South Asian Monsoon Rains Could Be Delayed, Decrease In Intensity Due to Climate Change
image: Diffenbaugh lab image
As if melting Himalayan glaciers weren't enough to radically (and perhaps catastrophically) reshape water supply in South Asia, a new report from researchers at Purdue University shows that summer monsoons could be weakened and delayed in starting due to climate change. Considering that summer monsoon rains are responsible for about 75% of annual rainfall in large parts of South Asia, and about 90% of India's water supply, this is decidedly not good news:Monsoon Could Start 15 Days LaterThis new research predicts a delay in the onset of the monsoon by 5-15 days by the end of this century and, while some aspects of monsoon circulation could increase in strength, overall monsoon intensity will be weakened.
It is the more subtle, local-scale processes that are key in this case. Our model shows a decrease in convective precipitation, which is critical for summer precipitation in this region. Our findings show it is not just a question of whether monsoon circulation is stronger or weaker. Even with a strong monsoon system, if circulation changes enough to change where and when rain is delivered, then that could have an impact that has not been captured in the large-scale evaluations.Rainfall Likely to Shift Eastward As WellIn addition, the monsoon is likely to shift eastward: Rainfall is likely to increase over the Indian Ocean, Bangladesh and Myanmar, while India, Nepal and Pakistan will see decreases. As the latter receive less rainfall, drier summer air would lead to less moisture in the clouds and reduced rainfall.
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