UNIVERSITY OF CAMBRIDGE
CREDIT: FRAZER CHRISTIE
Despite the rapid melting of ice in many parts of Antarctica during the second half of the 20th century, researchers have found that the floating ice shelves which skirt the eastern Antarctic Peninsula have undergone sustained advance over the past 20 years.
Ice shelves – floating sections of ice which are attached to land-based ice sheets – serve the vital purpose of buttressing against the uncontrolled release of inland ice to the ocean. During the late 20th century, high levels of warming in the eastern Antarctic Peninsula led to the catastrophic collapse of the Larsen A and B ice shelves in 1995 and 2002, respectively. These events drove the acceleration of ice towards the ocean, ultimately accelerating the Antarctic Peninsula’s contribution to sea level rise.
Currently, the jury is out on exactly how sea ice around Antarctica will evolve in response to climate change, and therefore influence sea level rise, with some models forecasting wholescale sea ice loss in the Southern Ocean, while others predict sea ice gain.
Now, an international team of researchers, from the Universities of Cambridge and Newcastle in the UK, and the University of Canterbury in New Zealand, have used a combination of historical satellite measurements, along with ocean and atmosphere records, to get the most detailed understanding yet of how ice conditions are changing along the 1,400-kilometre-long eastern Antarctic Peninsula.
They found that 85% of the ice shelf perimeter in this part of Antarctica has advanced since the early 2000s, in contrast to the extensive retreat of the previous two decades. The advance is linked due to decade-scale changes in atmospheric circulation, which has led to more sea ice being carried to the coast by wind.
The results, reported in the journal Nature Geoscience, suggest that sea ice plays an important role in stabilising ice shelves, much like ice shelves themselves stabilise and buttress ice sheets.
“We’ve found that sea-ice change can either safeguard from, or set in motion, the calving of icebergs from large Antarctic ice shelves,” said Dr Frazer Christie from Cambridge’s Scott Polar Research Institute (SPRI), the paper’s lead author. “Regardless of how the sea ice around Antarctica changes in a warming climate, our observations highlight the often-overlooked importance of sea-ice variability to the health of the Antarctic Ice Sheet.”
In 2019, Christie and his co-authors were part of a SPRI-led expedition to study ice conditions in the Weddell Sea offshore of the eastern Antarctic Peninsula, a notoriously difficult part of the Southern Ocean to reach given the thick and year-round presence of sea ice.
“During the expedition, we noted that parts of the ice-shelf coastline were at their most advanced position since satellite records began in the early 1960s,” said expedition chief scientist and study co-author Professor Julian Dowdeswell, also from SPRI.
Following the expedition, the team used satellite images going back 60 years, as well as state-of-the-art ocean and atmosphere models, to investigate in detail the spatial and temporal pattern of ice-shelf change.
So what caused the ice shelves to advance? In the absence of atmosphere and ocean warming over the past 20 years, the dominant control was found to be a change in regional wind patterns over the Weddell Sea, which served to push sea ice against the ice shelves.
Between 1985 and 2002, in contrast, wind conditions in the same area caused sea ice to move away from the coast. By removing the buttressing effect of the sea ice and exposing the ice shelves to damaging ocean waves, stress on the ice shelves increased, ultimately leading to calving of icebergs.
In almost all cases throughout the satellite era, calving from the eastern Antarctic Peninsula’s ice shelves only occurred during or shortly after the removal of sea ice in some form.
However, it’s possible that this period of ice advance may be ending. Since 2020, there has been a notable increase in the number of icebergs breaking away from the eastern Antarctic Peninsula. “It’s entirely possible we could be seeing a transition back to atmospheric patterns similar to those observed during the 1990s that encouraged sea-ice loss and, ultimately, more ice-shelf calving,” said co-author Dr Wolfgang Rack from the University of Canterbury.
The work was made possible thanks to the free, open-access availability of the historical satellite record by space agencies and partners including NASA and the joint European Commission—European Space Agency Copernicus Programme.
