Atlantic 'cold blob' may be reshaping Indian monsoon, steering rain northwest

Atlantic 'cold blob' may be reshaping Indian monsoon, steering rain northwest Lisa Lock Scientific Editor Robert Egan Associate Editor The Indian monsoon has shifted over the past quarter century. Northwest India now receives substantially more rain than it once did, while a lack of rain sends the Indo-Gangetic Plain toward drought. More than a billion people rely on the monsoon to confer economic stability across southern Asia; further changes to this weather system could lead to widespread hardship. Scientists have struggled to predict how this weather pattern will change moving forward because commonly used climate models fail to capture changes to the monsoon that have already occurred. In an article published in AGU Advances, Nimmakanti Mahendra and colleagues suggest that models do not adequately represent either changes in the temperature of the Atlantic Ocean or how those temperature changes are linked to weather patterns around the rest of the globe. As a result, the coupled models tend to fail to predict this monsoon shift. Specifically, current climate models lack the ability to incorporate information about the cold blob, a patch of cold water off the south of Greenland. When the researchers added the cold blob to climate model results, they found that it can alter the jet stream in a way that makes it pull moisture toward northwest India while also preventing storm systems from forming elsewhere. This is exactly the type of shift that has been observed in monsoon patterns. When a large-scale wind pattern prevents the formation of smaller-scale weather patterns in this way, it is called a barotropic governor mechanism. This barotropic governor mechanism also explains why midlatitudes around the globe have observed more storm activity in recent years. The results highlight the importance of connecting processes from disparate parts of the globe when formulating climate models, the authors write. Publication details Nimmakanti Mahendra et al, Missing Summer Westerly Jet Barotropic Governor Effect Explains Climate Models—Observation Discrepancies in the Indian Monsoon Trends, AGU Advances (2026). DOI: 10.1029/2025av002173 Journal information: AGU Advances Provided by Eos This story is republished courtesy of Eos, hosted by the American Geophysical Union. Read the original story here.