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CMIP5 Models Fail to Reproduce Post-1950 Indian Monsoon Trend

Paper Reviewed
Saha, A., Ghosh, S., Sahana, A.S. and Rao, E.P. 2014. Failure of CMIP5 climate models in simulating post-1950 decreasing trend of Indian monsoon. Geophysical Research Letters 41: 7323-7330.

In facing up to the facts of the matter, Saha et al. (2014) write that "the impacts of climate change on Indian Summer Monsoon Rainfall (ISMR) and the growing population pose a major threat to water and food security in India," noting that "adapting to such changes needs reliable projections of ISMR by general circulation models." However, they say their analysis of the subject reveals that the majority of CMIP5 models simply "fail to simulate the post-1950 decreasing trend of the ISMR," as does their multi-model average.

As for why this is so, the four Indian scientists say the weakening of the monsoon is associated with "the warming of the Southern Indian Ocean and strengthening of cyclonic formation in the tropical Pacific Ocean," while acknowledging that "these large-scale changes are not captured by CMIP5 models," which is, pure and simple, "the reason of this failure," as they put it.

As for the ramifications of their findings, Saha et al. conclude that "using CMIP5 multi-model projections of ISMR for adaptation planning may lead to incorrect policies." And with major threats to food and water security in India, as they report, that is not the message that is going to help the country very much, if at all.

Posted 6 April 2015