Claim: Coastal Glacier Retreat Linked to Climate Change

Peer-Reviewed Publication

UNIVERSITY OF TEXAS AT AUSTIN

Eqip Sermia in Greenland
IMAGE: EQIP SERMIA, LIKE MANY COASTAL GLACIERS IN GREENLAND, HAS RETREATED IN THE LAST TWO DECADES. NEW RESEARCH FROM THE UNIVERSITY OF TEXAS INSTITUTE FOR GEOPHYSICS AND GEORGIA TECH PROVIDES A WAY TO DETERMINE HOW MUCH CLIMATE CHANGE IS INFLUENCING LARGE-SCALE GLACIAL MELTING. view more  CREDIT: JOHN ERICH CHRISTIAN/UNIVERSITY OF TEXAS INSTITUTE FOR GEOPHYSICS/GEORGIA TECH

More of the world’s coastal glaciers are melting faster than ever, but exactly what’s triggering the large-scale retreat has been difficult to pin down because of natural fluctuations in the glaciers’ surroundings. Now, researchers at the University of Texas Institute for Geophysics (UTIG) and Georgia Tech have developed a methodology that they think cracks the code to why coastal glaciers are retreating, and in turn, how much can be attributed to human-caused climate change. Attributing the human role for coastal glaciers – which melt directly into the sea – could pave the way to better predictions about sea level rise. 

So far, scientists have tested the approach only in computer models using simplified glaciers. They found that even modest global warming caused most glaciers to melt, or retreat.

The next step, the researchers said, is for scientists to simulate the coastal glaciers of a real ice sheet, like Greenland’s, which holds enough ice to raise sea level by about 22 feet (7 meters). That will reveal whether they are retreating due to climate change and help predict when major ice loss might next occur.

“The methodology we’re proposing is a road map towards making confident statements about what the human role is [in glacial retreats],” said glaciologist John Christian, who is a postdoctoral researcher at both The University of Texas at Austin and Georgia Tech. “Those statements can then be communicated to the public and policymakers, and help in their decision making.”

Published July 13 in the journal The Cryosphere, the methodology is unique because it treats rapid glacier retreat as an individual probabilistic event, like a wildfire or tropical storm. For a large retreat to happen, the glacier must retreat past its “stability threshold,” which is usually a steep rise in the underlying bedrock that helps slow its flow. The probability of that happening varies depending on local climate and ocean conditions that change with natural fluctuations and human-caused warming. Even small variations can cause large changes in a glacier’s behavior, making them hard to predict and leading to cases where glaciers were found retreating right next to ones that weren’t. 

That, said co-author and UTIG glaciologist Ginny Catania, is why the last Intergovernmental Panel on Climate Change report found there was still too much uncertainty about coastal glaciers to say whether their retreat is due to human-caused climate change or natural climate fluctuations. 

The new study shows how to overcome the uncertainty by providing a methodology that accounts for differences between glaciers and natural climate fluctuations, while testing the effect of background trends such as global warming. According to Catania, the study means they can now attribute mass coastal glacier retreat to climate change and not just natural variability.

“And that’s the first time anyone’s done that,” she said.

To test the methodology, the team ran thousands of simulations of the past 150 years with and without global warming. The simulations showed that even modest warming dramatically increased the probability of ice sheet-wide glacier retreat. 

When the scientists ran models without human-caused climate change, they found it virtually impossible for more than a few of the glaciers to begin retreating within years of each other.

By contrast, since 2000, nearly all (200) of Greenland’s 225 coastal glaciers have been in varying states of retreat.

“This study gives us a toolbox to determine the role of humans in the loss of ice from Greenland and Antarctica, to say with confidence that it’s not just coincidence,” said Georgia Tech glaciologist and co-author Alex Robel.

The research on coastal glaciers builds on previous work to understand the human role on the retreat of mountain glaciers — which is now well-established. The latest study was funded by UTIG and the National Science Foundation. UTIG is a research arm of UT Austin’s Jackson School of Geosciences.


JOURNAL

The Cryosphere

DOI

10.5194/tc-16-2725-2022 

METHOD OF RESEARCH

Computational simulation/modeling

ARTICLE TITLE

https://doi.org/10.5194/tc-16-2725-2022

ARTICLE PUBLICATION DATE

13-Jul-2022

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Tom Halla
July 16, 2022 6:04 pm

More models.

