1-560x420.jpg 560w, https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-2-1-scaled-1-1920x1440.jpg 1920w" sizes="(max-width: 696px) 100vw, 696px" /></a>Figure 2.</em></strong><em> Pine invasion in a native forest patch following the 2017 wildfire. Image by Claudia Leal.</em></p>
<p>It should be noted that after the wildfire, a high number of young <em>Pinus radiata</em> individuals coincided with the presence of mature individuals established before the fire. This is due to the historical invasion process caused by land-use changes and landscape fragmentation. The large number of pinecones stored in the canopy of mature pines benefited from the conditions created by the fire, as suggested by other studies (Bustamante &amp; Simonetti, 2005; González et al., 2020; González et al., 2022; San Martín, 2022).</p>
<p>The presence of pines in highly threatened ecosystems negatively impacts the regeneration of native species post-fire, promoting transformations that catalyze the occurrence of new fires (positive feedback) and increasing competition with native species. Although the latter showed a high capacity to resprout after high-magnitude events, the effect of the invasion can significantly alter the natural trajectory and historical dynamics of these forests.</p>
<h4><strong>Recommendations</strong></h4>
<ol>
<li>Conduct early detection of post-fire biological invasions on remaining native forest fragments using remote sensing tools of different spatial resolutions.</li>
<li>Quantify biological invasions with a combination of methods that include remote and in situ data as critical input for decision-making on management strategies, control, and eradication of invasive species.</li>
<li>Control and eliminate adult pines established in native forest patches, as they are a source of seed dispersal after fires.</li>
</ol>
<h4><strong>References</strong></h4>
<p>CONAF. (2017). <em>Análisis de la Afectación y Severidad de los incendios Forestales ocurridos en enero y febrero de 2017 sobre los usos de suelo y los ecosistemas naturales presentes entre las regiones de Coquimbo y Los Ríos de Chile</em>.</p>
<p>Bowman, D. M., Moreira-Muñoz, A., Kolden, C. A., Chávez, R. O., Muñoz, A. A., Salinas, F., … &amp; Johnston, F. H. (2019). Human–environmental drivers and impacts of the globally extreme 2017 Chilean fires. <em>Ambio</em>, <em>48</em>, 350-362. <a href="https://doi.org/10.1007/s13280-018-1084-1">https://doi.org/10.1007/s13280-018-1084-1</a></p>
<p>Brooker, R. W., Maestre, F. T., Callaway, R. M., Lortie, C. L., Cavieres, L. A., Kunstler, G., … &amp; Michalet, R. (2008). Facilitation in plant communities: the past, the present, and the future. <em>Journal of ecology</em>, 18-34. <a href="https://doi.org/10.1111/j.1365-2745.2007.01295.x">https://doi.org/10.1111/j.1365-2745.2007.01295.x</a></p>
<p>Bustamante, R. O., &amp; Simonetti, J. A. (2005). Is Pinus radiata invading the native vegetation in central Chile? Demographic responses in a fragmented forest. <em>Biological Invasions</em>, <em>7</em>, 243-249.</p>
<p>Despain, D. G. (2001). Dispersal ecology of lodgepole pine (<em>Pinus contorta</em> Dougl.) in its native environment as related to Swedish forestry. <em>Forest Ecology and Management</em>, <em>141</em>(1-2), 59-68. <a href="https://doi.org/10.1016/S0378-1127(00)00489-8">https://doi.org/10.1016/S0378-1127(00)00489-8</a></p>
<p>Gómez-González, S., &amp; Cavieres, L. A. (2009). Litter burning does not equally affect seedling emergence of native and alien species of the Mediterranean-type Chilean matorral. <em>International Journal of Wildland Fire, 18</em>(2), 213-221. <a href="https://doi.org/10.1071/WF07074">https://doi.org/10.1071/WF07074</a></p>
<p>Gómez-González, S., Paula, S., Cavieres, L. A., &amp; Pausas, J. G. (2017). Postfire responses of the woody flora of Central Chile: Insights from a germination experiment. <em>PLOS ONE, 12</em>(7), e0180661. <a href="https://doi.org/10.1371/journal.pone.0180661">https://doi.org/10.1371/journal.pone.0180661</a></p>
<p>González, M. E., Sapiains, R., Gómez-González, S., Garreaud, R., Miranda, A., Galleguillos, M., Jacques, M., Pauchard, A., Hoyos, J., &amp; Cordero, L. (2020). <em>Incendios forestales en Chile: Causas, impactos y resiliencia</em>. Centro de Ciencia del Clima y la Resiliencia CR2.</p>
<p>González, M., Galleguillos, M., Lopatin, J., Leal, C., Becerra-Rodas, C., Lara, A., &amp; Martín, J. S. (2022). Surviving in a hostile landscape: <em>Nothofagus alessandrii </em>remnant forests threatened by megafires and exotic pine invasion in the coastal range of central Chile. <em>Oryx, 57</em>(2), 228-238. <a href="https://doi.org/10.1017/S0030605322000102">https://doi.org/10.1017/S0030605322000102</a></p>
<p>Kay, M. (1994). Biological control for invasive tree species. <em>New Zealand Forestry, 39</em>(3), 35-37.</p>
<p>Keeley, J. E. (2012). Ecology and evolution of pine life histories. <em>Annals of Forest Science, 69</em>(4), 445-453. <a href="https://doi.org/10.1007/s13595-012-0201-8">https://doi.org/10.1007/s13595-012-0201-8</a></p>
<p>Lara, A., Urrutia-Jalabert, R., Miranda, A., González, M., &amp; Zamorano-Elgueta, C. (2023). Bosques Nativos. En: <em>Informe País: Estado del medio ambiente y del patrimonio natural 2022 </em>(pp. 3-96).</p>
<p>McWethy, D. B., Pauchard, A., García, R. A., Holz, A., González, M. E., Veblen, T. T., Stahl, J., &amp; Currey, B. (2018). Landscape drivers of recent fire activity (2001-2017) in south-central Chile. <em>PLOS ONE, 13</em>(8), e0201195. <a href="https://doi.org/10.1371/journal.pone.0201195">https://doi.org/10.1371/journal.pone.0201195</a></p>
<p>Montenegro, G., Ginocchio, R., Segura, A., Keely, J. E., &amp; Gómez, M. (2004). Fire regimes and vegetation responses in two Mediterranean-climate regions. <em>Revista Chilena de Historia Natural, 77</em>(3). <a href="https://doi.org/10.4067/S0716-078X2004000300005">https://doi.org/10.4067/S0716-078X2004000300005</a></p>
<p>Peterken, G. F. (2001). Ecological eff ects of introduced tree species in Britain. <em>Forest ecology and management</em>, <em>141</em>(1-2), 31-42. <a href="https://doi.org/10.1016/S0378-1127(00)00487-4">https://doi.org/10.1016/S0378-1127(00)00487-4</a></p>
<p>San Martín, A. (2022). <em>Los bosques relictos de ruil: Ecología, biodiversidad, conservación y restauración</em>.</p>
<p>Turner, M. G. (2010). Disturbance and landscape dynamics in a changing world. <em>Ecology, 91</em>(10), 2833-2849. <a href="https://doi.org/10.1890/10-0097.1">https://doi.org/10.1890/10-0097.1</a></p>
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		<item>
		<title>Analysis CR2 &#124; June versus June</title>
		<link>https://www.cr2.cl/eng/cr2-analysis-june-versus-june/</link>
		
		<dc:creator><![CDATA[Nicole Tondreau]]></dc:creator>
		<pubDate>Wed, 10 Jul 2024 19:44:48 +0000</pubDate>
				<category><![CDATA[Analysis]]></category>
		<category><![CDATA[Featured]]></category>
		<category><![CDATA[Library]]></category>
		<category><![CDATA[atmospheric river]]></category>
		<category><![CDATA[drought]]></category>
		<category><![CDATA[mega drought]]></category>
		<category><![CDATA[tilted atmospheric river]]></category>
		<category><![CDATA[zonal atmospheric river]]></category>
		<guid isPermaLink="false">https://www.cr2.cl/eng/?p=20602</guid>

					<description><![CDATA[Author: René D. Garreaud, Deputy Director of the Center for Climate and Resilience Science (CR2) Editor: José Barraza, Science Communicator at CR2 The rainfall that fell over central Chile in June 2023 and June 2024 was similar and immense—equivalent to approximately 200 El Yeso reservoirs. However, the spatial and temporal distribution differed. The meteorological conditions [&#8230;]]]></description>
										<content:encoded><![CDATA[<p>Author: René D. Garreaud, Deputy Director of the Center for Climate and Resilience Science (CR2)</p>
<p style="text-align: right;"><strong>Editor: José Barraza, Science Communicator at CR2</strong></p>
<p>The rainfall that fell over central Chile in June 2023 and June 2024 was similar and immense—equivalent to approximately 200 El Yeso reservoirs. However, the spatial and temporal distribution differed. The meteorological conditions in these months largely determined the social impact of these events.</p>
<p>A sequence of frontal systems affected central Chile during June 2024, resulting in one of the rainiest months on record and significant social impacts between the Coquimbo and Araucanía regions, particularly impacting the coastal area of the Biobío region. The magnitude and extent of the disaster prompted the Government to declare a catastrophe zone between Coquimbo and Ñuble on June 12 of this year. According to Senapred reports from June 16 and 23, 2024, the storms damaged over 11,000 homes and caused massive power outages. On certain days, over 3,000 people were reported as isolated. <a href="https://ide.mop.gob.cl/Emergencias/#/home">The Ministry of Public Works&#8217; emergency viewer</a> reported dozens of road and bridge closures, especially in the coastal areas of Biobío and Valparaíso (Figure 1a).</p>
<figure id="attachment_20603" aria-describedby="caption-attachment-20603" style="width: 696px" class="wp-caption aligncenter"><a href="https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-1-1.png"><img loading="lazy" decoding="async" class="wp-image-20603 size-full" src="https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-1-1.png" alt="" width="696" height="573" srcset="https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-1-1.png 696w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-1-1-300x247.png 300w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-1-1-277x228.png 277w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-1-1-510x420.png 510w" sizes="(max-width: 696px) 100vw, 696px" /></a><figcaption id="caption-attachment-20603" class="wp-caption-text">Figure 1. Emergencies reported by the Road Directorate of the Ministry of Public Works for the period (a) June 9-22, 2024, and (b) June 20-30, 2023. Each symbol represents an incident. The color indicates the route status when accessing the platform (July 1, 2024). Source: GEOMOP Portal, https://ide.mop.gob.cl/Emergencias/#/home</figcaption></figure>
<p><strong>How much, where, and how did it rain?</strong></p>
<p>The upper panel of Figure 2 shows precipitation evolution between June 7-21, 2024, using hourly rainfall intensity (color scale in millimeters per hour) at stations across central Chile. In this time window, precipitation appeared in the Los Lagos region (between 45-40°S) on June 7, advancing northward to reach the Coquimbo region (30°S) at the beginning of June 8. Subsequently, three precipitation pulses can be distinguished, starting in the southern zone and moving northward, albeit with different reaches. Considering the Biobío region (36.6°S, indicated by dashed lines), the most significant precipitation occurred on June 8, 10, 11, 12, 16, 19, and 20.</p>
<p>In some stations in the Araucanía region, rains began in the last week of May and persisted for over three weeks, except for a break on June 16 (Mauricio Zambrano, personal communication). Intensities exceeding 10 mm/hour (intense rainfall by our standards) were observed at multiple stations throughout this precipitation period.</p>
<figure id="attachment_20604" aria-describedby="caption-attachment-20604" style="width: 696px" class="wp-caption aligncenter"><a href="https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-2-1.png"><img loading="lazy" decoding="async" class="size-large wp-image-20604" src="https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-2-1-1200x647.png" alt="" width="696" height="375" srcset="https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-2-1-1200x647.png 1200w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-2-1-300x162.png 300w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-2-1-768x414.png 768w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-2-1-423x228.png 423w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-2-1-696x376.png 696w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-2-1-1068x576.png 1068w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-2-1-778x420.png 778w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-2-1.png 1429w" sizes="(max-width: 696px) 100vw, 696px" /></a><figcaption id="caption-attachment-20604" class="wp-caption-text">Figure 2. Latitude (vertical axis) and time (in days, horizontal axis) diagram of precipitation in central Chile. The color indicates hourly precipitation at different meteorological stations. The stations are ordered by latitude, regardless of their altitude or longitude. The upper panel shows the period from June 7 to 22, 2024, while the lower panel shows the period from June 16 to 30, 2023. Hourly data from the General Water Directorate (DGA), the Chilean Meteorological Directorate (DMC), the Center for Advanced Studies in Arid Zones (Ceaza), Agromet, and RedMeteo were obtained from VisMet.</figcaption></figure>
<p>The accumulated precipitation between June 7-21, 2024, is presented in Figure 3a, using the same set of stations as in the previous figure. Values above 200 mm predominate between the Valparaíso and La Araucanía regions. The precipitation distribution is relatively uniform, with a moderate increase towards the foothills, although accumulations over 300 mm are observed in the Andes foothills in the Maule region. Also notable are the substantial accumulations on the coast of Biobío (such as 394 mm in Concepción) and Valparaíso (353 mm in Rodelillo).</p>
