This was not an isolated disaster – drought was a major concern just a few months before the monsoon floods. What causes this sequence of extreme events?
A team of scientists from Pakistan, the United States, Switzerland and Singapore have shown that the cause of these phenomena is an intensification of the hydrological cycle, which increases the frequency of droughts and floods.
Scientific evidence to support this hypothesis is provided by tree rings, which “record” the duration and intensity of past climatic conditions. Using data from the Hindu Kush mountains, the scientists were able to reconstruct the annual rainfall in the Kabul River Basin (see above) over a period of roughly four centuries spanning from 1637 to 2018.
“Our precipitation data show worrying trends,” shared Dr. Nguyen, corresponding author (Columbia University), “By looking at the trends in the past four centuries, we clearly see that droughts are getting more severe, shorter, and more frequent, punctuated by more frequent wetter periods.”
Floods and droughts are not mutually exclusive; It is characteristic of natural hydro-climatic contrast. But in warmer climates, the frequency and intensity of these phenomena are likely to increase – as we are seeing in Central Asia.
“The consequences for natural resource management are enormous,” added Dr. Galili, co-author from the Singapore University of Technology and Design. “The hydrological cycle affects many social and economic sectors, so we need to rethink our approach to infrastructure planning and operations. What we are beginning to see is the deep need for climate adaptation and mitigation.”
The study results were published in Geophysical Research Letters and presented at the fall meeting of the American Geophysical Union in December 2022.