Extreme ENSO-driven torrential rainfalls at the southern edge of the Atacama Desert during the Late Holocene and their projection into the 21th century

Ortega, Cristina; Vargas, Gabriel; Rojas, Maisa; Rutllant, José A.; Muñoz, Práxedes; Lange, Carina B.; Pantoja, Silvio; Dezileau, Laurent; Ortlieb, Luc

doi:10.1016/j.gloplacha.2019.02.011

Cited by 56 publications

(44 citation statements)

References 67 publications

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“…Changes associated with SWW variations have already shown visible effects in southern SA as an increase in desertification in northern Chile (Salinas and Mendieta, 2013;Ortega et al, 2019) and a notable decrease in annual precipitation from central Chile to central Patagonia (Boisier et al, 2018), exhibiting important impacts on socioeconomic activities in this region. Moreover, our results suggest that consequences related to SWW changes during the next decades, not only in southern SA (e.g., Vera et al, 2006;Meehl et al, 2007) but also at a global scale, for example through the release of CO 2 from the Southern Ocean to the atmosphere (e.g., Menviel et al, 2018;Saunders et al, 2018), could be expected.…”

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confidence: 99%

South Pacific Subtropical High from the late Holocene to the end of the 21st century: insights from climate proxies and general circulation models

et al. 2020

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Abstract. The South Pacific Subtropical High (SPSH) is a predominant feature of the South American climate. The variability of this high-pressure center induces changes in the intensity of coastal alongshore winds and precipitation, among others, over southwestern South America. In recent decades, strengthening and expansion of the SPSH have been observed and attributed to the current global warming. These changes have led to an intensification of the southerly winds along the coast of northern to central Chile and a decrease in precipitation from central to southern Chile. Motivated by improving our understanding about the regional impacts of climate change in this part of the Southern Hemisphere, we analyzed SPSH changes during the two most extreme climate events of the last millennium, the Little Ice Age (LIA) and the Current Warm Period (CWP: 1970–2000), based on paleoclimate records and CMIP5/PMIP3 model simulations. In order to assess the level of agreement of general circulation models, we also compare them with ERA-Interim reanalysis data for the 1979–2009 period as a complementary analysis. Finally, with the aim of evaluating future SPSH behavior, we include 21st century projections under a Representative Concentration Pathway (RCP8.5) scenario in our analyses. Our results indicate that during the relative warm (cold) period, the SPSH expands (contracts). Together with this change, alongshore winds intensify (weaken) south (north) of ∼35∘ S; also, southern westerly winds become stronger (weaker) and shift southward (northward). Model results generally underestimate reanalysis data. These changes are in good agreement with paleoclimate records, which suggest that these variations could be related to tropical climate dynamics but also to extratropical phenomena. However, although models adequately represent most of the South American climate changes, they fail to represent the Intertropical Convergence Zone–Hadley cell system dynamics, emphasizing the importance of improving tropical system dynamics in simulations for a better understanding of its effects on South America. Climate model projections indicate that changes recently observed will continue during the next decades, highlighting the need to establish effective mitigation and adaptation strategies against their environmental and socioeconomic impacts.

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confidence: 99%

South Pacific Subtropical High from the late Holocene to the end of the 21st century: insights from climate proxies and general circulation models

et al. 2020

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“…Changes associated to SWW variations have already shown visible effects in southern SA, as an increase of desertification in northern Chile (Salinas and Mendieta, 2013;Ortega et al, 2019)…”

Section: Climate Changes Over Southwestern South America Since the Lamentioning

confidence: 99%

South Pacific Subtropical High from the late Holocene to the end of the 21st century: insights from climate proxies and general circulation models