<figure id="attachment_20605" aria-describedby="caption-attachment-20605" style="width: 974px" class="wp-caption aligncenter"><a href="https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-3VF.png"><img loading="lazy" decoding="async" class="size-full wp-image-20605" src="https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-3VF.png" alt="" width="974" height="699" srcset="https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-3VF.png 974w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-3VF-300x215.png 300w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-3VF-768x551.png 768w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-3VF-318x228.png 318w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-3VF-696x499.png 696w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-3VF-585x420.png 585w" sizes="(max-width: 974px) 100vw, 974px" /></a><figcaption id="caption-attachment-20605" class="wp-caption-text">Figure 3. Accumulated precipitation at stations in central Chile (DGA, DMC, and Agromet) during the period (a) June 7-22, 2024, and (b) June 20-30, 2023. Hourly data from DMC, DGA, CEAZA, Agromet, and RedMeteo were obtained from VisMet.</figcaption></figure>
<p><strong>A year ago&#8230;</strong></p>
<p>At the end of June 2023, we commented on the return of the giants due to another exceptionally rainy period in central Chile. The lower panel of Figure 2 shows the latitude-time diagram between June 16 and 30 of that year, where a single precipitation event is observed that began on the 22nd and extended up to six days in some stations. In contrast to the 2024 storms, the 2023 pulse began more or less simultaneously between the Los Lagos and Metropolitan regions (45-33°S) and then the most intense precipitation, with accumulations over 10 mm/hr, remained stationary between the O&#8217;Higgins and Ñuble regions.</p>
<p>The differences between June 2023 and 2024 are also observed in the spatial distribution of precipitation. The 2023 accumulations comprise a smaller latitudinal range, with the absence of rain north of 33°S; moreover, they show a marked topographic enhancement, as in the Maule, Ñuble, and Biobío regions, accumulations on the coast and central valley fluctuated between 100 and 150 mm, while in foothill sectors they exceeded 500 mm, reaching 700 mm at the Bullileo Reservoir station. These accumulations were concentrated in a 72-hour period and a warm environment, giving rise to large-magnitude floods in the Andean rivers. This subsequently generated extensive flooding in the central valley and coastal sectors adjacent to river courses. Consistent with this, the MOP emergency viewer shows that most road and water infrastructure damage was concentrated in the central valley and foothills in the Maule and Ñuble regions (Figure 1b).</p>
<p><strong>The TAR family and the solitary ZAR</strong></p>
<p>Considering the area of central Chile between Coquimbo and La Araucanía, the rain that fell in 2023 and 2024 was 50 billion cubic meters, enough to fill about 200 reservoirs the size of El Yeso. These are extreme and similar values but the product of very different conditions.</p>
<p>The four precipitation pulses of 2024 (Figure 2) were due to the passage of cold fronts over central Chile. Each front occurred connected to a low-pressure center [2], moving in mid-latitudes from the Pacific towards South America. Figure 4 shows an example of this situation on June 20, 2024, where the letter B indicates this low-pressure center. Meanwhile, the cloudiness allows for inferring the approximate position of the cold front that caused rains over Biobío. Ahead of the cold front, there is a corridor of intense low-level winds that transport humidity from subtropical latitudes southward. When this transport is intense and concentrated in a long but narrow band, we refer to it as an atmospheric river (AR). All June 2024 events presented an AR, with the case of June 11 and 12 being particularly intense (Figure 5a), which, due to its intensity and persistence, qualified as a category 4 river (on the 1-5 scale of Ralph et al., 2019). Notably, the vapor transport in the 2024 events came from the northwest (NW), forming an angle of about 45° with the Andes Mountains. These cases are called tilted atmospheric rivers (TAR) and are the most frequent during the winter in central Chile.</p>
<figure id="attachment_20606" aria-describedby="caption-attachment-20606" style="width: 1034px" class="wp-caption aligncenter"><a href="https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-4.png"><img loading="lazy" decoding="async" class="size-full wp-image-20606" src="https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-4.png" alt="" width="1034" height="851" srcset="https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-4.png 1034w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-4-300x247.png 300w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-4-768x632.png 768w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-4-277x228.png 277w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-4-696x573.png 696w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-4-510x420.png 510w" sizes="(max-width: 1034px) 100vw, 1034px" /></a><figcaption id="caption-attachment-20606" class="wp-caption-text">Figure 4. Satellite image (GOES 16) of June 20, 2024, at 18 UTC (15 local time). Over the visible image (clouds in white or gray), the infrared image was superimposed, where yellow and orange colors indicate clouds with greater vertical development. The approximate position of the cold front is indicated by the line with triangles, the warm front by the line with semicircles, and the occluded front by the line with both symbols. Additionally, the location of the low-pressure center is identified with the letter B. The small black circle indicates the city of Concepción.</figcaption></figure>
<p>The article &#8220;Atmospheric Rivers in South-Central Chile: Zonal and Tilted Events&#8221; documents that NW winds during TARs tend to produce the most significant precipitation in the coastal mountain range, an orographic shadow (decrease in precipitation) over the central valley, and a moderate increase in precipitation over the Andes Mountains, due to the marked blocking it produces on the humid air attempting to cross it. Additionally, a good part of the precipitation during TARs tends to occur when the temperature begins to decrease &#8211; in connection with the arrival of the cold front &#8211; which favors snow accumulation on the Andes Mountains above 2000 m in altitude. These are precisely the ingredients that were observed during the June 2024 storms. However, the persistence of a TAR over the Biobío coast, the incredible intensity of rain in specific coastal sectors, and the effect of northern solid wind in the coastal strip have not yet received sufficient attention.</p>
<figure id="attachment_20607" aria-describedby="caption-attachment-20607" style="width: 934px" class="wp-caption aligncenter"><a href="https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-5.png"><img loading="lazy" decoding="async" class="size-full wp-image-20607" src="https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-5.png" alt="" width="934" height="887" srcset="https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-5.png 934w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-5-300x285.png 300w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-5-768x729.png 768w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-5-240x228.png 240w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-5-696x661.png 696w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-5-442x420.png 442w" sizes="(max-width: 934px) 100vw, 934px" /></a><figcaption id="caption-attachment-20607" class="wp-caption-text">Figure 5. Maps of the total column water vapor content (precipitable water in color scale) and integrated vapor transport (IVT, black arrows) for (a) June 11, 2024, and (b) June 23, 2023. The axis of the TAR (tilted atmospheric river) and ZAR (zonal atmospheric river) are indicated in each case. Data source: ERA-5 visualized through R-Explorer.</figcaption></figure>
<p>In contrast, the storm that occurred between June 22 and 26, 2023 was the product of a zonal atmospheric river (ZAR; Garreaud et al., 2024) immediately ahead of a stationary front. The ZAR arrived at the coast of the Los Ríos region and then moved slowly northward, remaining centered in the Maule region between June 23 and 25 (Figure 5b). Under these conditions, a strong moisture flow perpendicularly impacted the Andes, and the ascent concentrated on the foothills, where the most significant precipitation occurred.</p>
<p>Another marked difference with the 2024 TARs is that precipitation during the solitary ZAR occurred in a warmer environment, leaving snow above 3200 meters in altitude. Thus, the Andean basins quickly received a large amount of liquid precipitation, generating a much more marked hydrological response. For example, Figure 6 compares the hourly flow values of the Achibueno River at La Recova (about 20 kilometers inland from Linares) during June 2024 and 2023, along with daily precipitation values at the nearby Juan Amigo station.</p>
<p>In the case of 2024, the 475 mm accumulated were distributed over several days (with intensities below 100 mm/day) and caused maximum flows close to 500 m3/sec. In contrast, the 2023 ZAR accumulated over 700 mm in its five days of duration, with a maximum of over 200 mm/day, increasing the flow up to 3200 m3/s with an estimated return period of at least 50 years.</p>
<figure id="attachment_20608" aria-describedby="caption-attachment-20608" style="width: 763px" class="wp-caption aligncenter"><a href="https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-6.png"><img loading="lazy" decoding="async" class="size-full wp-image-20608" src="https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-6.png" alt="" width="763" height="618" srcset="https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-6.png 763w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-6-300x243.png 300w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-6-281x228.png 281w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-6-696x564.png 696w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-6-519x420.png 519w" sizes="(max-width: 763px) 100vw, 763px" /></a><figcaption id="caption-attachment-20608" class="wp-caption-text">Figure 6. Hourly flow data (blue line) of the Achibueno River at La Recova (36°S, 71.4°W) and daily precipitation data (light blue bars) at the Juan Amigo station for the period between June 7 and 30 of (a) 2024 and (b) 2023. Source: DGA.</figcaption></figure>
<p>The snow cover at the end of June is relevant, as it determines the water resources available for the summer. Due to the difference between the thermal conditions of the storms already described, the current snow cover (as of July 1) is substantially greater than its counterpart from a year ago, as seen in the satellite images in Figure 7. As an example, the Tinguiririca River basin (east of San Fernando in the O&#8217;Higgins region) currently has 92% of its area covered by snow, in contrast to the 52% it presented a year ago, according to data from the Andean Observatory based on MODIS images.</p>
<figure id="attachment_20609" aria-describedby="caption-attachment-20609" style="width: 696px" class="wp-caption aligncenter"><a href="https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-7.png"><img loading="lazy" decoding="async" class="size-large wp-image-20609" src="https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-7-1200x495.png" alt="" width="696" height="287" srcset="https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-7-1200x495.png 1200w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-7-300x124.png 300w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-7-768x317.png 768w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-7-553x228.png 553w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-7-696x287.png 696w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-7-1068x441.png 1068w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-7-1018x420.png 1018w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-7.png 1430w" sizes="(max-width: 696px) 100vw, 696px" /></a><figcaption id="caption-attachment-20609" class="wp-caption-text">Figure 7. MODIS satellite images over the Metropolitan and O&#8217;Higgins regions for (a) July 1, 2024, and (b) June 30, 2023.</figcaption></figure>
<p><strong>And what happened with La Niña?</strong></p>
<p>During 2023, an intense El Niño event developed, characterized, among other aspects, by the warming of the sea surface in the equatorial Pacific. In June of that year, this warming extended from the coast of South America to the dateline (Figure 8a) and probably contributed to the rainfall surplus observed in central Chile. This El Niño event culminated at the end of 2023 and beginning of 2024, when the Niño 3.4 index reached 2°C. However, in January, climate prediction models indicated a rapid transition towards a cold condition in the tropical Pacific by the middle of this year. In February, the consolidated forecast from the Interamerican Research Institute indicated a 50% probability of La Niña occurrence for the June-July-August (JJA) quarter and 65% for the July-August-September (JAS) quarter. As La Niña is associated with a deficit precipitation condition in central Chile, various press notes appeared predicting an extremely dry condition for the current winter. However, the seasonal precipitation forecast in central Chile has multiple uncertainties, and even with an accurate prediction of La Niña, it is not possible to predict the intensity of precipitation anomalies (read this CR2 Analysis) as we are currently seeing.</p>
