Ocean temperature patterns play key role in limiting spread of droughts worldwide: Study

Ahmedabad: A new study on global droughts over the past century suggests that ocean temperature patterns play a key role in limiting the simultaneous spread of droughts worldwide. The research offers crucial insights into climate patterns, helping to safeguard global agriculture and stabilise food markets.

Researchers at the Indian Institute of Technology Gandhinagar (IITGN) have suggested that ocean temperature patterns help limit the global spread of droughts. The findings have been published in Communications Earth & Environment.

The study has analysed global climate data from 1901–2020 and found that synchronised droughts affected between 1.8% and 6.5% of global land, far lower than earlier claims that one-sixth of the planet could dry out at once.

The study, led by Udit Bhatia, with co-authors from IITGN and the Helmholtz Centre for Environmental Research, Germany, examined how droughts in different parts of the world align in time and what controls their spread.

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

The team identified thousands of such "drought hubs" in Australia, South America, southern Africa, and parts of North America. They analysed historical yields of wheat, rice, maize, and soybean to assess how moderate drought affected food production.

The study suggests that natural climate processes, especially changes in sea‑surface temperatures in the Pacific and other oceans, limit how far and how uniformly droughts can spread.

A major driver of these shifts is the El Niño–Southern Oscillation, a natural warming-cooling cycle in the Pacific Ocean that reshapes rainfall worldwide.

During El Niño years, Australia becomes a prominent drought hub, while other regions respond differently. During La Niña, drought patterns shift again, often becoming more geographically dispersed," the study says.

The team also studied the interplay between rainfall and temperature to understand how both factors drive drought severity. They found that, over recent decades, about two‑thirds of the long‑term changes in drought severity can be traced to changes in precipitation, with the remaining one‑third linked to warming‑driven increases in evaporative demand.

“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 Rohini Kumar, the corresponding author and senior scientist from the Helmholtz Centre for Environmental Research.

The study highlights how data-driven research about climatic impact on global agricultural zones can transform our approach to safeguarding the world’s food supply.

By moving beyond isolated weather reports and looking at the Earth as an interconnected network, the team has created avenues to identify ‘early warning’ regions before a local dry spell becomes a global crisis.