Citizens of central Chile are accustomed to long spells of dry weather. But the past decade has brought an extreme drought that is remarkable even for a region with a semi-arid Mediterranean climate.
Central Chile, where most Chileans live, has received 30 percent less rainfall than normal over the past decade, a situation that scientists are referring to as “megadrought.” With rainfall deficits of 80 to 90 percent, 2019 has been particularly dry.
Landscapes that would normally be lush and green have withered. The map above depicts the Normalized Difference Vegetation Index (NDVI), a measure of the health and greenness of vegetation based on how much red and near-infrared light it reflects. Healthy vegetation with lots of chlorophyll reflects more near-infrared light and less visible light. The NDVI anomaly map above is based on data collected by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite between September 5 and November 5, 2019.
The map contrasts vegetation health against the long-term average (2000–2010) for that period. Brown indicates vegetation that is less abundant and healthy than normal for this time of year. MODIS-based land cover data has been used to highlight areas that are snowy, icy, or have minimal vegetation. These areas appear gray. Green areas, mostly in valleys near glaciers and snow cover, have unusually abundant vegetation, likely because of increased melt and runoff from snow and glaciers.
“An 80 percent deficit means that the semi-arid region north of Santiago has seen almost no water, as seen in the marked browning of the vegetation,” said René D. Garreaud, a scientist at the University of Chile. “South of Santiago has received some rain—100 to 300 millimeters (4 to 12 inches). That is still not much, but it has been enough to keep the vegetation green.”
Garreaud and colleagues have detailed the progression and causes of the drought in several reports published in recent years. “We believe that such a long drought is the product of a combination of natural variability—the negative phase of the Pacific Decadal Oscillation—and human-caused climate change,”
As the drought persists, news reports present an increasingly grim picture. Ranchers have seen tens of thousands of animals die. Beehives are getting wiped out, and reservoirs are running low.
References & Resources
- Al Jazeera (2019, October 11) Chile suffers the worst drought in 60 years. Accessed November 13, 2019.
- Bnamericas (2019, October 11) No end in sight to Chileâs drought crisis. Accessed November 13, 2019.
- Center for Climate and Resilience Research (2015) The 2010-2015 mega-drought: A lesson for the future. Accessed November 13, 2019.
- Diálogo Chino (2019, October 11) Chileâs mega-drought rolls on. Accessed November 13, 2019.
- Garreaud, R. et al. (2019) The Central Chile Mega Drought (2010-2018): A climate dynamics perspective. International Journal of Climatology.
- Garreaud, R. et al. (2017) The 2010-2015 megadrought in central Chile: impacts on regional hydroclimate and vegetation. Hydrol. Earth Syst. Sci., 21 (12), 6307-6327.
- NASA Earth Observatory (2019, April 18) Long-Term Drought Parches Chile.
NASA Earth Observatory image by Lauren Dauphin, using MODIS data from NASA EOSDIS/LANCE and GIBS/Worldview and topographic data from the Shuttle Radar Topography Mission (SRTM). Story by Adam Voiland.
