A lead author Felicia Chiang, who led the project as UCI Chiang and received her PhD in 2020 and is now a postdoctoral fellow at NASA's Goddard Institute for Space Studies in New York, said, ‘There have always been natural variations in drought events around the world, but our research shows the clear impact of humans on drying, particularly through anthropogenic aerosols, carbon dioxide and other greenhouse gases.’ She also revealed that her team's research showed significant changes in the characteristics of the drought in terms of frequency, duration, and intensity due to human influence, or what they anthropogenic drive. The researchers used the platform of the recently launched Coupled Model Inter comparison project to conduct climate simulations that show how the duration and intensity of droughts change under different scenarios, including natural, greenhouse gases and aerosol emissions. The natural conditions showed no regional changes in drought characteristics from the late 19th century to the late 20th century, but when the team considered the anthropogenic contribution of greenhouse gases and aerosols, there were increases in drought case in Southern Europe, Central and South America, West and South Africa, and East Asia.
The team found that by examining anthropogenic forcing separately, greenhouse gases had a greater impact in the Mediterranean, Central America, the Amazon, and Southern Africa. Whereas the anthropogenic aerosols played a greater role in monsoon regions and the subarctic of the northern hemisphere, where the aerosols emitted are particles that are small enough to be suspended in the air. They can come from power plants, car exhaust, and biomass burning (fires to clear the land or to burn agricultural waste). Questioning the factors that have worsened the global drought scenario is important as these events have a direct and indirect impact on everything from wildlife habitats to agricultural production and our economy as said by Co-author Amir AghaKouchak, Professor of Civil and Environmental Engineering and Earth Systems Science at UCI.