Bryan A
Reply to  Tom Halla
July 16, 2022 8:28 pm

12,000 years ago there were Coastal Ice Sheets and Floe Ice stretching down to Washington State in the Pacific and Long Island in the Atlantic. Then the Climate Changed and the floe ice receded northwards. Over the next 3,000 years the Ocean Sheet Ice was gradually replaced by seasonal floe ice and the land fast ice sheet began to melt away. 3,000 years later (4,000 once) the sea ice was gone and the seasonal floe ice had receded to just south of the bearing sea in the Pacific and south of the Labrador Sea south to Newfoundland. But the Climate continued to change and gradually, 3000 years later, the sea ice and floe ice reduction caused the glaciers to recede back to the margins of continental land glacial tongues over the oceans vanished. 3000 years later, the Climate continues to change and coastal glaciers have receded and reduced to land fast glaciers with glacial lakes and freshwater fjords between the calving margins and the oceans and the great land fast ice sheets have vanished. And the Climate continues to change…

Last edited 29 days ago by Bryan A
Bryan A
Reply to  Bryan A
July 16, 2022 10:38 pm

Dang autocorrect…(4000 once) should be (4000 bce)

Disputin
Reply to  Bryan A
July 17, 2022 3:47 am

4,000 BC?

Bryan A
Reply to  Disputin
July 17, 2022 5:13 pm

BC/AD = BCE/CE

Dave Fair
Reply to  Tom Halla
July 17, 2022 6:53 am

Certainly models: They tell you what you want to hear, Tom.

Ron Long
July 16, 2022 6:14 pm

During some natural climate cycles, while proto-humans were still in Africa, glaciers retreated naturally, how do you quantify the anthropogenic input? Models? NO. Measurements? NO. Using buzz words to get funding? Yes!

Scissor
Reply to  Ron Long
July 16, 2022 7:39 pm

Yes, it’s pretty funny that they use virtual reality to determine that something is virtually impossible in reality.

The fact is that the big warm up happened during mankind’s stone age when warming occurred and real and drastic sea level rise began to take place. It’s been fluctuating more or less above and below a cooling trend line since.

Last edited 29 days ago by Scissor
Old Man Winter
Reply to  Ron Long
July 16, 2022 11:18 pm

Researchers should occasionally look at the temperature graph below of the past 5M+ yrs to remind
themselves of the limits of trends.

A researcher said this about glaciers in NE Greenland: “the largest number of local glaciers in northeast Greenland have receded very greatly during recent decades, and it would not be exaggerating to say that these glaciers are nearing a catastrophe.”

That was from 1940!

https://realclimatescience.com/2022/04/1940-melting-greenland-glaciers-nearing-a-catastrophe/

“since 2000, nearly all (200) of Greenland’s 225 coastal glaciers have been in varying states of retreat”

It’s sad that my first instinct is to have to check to see if this is actually a true statement.

5MyT.jpg
Richard Page
Reply to  Old Man Winter
July 17, 2022 3:43 pm

Warm weather melts ice. Well holy sh$t, how on earth could we have possibly known that! It all makes sense now! sarc

Chris Hanley
July 16, 2022 7:05 pm

To test the methodology, the team ran thousands of simulations of the past 150 years

And they will keep running those simulations with different inputs until they get the answer they are looking for.

Bryan A
Reply to  Chris Hanley
July 16, 2022 8:30 pm

And if they can’t get their desired answer, they’ll torture the data until they do

Chris Hanley
Reply to  Chris Hanley
July 16, 2022 8:32 pm

Since there is no known mechanism that causes greenhouse gases to melt ice their entire study is an exercise in circular reasoning.

P_Vilefort
Reply to  Chris Hanley
July 16, 2022 9:12 pm

As I was reading this I kept wondering why there was no mention of previous Danish research on the Greenland ice sheets that show geothermal warming under the ice causing severe melting of the land glaciers. I was under the assumption that research builds upon previous research, but I guess it doesn’t. They keep looking for an atmospheric explanation when that is not where the heat is coming from.

Opus
July 16, 2022 7:12 pm

Modest warming causes ice to melt. Who’d have thunk it?

Coeur de Lion
Reply to  Opus
July 17, 2022 5:44 am

Yes, that struck me too. They ran ‘simulations’ where increases in temperature caused ice to melt. Wow.

