Ocean Salinities Reveal Intensification of the Water Cycle


New estimates of ocean surface salinity change over the past 50 years mark a clear symptom of climate change. Salinity measurements are valuable because they respond to changes in the water cycle (as manifest through precipitation and surface evaporation) over the poorly sampled global oceans that cover 71 percent of the Earth’s surface. These and other observations were compared with results from the Coupled Model Intercomparison Project (CMIP3; climate model output from simulations of past, present, and future climate), and the relationship between salinity changes and global water cycle changes was examined. The observationally based estimate of water cycle intensification (4 percent intensification from 1950 to 2000) is twice that predicted by most CMIP3 models, although the responses of individual models varied. Changes in the pattern of surface salinity provide independent evidence that wet regions are becoming wetter and dry regions drier, an expected result for a warming Earth. The CMIP3 projections of future climate change suggest that this pattern of change will intensify.

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Durack, P. J., S. E. Wijffels, and R. J. Matear. 2012. “Ocean Salinities Reveal Strong Global Water Cycle Intensification during 1950-2000,” Science 336(6080), 455-58. DOI: 10.1126/science.1212222.