Flores‐Aqueveque¹,

Rojas²,

Aguirre³

et al. 2019

Preprint

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Abstract. The South Pacific Subtropical High (SPSH) is a predominant feature of South American climate. The variability of this high-pressure center induces changes in the intensity of coastal alongshore winds and precipitation, among others, over southwestern South America. In recent decades, a strengthening and expansion of the SPSH have been observed and attributed to the current global warming. These changes have led an intensification of the southerly winds along the coast of northern to central Chile, and a decrease in precipitation from central to southern Chile. Motivated by improving our understanding about the regional impacts of climate change in this part of the Southern Hemisphere, we analyze SPSH changes during the two most extreme climate events of the last millennium: the Little Ice Age (LIA) and the Current Warm Period (CWP: 1970–2000), based on paleoclimate records and CMIP5/PMIP3 model simulations. In order to assess the level of agreement of general circulation models, we also compare them with ERA-Interim reanalysis data for the 1979–2009 period as a complementary analysis. Finally, with the aim of evaluating future SPSH behaviour, we include 21th century projections under a RCP8.5 scenario in our analyses. Our results indicate that during the relative warm (cold) period, the SPSH expands (contracts). Together with this change, alongshore winds intensify (weaken) south (north) of ~ 35º S; also, Southern Westerly Winds become stronger (weaker) and shift southward (northward). Model results generally underestimate reanalysis data. These changes are in good agreement with paleoclimate records, which suggest that these variations could be related to tropical climate dynamics but also to extratropical phenomena. However, although models adequately represent most of the South American climate changes, they fail in representing the Intertropical Convergence Zone - Hadley Cell system dynamics. Climate model projections indicate that changes recently observed will continue during next decades, highlighting the need to establish effective mitigation and adaptation strategies against their environmental and socio-economic impacts.

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“…CC BY 4.0 License. influence of extreme storms has resulted in important runoff erosive events in the past recorded by coarser grain size layers in both lacustrine and marine archives during the last 5,500 years in the Atacama Desert (Ortlieb, 1994(Ortlieb, , 1995Veit, 1996;Rein et al, 2005;Maldonado and Villagrán, 2006;Vargas et al, 2006;Martel-Cea et al, 2016;Tiner et al, 2018;Ortega et al, 2012Ortega et al, , 2019. The return time of extreme runoff erosive events decreased from 1 event/210 yrs.…”

Section: Introductionmentioning

confidence: 99%

Erosion after an extreme storm event in an arid fluvial system of the southern Atacama Desert: an assessment of magnitude, return time, and conditioning factors of erosion caused by debris flows

Aguilar¹,

Cabré²,

Fredes³

et al. 2019

Preprint

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Abstract. We have calculated a mean erosion of 1.3 mm caused by an individual storm event in March 2015 that impacted a large mountainous area of the southernmost Atacama Desert. The calculated erosion agrees with millennial erosion rates and with return time of high sediment discharge events previously reported in the study area. Here, we quantify for the first time the contribution of an individual extreme storm event to long-term erosion rates in the Atacama Desert. This is significant because erosion rates, related to high sediment discharge events in arid fluvial systems, are hard to measure with sediment load due the destruction of gauges by devastating flashfloods and thus have not been directly measured yet. During the March 2015 storm, debris flows were reported as the main sediment transport process. Erosion of gullies and channels are the main source of sediments that finally generate debris flows that reach the tributary junctions and the trunk valleys. The sediment yield to the tributary outlets strongly depends on the hydraulic capacity of catchments to store sediments in the drainage network between storms. Larger tributary catchments, high hydrological hierarchy, low topographic gradient and gentle slopes are the most susceptible catchments to generate debris flows that reach alluvial fans at any storm event from large debris volumes stored in the drainage network. Our findings better assess debris flow susceptibility of arid catchments, which is significant for the southernmost Atacama Desert valleys because human settlements and industries are mostly established in alluvial fans.

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Extreme ENSO-driven torrential rainfalls at the southern edge of the Atacama Desert during the Late Holocene and their projection into the 21th century

Cited by 56 publications

References 67 publications

South Pacific Subtropical High from the late Holocene to the end of the 21st century: insights from climate proxies and general circulation models

South Pacific Subtropical High from the late Holocene to the end of the 21st century: insights from climate proxies and general circulation models

South Pacific Subtropical High from the late Holocene to the end of the 21st century: insights from climate proxies and general circulation models

Erosion after an extreme storm event in an arid fluvial system of the southern Atacama Desert: an assessment of magnitude, return time, and conditioning factors of erosion caused by debris flows

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