Wednesday , December 8 2021

Greenlandic glaciers may lose more ice than expected, raising concerns about rising sea levels


What experts have less information about is how these key glaciers have changed in the past, especially in the centuries before satellite records existed. Understanding how glaciers have responded to past climate change may have an impact on scientists ’projections of how they might respond to future warming.

Researchers have found that Greenland’s glaciers are very sensitive to climatic conditions, and have lost ice in the 19th century. At the end of the century and the twentieth. At rates that match or exceed what was initially observed today. As the planet (and especially the Arctic) is expected to warm much more in this world, scientists have warned that ice loss in Greenland could exceed even the worst case projections.

David Holland, a professor of mathematics and environmental sciences at New York University, said the group’s findings show that the Arctic “is experiencing two touches in a world that is warming its skin in terms of losing its land and sea ice.”

Using historical photographs of the Jakobshavn, Helheim and Kangerlussuaq glaciers, the group calculated ice loss from 1880 to 2012. The amount of ice lost in these three glaciers alone was estimated to have risen to sea level by 8.1 millimeters. Hollande said that although the three glaciers are inherently important, they also serve as a representative of most of the other glaciers at the Greenland exit, to see how scientists play the entire ice sheet.

Research shows that the Greenland ice sheet has been melting as fast as it has at any time in the last 12,000 years

The Greenland ice sheet is a dynamic place that is constantly changing and moving. According to the moon, if we think that the interior of the ice sheet is a mountain lake, these exit glaciers are currents that flow out of the lake, carrying ice from there and in many cases to the ocean. When ice rises from the glacier and lands in the ocean, sea level rises.

“These three glaciers are one of the fastest moving in Greenland. When we think that these glaciers on all the edges of Greenland act as conveyor belts (they move ice to the ocean), they are one of the largest fast transporters in the ice sheet,” said Boulder, who did not participate in the Twila Moon study. ) Senior scientists from the National Snow and Ice Data Center.

Glaciers also have enough ice to raise sea levels by about 1.3 meters.

Ice loss is caused by natural changes in winds and ocean currents over time, and when warm waters approach glaciers, they melt, Hollande says. But human-caused warming has changed the climate and is changing how wind and oceans interact with the ice sheet, thus causing an amount of ice loss.

The group found that the ice loss rates of the Jakobshavn Glacier in the 1900s were comparable to the large loss rates observed today, and that the ice loss between 1880 and 1930 on the Kangerlussuaq Glacier was greater than it is today.

This is significant because it shows that glaciers were losing large amounts of ice at a time when global temperatures were lower than they are now.

In the worst case in which the concentration of these gases continues to rise to capture heat in the atmosphere, the planet could be warming to 3.7 degrees Celsius (6.66 Fahrenheit) by the end of this century.

If glaciers have already suffered significant ice losses when atmospheric and ocean temperatures were lower – and the planet would heat up even more in the future with high emissions – scientists say their findings could be models used to predict future ice loss. Greenland can underestimate how much it will lose by the end of the century.

Let’s talk about the climate apocalypse

This may also affect current projections of sea level rise.

Rising seas are already causing problems in many areas of the lower coast. And in places like New York and Shanghai, rising a meter or more above sea level can wreak havoc. Another recent study found that rising seas would cost the world economy $ 14.2 trillion in lost or damaged assets by the end of the century, and could cause 287 million people to experience episodic floods, now more than 171 million.

“I think in terms of the pace of change in Greenland and wherever the ice is anywhere in the world, we are already in a state of five alarms,” Moon said. “And this article is another huge monster paper that says that changes are really serious. They’re happening very fast and we need to take action as soon as possible so we can try to reduce the rate of change in the future.”

In the study, scientists said it was likely to underestimate ice loss “not just limited to these three glaciers,” and that it was important for models to capture rapid glacial retreat as a result of human-caused warming in our oceans and atmosphere. “because they are the main cause of mass loss.”

The group hopes that knowing how sensitive glaciers are to climate change will increase the reliability of future projections of ice loss.

“The Arctic is losing ice, and if we look at it in more detail over the last century, we see more and less losses, but always losses,” Hollande said. “Looking to the future with greater warming, increased ice loss can be expected to have serious negative effects on coastal cities around the world.”

CNN’s Ivana Kottasova contributed to this report.

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