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Atmospheric Warming Altering Ocean Salinity And The Water Cycle

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"Atmospheric Warming Altering Ocean Salinity And The Water Cycle"

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[Taking the opportunity I'm in the hospital to clear out some old unpublished posts -- JR.]

Lawrence Livermore Lab News Release

A clear change in salinity has been detected in the world’s oceans, signaling shifts and acceleration in the global rainfall and evaporation cycle tied directly to climate change.

In a paper published … in the journal Science, Australian scientists from the Commonwealth Scientific and Industrial Research Organisation (CSIRO) and Lawrence Livermore National Laboratory reported changing patterns of salinity in the global ocean during the past 50 years, marking a clear symptom of climate change.

Lead author 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 become 4 percent stronger from 1950-2000. This is twice the response projected by current generation global climate models.

“These changes suggest that arid regions have become drier and high rainfall regions have become wetter in response to observed global warming,” said Durack, a post-doctoral fellow at Lawrence Livermore National Laboratory.

Scientists monitor salinity changes in the world’s oceans to determine where rainfall has increased or decreased. “It provides us with a gauge — a method of monitoring how large-scale patterns of rainfall and evaporation (the climate variables we care most about) are changing,” Durack said.

With a projected temperature rise of 3 degrees Celsius by the end of the century, the researchers estimate a 24 percent acceleration of the water cycle is possible.

[JR: Actually the projected warming by century's end is closer to 5°C -- see review of literature here -- which would yield a stunning 40% acceleration of the water cycle.]

Scientists have struggled to determine coherent estimates of water cycle changes from land-based data because surface observations of rainfall and evaporation are sparse. According to the team, global oceans provide a much clearer picture.

“The ocean matters to climate — it stores 97 percent of the world’s water; receives 80 percent of all surface rainfall, and it has absorbed 90 percent of the Earth’s energy increase associated with past atmospheric warming,” said co-author, Richard Matear of CSIRO’s Wealth from Oceans Flagship.

“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.”

He said the intensification is an enhancement in the patterns of exchange between evaporation and rainfall, and with oceans accounting for 71 percent of the global surface area, the change is clearly represented in ocean surface salinity patterns.

In the study, the scientists combined 50-year observed global surface salinity changes with changes from global climate models and found “robust evidence of an intensified global water cycle at a rate of about 8 percent per degree of surface warming,” Durack said.

Durack said the patterns are not uniform, with regional variations agreeing with the ‘rich get richer’ mechanism, where wet regions get wetter and dry regions drier.

He said a change in freshwater availability in response to climate change poses a more significant risk 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,” Durack said.

Susan Wijffels, co-chair of the global Argo project and a co-author on the study, said maintenance of the present fleet of around 3,500 profilers is critical to observing continuing changes to salinity in the upper oceans.

This piece of research was originally published at the Lawrence Livermore National Laboratory.

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18 Responses to Atmospheric Warming Altering Ocean Salinity And The Water Cycle

  1. Check out how red the Atlantic is.

  2. Joan Savage says:

    As in, saltier.

    The label on the original figure is:

    Surface salinity changes for 1950 to 2000. Red indicates regions becoming saltier, and blue regions becoming fresher. Image by Paul Durack/LLNL

  3. J. Witte says:

    New NASA satellite will provide a more detailed view of the salinity of the oceans: new colorful animation of the first year of measurements around the world from the Aquarius satellite, http://www.nasa.gov/Aquarius

  4. Joan Savage says:

    So a basic reason for the global average decline in salinity is speed-up of the water cycle in a hotter climate. It’s important to get this in a nutshell.

    Beyond that, I yearn to know more about the dynamics that have lead to the pattern of fresher and saltier water in the map, as shifts in the pattern of thermohaline circulation of the ocean will drive the “where” of the droughts and deluges.

  5. Paul Klinkman says:

    Always, always, always, the climate change is worse than scientists expected. It’s apparently going to happen again and again in the near future. Why?

    If you were serving on a tenure track evaluation committee, wouldn’t you want to ask this question of each candidate for a climatology position?

    • Lou Grinzo says:

      I think I can jump in here and explain scientific reticence without being accused of serving my own interests, since I’m not a climate scientist.

      Scientists work exceedingly hard to tease the truth out of maddeningly incomplete, often contradictory (at least until it is further understood), and sometimes just plain bizarre (ditto) observations. As a result, their natural inclination is to take a stance much like the Hippocratic oath and attempt above all else to do no harm. Look at the history of science and see how much initial skepticism there was about tectonic plates or that whole asteroid wiping out the dinosaurs thing, for example.

