Thousands of Floating Ocean Sensors Report Ocean Warming Faster Than Anticipated

October 7, 2014 – In this months Letters posted in the journal Nature Climate Change, researchers from the Lawrence Livermore and Jet Propulsion Laboratories in California are reporting that we have underestimated global ocean warming since 1970. Why? Poor sampling of ocean temperatures particularly in the Southern Hemisphere. In their report entitled, Quantifying underestimates of long-term upper-ocean warming, the authors describe the global effort to deploy thousands of robotic sensors throughout the world’s oceans to develop accurate observations that they can then plug into models and simulations.

Called Argo, the floating array of sensors is providing oceanographers and climatologists with a very clear picture of observable changes both in temperature and acidity. Because the ocean is the largest carbon sink on the planet it is bearing the greatest global warming, more than the air and land.

The research shows that overall the ocean has warmed when compared to more limited data sets collected since 1970. The Argo data which has been collected since the programme launched in 2000 is consistent with the trend from 1970 to 2000.

The Southern Hemispheric ocean was the one area of the world ocean that oceanographers and climatologists suffered from a paucity of good data. That’s because human presence on the ocean in these areas was far less than in the Northern Hemisphere. The Argo programme has filled in the holes through deployment of thousands of sensors in the Southern Hemisphere.

And what Argo is telling us with the added southern data set that upper level ocean warming is happening at rates 24 to 58% faster than previously thought. A Scripps Institute oceanographer, Sarah Gille, who was not a contributor to the research described this study as stunning. In an article written by John Upton and published on Climate Central earlier this week, she is quoted as stating: “We continue to be stunned at how rapidly the ocean is warming…even if we stopped all greenhouse gas emissions today, we’d still have an ocean that is warmer than the ocean of 1950, and that heat commits us to a warmer climate. Extra heat means extra sea level rise, since warmer water is less dense, so a warmer ocean expands.”

A second report whose results appear this week in that same journal, in an article entitled, Deep-ocean contribution to sea level and energy budget not detectable over the past decade, further use Argo data to support findings that show ocean warming reaching to depths of almost 2,000 meters (6,500 feet). This rising warmth at depth, the study concludes, is contributing to overall expansion of the ocean water volume and rising sea levels. Not just the melting of land-based Arctic and Antarctic glaciers, therefore, are seen as the reasons for rising sea levels that are averaging 0.77 millimeters (0.03 inches) +/- 0.28 millimeters (0-.011 inches) annually.

For those who point to the recent slowdown in atmospheric warming, referred to as the global warming hiatus or pause, and tout this as refuting the general consensus on atmospheric warming, the evidence of ocean heating should give them pause. It appears our oceans are picking up much of the heat which brings up the question, for how much longer before that warmth gets released into the atmosphere. Oceanographers state its only a matter of time before ocean warmth renews atmospheric warming and now that we know the former is heating up faster than we originally thought, will we soon see the atmosphere begin to experience its own accelerated heating?

One thing for sure, contributing more carbon dioxide and greenhouse gases to the atmosphere will only exacerbate oceanic warming and acidification. Without addressing the carbon associated with our current human footprint the Argo robotic sensors will continue to send us confirming data that our planet is undergoing a remarkably fast, and by geological time standards, unprecedented change.

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