A new publication by John Fyfe and Nathan Gillett (Canadian Centre for Climate Modelling and Analysis) and Gareth Marshall (British Antarctic Survey) shows that summer rainfall patterns in the Southern Hemisphere have changed markedly in response to rising greenhouse gas concentrations and ozone layer depletion, both caused by human activity.

Since the 1960s, southern regions at mid-latitudes have become drier, whereas a zone around Antarctica has grown wetter. The team found that the observed trends agree with predicted precipitation patterns obtained from a set of 29 climate models, and that greenhouse gases and ozone changes were primarily responsible for the shifts in precipitation levels. Moreover, natural climate variability cannot explain the observed and modelled trends, the team found.

The publication was highlighted in the journal Nature (“Rain shifts bear human fingerprint,” Nature 492, 157, December 13, 2012) and is one of the "most viewed" American Geophysical Union (AGU) papers.

Citation: Fyfe, J.C., N.P. Gillett and G.J. Marshall. 2012. Human influence on extratropical Southern Hemisphere summer precipitation. Geophysical Research Letters 39(23), doi:10.1029/2012GL054199

Contact: John Fyfe, john.fyfe@ec.gc.ca, Climate Research Division