Secret Rain Pattern May Have Driven Long Spells of Dry and Wetter Periods Across Horn of Africa: Study

Researchers have found a secret rain pattern that potentially could have driven decades-long dry spells and wetter periods across the Horn of Africa over the past century. Crops, new research shows, are less shielded when rain comes from land sources rather than oceans. Land-based rain is usually weaker and less dependable, causing drought stress. Areas like the U.S. Midwest and East Africa are most vulnerable. The findings indicate that protecting forests and better managing land could help stabilize rainfall and protect crop yields in a warming climate.

Study Traces Rainfall Origins, Showing Land-Based Rain Increases Crop Drought Risk

According to a Nature Sustainability report, the University of California, San Diego monitored rainfall to trace exactly where it came from, be it oceans or land surfaces like soil, lakes, and forests. Drawing on nearly 20 years of satellite data, the study determined that when more than one-third of rainfall is from lands elsewhere, crops are at greater risk for drought and have less soil moisture and yield.

Whereas the ocean-sourced moisture tends to result in heavier, more reliable rain over broad areas.
Ocean moisture gets sent over great distances by storms, while rain that originates from the land is local and unpredictable, and can influence crop resilience at a crucial time in their life cycle.

Midwest and East Africa at Risk as Land-Based Rainfall Threatens Crop Yields

The U.S. Midwest was a large hot spot. Despite high productivity, reliance on interior moisture causes drying soils, reduced evaporation, and less rainfall, creating drought cycles threatening crops and global grain supplies.

East Africa is facing drought-stricken pastures and crops, as the expansion of cropland and deforestation deplete natural moisture reserves in a trend that threatens to lead to a long-term decline in food security unless land use practices are improved.