<figure id="attachment_20610" aria-describedby="caption-attachment-20610" style="width: 672px" class="wp-caption aligncenter"><a href="https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-8.png"><img loading="lazy" decoding="async" class="size-full wp-image-20610" src="https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-8.png" alt="" width="672" height="861" srcset="https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-8.png 672w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-8-234x300.png 234w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-8-178x228.png 178w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-8-328x420.png 328w" sizes="(max-width: 672px) 100vw, 672px" /></a><figcaption id="caption-attachment-20610" class="wp-caption-text">Figure 8. Sea surface temperature anomalies in (a) June 2023 and (b) June 2024. The anomalies correspond to the difference from the 1990-2020 average condition.</figcaption></figure>
<p>Although the cooling of the tropical Pacific began markedly on the South American coast, its extension to the west has been slower than anticipated, as indicated by the sea surface temperature (SST) anomaly map for June 2024 (Figure 8b) and a Niño 3.4 index still above 0°C. The Interamerican Research Institute forecast issued in mid-June 2024 reduced the probability of La Niña to 13% for the JJA quarter and 32% for JAS. Dynamic prediction models were also unable to foresee the establishment of a high-pressure center (blocking high) west of the Antarctic Peninsula that persisted for much of June and played an essential role in that month&#8217;s rainfall, as we will describe later.</p>
<p>Thus, the most recent information and predictions indicate that most of the present winter will be under a neutral condition of the El Niño Southern Oscillation (ENSO), where, historically, a rainfall deficit or surplus can occur in central Chile with the same chance, due to the influence of large-scale factors such as the Madden-Julian Oscillation or the Southern Annular Mode described in this previous Analysis. However, in the last twenty years, the relationship between ENSO and precipitation in central Chile has weakened, and most neutral years have ended in deficit rainfall conditions, including the megadrought period 2010-2022. Climate change and the warm blob in the southwestern subtropical Pacific are possible explanations for this. These additional factors to ENSO are considered by global climate models that serve as the basis for climate prediction and show a deficit precipitation condition for much of central Chile (Figure 9) during the JAS quarter. Even if this is fulfilled, the precipitation accumulation to date will result in an average or above-average year between the Valparaíso and La Araucanía regions.</p>
<figure id="attachment_20611" aria-describedby="caption-attachment-20611" style="width: 696px" class="wp-caption aligncenter"><a href="https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-9.png"><img loading="lazy" decoding="async" class="size-large wp-image-20611" src="https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-9-1200x624.png" alt="" width="696" height="362" srcset="https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-9-1200x624.png 1200w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-9-300x156.png 300w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-9-768x399.png 768w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-9-439x228.png 439w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-9-696x362.png 696w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-9-1068x555.png 1068w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-9-808x420.png 808w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-9.png 1264w" sizes="(max-width: 696px) 100vw, 696px" /></a><figcaption id="caption-attachment-20611" class="wp-caption-text">Figure 9. Seasonal forecast based on the ACCESS-2 model for the July-August-September quarter. The model was initialized in early July 2024. The colors indicate the predicted precipitation anomaly in millimeters of rain. Source: Australian Bureau of Meteorology (BOM).</figcaption></figure>
<p><strong>Broadening the view [4]</strong></p>
<p>In this last section, we present a hemispheric view that helps understand the rainfall anomalies in June 2023 and 2024.</p>
<p>We will start with the mean circulation between June 5 and 14, 2024, when the first two TARs arrived in central Chile. Figure 10a shows the average stream function anomalies at 200 hPa, which can be interpreted as pressure anomalies in the upper troposphere during this period. In the high latitudes of the South Pacific, an anticyclonic anomaly (red letter H) stands out throughout the tropospheric column. As shown by the time-longitude section at 60°S of surface pressure anomalies, this anomaly persisted for much of June near 120°W (Figure 11a). This blocking high over the Amundsen-Bellingshausen Sea was able to divert the storm track northward, as seen in the succession of opposite-sign anomalies in subtropical latitudes over the southeastern Pacific. The cyclonic anomalies (letter L; positive contours) at height are dynamically linked to depressions near the surface, which favored the formation of fronts and ARs that reached central Chile.</p>
<figure id="attachment_20612" aria-describedby="caption-attachment-20612" style="width: 936px" class="wp-caption aligncenter"><a href="https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-10.png"><img loading="lazy" decoding="async" class="size-full wp-image-20612" src="https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-10.png" alt="" width="936" height="640" srcset="https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-10.png 936w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-10-300x205.png 300w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-10-768x525.png 768w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-10-333x228.png 333w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-10-218x150.png 218w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-10-696x476.png 696w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-10-614x420.png 614w" sizes="(max-width: 936px) 100vw, 936px" /></a><figcaption id="caption-attachment-20612" class="wp-caption-text">Figure 10. Average stream function anomalies at 200 hPa (black contours), outgoing longwave radiation (colors), and wave activity flux (arrows) during (a) June 5-14, 2024, and (b) June 16-25, 2023. See text for more details. Source: Tokyo Climate Center.<br />Figure 10b shows the same field of stream function anomalies for the ten days prior to the zonal atmospheric river (ZAR) &#8216;s occurrence in June 2023. As in 2024, the condition was quite stationary, but with a spatial pattern consistent with a quadrupole (two centers of cyclonic anomaly, identified with the letter L, and two anticyclonic, identified with the letter H) over the South Pacific, which is recurrent in ZAR cases (Valenzuela et al., 2021; Garreaud et al., 2024).</figcaption></figure>
<p>At the same time, near New Zealand, there is a blocking anticyclone at high latitudes (Figure 11b) and a cyclonic anomaly at lower latitudes. These height anomalies extend to the middle and lower troposphere. The anticyclone transported cold air northward, contributing to forming a westerly wind jet stream at subtropical latitudes. For its part, the cyclonic anomaly at lower latitudes transported moist air towards the base of the jet stream, thus feeding the ZAR (Mudiar et al., 2024). In addition to this, near South America, a reinforced subtropical anticyclone and a cyclone at higher latitudes were observed, which favored the extension of the subtropical jet stream and the ZAR until reaching the coast of Chile.</p>
<figure id="attachment_20613" aria-describedby="caption-attachment-20613" style="width: 936px" class="wp-caption aligncenter"><a href="https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-11.png"><img loading="lazy" decoding="async" class="size-full wp-image-20613" src="https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-11.png" alt="" width="936" height="679" srcset="https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-11.png 936w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-11-300x218.png 300w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-11-768x557.png 768w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-11-314x228.png 314w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-11-324x235.png 324w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-11-696x505.png 696w, https://www.cr2.cl/eng/wp-content/uploads/2024/07/Figura-11-579x420.png 579w" sizes="(max-width: 936px) 100vw, 936px" /></a><figcaption id="caption-attachment-20613" class="wp-caption-text">Figure 11. Hovmöller diagrams (longitude-time) of sea level pressure anomalies (in pascals) averaged between 65°S and 60°S for (a) June 2024 and (b) June 2023. The letters H indicate the location of the anticyclone described in the text.</figcaption></figure>
<p>Although in June 2024 ENSO was transitioning towards the La Niña phase, while in June 2023 El Niño was developing, both months presented positive anomalies in sea surface temperature in the western sector of the tropical Pacific (Figure 8), with an extension towards the southeast in the form of a band reaching 15°S-120°W. These warmer-than-average conditions may have been partly responsible for the previously described circulation patterns and undoubtedly contributed to the atmosphere over that sector of the South Pacific having more water vapor than an average June. It is possible that part of this moisture fed the storms that eventually reached central Chile (Campos &amp; Rondanelli, 2023; Mudiar et al., 2024).</p>
<p><strong>References</strong></p>
<p>Campos, D., &amp; Rondanelli, R. (2023). ENSO‐Related Precipitation Variability in Central Chile: The Role of Large Scale Moisture Transport. Journal of Geophysical Research: Atmospheres, 128(17), e2023JD038671. <a href="https://doi.org/10.1029/2023JD038671">https://doi.org/10.1029/2023JD038671</a></p>
<p>Garreaud, R. D., Jacques-Coper, M., Marín, J. C., &amp; Narváez, D. A. (2024). Atmospheric Rivers in South-Central Chile: Zonal and Tilted Events. Atmosphere, 15(4), 406. <a href="https://doi.org/10.3390/atmos15040406">https://doi.org/10.3390/atmos15040406</a></p>
<p>Mudiar, D., Rondanelli, R., Valenzuela, R. A., &amp; Garreaud, R. D. (2024). Unraveling the dynamics of moisture transport during atmospheric rivers producing rainfall in the Southern Andes. Geophysical Research Letters, 51(13), e2024GL108664. <a href="https://doi.org/10.1029/2024GL108664">https://doi.org/10.1029/2024GL108664</a></p>
<p>Ralph, F. M., Rutz, J. J., Cordeira, J. M., Dettinger, M., Anderson, M., Reynolds, D., … &amp; Smallcomb, C. (2019). A scale to characterize the strength and impacts of atmospheric rivers. Bulletin of the American Meteorological Society, 100(2), 269-289. <a href="https://doi.org/10.1175/BAMS-D-18-0023.1">https://doi.org/10.1175/BAMS-D-18-0023.1</a></p>
<p>Valenzuela, R., Garreaud, R., Vergara, I., Campos, D., Viale, M., &amp; Rondanelli, R. (2022). An extraordinary dry season precipitation event in the subtropical Andes: Drivers, impacts and predictability. Weather and Climate Extremes, 37, 100472. <a href="https://doi.org/10.1016/j.wace.2022.100472">https://doi.org/10.1016/j.wace.2022.100472</a></p>
<p><strong>Notes</strong></p>
<p>[1] This analysis does not consider a fifth frontal system that affected the area between the Los Lagos and La Araucanía regions in late June 2024.</p>
<p>[2] Low-pressure center, depression, or extratropical cyclone.</p>
<p>[3] The historical probability of each ENSO phase (La Niña, Neutral, or El Niño) is 33%.</p>
<p>[4] This is a rather technical section.</p>
<p><strong>Editor&#8217;s note:</strong></p>
<p>Figure 3 and its interpretation were modified due to a date correction. It previously stated: *Accumulated precipitation at stations in central Chile (DGA, DMC, and Agromet) during the period (a) June 7-22, 2023, and (b) June 20-30, 2024*. Hourly data from DMC, DGA, CEAZA, Agromet, and RedMeteo were obtained from VisMet. It now states: *(a) June 7-22, 2024, and (b) June 20-30, 2023. *</p>
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		<title>Policy Brief CR2 &#124; Urban Climate, Climate-Sensitive Planning, and Urban Climate Justice in Chile</title>
		<link>https://www.cr2.cl/eng/policy-brief-cr2-urban-climate-climate-sensitive-planning-and-urban-climate-justice-in-chile/</link>
		
		<dc:creator><![CDATA[Nicole Tondreau]]></dc:creator>
		<pubDate>Wed, 03 Jul 2024 13:10:32 +0000</pubDate>
				<category><![CDATA[Featured]]></category>
		<category><![CDATA[Library]]></category>
		<category><![CDATA[Policy Briefs]]></category>
		<category><![CDATA[Resilient cities]]></category>
		<category><![CDATA[cities]]></category>
		<category><![CDATA[heat islands]]></category>
		<category><![CDATA[urban climate]]></category>
		<guid isPermaLink="false">https://www.cr2.cl/eng/?p=20639</guid>

					<description><![CDATA[Pamela Smith, Eugenia Gayó, Estela Blanco, Pablo Sarricolea, Karla Yohannessen, Anahí Urquiza, Marco Billi, CR2 researchers, and Teresita Alcántara, School of Government and Public Transformation, Tecnológico de Monterrey, Mexico Edited by: José Barraza, CR2 Science Disseminator The urban climate is characterized by the existence of heat islands, which implies that cities generally have a higher [&#8230;]]]></description>
										<content:encoded><![CDATA[<p><em>Pamela Smith, Eugenia Gayó, Estela Blanco, Pablo Sarricolea, Karla Yohannessen, Anahí Urquiza, Marco Billi, CR2 researchers, and Teresita Alcántara, School of Government and Public Transformation, Tecnológico de Monterrey, Mexico</em></p>
