Ocean robots detect minor deep ocean warming in some parts of the world

Antarctic sea ice [image credit: BBC]

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A minor rate of ocean warming as reported here could easily be normal natural variation. The use of ‘historic data from research vessels’ in addition to more recently collected data conflicts starkly with the estimated range of warming for ‘parts of the deep ocean’ given to four decimal places. Other parts – maybe not so much, or even strong cooling (in much of the western North Atlantic), but the study says ‘the warming trend dominates the global integral for the deep layer’. Any tiny increase in temperature somewhere gets tagged as a ‘hot spot’.
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New research published today shows that using data collected by deep ocean robots, called Deep Argo floats, combined with historic data from research vessels has increased confidence that parts of the global deep ocean are warming at a rate of 0.0036 to 0.0072 degrees Fahrenheit (0.002 to 0.004 degrees Celsius) each year, says NOAA.

“Ocean warming is the dominant element of global warming and a major driver of climate change,” said Greg Johnson, an oceanographer at NOAA’s Pacific Marine Environmental Lab and lead author of the study, which was published in the journal Geophysical Research Letters.

“This study confirms the previously reported deep ocean warming, and reduces the uncertainties about the global ocean heat uptake in waters below 1.2 miles (2000 meters), a key area of the ocean for predicting sea level rise and extreme weather.”

The new research also provides more detailed information about the geographic patterns of the deep ocean warming, which can help scientists better understand changes in the global ocean conveyor belt called the global meridional overturning circulation, also key to predicting weather and climate changes.

The research shows that the deepest ocean waters off Antarctica are a hot spot for warming. These bottom waters carry the warming north, traveling along the ocean conveyor belt.

Another hot spot of warming is in the deep ocean waters off Greenland, which no longer receive large amounts of sinking cold waters from the ocean surface due to increased atmospheric warming and freshening of those surface waters from ice melt.

More detailed information about deep ocean warming can help improve climate models used to prepare society for future changes in ocean and air temperatures that drive sea level increases, precipitation, tropical cyclone frequency and intensity, and their impacts on humans and the environment.

Full article here.
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Image: Antarctic sea ice [credit: BBC]

Study here.