News and Notes: Professor links dry spell to aerosol pollution

The team used long-term observational precipitation data sets to detect recent trends in the South Asian monsoon, as well as climate model experiments to simulate the South Asian monsoon’s response to natural and anthropogenic variations.

They found that aerosols induce an energy imbalance between the northern and southern hemispheres, leading to a weakening of boreal summer wind patterns. This reduces energy flow to the southern hemisphere, alleviating some of the asymmetry — but the weakened winds mean that there is nothing to trigger the monsoon, they said in their paper.

The scientists noted in their study that these aerosols are “located mainly in the northern hemisphere.”

But Ming and his colleagues cautioned that their findings should not necessarily be extrapolated to larger scale models.

“Although this theory can help explain some of the main characteristics of the model simulations and is consistent with the observed reduction in the South Asian monsoon rainfall, the extent to which it holds for the real climate still needs to be assessed carefully with more observations,” the authors explained.