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


The coldest and highest parts of the Greenland ice sheet, about two miles above sea level in many locations, are warming rapidly and showing changes unprecedented in at least a millennium, Scientists reported Wednesday.

That’s the finding from research that extracted several ice cores 100 feet or longer from the top of the world’s second largest ice sheet. The samples allowed the researchers to build a profile A new temperature record based on the oxygen bubbles stored within them, which reflects temperatures at the time the ice was originally applied.

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

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Since the warming has only continued since that time, the discovery is likely an underestimation of the climate The highlands of northern and central Greenland have changed. This is bad news for the planet’s coasts, as it signals the start of a long-term melting process that could eventually lead to a large, albeit difficult to quantify, portion of Greenland’s total mass in the oceans. All in all, Greenland contains enough ice to raise sea levels by more than 20 feet.

The study combined temperature records revealed by ice cores drilled in 2011 and 2012 with records found in older, longer cores that reflect temperatures above the ice sheet a millennium ago. The youngest ice found in these cores was older than 1995, which means they can’t say much about temperatures today.

The work also found that compared to the 20th century as a whole, this part of Greenland, the massive north-central region, is now 1.5 degrees Celsius (2.7 degrees Fahrenheit) warmer, and that the rate of melting and water loss from the ice sheet – which raises sea levels – has increased. increased in parallel with these changes.

The research was published in the journal Nature on Wednesday by Hörhold and a group of researchers at the Alfred Wegener Institute and two other institutions in Germany, the Niels Bohr Institute and the University of Bremen.

The new research “returns the instrument’s record 1,000 years using data from within Greenland that shows an unprecedented spike in warming in the recent period,” said Isabella Velicogna, a glaciologist at the University of California, Irvine who was not involved in the research.

“This doesn’t change what we already knew about the Greenland warming signal, the increased melting and the accelerating flow of ice in the ocean, and it’s going to be difficult to slow this down,” said Velikona. However, it adds momentum to the seriousness of the situation. This is bad news, bad for Greenland and for all of us.”

Scientists hypothesized that if the air over Greenland got warm enough, a feedback loop would occur: melting the ice sheet would cause it to sink to a lower elevation, which would naturally expose it to warmer air, which would cause further melting and shrinkage, and so on and so forth.

However, the fact that this north-central part of Greenland is 1.5°C warmer than it was in the 20th century does not necessarily mean that the ice sheet has reached the dreaded “tipping point”.

Recent research has I suggested Greenland’s dangerous threshold is around 1.5°C or higher of global warming – but that’s a different number than regional warming of the ice sheet. When the globe warms 1.5°C on average, which it could happen as soon as the 2030s, Greenland is likely to warm even higher – and even higher than it is now.

The researchers consulted by The Washington Post also highlight that the northern region of Greenland, where these temperatures were recorded, is known for other reasons to have the potential to cause significant sea level rise.

“We should be concerned about warming in northern Greenland because this region has dozens of sleeping giants in the form of vast tidal glaciers and ice streams…that have awakened the will Intensifying the contribution of sea level to Greenlandsaid Jason Box, scientist with the Geological Survey of Denmark and Greenland.

can Published research last year, suggesting that in the current climate Greenland is already destined to lose out An amount of ice equivalent to about a foot of sea level rise. This committed sea level rise is only going to get worse as temperatures continue to rise.

The concern is for the Northeast Greenland Ice Stream, which directs a large portion — 12 percent — of the ice sheet toward the sea. It is basically a huge slow moving river that ends with several very large glaciers that spill into the Greenland Sea. He already is the thinnestand the glaciers at the endpoint lost mass—one of them, Zachariah Istrom, also lost its frozen shelf that once extended over the ocean.

Recent research It also showed that in past warm periods within Earth’s relatively recent history (i.e., the last 50,000 years or so), this part of Greenland often contained less ice than it does today. In other words, the glacial stream may extend far from central Greenland than can be tolerated at current temperatures, and be Very prone to moving backwards and giving up a lot of ice.

“Paleoclimate studies and modeling indicate that northeastern Greenland is particularly vulnerable to a warming climate,” said Beata Ksathu, an ice sheet expert at the University at Buffalo.

The same year that researchers were drilling into the ice core on which the current work is based — 2012 — An amazing thing happened in Greenland. That summer, in July, large parts of the ice sheet experienced melt conditions at the surface, including the very cold and high altitude areas where the research was conducted.

“This was the first year that melt was observed at these elevations,” Horhold said. “And now it continues.”

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