      The problem, of course, is that in this case the delay caused by this mindset is extremely dangerous; we’re already far behind the curve on our mitigation and adaptation efforts, so further delay quickly adds to the human and monetary pain we’ll inflict on ourselves and future generations.

      If we demand that scientists act quicker to jump to “obvious” conclusions and we can find some who will actually do that, then we’ll have to live with a much higher percentage of their findings being flat-out wrong.

      There’s also the fact that there simply isn’t enough money and people to do all the research climate scientists need in order to answer crucial questions. While they’re studying things are continuing to get worse and at an accelerating pace, leading to yet more “it’s worse than we thought” horrors.

      • Sandy says:

        My background is in science and I have great respect for care in getting the best information from one’s research before bringing it to the public. I think that in addition to the climate scientists’ normal caution though, they have been fought, discredited and accused of doing ‘bad/sloppy science’ for personal gain (grants) and of being ‘alarmists.’ The debunked “Climate Gate” accusations, James Hansen’s work redacted by the Bush Administration, the phoney Nongovernmental International Panel on Climate Change, the distortions, untruths and denials formulated in Conservative ‘think tanks.’ Our Planet isn’t dying, it’s being murdered for profit.

        • Mulga Mumblebrain says:

          Yes, it is hard to criticise climate scientists for being cowed by the Forces of Evil when they are the victims of a brutally vicious hate campaign. However, now is the time to gird up your loins (now, where did I leave them?)and finally fight back. It means even more vicious abuse, vilification and intimidation, but that’s guaranteed already. It absolutely means violent resistance from the Evil Ones, as any poor world environmentalist can tell us. And it will mean concerted repression and abuse from the political stooges of capital, but, there is now, plainly, ‘No Alternative’. The Obama confidence trick was surely, the very last straw. It’s go down fighting or go down on your knees, I’d say, but we can still hope for some improbable miracle, but only if we make it happen now.

    • Joan Savage says:

      Good question.

      I’d want to hear an answer that demonstrates some understanding of the entropy and enthalpy processes in the decay of the earth’s system.

      (I’d need at least a few months myself to prepare a solid answer.)

      • Jim Baird says:

        Joan the oceans are accumulating 330 terawatts of heat/year. Unless you are converting some of this to work you are doing nothing for the entropy/enthalpy situation. You can claim to be doing something with nuclear or fusion but all you are doing is increasing the waste heat. Conventional and solar or wind simply maintains the status quo with respect to the production side. All energy will increase enthalpy with use.

    • Merrelyn Emery says:

      Their predictions are based on the process of analysis of rates of change in individual variables followed by attempts to re-synthesize through the most comprehensive models they can compute. This process can only ever be a very rough approximation of the rate of change in a system when a critical variable is perturbed. Maths for systemic disturbance are available but have been ignored, ME

      • Paul Klinkman says:

        Detrendent correspondence analysis, a statistical tool, might do a passable job, except that Mother Nature has almost never tampered this badly with the eaarth.

  6. Rabid Doomsayer says:

    This is going to change the Meridional Overturning Circulation. You can already see how it will be the salty equatorial waters that will sink.

    Could get interesting. Looks like what was expected to take thousands of years is about to happen much sooner. Still I would not like to guess at a time frame.

  7. Jakob Wranne says:

    JR – Best wishes, we hope everything is OK!

    Our best climate journalist, the best climate journalist in Sweden, resigns. Last day at work is March 31. Her impact has been tremendous and it can not be underestimated. This is a loss to the swedish debate, not possible to cure.

    Where Karin Bojs is going we do not know today. We do not know the reason why she is resigning.

    But, during the last year her sharp and crystal clear reporting on climate has disappeared from the pages. In her place has arrived dim, cloudy and disinforming text makers claiming there is doubt on climate change.

    Personally, I believe she is resigning because of a conflict on what she is allowed to publish.

    JR – Please, do not harbour a fatal illness. We need you. Your voice and you constantly telling us what you see from your position is so extremely important!

    • Merrelyn Emery says:

      Jakob, that is so sad, It hadn’t occurred to me that Scandinavia would be infected with the terrible denialist virus. But it can be overcome, you just need to fight like hell, and remember that the Earth is on your side, ME

    • Joe Romm says:

      No fatal illness, other than the one all humans share.

    • Mulga Mumblebrain says:

      People still seem to think that Sweden is some sort of ‘socialist’ paradise. That is long gone, and the slavishly pro-Empire Right rule as absolutely in Sweden as in Australia. The murder of Olof Palme by Rightists in the Swedish intelligence agencies set the scene for this tragic debacle.