Climate

The Oceans Are Hotter than Anyone Realized

A new report says the oceans have held on to 60 percent more heat every year than anyone expected, further messing up the accuracy of past predictions of how fast the Earth will heat from global warming.

One of the early unmistakable signs of global warming is increased flooding in coastal areas as sea levels rise.

Besides being the place where much of life began, the oceans have always functioned as the number one place for thermal and even carbon dioxide absorption on the planet. For those modeling the future of global warming, knowing precisely how much heat the oceans have absorbed is critical.

In the past, the method for figuring this out has been the Argo float program. This is an array of 3,800 free-drifting floats spread out across the globe. They measure temperature and salinity in the upper 2000 meters in the ocean. They also report that data near ‘real time’ and publicly.

The distribution of active floats in the Argo array, color coded by country that owns the float, as of February 2018. Photo: Hjfreeland, CC

As noted in a new study published on November 1 led by lead author Laure Resplandy, a geoscientist at Princeton University, the Argo float data appears to have been way off. As the authors note, the Argo approach uses an “imperfect ocean dataset” and it “share[s] additional uncertainties resulting from sparse coverage, especially before 2007” and because of its somewhat random physical sampling. To get more accurate readings, the authors have come up with an “independent estimate [of ocean warming] by using measurements of atmospheric oxygen (O2) and carbon dioxide (CO2) – levels of which increase as the ocean warms and releases gases – as a whole-ocean thermometer”.

The authors note that their “result – which relies on high-precision O2 measurements dating back to 1991 – suggests that ocean warming is at the high end of previous estimates”. The “high end” of the estimates amounts to the oceans absorbing about 60% more heat than previous estimates.

That is very bad news for climate change calculations in multiple ways.

For one thing, the higher ocean temperatures themselves impact the solubility of both oxygen and carbon dioxide. Lower oxygen levels in the water – along with the heat – has serious implications for the stability of life in the oceans. Less absorption of carbon dioxide means the oceans are and have been far less effective as a place for the planet to store excess carbon overall. Ocean photosynthesis is also going to be slowed more than expected, both because of higher temperatures themselves as well as because the amount of CO2 absorbed is lower.

Higher ocean temperatures also mean the oceans have less available thermal capacity to act as a heat sink for solar heat. One of the report calculations points to a 25% decrease in the “maximum cumulative CO2 emissions” to stay below near-term global warming temperature targets. That is a big error compared to past numbers.

Hotter oceans mean faster sea ice melting around the planet than anyone expected. This may in fact be most pronounced in areas that are not visible, underneath the Arctic and Antarctic ice sheets.

Hotter ocean temperatures also will have bigger impacts on weather currents around the planet. That would point to more powerful and faster-growing storms. It would also affect both ocean and air currents, creating new patterns of drought, torrential rains, extreme heat, and flooding.

Warmer oceans also mean faster ocean sea level rising just because the ocean itself is swelling in the heat at rates higher than previously thought. It may not seem like a lot, but the ocean warming on its own – not counting ice melts – contributes to sea level rise at a rate of between 1.34 to 1.74 millimeters per year, according to the new study. That, combined with other numbers, is bad news too.

In a recent interview with lead author Laure Resplandy, she about the new work that, “We thought that we got away with not a lot of warming in both the ocean and the atmosphere for the amount of CO2 that we emitted.” She went on, saying, “But we were wrong. The planet warmed more than we thought. It was hidden from us just because we didn’t sample it right.”

The new analysis is just another proof that the human race continues to underestimate how badly damaged the earth is from greenhouse gas emissions and global warming. As Trillions noted in the recent article, “The IPCC Report is Dead Wrong and Dangerous”, we are well past the point of being able to – metaphorically at least – pull out quickly before we drive ourselves off the cliff of global warming. Temperatures everywhere, in the air – and now too, in the oceans – are already far hotter than what most of us think.

The full report, “Quantification of ocean heat uptake from changes in atmospheric O2 and CO2 composition”, written by Laure Resplandy and 9 others including experts from the Scripps Institute of Oceanography and other highly-regarded research centers in the United States, China, Germany and France, was published in Nature on November 1, 2018.