Parts of Greenland are now warmer than at any time in the past 1,000 years

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The coldest and highest part of Greenland’s ice, in many places about two miles above sea level, is warming rapidly and undergoing changes unprecedented in at least a millennium. Scientists report Wednesday.

That’s the result of research that unearthed multiple 100-foot or more ice cores from the world’s second-largest ice sheet. The samples allowed the researchers to construct a The new temperature record is based on the oxygen bubbles stored inside them, which reflect the temperature when the ice was originally laid down.

“We consider the 2001-2011 decade to be the warmest of the entire 1,000-year period,” said Maria Horhold, a scientist at the Alfred Wegener Institute in Bremerhaven, Germany, and lead author of the study.

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And since warming has only continued since then, this finding likely underestimates how much the climate has changed The high-altitude area of ​​northern and central Greenland has changed. That’s bad news for the planet’s coastlines, as it suggests a long-term melting process is setting in motion that could eventually yield some significant, if difficult to measure, fraction of Greenland’s total mass to the ocean. Overall, Greenland has enough ice to raise sea level by more than 20 feet.

The study stitched together temperature records revealed by ice cores drilled in 2011 and 2012 with records from older and longer cores reflecting temperatures above the ice sheet a millennium ago. The youngest ice in these old cores was from 1995, meaning they can’t tell much about present-day temperatures.

The study also found that compared to the 20th century as a whole, this part of Greenland, the vast north-central region, is now 1.5 °C (2.7 °F) warmer, and that the rate of melting and loss of water from the ice sheet — which raises sea level — accounts for these changes. It has increased along with it

The study was published Wednesday in the journal Nature by a team of researchers from the Hörhold and Alfred Wegener Institutes and two other institutions in Germany, the Niels Bohr Institute and the University of Bremen.

The new study “uses data from within Greenland to push back the instrumental record back 1,000 years to show unprecedented recent warming,” said Isabella Velicogna, a glaciologist at the University of California, Irvine who was not involved in the study.

“This signals warming in Greenland, melting sea ice and accelerating runoff, and slowing it down will be challenging.” “However, this adds momentum to the seriousness of the situation. It’s bad, bad news for Greenland and for all of us.”

Scientists claim that if the air over Greenland warms enough, a feedback loop will be created: the melting of the ice sheet will cause it to descend to lower altitudes, which will naturally expose it to warmer air, which will further melt and shrink, and so on.

The fact that this north-central part of Greenland is now 1.5 degrees Celsius warmer than it was in 1900 does not mean that the ice sheet has reached this dreaded “tipping point”.

Recent studies have shown that Recommended That Greenland’s dangerous edge is about 1.5°C or more of global warming – but that’s a different picture than the ice’s regional warming. When the world reaches 1.5 degrees Celsius of average warming, which could happen as soon as the 2030s, Greenland will likely warm even more than that – and more than it does now.

The researchers, advised by The Washington Post, also highlighted that the northern part of Greenland, where these temperatures were recorded, is known to be prone to sea level rise for other reasons.

“We should be concerned about the warming of northern Greenland because the region has a dozen sleeping giants in the form of vast tidewater glaciers and an ice stream … that will wake up. Greenland contributes to sea level risesaid Jason Box, a scientist at the Geological Survey of Denmark and Greenland.

Box Published research Last year suggested that in the current climate, Greenland is already losing out An amount of ice equal to about one foot above sea level. This promised sea level rise will only get worse as temperatures continue to warm.

The concern focuses on the Northeast Greenland Ice Stream, which channels a major portion of the ice sheet — 12 percent — toward the ocean. It is essentially a large slow-moving river that terminates in several very large glaciers that spill into the Greenland Sea. It already is getting thinnerAnd the glaciers at its endpoints have lost mass—one of them, Zakaria Istrom, has also lost its frozen shelf that once extended above the ocean.

Recent research It also demonstrated that during past warmer periods of Earth’s relatively recent history (ie, the last 50,000 years or so), this part of Greenland often contained less ice than it does today. In other words, the ice stream could extend further outward from the center of Greenland Can and can be sustained at current temperatures Tends to move back strongly and release a lot of ice.

“Paleoclimate and modeling studies suggest that Northeast Greenland is particularly vulnerable to climate warming,” said Beata Sisatho, an ice sheet expert at the University of Buffalo.

In the same year that the researchers were drilling the ice cores on which the current work is based – 2012 – Something interesting happened in Greenland. That summer, in July, vast portions of the ice sheet saw surface-melt conditions, including cold and very high-altitude locations where the study took place.

“This was the first year that you’ve been observed melting at this altitude,” Horholdt said. “And now it continues.”

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