<p style="text-align: right;">Edited by: José Barraza, CR2 Science Disseminator</p>
<ul>
<li>The urban climate is characterized by the existence of heat islands, which implies that cities generally have a higher temperature relative to their rural surroundings.</li>
<li>In Chile, it has been verified that different temperatures exist within the same city. In summer, both daytime and nighttime temperatures are lower in higher-income neighborhoods and higher in lower-income neighborhoods.</li>
<li>The country lacks a legal framework that guarantees high-quality urban climates for the population.</li>
</ul>
<p>The 21st century marks a turning point both in terms of accelerated urban expansion and the increasingly evident impacts of climate change on our cities. At this intersection, attention &#8211; and concerns &#8211; about how changing climatic conditions behave and manifest within cities are beginning to take on increasing prominence.</p>
<p>Latin America is one of the most urbanized regions on the planet, with about 80% of its population living in cities. This phenomenon is even more evident in Chile, as the urban population reaches 88% (INE, 2017). It is known that urban growth modifies natural and semi-natural land covers, replacing them with artificial land uses and covers that alter energy balances and, therefore, generate different climatic conditions. This phenomenon is called urban climate, which is defined by modifications of the original conditions of temperature, air humidity, pollution, and albedo, among others.</p>
<p>Usually, the urban climate is characterized by the existence of heat islands, which imply that the city has a higher air temperature compared to its rural surroundings, which undoubtedly has effects, for example, on population health, thermal comfort, or energy demand for air conditioning [1].</p>
<p>Additionally, under climate change scenarios, it is anticipated that temperature extremes will intensify in the future, thus increasing the frequency of heat waves or nocturnal heat. These extreme temperature events interact with heat islands, increasing their intensity and duration. According to future projections (2035-2065) available on the ARClim platform, the occurrence of such extreme events and the urban heat island (UHI) would increase in all cities, especially in the northern and central zones of the country. This is concerning, as heat exposure can cause heat exhaustion or sunstroke and produce or exacerbate health conditions (e.g., headaches, dizziness) and aggravate existing chronic diseases, mainly due to the cardiovascular response to heat and dehydration.</p>
<p>Scientific evidence indicates that urban climate behavior is related to and depends on city design and planning at different scales, such as the percentage of soil sealing, the percentage of vegetation cover, colors and types of construction materials, or building heights (Smith &amp; Romero, 2016). Because urban morphology, green areas, and other parameters vary across the city, temperature also varies, with variations occurring at the neighborhood and block scale. Consequently, inequity arises regarding the degree to which different population groups are exposed to these climatic hazards. Work conducted by the CR2 Resilient Cities Line further indicates that these inequities are compounded by other social and economic conditions of inequality specific to each neighborhood (Sarricolea et al., 2022). For example, it has been verified that in different larger, medium-sized Chilean cities, the average summer surface temperature during the day and night is lower (lesser heat island) in neighborhoods with higher economic incomes (ABC1 and C2). The opposite occurs in neighborhoods with lower socioeconomic levels, regardless of latitude and position relative to the sea, city size, and number of inhabitants (Figure 1).</p>
<p><strong><em><a href="https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-1-VF-scaled-1.jpg"><img loading="lazy" decoding="async" class="aligncenter size-large wp-image-20640" src="https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-1-VF-scaled-1-1200x417.jpg" alt="" width="696" height="242" srcset="https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-1-VF-scaled-1-1200x417.jpg 1200w, https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-1-VF-scaled-1-300x104.jpg 300w, https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-1-VF-scaled-1-768x267.jpg 768w, https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-1-VF-scaled-1-656x228.jpg 656w, https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-1-VF-scaled-1-1536x534.jpg 1536w, https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-1-VF-scaled-1-2048x712.jpg 2048w, https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-1-VF-scaled-1-696x242.jpg 696w, https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-1-VF-scaled-1-1068x371.jpg 1068w, https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-1-VF-scaled-1-1208x420.jpg 1208w, https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-1-VF-scaled-1-1920x668.jpg 1920w" sizes="(max-width: 696px) 100vw, 696px" /></a>Figure 1</em></strong><em>. Relationship between summer daytime surface temperature (in °C) and the socioeconomic level of each analyzed block in the cities of Arica (left) and Coyhaique (right). Note: In the graph, red points represent extreme values of variance.</em></p>
<p>As an example of temperature differences within a city, Figure 2 shows the differences between the maximum temperatures reached and the number of heat wave episodes among official meteorological stations (SINCA and Meteochile network) located in different areas of the same city during an extremely hot summer. The differences between the two communes of Santiago city, Las Condes and Independencia, stand out, with one and six heat wave episodes, respectively, which could be explained because they represent very different environmental and urban conditions. Las Condes generally has lower construction densities and more vegetation cover, with trees and grass, which cools surfaces and provides shade.</p>
<p><strong><em><a href="https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-2-scaled-1.jpg"><img loading="lazy" decoding="async" class="aligncenter size-large wp-image-20641" src="https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-2-scaled-1-1128x1024.jpg" alt="" width="696" height="632" srcset="https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-2-scaled-1-1128x1024.jpg 1128w, https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-2-scaled-1-300x272.jpg 300w, https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-2-scaled-1-768x697.jpg 768w, https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-2-scaled-1-251x228.jpg 251w, https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-2-scaled-1-1536x1394.jpg 1536w, https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-2-scaled-1-2048x1858.jpg 2048w, https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-2-scaled-1-696x632.jpg 696w, https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-2-scaled-1-1068x969.jpg 1068w, https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-2-scaled-1-463x420.jpg 463w, https://www.cr2.cl/eng/wp-content/uploads/2024/08/Figura-2-scaled-1-1920x1742.jpg 1920w" sizes="(max-width: 696px) 100vw, 696px" /></a>Figure 2.</em></strong><em> Spatial differences in heat waves recorded in Santiago, summer 2015-2016. The column &#8220;T° above threshold&#8221; corresponds to the days when the maximum temperature exceeds the 90th percentile, as defined by the Chilean Meteorological Directorate. The &#8220;T°&#8221; column represents the maximum temperature reached during the period, from highest (red) to lowest (blue). Note: It should be noted that the Puente Alto and Parque O&#8217;Higgins stations are in vegetated areas; therefore, they do not adequately represent the urban conditions of their surroundings</em></p>
<p>In contrast, Independencia, a commune with a lower socioeconomic level than Las Condes, is characterized by higher construction density and less green space. This implies that the poorest neighborhoods in cities are more exposed to high temperatures. At the same time, people with a lower socioeconomic level have more significant difficulties in reducing the intensity of the urban heat island due to a lack of access to technological resources (e.g., air conditioning or housing with better thermal insulation) or potable water, which could allow them to maintain adequate thermal comfort conditions both outside and inside their homes. In this way, the inequitable distribution of heat islands (an urban design problem) combines with the inequitable distribution of income and poverty (a social justice problem) and radicalizes the vulnerability of the poorest populations. This forces us to reflect more deeply on the issues of climate injustice linked to extreme heat and urban planning.</p>
<p>Climate justice has garnered increasing interest in recent years associated with climate change, making visible recurrent inequity in the distribution of benefits and impacts (Schlosberg, 2013). On a global scale, this has led to questions such as whether and how there should be compensation from those countries and populations that have emitted or emit more greenhouse gases to those that have emitted less, but which today &#8211; or in the future &#8211; will suffer more markedly from the impacts of climate change, affecting their ways and quality of life (Williges et al., 2022). Despite the importance of justice and the effects of climate change in cities, they have yet to be considered in urban studies (Bulkeley et al., 2013), especially in our country.</p>
<h4><strong>Urban Planning and Climate</strong></h4>
<p>Although some Chilean cities are regulated by urban and environmental norms and standards (air quality, noise, etc.), in general, until now there has not been a legal framework in the country that guarantees high-quality urban climates for the population (Alcoforado et al., 2009). This lack of institutionalization could be explained, in part, by budgetary constraints, conflicts of interest, lack of political will, lack of adequate meteorological data, and short-term priority setting and planning.</p>
<p>Communal Regulatory Plans (PRC) in Chile are territorial planning instruments that define, among other things, occupancy density criteria, maximum building heights, buildability coefficients, and other urban parameters that can affect the urban microclimate and, in turn, the comfort of public spaces. However, climate behavior is not considered a factor contributing to decision-making. If what is declared in the PRCs is compared with current characteristics, the wide margin that many sectors in Chilean cities still must increase density and height is evident, which can mean a decrease in visible sky or sky openness, causing effects on direct solar radiation, and access to sun and shade within a street.</p>
<p>The documents and reports prepared in the country concerning adaptation and mitigation to climate change have meant the progressive installation of the climate factor in decision-making. For example, it can be mentioned that an essential part of the strategies presented in the &#8220;Adaptation Plan for Climate Change in Cities&#8221; (MMA, 2018) require implementation through local governments. Furthermore, with the enactment of the Framework Law on Climate Change (LMCC; Law 21,455, 2022), an obligation was generated for all communes to address the climate crisis with greater ambition to achieve resilience and carbon neutrality by 2050 at the latest through the development of Communal Climate Change Action Plans (Article 12, LMCC), in which they must indicate appropriate measures to address the climate risks faced by cities and their inhabitants, including UHIs and heat waves.</p>
<p>It should be noted that the LMCC establishes (in its Article 2, letter d) &#8220;Equity and Climate Justice&#8221; as one of its fundamental guiding principles, stating in this regard that &#8220;it is the duty of the State to ensure a fair allocation of burdens, costs, and benefits, safeguarding the capacity of future generations to meet their own needs, with a gender approach and special emphasis on sectors, territories, communities, and ecosystems vulnerable to climate change. Climate justice seeks fair treatment for all people, as well as avoiding discrimination that may be entailed by certain policies and decisions intended to address climate change.&#8221; This makes it necessary to incorporate, both in local climate planning instruments and in territorial planning, heat islands, extreme climate events, and their correlation with other forms of territorial inequality as crucial dimensions for diagnosis and action, identifying vulnerable groups to promote territorial justice and equity.</p>
<p>Additionally, municipalities in Chile have different environmental and climate management instruments or initiatives, three of which are voluntary: 1. The Municipal Environmental Certification System (SCAM) of the Ministry of Environment, whose highest level corresponds to Communal Environmental-Climate Governance, 2. the Energy Commune Program of the Energy Sustainability Agency, and 3. the communal water strategies of the Agency for Sustainability and Climate Change (ASCC). However, it is essential to remember that the elaboration and implementation of the documents mentioned above, as well as strategies, involve mobilizing resources, gathering information, and installing capacities that depend on the institutional capacity of each commune. This can mean widening existing gaps, resulting in different levels of adaptation and resilience to climate change in their territories. Indeed, significant differences are already revealed in the degree of preparation and action of local governments in the face of risks associated with climate change, as well as in the degree of updating and implementation of their territorial planning and management instruments (in some cases, such as Rapa Nui, that have not updated these instruments for several decades).</p>
