Pollution sapping Asian summer monsoon

XIAN, CHINA — The Asian summer monsoon typically brings about a lot of rainfall, but scientists have found that the rate of precipitation has actually been declining over the past eight decades, according to a study published in Geophysical Research Letters.

According to National Geographic, the summer monsoon usually takes place between the months of April to September.

New research from the journal Geophysical Research Letters says that rainfall during the Asian summer monsoon has been found to be decreasing in strength over the past 80 years.

Human-made atmospheric pollutants such as sulfate aerosol emissions could be contributing to the reduction, according to a University of Arizona news release.

Using climate models, scientists found that as the amount of pollutants in the atmosphere increases, the rate of monsoon rain tends to decline.

The researchers also looked at tree-ring data from north China over the past 450 years to determine precipitation rates over the decades. This is because trees tend to grow thicker rings during wetter years.

Factors such as solar variability and volcanic eruptions are also believed to impact the strength of the Asian summer monsoon.

As rainfall from the summer monsoon has been declining, this has had an impact on water availability, ecosystems and agriculture across the globe.