Warming: Asian Monsoon Loses Influence on Mediterranean Climate
A new study shows that climate warming weakens the 'monsoon-desert' mechanism, reducing the impact of the South Asian monsoon on the dry sky of the Mediterranean basin. The mechanism, linked to convection and atmospheric circulations, could intensify heatwaves in the region.
From the mountains of the Himalayas to the coasts of the Mediterranean, the South Asian monsoon has long acted as a giant climatic engine, creating a corridor of heat that dried the Mediterranean sky. Today, climate models indicate that this link is weakening: global warming reduces the monsoon's ability to project its influence more than 5000 km, leaving the Mediterranean more vulnerable to heatwave episodes.
What the study reveals: measurable weakening of the monsoon-desert mechanism
The study, published on September 29, 2026 in Phys.org, shows that global warming reduces the intensity of strong convections that characterize the South Asian monsoon. These convections release large quantities of heat into the troposphere, which, according to the 'monsoon-desert' mechanism, triggers large-scale atmospheric circulation. This circulation pushes hot air northwards and creates a descending air zone above the Mediterranean. Descending air prevents cloud formation and reduces precipitation, contributing to the region's hot and dry climate. Warming reduces the amount of heat released by the monsoon, thus weakening the chain of processes that leads to Mediterranean subsidence.
The South Asian monsoon is fed by a strong thermal contrast between the hot continent and the cooler ocean during summer. This contrast generates ascents of warm and humid air that, when they reach the tropopause level, release latent heat. This heat is then transported by jet streams to higher latitudes, influencing the dynamics of general circulation. In the context of the monsoon-desert mechanism, descending hot and dry air above the Mediterranean creates a high-pressure zone that inhibits cloud formation. When global warming increases the temperature of the Indian Ocean and the Arabian Sea, the thermal gradient between the continent and the sea decreases. A weaker gradient means less intense convection, and thus less heat transferred northwards, weakening Mediterranean subsidence.
How researchers studied the phenomenon
To dissect this phenomenon, scientists combined over four decades of atmospheric observations from ECMWF, satellite data from the Copernicus program, and in-situ measurements from Mediterranean weather stations. By crossing these sources, they could track the evolution of subsidence episodes' frequency and measure variations in heat released by the monsoon. The study highlights that despite uncertainties inherent to climate models, the overall trend shows a weakening of the link between the monsoon and the Mediterranean.