<h4><strong>Final Reflections</strong></h4>
<p>Cities are not uniform entities in terms of their climate and environmental quality. Unequal urban and environmental characteristics, combined with disparate population capacities and resources, generate marked climate inequality within urban boundaries. Not all people experience the same level of environmental quality; consequently, the climate threats to which they are exposed vary considerably.</p>
<p>Those who lack access to resources such as housing and air conditioning, for example, are in a situation of greater vulnerability and, therefore, at greater risk in the face of adverse climatic conditions. Differences in resources and capacities are also observed at the communal scale. Local governments vary in their ability to respond and prepare for climate and climate change challenges, resulting in unequal levels of adaptation and resilience.</p>
<h4><strong>Recommendations</strong></h4>
<ol>
<li>Promote the creation of climate refuges in the city. These spaces, which could be both open (parks, squares) and closed (gyms, libraries), would provide thermal comfort and strengthen community bonds.</li>
<li>Incorporating better materials, natural ventilation, and other measures in urban planning and design can significantly increase society&#8217;s adaptive capacity to high temperatures. This can also generate co-benefits by mitigating heat, increasing thermal comfort, and reducing energy needs, thus contributing to climate change mitigation.</li>
<li>Implement nature-based strategies that include green infrastructure. However, these must be carefully evaluated to avoid negative impacts, mainly related to water availability.</li>
<li>From a public health perspective, evidence-based strategies are urgently needed to address the health risks associated with exposure to extreme heat. These strategies should have a long-term territorial perspective rather than a short-term individual approach, such as using air conditioning or fans, which, while convenient, does not promote resilience in a lasting way.</li>
<li>Build low-carbon and climate-resilient development agendas through networking, reduction of regional disparities, exchange of good practices, generation of public policies that arise from the territories, continuous improvement of processes and evaluation mechanisms, expansion of binding decision-making spaces, and promotion of the democratization of technical-scientific knowledge.</li>
<li>Considering that the effects of high temperatures can quickly become life-threatening, especially for those vulnerable groups of the population (including older adults, children, pregnant women, people with chronic diseases, and those groups or individuals of lower socioeconomic level or who are socially isolated), public policies must focus on climate-sensitive urban planning, considering the design of public spaces that provide &#8211; from a climate justice perspective &#8211; access to shade, wind or sun protection. It is necessary to generate means that allow cities to adapt, improve their quality of life, and ensure the health of their populations.</li>
</ol>
<h4><strong>References</strong></h4>
<p>Alcoforado, M., Andrade, H., Lopes, A., &amp; Vasconcelos, J. (2009). <a href="https://www.sciencedirect.com/science/article/pii/S0169204608001746">Application of climatic guidelines to urban planning: the example of Lisbon (Portugal)</a>. <em>Landscape &amp; Urban Planning, 90</em>(1-2), 56 – 65.</p>
<p>Bulkeley, H. (2013). <em>Cities and climate change</em>. Routledge.</p>
<p>Sarricolea, P., Smith, P., Romero-Aravena, H., Serrano- Notivoli, R., Fuentealba, M., &amp; Meseguer-Ruiz, O. (2022). <a href="https://www.sciencedirect.com/science/article/pii/S0048969722022458">Socioeconomic inequalities and the surface heat island distribution in Santiago, Chile</a>. <em>Science of the Total Environment, 832</em>, 155152.</p>
<p>Schlosberg, D. (2013). <a href="https://www.tandfonline.com/doi/abs/10.1080/09644016.2013.755387">Theorising environmental justice: the expanding sphere of a discourse</a>. <em>Environmental politics, 22</em>(1), 37-55.</p>
<p>Smith, P., &amp; Romero, H. (2016). <a href="https://www.scielo.cl/scielo.php?pid=S0718-34022016000100004&amp;script=sci_arttext&amp;tlng=pt">Factores explicativos de la distribución espacial de la temperatura del aire de verano en Santiago de Chile</a>. <em>Revista de Geografía Norte Grande</em>, (63), 45 – 62.</p>
<p>Williges, K., Meyer, L. H., Steininger, K. W., &amp; Kirchengast, G. (2022). <a href="https://www.sciencedirect.com/science/article/pii/S095937802200019X">Fairness critically conditions the carbon budget allocation across countries</a>. <em>Global Environmental Change, 74</em>, 102481.</p>
<h4><strong>Notes</strong></h4>
<p>[1] Information on surface heat islands in Chilean metropolitan areas and larger medium-sized cities is available on the resilient cities’ platform developed by the Center for Climate and Resilience Research CR2 at the following link: <a href="https://ciudadesresilientes.cr2.cl/isladecalor">https://ciudadesresilientes.cr2.cl/isladecalor</a></p>
<p>[2] Cities between 100,000 and 299,999 inhabitants (Minvu, 2017)</p>
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		<title>Policy Brief CR2 &#124; Drought Indices for Monitoring Water Deficits in Chilean River Flows</title>
		<link>https://www.cr2.cl/eng/policy-brief-cr2-drought-indices-for-monitoring-water-deficits-in-chilean-river-flows/</link>
		
		<dc:creator><![CDATA[Nicole Tondreau]]></dc:creator>
		<pubDate>Wed, 15 May 2024 13:34:10 +0000</pubDate>
				<category><![CDATA[Policy Briefs]]></category>
		<category><![CDATA[Water and extremes]]></category>
		<category><![CDATA[drought]]></category>
		<category><![CDATA[drought indices]]></category>
		<category><![CDATA[mega drought]]></category>
		<category><![CDATA[water deficit]]></category>
		<category><![CDATA[water scarcity]]></category>
		<category><![CDATA[Water Security]]></category>
		<guid isPermaLink="false">https://www.cr2.cl/eng/?p=20516</guid>

					<description><![CDATA[Oscar M. Baez-Villanueva, Hydro-Climate Extremes Lab (H-CEL), Ghent University, Ghent, Belgium; Mauricio Zambrano-Bigiarini, associate researcher CR2; Diego G. Miralles, Hydro-Climate Extremes Lab (H-CEL), Ghent University, Ghent, Belgium; Hylke E. Beck, Climate and Livability Initiative, Physical Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia; Jonatan F. Siegmund, Ernst &#38; Young GmbH, [&#8230;]]]></description>
										<content:encoded><![CDATA[<p><strong>Oscar M. Baez-Villanueva, Hydro-Climate Extremes Lab (H-CEL), Ghent University, Ghent, Belgium; Mauricio Zambrano-Bigiarini, associate researcher CR2; Diego G. Miralles, Hydro-Climate Extremes Lab (H-CEL), Ghent University, Ghent, Belgium; Hylke E. Beck, Climate and Livability Initiative, Physical Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia; Jonatan F. Siegmund, Ernst &amp; Young GmbH, Wirtschaftsprüfungsgesellschaft, Stuttgart, Germany; Camila Alvarez-Garreton, CR2 researcher; Koen Verbist, UNESCO International Hydrological Programme, Paris, France; René Garreaud, CR2 deputy director; Juan Pablo Boisier, CR2 researcher; Mauricio Galleguillos, CR2 associate researcher.</strong></p>
<ul>
<li>Although there are many drought indices, not all of them are equally useful for monitoring the water flowing in the country&#8217;s rivers.</li>
<li>A recent study recommends using drought indices considering precipitation and evaporation variables.</li>
<li>The hydrological regime of each basin (pluvial, nival, or mixed) is of the utmost importance when deciding which index to use to monitor drought.</li>
</ul>
<p>Since 2010, central Chile has experienced a mega-drought due to both natural variability and anthropogenic climate change (CR2 2015; Garreaud, 2017). This condition of lower precipitation combined with higher water use has generated high or extreme water stress in most basins between the Elqui and Rapel rivers, decreasing water availability (Alvarez-Garreton et al., 2023).</p>
<p>Consequently, tools are necessary to monitor the drought affecting Chilean rivers, and one of these is the use of so-called &#8220;drought indices.&#8221; However, there is currently a wide variety of these indices, and no consensus has been reached on which are most suitable for monitoring water availability in the country&#8217;s main basins.</p>
<p>A scientific article published in <a href="https://hess.copernicus.org/articles/28/1415/2024/"><em>Hydrology and Earth System Sciences</em></a> (Baez-Villanueva et al., 2023) attempted to answer this question and identify a drought index suitable for monitoring the amount of water flowing in the rivers of Chile&#8217;s main basins. This would allow the development of proactive mitigation and management strategies to reduce the impact of drought on the population and ecosystems, considering the relatively limited existence of river monitoring stations.</p>
<p><strong>Methodology</strong></p>
<p>The study selected 100 basins in the country with streamflow data and minimal human intervention, e.g., no dams, less than 10% of flows for consumption, low extraction for irrigation, and less than 20% of the area covered by forest plantations. The selected basins varied in size, elevation, land cover type, aridity, and annual precipitation regime (Figure 1).</p>
<figure id="attachment_20578" aria-describedby="caption-attachment-20578" style="width: 614px" class="wp-caption aligncenter"><img loading="lazy" decoding="async" class="wp-image-20578 size-full" src="https://www.cr2.cl/eng/wp-content/uploads/2024/05/Figura-1.1-614x420-1.png" alt="" width="614" height="420" srcset="https://www.cr2.cl/eng/wp-content/uploads/2024/05/Figura-1.1-614x420-1.png 614w, https://www.cr2.cl/eng/wp-content/uploads/2024/05/Figura-1.1-614x420-1-300x205.png 300w, https://www.cr2.cl/eng/wp-content/uploads/2024/05/Figura-1.1-614x420-1-333x228.png 333w, https://www.cr2.cl/eng/wp-content/uploads/2024/05/Figura-1.1-614x420-1-218x150.png 218w" sizes="(max-width: 614px) 100vw, 614px" /><figcaption id="caption-attachment-20578" class="wp-caption-text"><em>Figure 1: In maps (a), (b), and (c), the differences in elevation (meters above sea level), land cover, and aridity can be seen, respectively. In map (d), the location of the selected basins and their predominant precipitation regimes can be seen.</em></figcaption></figure>
<p>Regarding the hydrological regime, 16 basins were selected where the main water source is snow (nival), 25 basins mainly fed by snow with a minor rain contribution (nivo-pluvial), 40 basins whose main water source is rain with a minor snow contribution (pluvio-nival), and 19 basins mainly fed by rain (pluvial).</p>
<p>In each basin, the Standardized Streamflow Index (SSI) was used to represent the drought affecting the rivers. Additionally, four other drought indices based on more widely available data were used: the Standardized Precipitation Index (SPI), Standardized Precipitation Evapotranspiration Index (SPEI), Empirical Standardized Soil Moisture Index (ESSMI), and Standardized Snow Water Equivalent Index (SWEI). These four indices were compared with the SSI to identify which one best approximated the streamflow index values, aiming to identify the index or indices to use in basins without streamflow data. All estimates were developed for 1979-2020.</p>
<p><strong>Results</strong></p>
<p>One of the main results is that there is no single drought index whose use can be recommended to adequately characterize and monitor streamflows in Chilean basins due to the spatial and temporal variability of precipitation, snow, and soil moisture in the territory.</p>
<p>In this sense, the hydrological regime of the basins influences the type of drought index that should be used to adequately monitor streamflows and the most appropriate temporal accumulation.</p>
<p><strong>Recommendations</strong></p>
<ol>
<li>To characterize streamflows in pluvial basins that rapidly accumulate water, the SPI and SPEI with a 3-month temporal accumulation (SPI-3 and SPEI-3) are recommended.</li>
<li>For nival basins, the SPI over 12 to 24 months (SPI-12 and SPI-24) and the SPEI over 18 months (SPEI-18) should be used, as their hydrological regime is based on snow, a slow water accumulation process.</li>
<li>For nivo-pluvial basins, the suggested temporal accumulation varies between 3 and 12 months (SPI-6, SPI-12, SPEI-3, and SPEI-9), while for pluvio-nival basins, it ranges from 3 to 6 months (SPI-3, SPI-6, and SPEI-3).</li>
<li>To evaluate the influence of snow on streamflow drought, this study considered the Standardized Snow Water Equivalent Index (SWEI). However, for future studies, we recommend using the Standardized Melt and Rainfall Index (SMRI; Staudinger et al., 2014). This index requires implementing and calibrating a model capable of representing snow processes in the target basins and has been widely used as a complement to the SPI because it considers both precipitation and snowmelt water deficits.</li>
</ol>
<p><strong>References</strong></p>
