January 24, 2022

Climate Change News

Saving The Planet

Ocean warming is accelerating more than previously thought, according to new research

Rising ocean temperatures can whiten corals, such as in Papua New GuineaCreditBelieve it(Jurgen Freund / NPL / Minden Pictures).

by Kendra Pierre-Louis, The New York Times, January 10, 2019

Scientists say the world’s oceans are warming much faster than previously thought, a finding with dire implications for climate change, because almost all of the excess heat absorbed by the planet ends up stored in its waters.

A new analysis, published Thursday in the magazine Science, found that the oceans are warming 40% more on average than an estimated UN group 5 years ago. The researchers also concluded that ocean temperatures have broken records for several years in a row.

“2018 will be the warmest year on Earth’s oceans,” said Zeke Hausfather, an energy systems analyst at independent climate research group Berkeley Earth and author of the study. “Because 2017 was the warmest year and 2016 was the warmest year.”

As the planet has warmed, the oceans have provided a critical buffer. They have curbed the effects of climate change by absorbing 93% of the heat trapped by greenhouse gases that humans pump into the atmosphere.

“If the ocean didn’t absorb so much heat, the earth’s surface would heat up much faster than it is now,” said Malin L. Pinsky, an associate professor in Rutgers ’department of ecology, evolution and natural resources. University. “In fact, the ocean is saving us from massive warming right now.”

But rising water temperatures are already killing marine ecosystems, raising sea levels and making hurricanes more destructive.

People in the tropics, who rely heavily on fish for protein, can be severely affected, said Kathryn Matthews, assistant chief scientist at the Oceana conservation group. “The actual capacity of warm oceans to produce food is much lower, so that means they will be approaching food insecurity faster,” he said.

Because they play such a critical role in global warming, the oceans are one of the most important areas of research for climate scientists. Average ocean temperatures are also a consistent way to track the effects of greenhouse gas emissions because they are not heavily influenced by short-term weather patterns, Hausfather said.

“The oceans are really the best thermometer we have for changes on Earth,” he said.

But historically, it has been difficult to understand ocean temperatures. A report with authority from the United Nations, published in 2014 by the Intergovernmental Panel on Climate Change, presented five different estimates of ocean heat, but all presented less warming than the levels projected by computer climate models, suggesting that climate change measures ocean heat or climate models were inaccurate.

Since the early 2000s, scientists have measured ocean heat using a network of drifting floats called “Argo,” which bears the name of Jason’s ship in Greek mythology. Floats measure the temperature and salinity of the top 6,500 feet of the ocean and load data using satellites.

But before Argo, researchers he confided temperature sensors that the ships went down to the ocean with copper wire. The cable transferred the sensor data to the ship to record it until the cable broke and the sensor moved away.

This method was subject to uncertainties, in particular as to the accuracy of the depth at which the measurement was taken. These uncertainties make it difficult for current scientists to unite twentieth-century temperature data into a global historical record.

In the new analysis, Mr. Hausfather and his colleagues evaluated three recent studies that best took into account the biases of older instruments. The results converged on an estimate of ocean warming higher than that of the United Nations Report 2014 and more in line with climate models.

Waters closer to the surface have warmed more and this warming has accelerated in the past two decades, according to data from the lead author of the new study, Lijing Cheng of the Beijing Institute of Atmospheric Physics.As the oceans warm, sea levels rise because warmer water takes up more space than colder water. In fact, most of the sea level rise observed so far is due to of this heating effect, ice caps do not melt.

The authors said that if there were no global actions to reduce carbon emissions, only warming would cause sea levels to rise by about a foot by 2100 and ice sheets would contribute more. This could aggravate the damage from severe coastal flooding and storm surges.

The effects of warming on marine life could also have far-reaching repercussions, Dr. Pinsky said. “As the ocean warms, it is driving fish to new places and we already see that this is causing conflicts between countries,” he said. “It goes far beyond fish, it becomes trade wars. It has become diplomatic disputes. In some cases, it has caused a rupture in international relations.

The study initially contained an error that caused its authors to revise their estimates downward. But, as it turned out, the downward revision brought the study’s estimates closer to the new consensus.

“The correction made it match much better with the other new observation records,” Hausfather said. “Previously it showed significantly greater warming than anyone, and this was potentially worrisome because it meant that our observational estimates could be problematic. Now his best estimate is practically dead with the other three recent studies. “

The scientists who published the four studies did not try to align their results, Hausfather said. “Groups working on ocean heat observations are not climate shapers,” he said.
“They are not particularly concerned about whether or not their observations agree with the climate models “.

A dead coral reef in Indonesian waters.CreditEthan Daniels / Stocktrek Images, via Science Source


A dead coral reef in Indonesian waters (Credit
Ethan Daniels / Stocktrek Images, via Science Source).

Laure Zanna, an associate professor of climate physics at Oxford University who did not participate in the study, said the new research was “a very nice summary of what we know about the ocean and how far it s ‘have joined the new estimates “.
Dr. Zanna published a study this week that used existing data to estimate ocean temperatures dating back to 1871. The goal was to find out places where sea level rise could occur even further. faster than expected due to the way ocean currents redistribute heat, allowing regions that are especially at risk to better plan for these changes.

“We are warming the planet, but the ocean is not warming evenly, so different places are warming more than others,” Dr. Zanna said. “And so the first consequence will be that sea level will be different in different places depending on the warming.”

While the new findings provide a bleak forecast for the future of the oceans, Hausfather said they would help efforts to mitigate global warming, including the 2015 Paris climate agreement. “I think there’s some reason to trust that we will avoid the worst results, “he said,” even if we are not on the right track to the results we want. “

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