Scientists at the Indian Institute of Technology Gandhinagar (IITGN), working with international collaborators, have discovered that ocean temperature patterns play a key role in limiting the extent to which droughts spread around the world. Their findings are: Communication Earth and Environmentbased on climate records spanning 1901 to 2020. Analysis shows that synchronous droughts typically affect only 1.8% to 6.5% of Earth’s land at a time. This is much lower than previous suggestions that up to one-sixth of the planet could experience drought at the same time.
The researchers investigated 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 from IITGN, with collaboration from researchers at IITGN and the Helmholtz Center for Environmental Research (UFZ, Leipzig, Germany).
“We treated the onset of drought as an event within a global network. If two distant regions experienced drought within a short period of time, 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.
Global “drought hubs” and crop risks
By compiling thousands of charts of these drought associations, the researchers identified several regions that often serve as major centers of drought activity. These so-called “drought hubs” include Australia, South America, southern Africa and parts of North America.
The research team also compared climate patterns and historical agricultural data to understand how moderate drought conditions affect food production. They analyzed wheat, rice, corn, and soybean yields across multiple regions.
“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.
Such risks could be severe if drought affected many agricultural areas at the same time, but the researchers found that natural climate processes can help prevent that scenario. Changes in sea surface temperatures, particularly in the Pacific Ocean, limit the extent to which drought conditions can spread across the continent.
El Niño and La Niña shape global drought patterns
One of the strongest influences on these changing patterns is the El Niño Southern Oscillation, a natural warming and cooling cycle in the Pacific Ocean that affects rainfall around the world.
During the El Niño phase, Australia is often the epicenter of drought, but other regions respond in different ways. When a La Niña event occurs, drought patterns tend to change again and spread over a wider area.
“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 currently pursuing his PhD at Northeastern University (USA).
Increased rainfall and temperature both affect drought severity
The researchers also investigated how rainfall and temperature affected drought intensity. Their analysis suggests that changes in precipitation explain about two-thirds of the long-term changes in drought severity over recent decades. The remaining third is related to increased evaporative demand due to rising temperatures.
“Globally, rainfall remains a major factor, particularly in regions such as Australia and South America, but 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, whose research focuses on interactions between water, land and climate systems.
Early warning signals for global food security
The findings demonstrate how large-scale, data-driven analysis of climate patterns can help protect the world’s food supply. By studying droughts as part of an interconnected planetary system rather than as isolated weather events, scientists can identify potential early warning areas before localized droughts escalate into broader crises.
Professor Vimal Mishra, IITGN’s leading water and climate expert and winner of India’s highest interdisciplinary science award, the Shanti Swarup Bhatnagar Prize, emphasized the broader implications.
“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 take advantage of this natural diversity to buffer the world’s food supply.”
Leverage climate insights to reduce future risks
Dr. Bhatia noted that this research highlights how understanding the climate system can guide better policy decisions in a warming world.
“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 acknowledged support from the Anusandhan National Research Foundation (SERB) Network of Networks grant in sustainable cities, Project DEAL, and the AI Center of Excellence (AICoE).
