Researchers calculate decades of 'scary' Greenland ice melting

The Zachariae Glacier on Greenland's east coast is seen in a photograph taken by a NASA satellite
The Zachariae Glacier on Greenland's east coast is seen in a photograph taken by a NASA satellite

Measuring melting ice is a fairly precise business in 2019—thanks to satellites, weather stations and sophisticated climate models.

By the 1990s and 2000s, scientists were able to make pretty good estimates, although work from previous decades was unreliable due to less advanced technology.

Now, researchers have recalculated the amount of ice lost in Greenland since 1972, the year the first Landsat satellites entered orbit to regularly photograph the Danish territory.

"When you look at several decades, it is best to sit back in your chair before looking at the results, because it is a bit scary to see how fast it is changing," said French glaciologist Eric Rignot, of the University of California at Irvine.

Rignot co-authored the study, published in the Proceedings of the National Academy of Sciences (PNAS),with colleagues in California, Grenoble, Utrecht and Copenhagen.

"It's also something that affects the four corners of Greenland, not just the warmer parts in the south," he said.

Ice melting six times faster

Glaciologists use three methods to measure ice melting.

Firstly, satellites measure altitude with a laser: if a glacier melts, the satellite picks up its reduced height.

A second technique involves measuring variations in gravity, as ice loss can be detected through a decrease in gravitational pull. This method has been available since 2002 using NASA satellites.

Satellites are used to measure ice loss in Greenland
Satellites are used to measure ice loss in Greenland

Thirdly, scientists have developed so-called mass balance models, which compare mass accumulated (rain and snow) with mass lost (ice river discharges) to calculate what is left.

These models, confirmed with field measurements, have become very reliable since the 2000s, according to Rignot—boasting a five to seven percent margin of error, compared to 100 percent a few decades ago.

The research team used these models to "go back in time" and reconstruct Greenland's ice levels in the 1970s and 1980s.

The limited data available for this period—medium-quality satellite photos, aerial photos, ice cores and other observations—helped refine them.

"We added a little bit of history that did not exist," said Rignot.

The results: during the 1970s, Greenland accumulated 47 gigatonnes of ice per year, on average. Then, it lost an equivalent volume in the 1980s.

The melting continued at that rate in the 1990s, before a sharp acceleration in the 2000s (187 Gt/year) and even more since 2010 (286 Gt/year).

Ice is melting six times faster than in the 1980s, researchers estimate—and Greenland's glaciers alone have contributed to a 13.7 millimeter rise in sea levels since 1972, they believe.

"This is an excellent piece of work by a well-established research group using novel methods to extract more information from the available data", said Colin Summerhayes, of the Scott Polar Research Institute in Cambridge.

As with a similar study carried out by the same team on Antarctica, the new study affords a longer term view of the rapid ice melt being observed in Greenland in recent years.

"This new data better enables us to put recent, dramatic, changes to Greenland's contribution to global sea level rise into a longer-term context—the ice loss we've seen in the last eight years is as much as was lost in the preceding four decades," said Amber Leeson, a lecturer in Environmental Data Science at Lancaster University.


Explore further

Melting glaciers causing sea levels to rise at ever greater rates

More information: Jérémie Mouginot el al., "Forty-six years of Greenland Ice Sheet mass balance from 1972 to 2018," PNAS (2019). www.pnas.org/cgi/doi/10.1073/pnas.1904242116

© 2019 AFP

Citation: Researchers calculate decades of 'scary' Greenland ice melting (2019, April 22) retrieved 18 July 2019 from https://phys.org/news/2019-04-decades-scary-greenland-ice.html
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Apr 22, 2019
Greenland's glaciers alone have contributed to a 13.7 millimeter rise in sea levels since 1972, they believe

13.7 millimeters is about half an inch. That works out to...divide by 47 years... Greenland's melting glaciers contribute 0.29 millimeters per year to sea level rise...they think.

It's pretty hard to get worked up about that, but I'm not a climate alarmist. The "scary" Greenland glacier melt is having no meaningful impact to anyone on earth.

Fyi, latest measurements of global sea level rise trend, according to satellite telemetry, here:

http://sealevel.colorado.edu/

Apr 22, 2019
it is best to sit back in your chair before looking at the results

Actually, it would be better if you sat back in your toilet, since this is just more shite from the AGW Cult.
https://notricksz...0-years/

Apr 22, 2019
Goony little bozo climate deniers. We'll easily get 7 meters of sea level rise from just Greenland's ice melt from anthropogenic global warming (AGW ie... man-made global warming from CO2 and other greenhouse gasses). https://www.scien...meltdown

But to you bozos it doesn't matter does it. You have not life, nor do you care about it. To you deniers, it's all about supporting TRUMP and the idiot squad that voted for the moron.


