Heavy Precipitation Over the US: Has it Increased as Some have Predicted it Should?
Mahajan, S., North, G.R., Saravanan, R. and Genton, M.G. 2012. Statistical significance of trends in monthly heavy precipitation over the US. Climate Dynamics 38: 1375-1387.
In doing so, Mahajan et al. report that trends estimated from the two data sources they employed "straddle the margin of statistical significance, and hence a definitive answer to the question of increasing trend of heavy precipitation over the US cannot be arrived at by looking at observational data." And with nearly half (9 out of 20) of the GCMs employed in their study predicting trends that are "significantly different from the observations," they are forced to conclude that "the GCMs are not yet fully capable of simulating extremes of precipitation at a regional level," as they say that only "one GCM simulation of the twentieth century does demonstrate a statistically significant upwards trend in monthly heavy precipitation."
When all was said and done, the four scientists concluded the report of their research by writing "we cannot definitively answer if the heavy precipitation in the US has been increasing in the past century." Yet they continue to repeat the ominous refrain that "GCM integrations suggest that it is very likely to increase in the future." Only time will tell.
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