<p>Alvarez-Garreton, C., Boisier, J.P., Blanco, G., Billi, M., Nicolas-Artero, C., Maillet, A., Aldunce, P., Urrutia-Jalabert, R., Zambrano-Bigiarini, M., Guevara, G., Galleguillos, M., Muñoz, A., Christie, D., Marinao, R., &amp; Garreaud, R. (2023). <em>Water Security in Chile: Characterization and Future Perspectives.</em> Climate and Resilience Sciences Center CR2 (ANID/FONDAP/1522A0001), 72 pp. Available at <a href="https://www.cr2.cl/seguridadhidrica/">www.cr2.cl/seguridadhidrica</a></p>
<p>Baez-Villanueva, O.M., Zambrano-Bigiarini, M., Miralles, D.G., Beck, H.E., Siegmund, J.F., Alvarez-Garreton, C., Verbist, K., Garreaud, R., Boisier, J.P., Galleguillos, M. (2024). On the timescale of drought indices for monitoring streamflow drought considering catchment hydrological regimes, <em>Hydrology and Earth System Sciences</em> 28, 1415–1439, <a href="https://doi.org/10.5194/hess-28-1415-2024">https://doi.org/10.5194/hess-28-1415-2024</a></p>
<p>Climate and Resilience Sciences Center CR2. (2015). The 2010-2015 mega-drought: a lesson for the future. Climate and Resilience Sciences Center CR2 (ANID/FONDAP/1522A0001), 26 pp. Available at <a href="https://www.cr2.cl/eng/the-2010-2015-mega-drought-a-lesson-for-the-future/">https://www.cr2.cl/megasequia/</a></p>
<p>Garreaud, R.D., Alvarez-Garreton, C., Barichivich, J., Boisier, J.P., Christie, D., Galleguillos, M., LeQuesne, C., McPhee, J., &amp; Zambrano-Bigiarini, M. (2017). The 2010–2015 megadrought in central Chile: Impacts on regional hydroclimate and vegetation. Hydrology and Earth System Sciences, 21(12), 6307–6327. <a href="https://doi.org/10.5194/hess-21-6307-2017">https://doi.org/10.5194/hess-21-6307-2017</a></p>
<p>Staudinger, M., Stahl, K., &amp; Seibert, J. (2014). A drought index accounting for snow, <em>Water Resources Research</em>, 50, 7861–7872, <a href="https://doi.org/10.1002/2013WR015143">https://doi.org/10.1002/2013WR015143</a></p>
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		<title>Policy brief CR2 &#124; Effects of Native Forest Cover Loss from Forestry Activity and Beavers on Carbon Reservoirs in the Chilean Patagonia</title>
		<link>https://www.cr2.cl/eng/effects-of-native-forest-cover-loss-from-forestry-activity-and-beavers-on-carbon-reservoirs-in-the-chilean-patagonia/</link>
		
		<dc:creator><![CDATA[Jose Barraza]]></dc:creator>
		<pubDate>Tue, 30 Apr 2024 20:32:33 +0000</pubDate>
				<category><![CDATA[Land use change]]></category>
		<category><![CDATA[Policy Briefs]]></category>
		<category><![CDATA[beavers]]></category>
		<category><![CDATA[carbon]]></category>
		<category><![CDATA[forestry]]></category>
		<guid isPermaLink="false">https://www.cr2.cl/eng/?p=20403</guid>

					<description><![CDATA[By Alejandro Miranda, Department of Forest Sciences, University of La Frontera and CR2 Associate Researcher; Jorge Hoyos-Santillan, Associate Researcher Smithsonian Tropical Research Institute and CR2 Associate Researcher; Antonio Lara, CR2 Associate Researcher; Rayén Mentler, ETH Zurich; Alejandro Huertas-Herrera, Center for Research on Patagonian Ecosystems (CIEP) Researcher; Mónica Toro-Manríquez, CIEP Researcher; and Armando Sepúlveda-Jauregui, CR2 Collaborating [&#8230;]]]></description>
										<content:encoded><![CDATA[<p><strong>By Alejandro Miranda, Department of Forest Sciences, University of La Frontera and CR2 Associate Researcher; Jorge Hoyos-Santillan, Associate Researcher Smithsonian Tropical Research Institute and CR2 Associate Researcher; Antonio Lara, CR2 Associate Researcher; Rayén Mentler, ETH Zurich; Alejandro Huertas-Herrera, Center for Research on Patagonian Ecosystems (CIEP) Researcher; Mónica Toro-Manríquez, CIEP Researcher; and Armando Sepúlveda-Jauregui, CR2 Collaborating Researcher and IGB-Leibniz Researcher.</strong></p>
<ul>
<li>Forestry activity contributed around 46% to carbon loss, while beavers contributed around 54%.</li>
<li>Native forest cover has decreased by 15.5% over thirty years. Of this percentage, 56% was due to the impact of beavers and 44% to forestry activity.</li>
</ul>
<p>Native forests are not just important, they are crucial in mitigating climate change. Their unique ability to capture and store carbon is vital to our planet&#8217;s natural defense system. However, these ecosystems have always been under constant threat due to industrial timber extraction, agricultural expansion, grazing, and wildfires.</p>
<p>Globally, 35% of the native forest cover that existed since the pre-industrial era has been lost, and less than 20% has remained largely undisturbed. The most significant loss has occurred in Latin America, mainly due to agriculture and logging, in addition to other factors such as invasive species introduced by humans.</p>
<p>In the case of the forests of Southern Patagonia, the impacts have been smaller, making them a crucial part of Chile&#8217;s climate strategy. These forests hold the southernmost carbon reservoirs on the planet, but they are also considered unrecoverable if affected, as their recovery can take centuries. This underscores the urgent need for conservation efforts.</p>
<p>Despite the above, Southern Patagonia has been affected by various disturbances. One of them is beavers, a species introduced to the Isla Grande de Tierra del Fuego from Argentina in 1946, which increased from 50 to more than 100,000 individuals, colonising 98% of its basins, building more than 200,000 dams and impacting the cover and carbon reservoirs of the natural forests dominated mainly by lenga. Another significant disturbance has been the industrial logging of forests, which remains an economically important activity in the area.</p>
<p>To determine the loss of native forest cover and carbon reservoirs over the last 30 years (1986-2019), a study was conducted to compare the impact of both beavers and tree felling within the Chilean territory of Tierra del Fuego. The results were published in the journal Scientific Reports and are summarised below.</p>
<p style="text-align: center;"><em><a href="https://www.cr2.cl/eng/wp-content/uploads/2024/04/Imagen-1.jpg"><img loading="lazy" decoding="async" class=" td-modal-image aligncenter wp-image-20404 size-large" src="https://www.cr2.cl/eng/wp-content/uploads/2024/04/Imagen-1-1200x366.jpg" alt="" width="696" height="212" srcset="https://www.cr2.cl/eng/wp-content/uploads/2024/04/Imagen-1-1200x366.jpg 1200w, https://www.cr2.cl/eng/wp-content/uploads/2024/04/Imagen-1-300x91.jpg 300w, https://www.cr2.cl/eng/wp-content/uploads/2024/04/Imagen-1-768x234.jpg 768w, https://www.cr2.cl/eng/wp-content/uploads/2024/04/Imagen-1-748x228.jpg 748w, https://www.cr2.cl/eng/wp-content/uploads/2024/04/Imagen-1-696x212.jpg 696w, https://www.cr2.cl/eng/wp-content/uploads/2024/04/Imagen-1-1068x325.jpg 1068w, https://www.cr2.cl/eng/wp-content/uploads/2024/04/Imagen-1.jpg 1280w" sizes="(max-width: 696px) 100vw, 696px" /></a></em></p>
<p style="text-align: center;"><em><strong>Figure 1.</strong> Satellite images from 2020 (Google Earth) show beavers&#8217; impact along major waterways. The orange area in the second image is peatlands.</em></p>
<h5><strong>Loss of Cover and Carbon Reserves</strong></h5>
<p>The study shows that the native forest cover of Tierra del Fuego decreased by 15.5% between 1986 and 2019. Of this percentage, beavers were responsible for 56%, while forestry activity accounted for 44%. It is essential to indicate that the impact of beavers was more significant in lands near streams, lakes, and peatlands in remote southern areas. Meanwhile, the effect of tree felling was more critical in the north, in areas close to transportation routes.</p>
<p>Regarding carbon reserves, it is estimated that beavers contributed to a carbon loss of 1.4 million tons, while tree felling contributed 1.2 million tons. However, native forests impacted by tree felling lost 47% of their carbon storage, while those affected by beavers lost 44%. It should be noted that there were differences in this loss, as beavers redistribute reserves in living and dead biomass, while tree felling represents a direct extraction of carbon from the ecosystem.</p>
<p><em><a href="https://www.cr2.cl/eng/wp-content/uploads/2024/04/Imagen-2.jpg"><img loading="lazy" decoding="async" class=" td-modal-image aligncenter wp-image-20405 size-large" src="https://www.cr2.cl/eng/wp-content/uploads/2024/04/Imagen-2-1200x675.jpg" alt="" width="696" height="392" srcset="https://www.cr2.cl/eng/wp-content/uploads/2024/04/Imagen-2-1200x675.jpg 1200w, https://www.cr2.cl/eng/wp-content/uploads/2024/04/Imagen-2-300x169.jpg 300w, https://www.cr2.cl/eng/wp-content/uploads/2024/04/Imagen-2-768x432.jpg 768w, https://www.cr2.cl/eng/wp-content/uploads/2024/04/Imagen-2-405x228.jpg 405w, https://www.cr2.cl/eng/wp-content/uploads/2024/04/Imagen-2-696x392.jpg 696w, https://www.cr2.cl/eng/wp-content/uploads/2024/04/Imagen-2-1068x601.jpg 1068w, https://www.cr2.cl/eng/wp-content/uploads/2024/04/Imagen-2-747x420.jpg 747w, https://www.cr2.cl/eng/wp-content/uploads/2024/04/Imagen-2.jpg 1280w" sizes="(max-width: 696px) 100vw, 696px" /></a></em></p>
<p style="text-align: center;"><em><strong>Figure 2.</strong> In images A and B, the waterways affected by beavers and dead biomass can be seen. In images C and D, the impact of forestry activity is visible. Source: Miranda et al., 2023. Images A and B were taken by Jorge Hoyos-Santillán, and images C and D are from Google Earth. All from 2020.</em></p>
<p>These values differ from the idea that beavers are the only disturber of forest cover, as their impact is very similar to that caused by logging. Furthermore, the damage caused by beavers and forestry activity persists over time. For example, the dams associated with beavers affect the structure of the forests and biodiversity and change soil moisture, which limits natural regeneration. On the other hand, tree felling increases the forest&#8217;s susceptibility to being affected by wind, biological invasions, droughts, or browsing.</p>
<p>The indirect impact of forest loss could be even more significant, affecting the hydrological regime in peatlands, ecosystems of vital importance for mitigating climate change, as they contain approximately five times more carbon than all the forests and plantations in the country (Hoyos-Santillán et al. 2019). In Tierra del Fuego, it has been observed that beavers, in certain peatlands where they establish themselves, create channels that partially drain them, which decreases their groundwater, altering the dynamics of carbon within this ecosystem.</p>
<h5><strong>Recommendations</strong></h5>
<ol>
<li>Chile&#8217;s climate strategy for carbon neutrality depends on native forests. Therefore, to meet its Nationally Determined Contribution, emphasis will have to be placed on protecting these Patagonian ecosystems, which comprise more than 70% of the country&#8217;s native forest.</li>
<li>Policies and programs focused on the conservation, restoration, and management of these forests should be developed, but considering the impact of both beavers and forestry activity in the national climate strategy to meet Chile&#8217;s climate change mitigation commitments.</li>
<li>To establish the best strategies to meet this objective, the time horizons for the recovery of natural forests must be considered compared to the horizon considered for carbon neutrality.</li>
<li>Old-growth forests, considered irretrievable carbon reservoirs on a global scale, must be preserved throughout the national territory as the number one strategy to achieve carbon neutrality. This is consistent with international commitments to bring to zero the loss of ecosystems of high ecological integrity due to their importance for biodiversity (UNEP, 2022).</li>
<li>Avoiding the loss of high-carbon reservoir ecosystems, such as old-growth forests and peatlands, is the most cost-effective alternative to meet national and international commitments in the context of global changes.</li>
</ol>
<h5><strong>References</strong></h5>
<p>Hoyos-Santillan, J., Miranda, A., Lara, A., Rojas, M., &amp; Sepulveda-Jauregui, A. (2019). Protecting Patagonian peatlands in Chile. <em>Science, 366</em>(6470), 1207-1208.</p>
<p>Miranda, A., Hoyos-Santillan, J., Lara, A., Mentler, R., Huertas-Herrera, A., Toro-Manríquez, M. D., &amp; Sepulveda-Jauregui, A. (2023). Equivalent impacts of logging and beaver activities on aboveground carbon stock loss in the southernmost forest on Earth. <em>Scientific Reports, 13</em>(1), 18350.</p>
<p>United Nations Environment Programme (UNEP). (2022). <em>The COP15 concludes with a historic agreement for biodiversity</em>. <a href="https://www.unep.org/news-and-stories/story/cop15-concludes-historic-agreement-biodiversity" target="_blank" rel="noopener">https://www.unep.org/news-and-stories/story/cop15-concludes-historic-agreement-biodiversity</a></p>
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		<title>Water Crisis in Chile: Are We Close to Day Zero?</title>
		<link>https://www.cr2.cl/eng/water-crisis-in-chile-are-we-close-to-day-zero/</link>
		
		<dc:creator><![CDATA[Jose Barraza]]></dc:creator>
		<pubDate>Tue, 30 Apr 2024 19:38:11 +0000</pubDate>
				<category><![CDATA[News Reports]]></category>
		<category><![CDATA[Water and extremes]]></category>
		<category><![CDATA[Day Zero]]></category>
		<category><![CDATA[Megadrought]]></category>
		<category><![CDATA[water crisis]]></category>
		<category><![CDATA[water scarcity]]></category>
		<guid isPermaLink="false">https://www.cr2.cl/eng/?p=20397</guid>

					<description><![CDATA[The water crisis in the central and southern basins of Chile over the past decade has been mainly caused by mega-drought and climate change, as stated in the Report to the Nations developed by researchers from the Center for Climate Science and Resilience at the University of Chile (CR2). Due to the increasing trend in [&#8230;]]]></description>
