Technology Greenland's glaciers could lose more ice than previously thought, raising concerns for sea level rise

08:55  18 november  2020
08:55  18 november  2020 Source:   cnn.com

Greenland Faces a Century of Unprecedented Ice Loss

  Greenland Faces a Century of Unprecedented Ice Loss Hey, we haven’t checked in on the Greenland in awhile, let’s see what’s hap Oh. Oh no.New research published on Wednesday in Nature shows the Greenland ice sheet is already pushing the boundaries of mass loss seen over the past 12,000 years. Even under the best-case climate scenario, where humanity rapidly draws down emissions starting ASAP, the ice sheet is set to hit unprecedented levels of loss over the course of the century.

Greenland ' s largest glaciers could lose even more ice than previously predicted -- a development that could have huge consequences for the rate of global sea level rise , according to a new study published Tuesday.

Greenland is known as the largest contributor to rising sea levels but a new study explores how the island' s glaciers could lose more ice than previously predicted. The three largest glaciers , Jakobshavn Isbræ, Kangerlussuaq and Helheim, are responsible for about 12% of the entire ice sheet

Greenland's largest glaciers could lose even more ice than previously predicted -- a development that could have huge consequences for the rate of global sea level rise, according to a new study published Tuesday.

a fish located in a body of water © NASA's Digital Mapping System team

Greenland's ice sheet is already melting rapidly, and that ice loss is one of the main contributors to rising sea levels. Planet-heating greenhouse gas emissions like carbon dioxide are accelerating this melt.

But what experts have less information on is how these vital glaciers have changed in the past, particularly in the centuries before satellite records existed. Understanding how glaciers have responded to past changes in climate can impact projections scientists make about how they may respond to future warming.

Greenland could lose more ice this century than it has in 12,000 years

  Greenland could lose more ice this century than it has in 12,000 years The rate of ice melt over the last two decades was comparable to the highest points in recent geologic history—and it’s still speeding up.The speed with which the Greenland ice sheet is melting is too quick to be part of a natural cycle, scientists say. If the entire sheet went away, it would add 24 feet to global sea levels.

Greenland ’ s melting ice sheet could generate more sea level rise than previously thought if greenhouse gas emissions continue to increase and warm the This new estimate is 80 percent higher than previous estimates, which forecasted up to 35 inches of sea level rise from Greenland ’ s ice .

A new study warns that Greenland ’ s ice is melting faster than scientists previously thought . However, Greenland is dwarfed by the Antarctic ice sheet, which could raise sea level 57 meters if And it’s clear more of the overall ice loss is coming from the surface than marine terminating glaciers

The new study, published in the journal Nature Communications, has filled in some of those gaps.

The researchers found that Greenland's glaciers are very sensitive to climate conditions, and have lost ice in the late-19th and early-20th century at rates that rival or surpass those seen today. With the planet -- and the Arctic in particular -- expected to warm much more this century, the scientists warn their findings show that ice loss on Greenland could exceed even the worst-case projections.

David Holland, a professor of mathematics and environmental science at New York University and a co-author of the study, said the team's findings show that the Arctic "is undergoing a one-two punch with respect to the loss of its land and sea ice covers in a warming world."

Hydrofracturing Is the Latest Concern for Antarctica’s Ice Shelves

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"The Greenland Ice Sheet is the largest land ice contributor to sea - level rise ," the study states. Future ice loss projections for glaciers — which drain approximately 12% of the Greenland Ice CNN also reported that sea - level rising could cause immense damages to cities located near water, such

Sea level rise is already subsuming coasts around the world, including many sandy or low-lying islands. But sometimes, if the coasts are steep, jagged, and formerly ice covered, melt can actually expose coastal features including whole islands. That’ s because many glaciers and ice sheets spill

Using historical photographs of the Jakobshavn, Helheim and Kangerlussuaq glaciers, the team calculated ice loss from 1880 to 2012. They estimated that the amount of ice lost from these three glaciers alone resulted in a sea level rise of 8.1 millimeters. Holland said that while the three glaciers are important in their own right, they also serve as proxies for the majority of the other outlet glaciers in Greenland, giving scientists a glimpse at how the entire ice sheet behaves.

Greenland's ice sheet is a dynamic place that is constantly shifting and moving. If we think of the interior of the ice sheet as a mountain lake, Moon says, these outlet glaciers are the streams fanning out from the lake, carrying ice away from it and in many cases, into the ocean. When ice breaks off from the glacier and lands in the ocean, it raises sea levels.

