Concentrated Precipitation Patterns Drive Global Landscape Drying

New Driver of Aridification

Researchers from Dartmouth College and the Université du Québec à Montréal have identified a new driver of aridification that may change the global understanding of drought. According to a study published Wednesday in the journal *Nature*, the concentration of precipitation—rather than just the total amount of rain—exerts a significant influence on how landscapes retain moisture.

The study indicates that when precipitation becomes more concentrated into fewer, more intense events, it leads to a decrease in terrestrial water storage (TWS). This "land-drying effect" occurs even if the total annual rainfall remains the same.

Global Precipitation Trends

To reach these conclusions, researchers analyzed global precipitation records spanning from 1980 to 2022. The data revealed that annual rainfall has become more concentrated across the globe.

The findings were consistent across three different precipitation datasets, which the authors state indicates a "robust, leading-order influence" of the distributional character of precipitation on terrestrial water storage.

Regional Impacts in the United States

Specific regional impacts are being observed in the western United States. New research shows that many parts of California and the western U.S. are drying as more rain is concentrated into heavier storms and accompanied by longer dry spells.

While the overall trend points toward drying, some specific environments respond differently to these patterns. According to the Stanford Doerr School of Sustainability, a little over half of certain crops and forests fared better in years with fewer but more intense wet days. This includes croplands as well as drier landscapes such as deserts and grasslands, which more commonly showed increased growth under these conditions.