New research suggests a fresh perspective on drought and aridification worldwide. A study from Dartmouth College and the Université du Québec à Montréal reveals that how rainfall is distributed affects how much moisture stays in the ground.
The researchers found that when heavy rainfall occurs in just a few large storms, it saturates the soil, creating surface water pools that evaporate quickly. This means less water reaches streams and rivers. Even if total annual rainfall remains the same, these patterns can still lead to dryer landscapes, especially following long dry periods.
“If you ask land to absorb water like a fire hose, it won’t retain much,” said Justin Mankin, a geography professor and senior author of the study. “Concentrated rainfall results in less water soaking into the ground.”
Mankin and Corey Lesk used multiple datasets to track where precipitation is becoming more concentrated. They identified two significant “hotspots” since 1980: the Amazon and parts of the American West, particularly Colorado and Wyoming.
The American West has been enduring a “megadrought,” leading water supplies to dwindle and states to argue over limited resources. This study deepens the understanding of changing moisture cycles and their risks, especially for regions accustomed to receiving predictable amounts of water.
“The patterns observed in this study are not just theoretical; they are real and measurable,” said Bryan Shuman, a paleoclimatologist not involved in the research. “We may face both flooding and worse droughts than before, despite similar rainfall amounts.”
The upcoming El Niño weather pattern might affect rainfall patterns, potentially leading to even more concentrated rainfall followed by drying periods, Mankin explained. This is an area he aims to investigate further.
Infrastructure built over the last century, including dams and canals, has relied on predictable water flows. However, this system may not suit the rapidly changing climate, where heavy rains might not translate into usable water. Mankin noted, “Moisture consolidation—how rainfall is behaving in a warming climate—complicates predictions and management.”
In an era of climate change, understanding precipitation trends is more crucial than ever. As Shuman summarized, our future might bring both intense storms and serious droughts—even if the total rainfall remains static.
For more about climate trends and their impacts, check out [Nature’s report on precipitation](https://www.nature.com/articles/s41586-026-10487-7).
Source link
Climate Change,Drought,droughts,megadrought,precipitation,rain,rainfall,snow,snow drought,snowpack
