The 2010–2015 megadrought in central Chile: impacts on regional hydroclimate and vegetation

Abstract

Abstract. Since 2010 an uninterrupted sequence of dry years, with annual rainfall deficits ranging from 25 to 45 %, has prevailed in central Chile (western South America, 30-38 • S). Although intense 1-or 2-year droughts are recurrent in this Mediterranean-like region, the ongoing event stands out because of its longevity and large extent. The extraordinary character of the so-called central Chile megadrought (MD) was established against century long historical records and a millennial tree-ring reconstruction of regional precipitation. The largest MD-averaged rainfall relative anomalies occurred in the northern, semi-arid sector of central Chile, but the event was unprecedented to the south of 35 • S. ENSO-neutral conditions have prevailed since 2011 (except for the strong El Niño in 2015), contrasting with La Niña conditions that often accompanied past droughts. The precipitation deficit diminished the Andean snowpack and resulted in amplified declines (up to 90 %) of river flow, reservoir volumes and groundwater levels along central Chile and westernmost Argentina. In some semi-arid basins we found a decrease in the runoff-to-rainfall coefficient. A substantial decrease in vegetation productivity occurred in the shrubland-dominated, northern sector, but a mix of greening and browning patches occurred farther south, where irrigated croplands and exotic forest plantations dominate. The ongoing warming in central Chile, making the MD one of the warmest 6-year periods on record, may have also contributed to such complex vegetation changes by increasing potential evapotranspiration. We also report some of the measures taken by the central government to relieve the MD effects and the public perception of this event. The understanding of the nature and biophysical impacts of the MD helps as a foundation for preparedness efforts to confront a dry, warm future regional climate scenario.

Observed trends and relationships between ENSO and standardized hydrometeorological drought indices in central Chile

“…Rivadavia for SPEI and Rio Toro for SSI in the semiarid zone, Vilcuya and Potrero Grande for SPEI and Rio Aconcagua and Rio Palos for SSI in the Mediterranean zone, and Quilaco and Canal Bajo Osorno for SPEI and Rio Lirquen and Rio Coiheuco for SSI in the temperate oceanic zone). This 20‐year period was chosen due to strong ENSO phenomena covering the severe 1998/1999 drought that resulted in electricity shortages and the recent megadrought starting in 2010 (Garreaud et al, ). From Figure the 1998/1999 drought is detected by the SPEI and SSI in all locations.…”

“…Winter precipitation generally increases during El Niño and decrease during La Niña events (Aceituno, ; Lima, Marquet, & Jaksic, ; Montecinos & Aceituno, ; Waylen & Poveda, ). In particular, the 2010/2011 La Niña event has probably influenced the Megadrought in central Chile (Garreaud et al, ), although recent evidence points towards more complex mechanisms, as a circulation dipole and extratropical warming that hinders the arrival of frontal systems (Garreaud et al, ). Besides, the ENSO influence on drought events is also documented for much longer time scales (i.e.…”

The cascade impacts of climate change could threaten key ecological interactions

“…Also, these forests are experiencing drought events that had increased in frequency and magnitude within the last two decades (Garreaud et al. ), making it ideal for studying the effects of climate change on ecological interactions.…”

Modelling the current and future biodiversity distribution in the Chilean Mediterranean hotspot. The role of protected areas network in a warmer future

“…Because climate change has been reported as one of the significant threats to biodiversity (Klausmeyer & Shaw, ), this study was set out to investigate how climate change scenarios may affect biodiversity patterns in a mediterranean biodiversity hotspot, using the Mediterranean area of Central Chile as a case study. For this area of the world, climate change predictions estimate a general decrease in precipitation and up to 4°C increase in temperature (Garreaud et al, ). The current protected area system for Chile protects 21% of the territory.…”