										<content:encoded><![CDATA[<ul>
<li>The water crisis in the central and southern basins of Chile over the past decade has been mainly caused by mega-drought and climate change, as stated in the Report to the Nations developed by researchers from the Center for Climate Science and Resilience at the University of Chile (CR2).</li>
<li>Due to the increasing trend in water consumption, an adverse scenario is predicted where most of these basins will face permanently high and extreme levels of water stress by the middle of the century.</li>
</ul>
<p>By: CR2 Communications</p>
<p>&#8220;The uses of surface and groundwater are approaching or exceeding water availability in basins in north-central Chile. This generates socioeconomic and ecological impacts and poses an intergenerational dilemma as we move towards depleting reserves (or day zero),&#8221; warns the report &#8220;Water Security in Chile: Characterization and Future Perspectives,&#8221; presented last November by the Center for Climate Science and Resilience CR2.</p>
<p>The report also outlines the levels of water security during the 21st century in the context of climate change. It provides specific recommendations to move towards water security, considering the territorial reality regarding water use, availability, and governance.</p>
<p>In simple terms, water security is defined as the possibility of accessing water in adequate quantity and quality for human sustenance, health, and socioeconomic development, considering the ecosystemic particularities of each basin and promoting resilience against threats such as drought, floods, and pollution.</p>
<p>The report describes Chile&#8217;s current state, establishing that the high levels of water stress in central Chile, where the main source of supply is fresh surface water, suggest that the country&#8217;s central zone would be close to &#8220;day zero,&#8221; described as the moment when water demand can no longer be satisfied due to a lack of availability.</p>
<p>On the other hand, the absolute day zero is the moment when groundwater reserves are depleted in addition to surface sources. According to the report, &#8220;Unlike the time it takes to deplete the water from a surface reservoir, estimating the time to deplete groundwater reserves and reach an absolute day zero is uncertain, as it depends on variables that are difficult to quantify precisely, such as the volume of the aquifer, as well as the rates of recharge and extraction of groundwater.&#8221;</p>
<p>However, partial or total aquifer depletion represents extreme environmental damage due to the long recharge times. The report states that &#8220;this situation also poses an intergenerational justice dilemma because, if the unsustainable use of these resources is not reversed, a future generation will be the one to face the impacts of a major disturbance of aquifers.&#8221;</p>
<p>While these are rough estimates, they provide an order of magnitude of several decades to a few centuries to reach an absolute day zero in the capital of Chile.</p>
<p>Camila Álvarez, a researcher at the Center for Climate Science and Resilience CR2 and coordinator of the report, argues that water consumption during the years of mega-drought has been at the expense of exploiting groundwater sources, which is causing a sustained decline in these reserves and leading us towards a total depletion of water resources or an &#8220;absolute day zero.&#8221;</p>
<p>&#8220;If we consider the current water uses in the basin and a proportion of groundwater use concerning total use between 30 and 65%, the time to deplete the aquifer would be between 50 and 200 years. While these are rough estimates, they provide an order of magnitude of several decades to a few centuries to reach an absolute day zero in the capital of Chile,&#8221; explains the researcher.</p>
<p>In this sense, she warns that &#8220;in an adverse scenario of lower water availability and higher water use, it is likely that most of the basins in the central and northern part of the country will experience permanently high and extreme levels of water stress by the middle of this century.&#8221;</p>
<p>She adds, &#8220;By the end of the 21st century, conditions similar to those of the mega-drought are projected permanently, with precipitation decreases of around 30% and a lower capacity for snow storage in the Andes. This scenario implies a significant decrease in surface water availability, particularly during the summer when there is a higher water demand, representing a risk for the agricultural industry and food security.&#8221;</p>
<p>On the other hand, Juan Pablo Boisier, a CR2 researcher, an academic from the Department of Geophysics at the University of Chile, and a report coordinator, agreed that future water projections for Chile in climate change are negative. &#8220;In general, the scenario is adverse, in the sense that we already know that we have a climate change signal that leads to lower water availability in the central zone of Chile.&#8221;</p>
<p>The researcher also suggests that &#8220;we could have a condition similar to the mega-drought, but in a permanent regime, not just years, but that will be our climate, which entails a lot of impact for water stress.&#8221;</p>
<h5><strong>Current State of Chile</strong></h5>
<p>The report coordinator, Camila Álvarez, explains that &#8220;from a longer historical perspective, the trends over the last six decades indicate a significant increase in water stress levels in central Chile. This increase is first associated with the increase in water consumption and, to a lesser extent, with the decrease in surface water availability. During this period, consumptive water uses have doubled, driven mainly by the development of the agricultural and forestry industries.&#8221; In fact, according to the data studied in the report, Chile doubled its water use from 1960 to the present.</p>
<p>Regarding the current situation, the work indicates that &#8220;the mega-drought is directly related to the stress levels of the basins in this area. However, the increase in uses has been the predominant factor in the increase in long-term stress.&#8221;</p>
<p>The researcher adds that this mega-drought is partly caused by natural climate variability. Still, it overlaps and exacerbates &#8220;a trend observed over several decades towards a drier climate in central Chile, which we associate with a climate change signal.&#8221;</p>
<p>The Elqui, Limarí, Petorca/La Ligua, Aconcagua, Maipo, and Rapel basins, as well as those located in the coastal area of the Valparaíso and O&#8217;Higgins regions, are facing the most critical reality today. &#8220;Most of the basins between the Coquimbo and Maule regions have experienced high to extreme levels of water stress during the 2010-2020 decade. This situation is directly linked to the mega-drought and the lower water availability in this period. Still, it is substantially aggravated due to high levels of water use in these regions,&#8221; details Camila Álvarez.</p>
<h5><strong>Water Code and Ecological Flow</strong></h5>
<p>The report concludes that the ecological flow protected in Chile cannot meet the minimum environmental requirements, causing severe degradation and modification of aquatic ecosystems.</p>
<p>This ecological flow was included in the Water Code, which was amended in 2005. It is established that every new right to use surface water must safeguard an environmental flow, defined as the minimum amount of water that must be maintained in a surface source.</p>
<p>Under the current regulations, this flow maintains a maximum limit of 20% of the basins&#8217; annual average flow, which obliges the delivery of between 80 and 100% of the surface water use rights.</p>
<p>According to the report, despite the progress in the regulation, this safeguard does not meet minimum environmental requirements and allows &#8220;water uses associated with extreme levels of water stress.&#8221; Furthermore, it details that &#8220;if all surface water use rights permitted by law were granted and exercised, all basins in Chile would have water stress indicators above 80%, which is associated with an extreme level of water stress.&#8221; Therefore, safeguarding the ecological flow does not meet minimum environmental requirements.</p>
<p>Another problem highlighted by the report is that surface and groundwater rights are assigned as fixed absolute values over time without considering long-term changes in water availability due to climate. On the other hand, the declaration of water scarcity zones exempts safeguarding ecological flows. It promotes the maintenance of water uses in times of greater availability, so its successive application promotes structural conditions of overuse and degradation of ecosystems.</p>
<p>It is also worth noting that the amendments to the Water Code are not retroactive. This implies that the 370 m3/s granted as Surface Water Use Rights (DAA) before 2005, corresponding to 72% of the total given to date, were not modified to include safeguarding ecological flows.</p>
<h5><strong>Recommendations</strong></h5>
<p>The report also presents recommendations to increase Chile&#8217;s water security indices, among which the following stand out:</p>
<p>Modify <a href="https://www.bcn.cl/leychile/navegar?idNorma=1174443">article 129 bis 1° of the Water Code</a> that <strong>defines the ecological flow</strong>, eliminating the upper limit of 20% of the annual average flow.</p>
<p>In the same aspect, the report mentions the urgency of <a href="https://www.bcn.cl/leychile/navegar?idNorma=1073494">modifying Decree 71 of the Ministry of the Environment</a>, which defines the criteria for calculating the ecological flow, to adopt a formulation that considers the minimum levels of ecosystem protection and the natural seasonal variation of the streams.</p>
<p>Along these lines, the report also proposes <strong>water security goals in public policy</strong> <strong>based on an objective indicator of the maximum tolerable level of water stress in the basins</strong>, considering the impacts of exceeding this level on society and ecosystems. &#8220;The objective of limiting water stress, together with goals focused on other aspects of water security (access, quality, prioritisation of uses, etc.), should guide in a cross-cutting manner the different public policy instruments, as well as political and sectoral programs,&#8221; proposes CR2 researcher Camila Álvarez.</p>
<p>The report <a href="https://www.cr2.cl/seguridadhidrica/">&#8220;Water Security in Chile: Characterization and Future Perspectives&#8221;</a> invites you to learn more.</p>
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		<title>Analysis CR2 &#124; Extreme Heat in Sight? Heat Waves, Wildfires, and Red Tide</title>
		<link>https://www.cr2.cl/eng/analysis-cr2-extreme-heat-in-sight-heat-waves-wildfires-and-red-tide/</link>
		
		<dc:creator><![CDATA[Jose Barraza]]></dc:creator>
		<pubDate>Tue, 30 Apr 2024 19:21:36 +0000</pubDate>
				<category><![CDATA[Analysis]]></category>
		<category><![CDATA[Library]]></category>
		<category><![CDATA[Water and extremes]]></category>
		<category><![CDATA[Heat Waves]]></category>
		<category><![CDATA[Red Tide]]></category>
		<category><![CDATA[wildfires]]></category>
		<guid isPermaLink="false">https://www.cr2.cl/eng/?p=20382</guid>

					<description><![CDATA[Martín Jacques Coper, Principal Researcher of the Center for Climate Science and Resilience CR2, and Christian Segura, CR2 Data Analyst Recent research has identified two atmospheric precursors that can help anticipate the occurrence of heat waves in the central-southern zone of Chile. When both factors are observed in sequence, a heat wave may develop approximately [&#8230;]]]></description>
										<content:encoded><![CDATA[<p><em>Martín Jacques Coper, Principal Researcher of the Center for Climate Science and Resilience CR2, and Christian Segura, CR2 Data Analyst</em></p>
<ul>
<li>Recent research has identified two atmospheric precursors that can help anticipate the occurrence of heat waves in the central-southern zone of Chile.</li>
<li>When both factors are observed in sequence, a heat wave may develop approximately two weeks later in central-southern Chile.</li>
<li>Currently, these two precursors are active, so a heat wave is likely to occur in central-southern Chile in late January and early February 2024.</li>
</ul>
<p>We are in the second half of January 2024, and summer is in full swing. In this context, heat waves are one of the extreme weather events that garner the most interest, partly due to their potential impacts.</p>
<p>A year ago, we conducted an analysis that shared information on their definition, some interannual variability, and long-term trends. Moreover, we have complemented and updated this information in a recent report highlighting some aspects of González-Reyes et al. (2023).</p>
<p>However, currently, under El Niño conditions—which alone do not imply warmer conditions in central-southern Chile, unlike the northern coastal region of the country—and as indicated by the Meteorological Directorate of Chile (DMC), no heat waves have been registered in the last 90 days in this macro-region (Figure 1).</p>
<p><a href="https://www.cr2.cl/eng/wp-content/uploads/2024/04/Figure-1.png"><img loading="lazy" decoding="async" class=" td-modal-image aligncenter wp-image-20383 size-large" src="https://www.cr2.cl/eng/wp-content/uploads/2024/04/Figure-1-1200x688.png" alt="" width="696" height="399" srcset="https://www.cr2.cl/eng/wp-content/uploads/2024/04/Figure-1-1200x688.png 1200w, https://www.cr2.cl/eng/wp-content/uploads/2024/04/Figure-1-300x172.png 300w, https://www.cr2.cl/eng/wp-content/uploads/2024/04/Figure-1-768x441.png 768w, https://www.cr2.cl/eng/wp-content/uploads/2024/04/Figure-1-397x228.png 397w, https://www.cr2.cl/eng/wp-content/uploads/2024/04/Figure-1-696x399.png 696w, https://www.cr2.cl/eng/wp-content/uploads/2024/04/Figure-1-1068x613.png 1068w, https://www.cr2.cl/eng/wp-content/uploads/2024/04/Figure-1-732x420.png 732w, https://www.cr2.cl/eng/wp-content/uploads/2024/04/Figure-1.png 1576w" sizes="(max-width: 696px) 100vw, 696px" /></a></p>