Apr 22, 2019
pretty hard to melt Greenland when its at least 15 below freezing year round . so they are saying the earths temps are going to rise 20 degrees

Apr 22, 2019
to aksdad: get a life, give me your email adress if you need money I will send it to you, but please stop doing this contribution to climate destuction if you have any hearth left.

melting is accelerating fast, these gas will stay 350 years in the atmosphere,
Multiply 1 by 2, then 2 x 2, than 4 by 2, and so on until 64, the result and the sum of all is immense soon.
At this rate of melting acceleration, the loss of Greenland pretty will prove too much in several generations.


Apr 22, 2019
pretty hard to melt Greenland when its at least 15 below freezing year round. so they are saying the earth's temps are going to rise 20 degrees
You wish Greenland was 15 below-zero year round. BS. Fake factoid dude! Greenland is melting and very fast as are ice sheet across the globe like glaciers, the Arctic and Antartic ice sheets. Even Russia's massive Siberian permafrosts are now being devastated by global warming.

It's common knowledge that higher temperatures melt ice more quickly. If you think otherwise, there is something seriously wrong with your brain cells. You may have Rightwing Flakeoid Disease.

Apr 22, 2019
Goony little bozo climate deniers. We'll easily get 7 meters of sea level rise from just Greenland's ice melt from anthropogenic global warming (AGW ie... man-made global warming from CO2 and other greenhouse gasses). https://www.scien...meltdown

But to you bozos it doesn't matter does it. You have not life, nor do you care about it. To you deniers, it's all about supporting TRUMP and the idiot squad that voted for the moron.



Maybe you should go somewhere else to insult people. If you don't want to have a respectful discussion then don't say anything at all!

Apr 22, 2019
Liar... Liar.. Pants on fire.....

pretty hard to melt Greenland when its at least 15 below freezing year round . so they are saying the earths temps are going to rise 20 degrees


If global temperatures rose by just 8'C then the human race would largely go extinct.

Apr 22, 2019
Maybe you should go somewhere else to insult people. If you don't want to have a respectful discussion then don't say anything at all!
Yeah... maybe you should do something then, like actually contribute to the discussion. I'm just a pissed off scientist. Go eat me.

The issue here are morons that refuse to see science for what it is. You certainly qualify for one of those bozo types if I may add instead of agreeing with the article. Facts are facts boys. You're either with the nimwit side or you're the side that wants to help our planet and mankind's aspirations and ascensions.

Apr 22, 2019
excellent news, if it continues this pace of accelerated melting canada, northern europe and russia and norther united states should benefit greatly from higher average temperatures due to reduced albedo. also, greenland itself will have more arable liveable area. keep up the great work and keep melting that ice baby!

Apr 23, 2019
Wow! Millions of acres of new land will be usable in Canada, Greenland, Norway, Iceland, Russia. That's a pretty good trade-off for some crappy islands and old coastal cities with infrastructures so decrepit it'll cost TRILLIONS to fix them. There IS no downside.

Apr 23, 2019
"The acceleration in mass loss switched from positive in 2000–2010 to negative in 2010–2018 due to a series of cold summers" -French glaciologist Eric Rignot, of the University of California at Irvine

That is some dangerously serious weapons-grade Bovine Scatology when you have to admit and cannot deny that the Greenland Ice Sheet is and has been expanding since 2010 as acceleration in mass loss switched from positive to negative.

Super Grand Solar Minimum Much? Check with Professor Valentina Zharkova for some fact about upcoming major crop losses, mass starvation, collapse of governments due to our Maunder Minimum.

Apr 23, 2019
Greenland is melting and very fast as are ice sheet across the globe like glaciers, the Arctic and Antartic ice sheets..


From: "An Inconvenient Glacier: Study Shows Greenland Glacier Growing "

"Over the past two decades, the Jakobshavn Glacier in Greenland had been melting at what climate alarmists might term an alarming rate. However, a new study published in Nature Geoscience has concluded that since 2016, the Jakobshavn Glacier is now growing again."

Apr 23, 2019
The water in Disko Bay, where the glacier meets the Atlantic, is now 3.6 degrees Fahrenheit cooler than it was just a few years ago, causing the Jakobshavn Glacier to grow. Water temperatures in the vicinity of the glacier are now colder than they've been since the mid-1980s.

Apr 26, 2019
The Giant Camels of the Prehistoric High Arctic
https://www.natio...-arctic/

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