Scientists have discovered that patterns in ocean temperatures can help prevent droughts from spreading around the world at once. The study, led by the Indian Institute of Technology Gandhinagar (IITGN) with international collaborators, suggests that natural climate changes in the oceans are acting as a global brake on repeated droughts.
Published in Communication Earth and Environmentthe study examined climate records from 1901 to 2020. Researchers found that simultaneous droughts affected only 1.8% to 6.5% of Earth’s land area at the same time. This estimate is much lower than previous claims that one-sixth of the Earth could dry out at the same time.
Mapping drought as a global network
The study was led by Dr. Udit Bhatia, with co-authors from IITGN and the Helmholtz Center for Environmental Research (UFZ, Leipzig, Germany). The researchers investigated how droughts in distant regions line up over time, and the factors that influence whether they spread together or remain separate.
“We treated the onset of drought as an event within a global network. If two distant regions experienced drought within a short time frame, they were considered to be synchronized,” explained Dr. Bhatia, first author and principal investigator at IITGN’s Machine Intelligence and Resilience Lab and AI Resilience and Command (ARC) Center.
Researchers have identified several major ‘drought hubs’ by tracing the connections between thousands of droughts around the world. These include Australia, South America, southern Africa, and parts of North America. The research team also looked at historical yields of wheat, rice, corn and soybeans to understand how moderate droughts affect food production.
Drought bases and risk of crop failure
“In many major agricultural regions, when moderate drought occurs, the probability of crop failure increases rapidly, often by more than 25% for crops such as corn and soybean, and in some regions by more than 40-50% for crops such as corn and soybean,” said Hemant Poonia, an AI scientist at IITGN who completed his bachelor’s and graduate degrees in civil engineering at the institute.
These risks would be particularly concerning if many major agricultural regions were to experience drought at the same time. But the study found that natural climate behavior, particularly changes in sea surface temperatures in the Pacific and other oceans, helps limit how far and how evenly droughts spread.
El Niño and La Niña change drought patterns
One of the main factors behind these global changes is the El Niño Southern Oscillation. El Niño Southern Oscillation is a natural warming and cooling cycle in the Pacific Ocean that affects rainfall patterns around the world.
During El Niño periods, Australia often emerges as a drought epicenter, but other regions respond in different ways. During a La Niña event, the pattern changes again, and droughts are often more geographically dispersed rather than concentrated in one global pattern.
“These ocean-driven fluctuations create a patchwork of regional responses, limiting the occurrence of a single global drought covering many continents at once,” explained co-author Denmark Mansour Tantary. He is a former IITGN master’s student and is pursuing his PhD at Northeastern University (USA).
Rainfall remains the main driver of drought severity
The researchers also investigated how rainfall and temperature work together to influence drought severity. Their analysis found that over recent decades, roughly two-thirds of the long-term changes in drought severity can be linked to changes in precipitation. The remaining third is related to increased evaporative demand due to rising temperatures.
“While rainfall remains the dominant factor globally, particularly in regions such as Australia and South America, the influence of temperature is clearly increasing in some mid-latitude regions such as Europe and Asia,” said corresponding author Dr. Rohini Kumar, a senior research fellow at the Helmholtz Center for Environmental Research, which works on hydro-climate linkages.
A new way to protect the world’s food supply
The findings demonstrate how data-driven climate research can help improve strategies to protect global agriculture. Rather than focusing solely on isolated weather events, the research team considered the Earth as an interconnected system. This approach could help scientists identify “early warning” areas before localized droughts begin to impact global food markets.
Professor Vimal Mishra emphasized that these findings have important implications for planning, trade and food security.
“These findings highlight the importance of international trade, storage and flexible policies. Droughts do not hit all regions at the same time, so with smart planning we can harness this natural diversity to buffer the world’s food supply.” Professor Mishra is a leading water and climate expert at IITGN and recipient of India’s highest interdisciplinary science award, the Shanti Swarup Bhatnagar Prize.
Climate change planning in a warming world
Dr Bhatia said the study offered a more hopeful message about the risks of drought in a changing climate.
“Our research makes clear that we are not helpless in the face of global warming,” said Dr. Bhatia. “By understanding the delicate balance between oceans, rainfall, and temperature, policymakers can focus resources on specific drought hubs and build pipelines to stabilize global markets before crop failures in one region trigger price spikes in others.”
The authors gratefully acknowledge support from the Anusandhan National Research Foundation (SERB) Network of Networks grant, Project DEAL, and the AI Center of Excellence in Sustainable Cities (AICoE).
