What is the issue ?
- Studies have found that the monsoon plays a critical role in flushing out pollutants over Asia.
- However, increased air pollution, specifically from coal burning is a hinderence to monsoon's cleansing ability.
What the studies have found :
- The summer monsoon (in the upper troposphere between the Mediterranean and Indian ocean) sustained a “remarkably efficient” cleansing mechanism in which contaminants are rapidly oxidised and deposited on the earth’s surface.
- However, some pollutants were lifted above the monsoon clouds, and chemically processed in a reactive reservoir before being redistributed globally, including to the stratosphere.
How do polluting particles have a direct bearing on the monsoon ?
- Pollution particles can cool the sea surface temperature, mostly in winter. When the circulation reverses in summer, the cooler sea surface evaporates less, which can reduce the moisture flux into the monsoon convection, i.e. weaken the monsoon.