The research was supported in part by the Flotilla Foundation, Marine Archaeology Consultants Switzerland, and the Prince Albert II of Monaco Foundation.
JOURNAL
Nature Geoscience
DOI
ARTICLE TITLE
Antarctic ice-shelf advance driven by anomalous atmospheric and sea-ice circulation
ARTICLE PUBLICATION DATE
5-May-2022
This study was superfluous.
The “Ship Of Fools” excursion demonstrated quite dramatically how the force of sea ice can arrest movement.
YouReekAlot! Say no more.
See my just posted comment below.
Hmm what can we say about Antarctic ice today?
Cue griff and a penguin…
Aren’t they “birdbrains of a feather” as they both have “laid an egg” many times? 😮
The health of a continental glacier system is 99% determined by events in the Recharge Zone. This is the internal continental area that is snowed on, accumulates sufficient load to compress the snow into ice which has a plastic state, and flows down-slope. OK, if you are a passenger on the Ship Of Fools you should monitor thr peripheral floating ice, but otherwise forgetaboutit.
Zwally’s two most recent Antarctic ice mass balance papers have it neutral or slightly positive. Reason being a slightly warmer summer means more snow. Usually in winter it is too cold and dry to snow anywhere in Antarctica at all except on the Peninsula.
“Following the expedition, the team used satellite images going back 60 years, as well as state-of-the-art ocean and atmosphere models, to investigate in detail the spatial and temporal pattern of ice-shelf change.”
GIGO Alert. and when they got home they played video games.
More junk non-science. Nothing to see here. Move along.
They found that the models were crap, but just didn’t have the heart to say it.
”State-of-the-art” apparently means “we just can’t get these models to work in the real world but they will always satisfy our natural pessimism”.
“the Prince Albert II of Monaco Foundation.”
Was he in a can?
😁thanks for the laugh😁
No, but he is in the bag.
This claim has been made for years. However, I find it dubious at best. Newton’s First Law states that an object in motion will maintain its direction and speed unless acted on by some external force. Floating pack ice experiences negligible friction with the water. However, if it freezes onto the leading edge of a glacier, it inherits the momentum of the ice. That is, it will continue the direction and speed of the glacier.
For calving to occur, there must be tension cracks. If the pack ice were resisting the glacier, any tension cracks would be closed and the pressure would fuse the two blocks of ice.
Now, if the pack ice were thick enough to reach an underwater bedrock ridge, or submerged terminal moraine, then it would experience resistance from the unmoving bottom because the bottom has no forward momentum. However, if the glacier were to advance sufficiently, it also would experience the same resistance, with or without pack ice. What they may be observing is an underwater barrier resisting the pack ice frozen to the glacier snout.
For pack ice that freezes to the shoreline, it will experience some adhesion that will create stress along the boundary between the stationary and moving pack ice. However, all things considered, I think that the friction of ice over bedrock is going to be orders of magnitude greater than the lateral stress between the moving and stationary ice.
If the bedrock has been planed smooth by a glacier, and has few irregularities, then the friction can be reduced by melting at the contact, allowing the water to act as a lubricant. However, I don’t see how the presence of pack ice can affect the melting of ice. One possibility might be that the tides will lift the pack ice and in doing so add some buoyancy to the glacial ice it is frozen to, and allow sea water to get under the leading edge.
Currents driven by wind are probably a greater force acting on the pack ice than anything else.
Like so much of climastrology, there is still a lot that is poorly known and I don’t give a lot of credence to the claims of pack ice acting as a buttress.
You’re right Clyde…the ice shelf can’t “push back” on the glacier ice unless it is in a fjord or grounded…the only force on it is the prevailing winds, maybe some freezing “stiction” which tension cracks will soon eliminate…..whether the floating shelf is there or not won’t make any change to the downslope advance of an on-land glacier that terminates in the ocean.
Posted in wrong place.