Dave Fair
Reply to  Coeur de Lion
July 17, 2022 6:59 am

And then they attributed the increases to Man, without specifying the proof. It appears their “proof” is models.

Richard Page
Reply to  Dave Fair
July 17, 2022 3:47 pm

Exactly. Billions and billions of dollars spent on research over 50-odd years and still not one single shred of proof – just an interminable number of crappy studies linking an unprovable hypothesis to naturally occurring weather. Otherwise rational people have wasted their entire lives on this shit – what a terrible waste.

markl
July 16, 2022 7:52 pm

Another example of if you don’t look for it you won’t find it which seems to be the common denominator for all the “proof” of AGW.

Bob
July 16, 2022 8:12 pm

What on earth? Is it really that hard to find something useful to do with their (our) money rather than waste it on yet more models.

Gary Pearse
July 16, 2022 8:21 pm

I think these people actually believe that running hundreds of runs of their models generates real data! The very long word salad gives no hint of what the science is all about. In my experience, this is a ‘tell’ that this fanciful data will be put through a variety of statistical manipulations and p-hacking probes until they get a trend which they will interpret to show CO2 rise done it.

They haven’t got the memo yet that prominent climate modelers have admitted that the CO2 “temperature control knob models are running a way too hot and they don’t know why! (NASA’s Gavin Schmidt). For the last 8yrs, temperatures have been falling even though CO2 is galloping faster and faster. So what other agency generated by human activity is being called upon to shrink glaciers and why is sealevel rise linear at ~1.8mm a year over over more than a century? You gotta keep up girls!

DMacKenzie
Reply to  Gary Pearse
July 17, 2022 9:35 am

They even call a run of their models an “experiment”. … QED…

ATheoK
Reply to  Gary Pearse
July 17, 2022 6:24 pm

I think these people actually believe that running hundreds of runs of their models generates real data!”

Their quote:

To test the methodology, the team ran thousands of simulations of the past 150 years with and without global warming. The simulations showed that even modest warming dramatically increased the probability of ice sheet-wide glacier retreat.”

Which proves you are correct.

Thousands of simulations?
Not a mention of how much time they spent on every run. More likely they just piled up the ones they liked or in which they were personally involved.

Terry
July 16, 2022 9:31 pm

I can tell you why they are retreating – we’re coming out of the LIA where they expanded. Something we should all be grateful for. But listen you guys go ahead with your models, there is zero research money coming to you for stating the obvious.

Dave Fair
Reply to  Terry
July 17, 2022 7:01 am

And they expanded during the 1970s, at least.

Steve Case
July 16, 2022 11:52 pm

since 2000, nearly all (200) of Greenland’s 225 coastal glaciers have been in varying states of retreat.
____________________________________________________________

Loss or gain of Greenland ice is a function of how much snow fell years, decades, centuries or millennia ago, and how much ice calves into the sea. Given that the temperature over Greenland’s ice cap is rarely above freezing, temperature doesn’t have a lot to do with any ice gain or loss.

P_Vilefort
Reply to  Steve Case
July 17, 2022 1:24 am

There was a Danish research paper that I read in 2016 that showed from empirical measurements that the water rushing out from under one of the glaciers in the northern area of Greenland was at 32 F. If that is the temperature of the ice in contact with the bedrock, then there is a significant amount of heat being added to make the phase change from a solid to a liquid. The research paper stated that the heat is coming through the bedrock. The glaciers are melting from geothermal energy not any climate change. Something similar is occurring in Iceland.
That leads me to wonder if the same thing could be occurring throughout the Arctic and maybe even in the Antarctic region?

Disputin
Reply to  P_Vilefort
July 17, 2022 3:46 am

Certainly in the Antarctic. There over 100 active volcanoes under/through the ice in Western Antarctica.

Reply to  Disputin
July 17, 2022 7:48 am

Do you think that’s why the Antarctic seaice reached a minimum (satellite era) this year?

Right-Handed Shark
July 17, 2022 1:54 am

It’s bad enough when they attribute human influence to actual events, eg; “that hurricane was 10% stronger due to CO2” or whatever, but attribution studies on model outputs? What are these idiots smoking?

Last edited 29 days ago by Right-Handed Shark
Disputin
July 17, 2022 3:20 am

…could pave the way to better predictions about sea level rise.

We’ve already got very good predictions about sea level rise – i.e. at the same rate as for the last century and a half. Why would we need better ones?

