Ocean temperatures may be protecting Earth from a planet-wide drought

The research team examined how droughts begin in different parts of the world and whether they occur at roughly the same time. The study was led by Dr. Udit Bhatia of IITGN, with contributions from researchers at IITGN and the Helmholtz Centre for Environmental Research -- UFZ in Leipzig, Germany.

"We treated drought onsets as events in a global network. If two distant regions entered drought within a short time window, they were considered synchronized," explained Dr. Bhatia, the lead author and principal investigator of the Machine Intelligence and Resilience Lab and the AI Resilience and Command (ARC) Centre at IITGN.

Global "Drought Hubs" and Crop Risk

By charting thousands of these drought connections, researchers identified several regions that often act as major centers of drought activity. These so called "drought hubs" include Australia, South America, southern Africa, and parts of North America.

The team also compared climate patterns with historical agricultural data to understand how moderate drought conditions influence food production. They analyzed crop yields for wheat, rice, maize, and soybean across multiple regions.

"In many major agricultural regions, when moderate drought occurs, the probability of crop failure rises sharply -- often above 25%, and in some areas, above 40-50% for crops like maize and soybean," said Hemant Poonia, an AI Scientist at IITGN who completed his undergraduate and postgraduate degrees in Civil Engineering from the Institute.

Although such risks could become severe if drought affected many farming regions at the same time, the researchers found that natural climate processes help prevent that scenario. Changes in sea surface temperatures, particularly in the Pacific Ocean, limit how widely drought conditions spread across continents.

El Niño and La Niña Shape Global Drought Patterns

One of the strongest influences on these shifting patterns is the El Niño-Southern Oscillation, a natural warming and cooling cycle in the Pacific Ocean that affects rainfall around the world.

During El Niño phases, Australia often becomes a major drought hub, while other regions respond in different ways. When La Niña conditions develop, drought patterns shift again and tend to spread across a wider range of locations.

"These ocean-driven swings create a patchwork of regional responses, limiting the emergence of a single, global drought covering many continents at once," explained co-author Danish Mansoor Tantary, a former IITGN master's student who is now pursuing his PhD at Northeastern University (USA).

Rainfall and Rising Temperatures Both Affect Drought Severity

Researchers also investigated how rainfall and temperature together influence the intensity of drought. Their analysis suggests that precipitation changes account for about two thirds of long term shifts in drought severity over recent decades. The remaining third is linked to increasing evaporative demand caused by rising temperatures.

"Rainfall remains the dominant driver globally, especially in regions like Australia and South America, but the influence of temperature is clearly growing in several mid-latitude regions, such as Europe and Asia," said Dr. Rohini Kumar, the corresponding author and senior scientist at the Helmholtz Centre for Environmental Research, whose work focuses on interactions between water, land, and climate systems.

Early Warning Signals for Global Food Security

The findings show how large scale, data driven analysis of climate patterns can help protect global food supplies. By studying drought as part of an interconnected planetary system rather than as isolated weather events, scientists can identify potential early warning regions before local droughts expand into broader crises.

Prof Vimal Mishra, a leading water and climate expert at IITGN and recipient of the Shanti Swarup Bhatnagar Prize, India's highest multidisciplinary science award, emphasized the broader implications.

"These findings underline the importance of international trade, storage, and flexible policies. Because droughts do not hit all regions at the same time, smart planning can use this natural diversity to buffer global food supplies."

Using Climate Insights to Reduce Future Risk

Dr. Bhatia noted that the research highlights how understanding climate systems can guide better policy decisions in a warming world.

"Our research highlights that we are not helpless in the face of a warming planet," said Dr. Bhatia. "By understanding the delicate balance between oceans, rainfall, and temperatures, policymakers can focus their resources on specific drought hubs and create pipelines to stabilize the global market before crop failures in one region trigger price spikes in another."

The authors acknowledged support from the Anusandhan National Research Foundation (SERB) Network of Networks grant, Projekt DEAL, and AI Centre of Excellence (AICoE) in sustainable cities.