The words in question (from the article):
“By removing the buttressing effect of the sea ice and exposing the ice shelves to damaging ocean waves, stress on the ice shelves increased, ultimately leading to calving of icebergs.
“In almost all cases throughout the satellite era, calving from the eastern Antarctic Peninsula’s ice shelves only occurred during or shortly after the removal of sea ice in some form.”
The word ‘buttressing’ is half figurative: the authors are not saying sea ice pushes back against glaciers but that it prevents melting by protecting the ice shelf from waves. We might add that the sea ice also prevents salt spray on the glaciers and lowers the temperature slightly. Whatever the mechanism, the claimed correlation is the overriding takeaway. –AGF
Then they should have used the words “barrier” or “armor.” It is common to use the term “armored” with respect to placing rip-rap on coasts to reduce the impact of waves on the beach or cliffs. If the authors are indeed not claiming that the shelf ice impedes the forward movement of the glacier, then is it a significant departure from what has been claimed for years.
I suspect that cracks will occur in any expanding pack ice as the circumference is increasing, and the edge of the ice sheet has to either get thinner or crack as it is pushed out
Except that the ice isn’t actually expanding. New ice is crystallizing on the leading edge, allowing space to be filled in by ice.
An ice shelf is nothing but sea ice that has come from the land out over the water. The alarmist scientists continually speak of them as if they are stable, permanent, structures. They are no such thing. They are big damned ice cubes that are attached to terrestrial ice that is grounded.
Their size and very existence depend on many variables. And not matter what, they have liquid salt water underneath them that is not freezing. Never mind weather effecting the feeding glacier and conditions of the ocean they float upon. And then of course there is seismic activity and vulcanism.
“During the late 20th century, high levels of warming in the eastern Antarctic Peninsula led to the catastrophic collapse of the Larsen A and B ice shelves in 1995 and 2002, respectively. “
How can this be ‘catastrophic’? It’s ice and can melt or calve or freeze.
Yea, people think that catastrophic can only mean an event causing mass hardship, injury, or death. When in fact one definition is merely a sudden large scale change in a body, mass, or structure.
To them, catastrophic means any change. because any change is bad and caused by humans. Doesn’t matter if the same changes occurred before humans even existed.
I think we should call “them” Climate Karens.
Anything that happens naturally can be called “catastrophic” due to its sheer size. Volcanoes, landslides and floods for instance. But there are different sizes of catastrophe, all are subjectively measured and usually involve loss of human lives or property. None of which are quantified in this article.
Antarctica is 14,200,000 km² and except for the peninsula is 100% frozen at all times. The peninsula is 522,000 km² and is 80% frozen. The Larsen A and B ice shelves together are much smaller than that and are both are above 70 degrees south latitude.
No humans were lost or injured in the “catastrophic collapse” and it certainly has happened before because ice never stops flowing.
Yeah. Claims of catastrophe come from the “Climate Should Never Change!” camp.
There are time-lapse videos that showed the alleged “collapse” of the Larsen A & B ice shelves were temporary as they quickly refroze nearby.
“Watch the Wilkins ice shelf collapse in time lapse animation – looks like ‘current’ events to me”
Not possible. Flawed science: no mention of CO2.
You know Eureka Alert is bad when the first sentence about this paper talks about a half century of Antarctic ice sheet melt. It hasn’t—too cold. The peak summer temperature at McMurdo (on the coast) ranges between 23F and 31F. Icebergs do calve off, float away, and eventually melt far away from the ice sheet that spawned them.
And Zwally’s two most recent papers on the Antarctic ice mass balance show it is either neutral or slightly positive (net small gain DESPITE global warming). Because ‘warmer’ means more summer snow to replenish the ice sheet.
This new research paper would have been better described as an Antarctic all expenses paid (research) summer vacation followed by a publish or perish writeup of playing some computer games (climate models).
