Friday, April 27, 2012
Earth's water cycle intensifying with atmospheric warming
CSIRO News (Australia): In a paper published today in the journal Science, Australian scientists from the Commonwealth Scientific and Industrial Research Organisation (CSIRO) and the Lawrence Livermore National Laboratory, California, reported changing patterns of salinity in the global ocean during the past 50 years, marking a clear fingerprint of climate change.
Lead author, Dr Paul Durack, said that by looking at observed ocean salinity changes and the relationship between salinity, rainfall and evaporation in climate models, they determined the water cycle has strengthened by four per cent from 1950-2000. This is twice the response projected by current generation global climate models.
"Salinity shifts in the ocean confirm climate and the global water cycle have changed. These changes suggest that arid regions have become drier and high rainfall regions have become wetter in response to observed global warming," said Dr Durack, a post-doctoral fellow at the Lawrence Livermore National Laboratory.
With a projected temperature rise of 3ºC by the end of the century, the researchers estimate a 24 per cent acceleration of the water cycle is possible.
Scientists have struggled to determine coherent estimates of water cycle changes from land-based data because surface observations of rainfall and evaporation are sparse. However, according to the team, global oceans provide a much clearer picture. "Warming of the Earth’s surface and lower atmosphere is expected to strengthen the water cycle largely driven by the ability of warmer air to hold and redistribute more moisture."....