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Looking for Progress in Modeling the Continental Indian Monsoon
Ramesh, K.V. and Goswami, P. 2014. Assessing reliability of regional climate projections: the case of Indian monsoon. Scientific Reports 4: 10.1038/srep04071.

The authors write that "accurate projections of regional climate systems, like the Continental Indian Monsoon (CIM), are critical for assessing the sustainability of a large section of the world's population and to determine the future of the global climate system," noting in this regard, however, that "assessing reliability of climate change projections, especially at regional scales, remains a major challenge." And they thus say that an important question to be answered "is the degree of progress made since the earlier IPCC simulations (CMIP3) to the latest recently completed CMIP5."

What was done
Using the CIM as a case study, Ramesh and Goswami say they applied "a hierarchial approach for assessing reliability, using the accuracy in simulating the historical trend as the primary criterion" and considering only CIM rainfall (June-September), which "allowed a robust analysis with multiple sets of observations."

What was learned
First of all, the two researchers found that "both CMIP3 and CMIP5 simulations exhibit large spreads in simulations of average monsoon rainfall and their inter-annual variability." Second, they say that "the all-simulation ensemble of CMIP5 shows a decadal variability but with phases essentially opposite to those of observations," leading them to admit that CMIP5 models "have poorer quality than the CMIP3 in simulating the observed features of CIM."

What it means
Quoting Ramesh and Goswami, "our results show that no significant progress has been achieved in our ability to simulate basic quantities like observed seasonal mean and trend, and hence to project the regional climate system, namely CIM, with reasonable certainty," which leads us to suggest that this aspect of the climate modeling enterprise of the past few years has actually led to retrogression rather than progression.

Reviewed 14 May 2014