A new study has found that an unusual patch of cold water in the North Atlantic Ocean known as the “cold blob,” may be altering the Indian summer monsoon and affecting rainfall patterns across South Asia.
Researchers discovered that since 1999, rainfall distribution during the monsoon season has shifted significantly. Northwestern parts of India now receive about 25% more rainfall than before, while the fertile Indo Gangetic Plain receives around 4% less rainfall. These changes have increased flood risks in some areas while creating drought conditions in others, posing challenges for agriculture and food security.
The study links these changes to the Atlantic cold blob, a region southeast of Greenland where ocean temperatures have remained unusually cool despite global ocean warming. Scientists believe this cooling is connected to the weakening of the Atlantic Meridional Overturning Circulation, a major system of ocean currents that helps regulate Earth’s climate.
Using climate models and observational data, researchers found that the cold blob alters atmospheric circulation patterns across Eurasia. It strengthens the jet stream over the North Atlantic and affects pressure systems over Russia and Asia. These atmospheric changes redirect moisture-laden winds toward northwestern India while reducing rainfall over other regions.
The findings are important because more than one billion people across India and neighboring countries depend on monsoon rainfall for agriculture, water supplies, and economic stability. Better understanding of the connection between the North Atlantic and the Indian monsoon could improve seasonal forecasting and help governments prepare for floods and droughts.
The research, published in AGU Advances, also suggests that the Indian monsoon may have crossed a climatic tipping point around 1999, leading to a long lasting reorganization of rainfall patterns. However, scientists caution that future changes remain uncertain because climate models still differ in their predictions about how the North Atlantic and global climate system will evolve.
The study highlights how climate changes occurring thousands of kilometers away in the North Atlantic can have major consequences for weather, agriculture, and livelihoods across South Asia.