Droughts occurring simultaneously in different parts of the world could put an unprecedented strain on the global agricultural system and jeopardize the water security of millions of people, according to a new study published in Nature Climate Change.
Findings of Research:
A research team led by Washington State University analyzed climate, agricultural, and population growth data to show that continued reliance on fossil fuels will increase the likelihood of co-occurring droughts by 40% by the mid-twentieth century and 60% by the late-twentieth century, compared to the late-twentieth century. Unless steps are taken to reduce carbon emissions, this amounts to a ninefold increase in agricultural and human population exposure to severe co-occurring droughts.
"By the end of the century, there could be around 120 million people worldwide exposed to severe compound droughts at the same time," said lead author Jitendra Singh, a former postdoctoral researcher at the WSU School of the Environment who is now at ETH Zurich in Switzerland. "Many of the regions that our analysis indicates will be most affected are already vulnerable, so the potential for droughts to turn into disasters is high."
Singh and colleagues estimate that the increased risk of compound droughts is due to a warming climate combined with a projected 22% increase in the frequency of El Nino and La Nina events, the two opposing phases of the El Nino Southern Oscillation (ENSO).
According to the researchers' projections, nearly 75 percent of future compound droughts will coincide with these irregular but recurring periods of climatic variation in the world's oceans, which have played a significant role in some of the world's worst environmental disasters.
For example, El Nino-fueled droughts that occurred concurrently across Asia, Brazil, and Africa in 1876-1878 caused synchronous crop failures, which were followed by famines that killed more than 50 million people.
"While technology and other circumstances are much different today than they were in the late nineteenth century, crop failures in multiple breadbasket regions still have the potential to affect global food availability," said study coauthor Deepti Singh, an assistant professor in WSU's School of the Environment. "This, in turn, could increase volatility in global food prices, affecting food access and exacerbating food insecurity, particularly in regions already vulnerable to environmental shocks like droughts."
The study focused on ten regions of the world that receive the majority of their rainfall between June and September, have high variability in monthly summer precipitation, and are affected by ENSO variations, all of which increase the likelihood of co-occurring drought. Several of the regions studied include important agricultural regions as well as countries that are currently experiencing food and water insecurity.
"The potential for a food security crisis grows even if these droughts do not affect major food-producing regions, but rather many regions that are already vulnerable to food insecurity," said coauthor Weston Anderson, an assistant research scientist at the University of Maryland's Earth System Science Interdisciplinary Center. "Simultaneous droughts in food-insecure regions could amplify stresses on international disaster relief agencies by necessitating the provision of humanitarian aid to a greater number of people at the same time."
Anderson stated that there is some good news. The researchers' work is based on a high fossil fuel emissions scenario, and in recent years, the global community has made strides toward lowering carbon emissions, which would significantly reduce the frequency and intensity of co-occurring droughts by the end of the twenty-first century.
Furthermore, the occurrence of nearly 75% of compound droughts alongside ENSO events in the future climate highlights the potential to predict where these droughts may occur with up to a nine-month lead time.
Moving forward, the researchers intend to investigate how co-occurring droughts will affect various aspects of the global food network, how vulnerable communities are affected by and adapting to such climate extremes, and how society can be better prepared to deal with the risk of increasing simultaneous disasters.
Researchers from WSU, Oak Ridge National Laboratory, the University of Massachusetts, Lowell, Columbia University, and the Indian Institute of Technology Gandhinagar, India collaborated on the project.
(Source: Washington State University)
