'South Asian monsoon variations hard to fathom'

T.V. Padma in SciDev.net:  Understanding how the South Asian monsoon will change in response to global warming  and resolving the uncertainties in projected changes are ‘demanding tasks’ for climate science, a review says.

Current state-of-the-art general circulation models have difficulty simulating the regional distribution of monsoon rainfall, the 24 June review in Nature Climate Change says. The vagaries of the monsoon on short- and long-term timescales impact the lives of more than a billion people in South Asia who depend on rainfall for agriculture, power generation, industrial development and basic human needs.

Authors, Andrew Turner, National Centre for Atmospheric Science-Climate, University of Reading, and Harisubramaniam Annamalai, International Pacific Research Centre, School of Ocean and Earth Science, University of Hawaii, say variations in the amount of monsoon rains in different years are low (10 per cent of the total summer rainfall).

But, variations within each season, over timescales of a few days or weeks, often have large impacts on agriculture or water supply.

"Perhaps the single biggest scientific challenge is in understanding monsoon variability at intra-seasonal timescales (several weeks), the so-called active and break events in the monsoon, and how they will change in the future," Turner told SciDev.Net. They "are poorly understood and difficult to predict," he said....

Monsoon rains in Cambodia, shot by Julie Rigsby, Wikimedia Commons, under the Creative Commons Attribution 2.0 Generic license