Global warming could delay, weaken monsoons: study

CHICAGO, March 1, 2009 (AFP) – Global warming could delay the start of the summer monsoon by five to 15 days within the next century and significantly reduce rainfall in much of South Asia, a recent study has found. “These circulation changes decrease moisture flow over the land, and we see longer periods without rain, along with hot conditions.”

Ashfaq used a high-resolution climate model to map how global warming will affect the complex topography of South Asia by recreating the monsoon season of past years.

He found that increasing temperatures strengthen some aspects of large-scale monsoon circulation but weaken the fine-scale interactions of the land with the moisture in the atmosphere.

“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,” Ashfaq said.

The study was published in the January issue of the peer-reviewed journal Geophysical Research Letters. Rising global temperatures will likely lead to an eastward shift in monsoon circulation which could result in more rainfall over the Indian Ocean, Myanmar and Bangladesh but less over Pakis