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The Recent Decline in Drought Over the Southeast USA

Paper Reviewed
Mitra, S. and Srivastava, P. 2017. Spatiotemporal variability of meteorological droughts in southeastern USA. Natural Hazards 86: 1007-1038.

Based on computer model projections, concern has been expressed that global warming will usher in a period of more frequent and intense drought. But is this correct?

One way to test this hypothesis is to examine historic trends in drought for evidence of recent change during the modern era, in particular over the past two or three decades, during which time the atmosphere experienced the bulk of the carbon dioxide increase since preindustrial times. And the latest research team to do that was Mitra and Srivastava (2017). Working with two different datasets (Climate Research Unit and the University of Delaware) and two drought indices (Standardized Precipitation Index and Standardized Precipitation Evapotranspiration Index) the two Auburn University researchers analyzed drought characteristics for the southeast USA over the period 1901-2005.

And what did their analysis reveal?

As described by Mitra and Srivastava, (1) droughts showed "high spatial and temporal variability," (2) droughts were more severe and frequent during the early (1901-1935) and mid (1936-1970) of the twentieth century [compared to the latter 1971-2005 period]," (3) "trend analysis confirms that the study domain has become wetter over the last 105 years" and that (4) such "wetting trends were more prominent in the agricultural season."

In light of these several findings, Mitra and Srivastava say that their work "provides a robust conclusion that irrespective of the dataset or methodology used the southeast region [of the USA] has become wetter during the recent decades especially during the agricultural seasons." Therefore, it would appear that CO2-induced global warming has not had any impact on drought in the southeast USA other than to alleviate it, especially during the all-important agricultural producing season.

Posted 22 September 2017