Climate change is fueling an alarming increase in the frequency of sudden shifts from severe drought to heavy rains, a phenomenon that is becoming more common globally, according to a new study. Researchers believe that feedback loops from the land itself are likely contributing to this trend.
The study, published in the journal Nature Communications Earth & Environment, analyzed four decades of meteorological and hydrological data globally and identified seven regional hotspots where the trend was worsening: eastern North America, Europe, East Asia, Southeast Asia, southern Australia, southern Africa, and southern South America.
Zong-Liang Yang, a co-author of the study and a professor at The University of Texas at Austin Jackson School of Geosciences, expressed concern about the societal impacts of these rapid shifts.
“Society usually has difficulty responding to one kind of natural disaster like drought, but now you suddenly have floods too. And this has been happening in many places,” said Professor Yang.
The research team, which also included scientists from Hong Kong Polytechnic University and Columbia University, examined three global sets of meteorological and hydrological data from 1980 to 2020.
The experts found that the likelihood of a sudden shift from drought to dangerous downpours increased by roughly a quarter of a percent to 1% per year over that period, depending on the location.
A notable example of this phenomenon occurred in California in 2022 and 2023. In December 2022, California was experiencing its worst drought in a millennium, only for it to be followed by record flooding in January, February, and March of 2023.
Land-based feedback loops
While factors like the El Niño and La Niña climate patterns and climate change itself are known to contribute to sudden changes in climate and weather, this study was the first to explore the potential impact of land-based processes.
Using causality analysis, a statistical technique that helps determine if one factor is directly responsible for another, researchers discovered two land-based feedback loops.
In humid regions, heavy droughts cause evaporation of water from soil and plants to go into overdrive, pushing precipitation into the air and providing a moisture source for heavy rainfall to develop.
In arid regions, hot weather and low pressure during heavy drought create a pressure gradient that draws in moisture from other areas, such as the ocean.
Study co-author Professor Shuo Wang said that these rapid shifts are expected to become more likely with climate change. He emphasized the importance of the study’s findings for improving the accuracy of predictive climate models and helping communities prepare for swings between drought and heavy rain conditions.
“Climate change is fueling back-to-back droughts and floods which have caused widespread devastation, resulting in loss of life and damages to property, infrastructure, and the environment,” said Professor Wang. “Our findings provide insights into the development of early warning systems for mitigating the impacts of rapid dry-wet transitions.”
Overall, the study underscores the urgent need for proactive measures to mitigate the impacts of these rapid climatic shifts, which are exacerbating the challenges already posed by climate change.
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