Climate Science

Soon It's Gonna Rain

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Science  02 Mar 2012:
Vol. 335, Issue 6072, pp. 1020-1021
DOI: 10.1126/science.335.6072.1020-d

As climate warms, the atmosphere holds more moisture, and increased global precipitation is expected even while deserts may expand or move as areas receiving precipitation shift. This physics is captured in global climate models, and their results show changes even for warming over the 20th century. However, observational data seem to show an even greater increase in precipitation. Noake et al. take a closer look, comparing three data sets of on-land precipitation covering the latter half of the 20th century with the output from 54 climate model runs. Their analysis shows that precipitation increased most noticeably at higher latitudes in the Northern Hemisphere from December through May and over a wider belt in the fall; summer precipitation decreased slightly at lower latitudes. The model results are consistent with the pattern seen, but underestimate the spring increases seen at higher latitudes. Most useful for planning are estimates of the likely extremes in precipitation, as these affect flood forecasts and mitigation contingencies. Mishra et al. conduct an analysis comparing regional climate models and observations of urban extreme precipitation events across the United States. Their comparison similarly implies that regional models generally underestimate short-lived precipitation extremes but do somewhat better (about 25% success) with daily averages.

Geophys. Res. Lett. 39, L03706; L03407 (2012).

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