<p style="text-align: center;"><em><strong>Figure 1.</strong> (left) The left panel is a map of Meteorological Directorate of Chile (DMC) stations; those that register heat waves between October 18, 2023, and January 16, 2024, are highlighted in red. The right panel shows the daily maximum temperature recorded at the General Bernardo O&#8217;Higgins station in Chillán, in the October 2023 &#8211; January 2024 period (black curve); the red curve represents the climatological threshold above which heat waves are defined if the maximum temperature persists above it for at least three consecutive days. As shown, no heat waves have been recorded at this station during the last 90 days, defined as periods with maximum temperature above the threshold for at least three consecutive days. Source: DMC. <a href="https://climatologia.meteochile.gob.cl/application/mensual/olasDeCalorRecientes/360011/2024/01/16">https://climatologia.meteochile.gob.cl/application/mensual/olasDeCalorRecientes/360011/2024/01/16</a></em></p>
<p>However, the fact that no heat waves have been recorded in recent months does not imply that the 2023-2024 summer will end without them. Weather forecasts announce high temperatures for this area in the coming days, and we will likely record the first heat waves of the year. Remember that to form a heat wave, the maximum temperature must exceed an intensity threshold and persist for at least three days. Precisely, it is during the next few weeks (between late January and early February) when the highest maximum temperatures of the year are expected; therefore, this period also corresponds to the highest threshold values of the entire year, as can be seen by observing the red curve in Figure 1.</p>
<p>As we shared in Figure 1 of a previous CR2 Analysis, heat waves result from a very particular meteorological configuration that can be summarised as an atmospheric blocking pattern that promotes clear skies and high solar radiation (Jacques-Coper et al., 2021; Demortier et al., 2021). The ability to anticipate both types of conditions over a time frame greater than a week is essential to mitigate potential related impacts. This is particularly sensitive in the case of wildfires, where one factor is extreme meteorology in a changing climate regime.</p>
<p>To move towards heat wave forecasts in this time range, our research (Jacques-Coper et al., 2021) has detected two potential precursors of these events through atmospheric teleconnections. The first is a dipole of atmospheric circulation at mid-levels over the southern Indian Ocean. The standardised extra-tropical index (sETI) is used to monitor this dipole&#8217;s occurrence. When sETI exceeds a value of 1, it means this dipole is active, which can cause extreme heat in central-southern Chile in a timeframe close to two weeks. This occurred, for example, on December 11, 2023, when sETI exceeded the value of 1, and two weeks later, there was a hot Christmas on the 25th, with temperatures exceeding 35°C.</p>
<p>The second precursor refers to the activity of the Madden-Julian Oscillation (MJO), the primary modulator of intraseasonal variability (i.e., in the range of a few weeks) in the tropics, influencing the meteorology of the subtropical and extratropical zones. Specifically, we identified the active phase 4 of the MJO as the second precursor of heat waves in central-southern Chile. This active phase 4 situation means intense convection (i.e., regional ascent of air and formation of vertically developed clouds) occurs near Indonesia.</p>
<p>Both sETI greater than one and the active phase 4 of the MJO is associated with the propagation of atmospheric waves relevant to the atmospheric configuration that triggers heat waves in the central-southern zone of Chile. With this information, it is necessary to inquire about the current values that both precursors present. To monitor such values, we have implemented a heat wave precursor platform. As shown in Figure 2, sETI has exceeded the threshold of 1, indicating the presence of the southern Indian Ocean dipole. This means the first potential heat wave precursor is active (note that sETI also approached one on January 7).</p>
<p style="text-align: center;"><em><strong><a href="https://www.cr2.cl/eng/wp-content/uploads/2024/04/Figure-2.png"><img loading="lazy" decoding="async" class=" td-modal-image aligncenter wp-image-20388 size-large" src="https://www.cr2.cl/eng/wp-content/uploads/2024/04/Figure-2-1200x431.png" alt="" width="696" height="250" srcset="https://www.cr2.cl/eng/wp-content/uploads/2024/04/Figure-2-1200x431.png 1200w, https://www.cr2.cl/eng/wp-content/uploads/2024/04/Figure-2-300x108.png 300w, https://www.cr2.cl/eng/wp-content/uploads/2024/04/Figure-2-768x276.png 768w, https://www.cr2.cl/eng/wp-content/uploads/2024/04/Figure-2-635x228.png 635w, https://www.cr2.cl/eng/wp-content/uploads/2024/04/Figure-2-696x250.png 696w, https://www.cr2.cl/eng/wp-content/uploads/2024/04/Figure-2-1068x384.png 1068w, https://www.cr2.cl/eng/wp-content/uploads/2024/04/Figure-2-1169x420.png 1169w, https://www.cr2.cl/eng/wp-content/uploads/2024/04/Figure-2-1920x690.png 1920w" sizes="(max-width: 696px) 100vw, 696px" /></a></strong></em></p>
<p style="text-align: center;"><em><strong>Figure 2.</strong> Standardised extra-tropical index (sETI), representing mid-level atmospheric circulation anomalies over the southern Indian Ocean. The vertical segmented line separates the analyses of the model towards the past and the probabilistic forecasts towards the future for a 16-day horizon, using the 20-member GEFS &#8220;ensemble&#8221; (orange curves) that define an average curve (red curve), as well as an operational run at higher spatial resolution (green curve)—source: olasdecalor.cr2.cl.</em></p>
<p>As for the MJO, as shown in Figure 3, we are currently observing the active phase 4. In other words, the second potential heat wave precursor is also active. Furthermore, the MJO is expected to evolve towards its active phase 6 by late January, which is favourable for the occurrence of heat waves in central-southern Chile (Jacques-Coper et al., 2021).</p>
<p>Together, both precursors indicate an increase in temperatures in central-southern Chile that could evolve into a heat wave for the January-February 2024 transition, which, as we mentioned earlier, is the warmest period of the year. If we recall, it is no coincidence that in 2017 and 2023, devastating summers due to mega wildfires exceeded the 40°C threshold during that period.</p>
<p><a href="https://www.cr2.cl/eng/wp-content/uploads/2024/04/FIGURA-3.jpg"><img loading="lazy" decoding="async" class=" td-modal-image aligncenter wp-image-20385 size-full" src="https://www.cr2.cl/eng/wp-content/uploads/2024/04/FIGURA-3.jpg" alt="" width="540" height="540" srcset="https://www.cr2.cl/eng/wp-content/uploads/2024/04/FIGURA-3.jpg 540w, https://www.cr2.cl/eng/wp-content/uploads/2024/04/FIGURA-3-150x150.jpg 150w, https://www.cr2.cl/eng/wp-content/uploads/2024/04/FIGURA-3-300x300.jpg 300w, https://www.cr2.cl/eng/wp-content/uploads/2024/04/FIGURA-3-228x228.jpg 228w, https://www.cr2.cl/eng/wp-content/uploads/2024/04/FIGURA-3-420x420.jpg 420w" sizes="(max-width: 540px) 100vw, 540px" /></a></p>
<p style="text-align: center;"><em><strong>Figure 3.</strong> Diagram showing the progression of the Madden-Julian Oscillation (MJO) through each of its phases over the last forty days (December 7, 2023, to January 15, 2024). The purple line corresponds to the MJO in December, and the red line to January (each with the respective days of the month). From January 15, the yellow curve represents a forecast of the evolution of the MJO, and the green line is an average. It is seen that the MJO is already in phase 4 and could advance to phase 6, which creates conditions for heat in the central-southern zone of Chile. Source: <a href="https://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/foregfs.shtml">https://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/foregfs.shtml</a></em></p>
<h5><strong>Heat Waves and Red Tide</strong></h5>
<p>In the case of southern Chile (approximately between 38° and 45°S), the El Niño condition is related to summers that tend to be dry. Furthermore, another seasonal-scale climatic factor is relevant in this region: the Southern Annular Mode (SAM), which modulates the north-south atmospheric pressure gradient between subpolar and polar regions (see this CR2 Analysis). The positive phase of SAM—which has been observed during the last month—also generates below-normal precipitation in the described region.</p>
<p>The current situation of the superposition of El Niño and the positive phase of SAM has previously been identified as a relevant forcing of harmful algal blooms (traditionally known as &#8220;red tide&#8221;) in the Los Lagos region, as was the case in 2016 (León-Muñoz et al., 2018; Garreaud, 2018). Transcending the seasonal scale towards shorter periods, where meteorology becomes relevant, recent research shows the connection between conditions of extreme and persistent heat with events of high phytoplankton biomass in the Inner Sea of Chiloé (Jacques-Coper et al., 2023).</p>
<p>Indeed, as shown in Figure 4, exceptionally high levels of summer chlorophyll-a and fluorescence detected via satellite (panels a and b) are preceded and accompanied by positive anomalies of solar radiation (panel c), an increase in sea surface temperature (panel d), and a reduction in the upper layer of the ocean (panel e), all of which represents greater stratification of the upper levels of the water column. This period of atmospheric stability may eventually include light and transient precipitation. Although these events do not necessarily represent harmful algal blooms, both can be related, as has occurred on previous occasions.</p>
<p>Extreme heat events in central and southern Chile constitute first-order meteorological threats during the summer. This warrants that we continue to monitor the atmosphere and its teleconnections, aiming to communicate potentially relevant information to better prepare for and mitigate possible impacts.</p>
<p><a href="https://www.cr2.cl/eng/wp-content/uploads/2024/04/FIGURA-4.jpg"><img loading="lazy" decoding="async" class=" td-modal-image aligncenter wp-image-20386 size-full" src="https://www.cr2.cl/eng/wp-content/uploads/2024/04/FIGURA-4.jpg" alt="" width="354" height="508" srcset="https://www.cr2.cl/eng/wp-content/uploads/2024/04/FIGURA-4.jpg 354w, https://www.cr2.cl/eng/wp-content/uploads/2024/04/FIGURA-4-209x300.jpg 209w, https://www.cr2.cl/eng/wp-content/uploads/2024/04/FIGURA-4-159x228.jpg 159w, https://www.cr2.cl/eng/wp-content/uploads/2024/04/FIGURA-4-293x420.jpg 293w" sizes="(max-width: 354px) 100vw, 354px" /></a></p>
<p style="text-align: center;"><strong>Figure 4.</strong> Events of high phytoplankton biomass presence along the Inner Sea of Chiloé (between 41.5° and 43.5°S). The white segmented line marks the beginning of the events. The figure spans 15 days (one week before and one week after such events). All variables are presented as anomalies, i.e., deviations from the average. The panels correspond to (A) fluorescence, (B) chlorophyll-a, (C) solar radiation, (D) sea surface temperature, and (E) depth of the photic layer (upper layer of the ocean where up to 1% of solar light penetrates). Source: Jacques-Coper et al., 2023</p>
<h5><strong>References</strong></h5>
<p>Demortier, A., Bozkurt, D., &amp; Jacques-Coper, M. (2021). Identifying fundamental driving mechanisms of heat waves in central Chile. Climate Dynamics, 57(9), 2415-2432. <a href="https://doi.org/10.1007/s00382-021-05810-z">https://doi.org/10.1007/s00382-021-05810-z</a></p>
<p>Garreaud, R. D. (2018). Record-breaking climate anomalies led to severe drought and environmental disruption in western Patagonia in 2016. Clim Res. 74, 217–229. doi: <a href="https://doi.org/10.3354/cr01505">https://doi.org/10.3354/cr01505</a></p>
<p>González-Reyes, A., Jacques-Coper, M., Bravo, C., Rojas, M., Garreaud, R. (2023): Evolution of heataves in Chile since 1980, Weather and Climate Extremes, 41, 100588, <a href="https://doi.org/10.1016/j.wace.2023.100588">https://doi.org/10.1016/j.wace.2023.100588</a></p>
<p>Jacques‐Coper, M., Veloso‐Aguila, D., Segura, C., &amp; Valencia, A. (2021). Intraseasonal teleconnections leading to heat waves in central Chile. International Journal of Climatology, 41(9), 4712-4731. <a href="https://doi.org/10.1002/joc.7096">https://doi.org/10.1002/joc.7096</a></p>
<p>Jacques-Coper, M., Segura, C., de la Torre, M.B., Valdebenito, P., Vásquez, S.I., Narváez, D. (2023). Synoptic-to-intraseasonal atmospheric modulation of phytoplankton biomass in the Inner Sea of Chiloé, Northwest Patagonia (42.5º-43.5ºS, 72.5º-74ºW), Chile, Front. Mar. Sci. Sec. Coastal Ocean Processes, 10, <a href="https://doi.org/10.3389/fmars.2023.1160230">https://doi.org/10.3389/fmars.2023.1160230</a></p>
<p>León-Muñoz, J., Urbina, M. A., Garreaud, R., and Iriarte, J. L. (2018). Hydroclimatic conditions trigger record harmful algal bloom in western Patagonia (summer 2016). Sci. Rep. 8 (1), 1–10. doi: <a href="https://doi.org/10.1038/s41598-018-19461-4">https://doi.org/10.1038/s41598-018-19461-4</a></p>
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