"These three glaciers are among the fastest moving in Greenland. When we think about these glaciers all around the edge of Greenland acting like conveyor belts (moving ice towards the ocean), these are some of the fastest, largest conveyor belts on the ice sheet," said Twila Moon, deputy lead scientist at the National Snow and Ice Data Center in Boulder, Colorado, who wasn't involved in the study.

"Greenland": Disaster thriller starring Gerard Butler hits theaters even earlier

 Originally planned for Christmas and then moved forward to October 29th, the hail of comets will hit German cinemas next week, October 22nd . Wherever the film has been shown in theaters so far, it has been a hit. © Metropolitan FilmExport "Greenland": disaster thriller with Gerard Butler comes to the cinema even earlier These days we have to keep reporting that film XY has been postponed again. But it also works the other way around.

Scientists say the loss of ice in Greenland lurched forward again last year, breaking the previous But the authors say ongoing emissions of carbon are pushing Greenland into an era of more Over the past 30 years, Greenland ' s contribution to global sea levels has grown significantly as ice losses

The three largest glaciers in Greenland —which hold enough frozen water to lift global sea levels some 1.3 metres— could melt faster than even the worst-case warming predictions, research published Tuesday showed. Until 2000, the main driver of sea level rise was melting glaciers and the

The glaciers also hold enough ice to raise global sea levels by roughly 1.3 meters.

Ice loss over time is driven by natural shifts in winds and ocean currents, and when warm waters get near the glaciers, they melt, Holland says. But human-caused warming has altered the climate and is changing how the winds and ocean interact with the ice sheet, and therefore influencing the amount of ice loss.

The team found that rates of ice loss for the Jakobshavn Glacier in the early 1900s were comparable to the huge rates of loss seen today, and for the Kangerlussuaq Glacier, ice loss between 1880 and 1930 was actually larger than present day.

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

Under a worst case-scenario in which humans continue to raise concentrations of these heat-trapping gases in the atmosphere, the planet could warm by 3.7 degrees Celsius (6.66 degrees Fahrenheit) by the end of this century.

If the glaciers have already suffered large ice losses when atmospheric and ocean temperatures were lower -- and the planet is set to warm even more under a high-emissions future -- the scientists say their findings could mean models used to predict future ice loss in Greenland could be underestimating how much will be lost by the end of the century.

Greenland's Most Threatened Glaciers Are in Even More Danger Than We Thought

  Greenland's Most Threatened Glaciers Are in Even More Danger Than We Thought Someday, I would like to write a happy story about ice. Today is not that day. © Photo: Sean Gallup (Getty Images) Ice breaking off from the 656-foot-tall (200-meter) face of the Eqip Sermia Glacier. Using historical photos and modern satellites, scientists have taken an unprecedented dive into understanding some of Greenland’s most imperiled glaciers.

That could also impact current projections of sea level rise.

Rising seas are already causing problems in many low-lying coastal areas. And for places like New York and Shanghai, 1 meter or more of sea level rise could spell disaster. Another recent study found that rising seas could cost the global economy $14.2 trillion in lost or damaged assets by the end of the century, and expose as many as 287 million people to episodic flooding, up from 171 million today.

"I think when it comes to the pace of change in Greenland and really with ice everywhere in the world, we're already at five-alarm status," said Moon. "And this paper is one more paper in that monstrous pile that says these are really serious changes, they're happening very quickly and we we need to be taking action as soon as possible so that we can try to reduce the rate of change in the future."

In the study, the scientists said that the possible underestimation of ice loss is likely "not limited to just these three glaciers," and that it was important that models capture rapid glacial retreat as a result of human-induced warming of our oceans and atmosphere "as they are the primary driver of mass loss."

The team hopes their findings on how glaciers are sensitive to changes in the climate will help increase the reliability of future projections of ice loss.

"The Arctic is losing ice, and as you look in greater detail over the last century, you see periods of more loss and less loss, but always loss," Holland said. "With increased warming projected to continue into the future, increased ice loss can be expected with potentially serious negative consequences for coastal cities around the world."

Ötzi the Iceman may have scaled ice-free Alps .
Ötzi the Iceman may have scaled ice-free AlpsThe ice that preserved Ötzi upon his death in about 3300 B.C. has melted since the mummy was discovered in 1991. But a new analysis of ice only 7.4 miles (12 kilometers) from where Ötzi was found suggests that only the very highest peaks were covered in glaciers until slightly before the iceman's lifetime. Just a few hundred years before Ötzi was born, nearby mountains may have been ice-free.

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