Extreme Temperature Diary- Tuesday March 28th, 2023/ Main Topic: Greenland Ice Sheet Maybe Beyond Hope of Saving

The main purpose of this ongoing blog will be to track global extreme or record temperatures related to climate change. Any reports I see of ETs will be listed below the main topic of the day. I’ll refer to extreme or record temperatures as ETs (not extraterrestrials).😉

Main Topic: Greenland Ice Sheet Maybe Beyond Hope of Saving

Dear Diary. Some of the direst tipping points that I’ve been tracking for decades are those affecting the Greenland ice sheet. Greenland is becoming much more vulnerable as surrounding sea ice disappears. If all of Greenland’s ice were to melt our seas would rise approximately twenty feet, inundating all coastal cities worldwide. As of 2023 can we save it by stopping the use of fossil fuels cold turkey? Yes, according to a new study, but it doesn’t look like we as a species will shut off the fossil fuel spigots completely anytime soon.

Certainly, we should accelerate our efforts to go towards a green society and away from fossil fuels. But when does climate reality trump those trying to mitigate the climate crisis who are presenting a rosy picture for activism? After reading the following report you decide:

MARCH 27, 2023

 Editors’ notes

The Greenland Ice Sheet is close to a melting point of no return, says new study

by American Geophysical Union

Equilibrium states of the volume of the Greenland Ice Sheet (GIS) (black dots) with respect to pre-industrial as a function of atmospheric CO2 concentration (top left) and corresponding temperature anomaly (top right). The blue curve refers to increasing CO2 concentration starting from the pre-industrial GIS, the other curves to decreasing CO2 starting from a completely ice free GIS (red curve) and from intermediate states (yellow and purple curves), respectively. The bottom panel illustrates the GIS thickness at the points A–D. Credit: Geophysical Research Letters (2023). DOI: 10.1029/2022GL101827

The Greenland Ice Sheet covers 1.7 million square kilometers (660,200 square miles) in the Arctic. If it melts entirely, global sea level would rise about 7 meters (23 feet), but scientists aren’t sure how quickly the ice sheet could melt. Modeling tipping points, which are critical thresholds where a system behavior irreversibly changes, helps researchers find out when that melt might occur.

Based in part on carbon emissions, a new study using simulations identified two tipping points for the Greenland Ice Sheet: releasing 1000 gigatons of carbon into the atmosphere will cause the southern portion of the ice sheet to melt; about 2500 gigatons of carbon means permanent loss of nearly the entire ice sheet.

Having emitted about 500 gigatons of carbon, we’re about halfway to the first tipping point.

“The first tipping point is not far from today’s climate conditions, so we’re in danger of crossing it,” said Dennis Höning, a climate scientist at the Potsdam Institute for Climate Impact Research who led the study. “Once we start sliding, we will fall off this cliff and cannot climb back up.”

The study was published in the journal Geophysical Research Letters.

The Greenland Ice Sheet is already melting; between 2003 and 2016, it lost about 255 gigatons (billions of tons) of ice each year. Much of the melt to date has been in the southern part of the ice sheet. Air and water temperatureocean currents, precipitation and other factors all determine how quickly the ice sheet melts and where it loses ice.

The complexity of how those factors influence each other, along with the long timescales scientists need to consider for melting an ice sheet of this size, make it difficult to predict how the ice sheet will respond to different climate and carbon emissions scenarios.

Previous research identified global warming of between 1 degree to 3 degrees Celsius (1.8 to 5.4 degrees Fahrenheit) as the threshold beyond which the Greenland Ice Sheet will melt irreversibly.

To more comprehensively model how the ice sheet’s response to climate could evolve over time, Höning’s new study for the first time used a complex model of the whole Earth system, which includes all the key climate feedback processes, paired with a model of ice sheet behavior. They first used simulations with constant temperatures to find equilibrium states of the ice sheet, or points where ice loss equaled ice gain. Then they ran a set of 20,000-year-long simulations with carbon emissions ranging from 0 to 4,000 gigatons of carbon.

From among those simulations, the researchers derived the 1,000-gigaton carbon tipping point for the melting of the southern portion of the ice sheet and the even more perilous 2,500-gigaton carbon tipping point for the disappearance of nearly the entire ice sheet.

As the ice sheet melts, its surface will be at ever-lower elevations, exposed to warmer air temperatures. Warmer air temperatures accelerate melt, making it drop and warm further. Global air temperatures have to remain elevated for hundreds of years or even longer for this feedback loop to become effective; a quick blip of 2 degrees Celsius (3.6 degrees Fahrenheit) wouldn’t trigger it, Höning said. But once the ice crosses the threshold, it would inevitably continue to melt. Even if atmospheric carbon dioxide were reduced to pre-industrial levels, it wouldn’t be enough to allow the ice sheet to regrow substantially.

“We cannot continue carbon emissions at the same rate for much longer without risking crossing the tipping points,” Höning said. “Most of the ice sheet melting won’t occur in the next decade, but it won’t be too long before we will not be able to work against it anymore.”

More information: Dennis Höning et al, Multistability and Transient Response of the Greenland Ice Sheet to Anthropogenic CO2 Emissions, Geophysical Research Letters (2023). DOI: 10.1029/2022GL101827

Journal information: Geophysical Research Letters 

Provided by American Geophysical Union 

Explore further

Vast ice sheet facing climate fight on two fronts, study finds

Here are some “ET’s” recorded from around the planet the last couple of days, their consequences, and some extreme temperature outlooks, as well as any extreme precipitation reports:

Here is more climate and weather news from Tuesday.

(As usual, this will be a fluid post in which more information gets added during the day as it crosses my radar, crediting all who have put it on-line. Items will be archived on this site for posterity. In most instances click on the pictures of each tweet to see each article. The most noteworthy items will be listed first.)

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Guy Walton… “The Climate Guy”

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