M.W.Plia
July 17, 2022 5:37 am

Sublimation from nightly drier air is reducing the planet’s mountain glaciers to their previous “normal” positions. Glacial retreat moves quickly in comparison to glacial advance. Retreating ice is now revealing remnants of previous climate periods.

End moraines of glacier advances prior to the Medieval Warm Period indicate the glaciers of the Little Ice Age are the longest of the Holocene. The MWP/LIA is the last of four cycles of minor glacial advance and retreat in the past 6,000 years, perhaps linked to solar activity (sunspots) cycles. The colder “Dark Ages” and the “Roman Warm Period” were the previous cycle.

We may now be at or past the start of the warm half of the next millenial cycle, the “Current Warm Period” which, if like the last, may have legs for another century or two.

So this is common knowledge. Glacial advance/retreat is a natural phenomenon. The problem is the man made climate concept has been successfully oversold. Could be a long time before this nonsense finds its place on the back shelves alongside all the other stinky hobgoblins have come and gone.

Dave Etchells
July 17, 2022 5:44 am

This reminds me of how “warming” was attributed to CO2: “Well, we can’t make our models work unless we throw in a fudge factor that attributes “excess warming” to anthropogenic CO2″ (Of course, the data they were trying to fit to was gridded climate station data that pretty much only adjusts in the direction of increased warming. – That plus the UHI effect that pollutes a significant amount of the climate dataset.)

So it basically comes down to “We can’t figure it out, so we’ll just decide that it’s the fault of this Bad Thing that must be stopped.”

H. D. Hoese
July 17, 2022 7:38 am

“We emphasize that this study is not itself a formal attribution assessment for a particular glacier or region. Rather, we identify key physical principles that affect the likelihood of rapid marine-terminating glacier retreats in a noisy climate and show how model ensembles can be used to clarify the effects of anthropogenic forcing…..That is, we are fundamentally focusing on a conditional probability of industrial-era retreat (i.e., conditioned on the glacier not having already retreated)…..We assess this by running groups of aleatory ensembles, …..The simulations shown in Figs. 7a and 7b show only one realization of random climate anomalies. This means that the number of large retreats (in both scenarios) depends partly on the particular sequence of random anomalies. To illustrate this approach more generally, we run simulations for the same population of 177 glaciers with six levels of anthropogenic trends, using small aleatory ensembles ….In this paper, we have proposed a framework for attributing rapid marine-terminating glacier retreats to anthropogenic forcing trends…..Even if attribution statements have large uncertainty bounds at first, pursuing such studies may still clarify remaining challenges……Formal assessments would help focus discussion of recent and ongoing cryospheric change both within the scientific community and in the public.”

Aleotory– (from gambling) “1 Depending on an uncertain event or contingency as to both profit and loss 2 Relating to luck and esp. to bad luck.”

Dave Fair
Reply to  H. D. Hoese
July 17, 2022 8:17 am

Even if attribution statements have large uncertainty bounds at first, pursuing such studies may still clarify remaining challenges……Formal assessments would help focus discussion of recent and ongoing cryospheric change both within the scientific community and in the public.” Translation: This study is just guessing and shouldn’t be used for decisionmaking.

Pflashgordon
July 17, 2022 9:31 am

The current retreat in coastal glaciers began long before the modern rapid rise in CO2.

Hmm. If coastal temperatures and terrestrial temperatures increase slowly, then, duh, glaciers will tend to retreat (barring other influences). So those t-sips over in Austin (Texas A&M Aggies’ pejorative for our cross-state rivals) have revealed nothing new.

As for model projections, we all know they are sci-fi.

Walter Sobchak
July 17, 2022 11:43 am

Whenever these posts get to the words “computer models” I stop reading.

It saves time and brain cells.

ATheoK
July 17, 2022 6:13 pm

Now, researchers at the University of Texas Institute for Geophysics (UTIG) and Georgia Tech have developed a methodology that they think cracks the code to why coastal glaciers are retreating, and in turn, how much can be attributed to human-caused climate change. Attributing the human role for coastal glaciers – which melt directly into the sea – could pave the way to better predictions about sea level rise.”

More delusional grant seekers.

Let me know when their base period uses glaciers as they existed 5,000 years ago. Instead of peak glaciers during the LIA.

John in Oz
July 17, 2022 8:04 pm

attribute mass coastal glacier retreat to climate change and not just natural variability.

Why is climate change not part of natural variability?

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