Big Changes in Ocean Salinity Intensifying Water Cycle

Surface salinity changes for 1950 to 2000. Red indicates regions becoming saltier, and blue regions becoming fresher: P.J. Durack, et al. 2012. Science. DOI:10.1126/science.1212222

Surface salinity changes from 1950 to 2000. Red shows regions becoming saltier, blue regions becoming fresher:  P.J. Durack, et al. Science. 2012. DOI:10.1126/science.1212222

A paper in Science today finds rapidly changing ocean salinities as a result of a warming atmosphere have intensified the global water cycle (evaporation and precipitation) by an incredible 4 percent between 1950 and 2000. That’s twice the rate predicted by models. 

These same models have long forecast that dry areas of Earth will become drier and wet areas wetter in a warming climate—an intensification of the water cycle driven mostly by the capacity of warmer air to hold and redistribute more moisture in the form of water vapor.

satellite image shows the distribution of water vapor over Africa and the Atlantic Ocean on  2 Sept 2010: NASASatellite image shows the distribution of water vapor over Africa and the Atlantic Ocean on 2 Sept 2010: NASA

But the rate of intensification of the global water cycle is happening far faster than imagined: at about 8 percent per degree Celsius of ocean warming since 1950.

At this rate, the authors calculate:

  • The global water cycle will intensify by a whopping 16 percent in a 2°C warmer world
  • The global water cycle will intensify by a frightening 24 percent in a 3°C warmer world

 

A schematic representation of the global water cycle, with the key role of the ocean and surface rainfall and evaporation fluxes expressed: Durack et al. Science. 2012. DOI:10.1126/science.1212222

A schematic representation of the global water cycle, with the key role of the ocean and surface rainfall and evaporation fluxes expressed: Durack et al. Science. 2012. DOI:10.1126/science.1212222 

The changes will not be uniform across the globe, but trend toward increased drying of arid areas and  increased flooding of wet areas.

And the resulting changes in freshwater availability are likely to be far more destabilizing to human societies and ecosystems than warming alone. 

“Changes to the global water cycle and the corresponding redistribution of rainfall will affect food availability, stability, access, and utilization,” says lead author Paul Durack at the University of Tasmania and the Lawrence Livermore National Laboratory.

The paper:

  • Paul J. Durack, Susan E. Wijffels and Richard J. Matear. Ocean Salinities Reveal Strong Global Water Cycle Intensification During 1950 to 2000. Science 2012. DOI:10.1126/science.1212222

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SIX TRUTHS

Reclaiming power from those who abuse it often starts with telling the truth. And in "This Is How Authoritarians Get Defeated," MoJo's Monika Bauerlein unpacks six truths to remember during the homestretch of an election where democracy, truth, and decency are on the line.

Truth #1: The chaos is the point.

Truth #2: Team Reality is bigger than it seems.

Truth #3: Facebook owns this.

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Truth #5: It's about minority rule.

Truth #6: The only thing that can save us is…us.

Please take a moment to see how all these truths add up, because what happens in the weeks and months ahead will reverberate for at least a generation and we better be prepared.

And if you think journalism like Mother Jones'—that calls it like it is, that will never acquiesce to power, that looks where others don't—can help guide us through this historic, high-stakes moment, and you're able to right now, please help us reach our $350,000 goal by October 31 with a donation today. It's all hands on deck for democracy.

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