Melting ice caps cannot replace the ocean current


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Most of our future climate models are very sensitive to the melting of Arctic ice as a cause of rapid change in ocean currents, according to new research led by by scientists at the University of Wisconsin – Madison.

Scientists have listed the Atlantic Meridional Overturning Circulation (or AMOC) among the most specific points on the path to a global catastrophe. The current of the Atlantic Ocean is like a conveyor belt that carries hot water in the north and the colder, deeper the water in the south.

“We were taught to pick it up as a conveyor belt – even though in middle school and high school now, it’s taught in this way – to be closed when clean water comes in. from the melting ice, “said Feng He, an associate scientist at UW– Madison’s Center for Climatic Research.

However, building on the previous work, he said the researchers are revising their understanding of the relationship between AMOC and clean water from the melting of polar ice.

In the past, an AMOC recorded has also attended climate events such as the warming of Bølling-Allerød, which is 14,500 years old, much higher than global warming. He presented the event successfully using a model led in 2009 as a UW -Madison graduate.

“That’s a challenge, a re -creation of the warming of about 14,700 years ago that was seen in paleoclimate history,” He says, now. “But we didn’t stay straight at that time of immediate change.”

But while the Earth’s temperature will cooler after this warming before rising again to new highs for the past 10,000 years, the 2009 model is unlikely to continue to rise. fast. The warming in the northern hemisphere is not in line with the rise in temperatures observed in geological databases, such as icebergs.

In a study published this week in the journal Nature Climate Change, He and Oregon State University paleoclimatologist Peter Clark described a recent model of the temperature of the past 10,000 years. And they worked to eliminate the reason why most scientists believe in stores and do not replace AMOC.

Warmer temperatures on Earth’s surface melt sea ice in the Arctic Ocean and the Greenland Ice Sheet, releasing fresh water into the ocean. Scientists believe that the flow of clean water will affect the various parts of the North Atlantic which will make the AMOC flow straight back to the south.

“The problem,” he said, “is with global data.”

While climate history shows that much of the clean water came from the recent melting of ice in North America and Europe, the AMOC has not changed. Therefore, he removed the concept of clean water from his model.

“Without clean water to extend the AMOC to the model, we get a simulation with better agreement with the temperature data from the climate history,” he said. “The significant impact of the AMOC will not be seen in improving water more than expected, according to data and analysis.”

This is important in models evaluating the response of AMOC to the rise of clean water from ice melting.

“It’s built into a lot of features,” he says. “Global warming comes from increasing carbon dioxide in the air to melt sea ice, and clean water from melted ice is thought to weaken AMOC.”

The broad effects of the AMOC’s weakening effect on rapid sea level rise on the east coast of North America, drowning over Europe could wipe out agriculture, an Amazon rainforest. drought and the end of the Asian monsoons. The new modeling study suggests a small reduction in AMOC intensity, but it does not rule out an immediate change.

“We believe that until this problem is resolved, AMOC changes should be considered as a result of improving fresh water,” he said. “We can’t understand why the AMOC was closed in the past. But we know it’s changed. And it could change again.”

It looks like the ocean system is approaching

More information:
Feng He et al, rediscovered the Atlantic Meridional Overturning Circulation, Nature Climate Change (2022). DOI: 10.1038 / s41558-022-01328-2

Presented by the University of Wisconsin-Madison

Directions: Ocean ice caps cannot be replaced (2022, April 9) retrieved April 9, 2022 from current.html

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