“Currently, the jury is out on exactly how sea ice around Antarctica will evolve in response to climate change”
So the science is not settled and we have no idea if ice is growing or shrinking now or in the future
Even though they started with “Despite the rapid melting of ice in many parts of Antarctica during the second half of the 20th century”
Words fail
Quote concerning sea ice:
“Partial explanations have been offered, but we don’t have the complete picture,” said Ted Scambos, a scientist at NSIDC DAAC. “This may just be a case of ‘we don’t know yet.’”
https://wattsupwiththat.com/2021/02/01/unexpected-ice/
Next thing you know, they’ll admit “the science may not be settled” yet- pigs will fly & the weather
bureau will report that Hell froze over, too!
As an aside, Scambos was a lead author of a paper that used actual satellite data to locate what
may have been the coldest temperature on earth @ 82.07°S, 60.72°E on 22/23 Jul 2004. The
estimate was from a slight sinkhole, the same phenomena found @ Peter Sinks (& nearby Middle
Sink- S of US89, just E of Logan Canyon, which is a very scenic drive on a sunny day)
in NE Utah in 1983- 41°54′45″N 111°30′50″W. Using data- not models- & using the phrase “we
don’t know yet” are sure signs he needs to be re-educated!
https://en.wikipedia.org/wiki/Lowest_temperature_recorded_on_Earth#cite_note-5
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018GL078133
https://en.wikipedia.org/wiki/Peter_Sinks
Floating sea ice slows up grounded ice flowing into the sea…
Nonsense.
All of the graphics and pictures in their paper do not prove any part of their belief system.
However:
It is all models and confirmation bias.
Their lead off sentence in the abstract clearly identifies their presumption/preference for global warming as the primary cause.
Let me repeat:
The words in question (from the article):
“By removing the buttressing effect of the sea ice and exposing the ice shelves to damaging ocean waves, stress on the ice shelves increased, ultimately leading to calving of icebergs.
“In almost all cases throughout the satellite era, calving from the eastern Antarctic Peninsula’s ice shelves only occurred during or shortly after the removal of sea ice in some form.”
The word ‘buttressing’ is half figurative: the authors are not saying sea ice pushes back against glaciers but that it prevents melting by protecting the ice shelf from waves. We might add that the sea ice also prevents salt spray on the glaciers and lowers the temperature slightly. Whatever the mechanism, the claimed correlation is the overriding takeaway. –AGF
I think that you are misrepresenting what at least the abstract says:
You suggest that waves lapping at the seaward edge of the Larson ice shelves were responsible for them breaking away — they are HUGE and it is difficult to imagine how what is happening at the seaward edge is going to cause them to break away ten’s of miles inland.
I suppose if the volcanic seam ran under the ice shelves rather than under the land ice …
One of the pillars of the failure and dysfunction of climate science is reductionism – seeing the system a clockwork mechanism of simple linear causation and refusing to accept the implications of complexity and emergent system dynamics.
This leads to these endless and pointless chicken-and-egg circular arguments about what caused what. These arguments only advertise their wilful ignorance of the true nature of the system. The atmosphere-ocean-cryosphere is a coupled system; although the most influential and longest term dynamics and changes are probably those of the ocean, since that’s where most of the energy is. Followed by the massive Antarctic cryosphere.
The least influential of all parts is the atmosphere. Myopic focus on the atmosphere only is another signature of failure of climate science. I guess the cultural paradigm of a tiny minority ruling the vast majority – our current retro-medieval techno-feudalism, makes these folks unconsciously project such a paradigm onto the climate. 97% of the focus on the part containing 3% of the energy and importance. They have no trouble assuming that the ocean is simply passive and obedient to the atmosphere. Mistakes don’t get any bigger than that.
https://ptolemy2.wordpress.com/2021/11/13/climate-pandemonium/
There are a couple of contradicting statements in this summary:
“85% of the ice shelf perimeter in this part of Antarctica has advanced since the early 2000s, in contrast to the extensive retreat of the previous two decades”.
“it’s possible that this period of ice advance may be ending. Since 2020, there has been a notable increase in the number of icebergs breaking away”
The time “since 2020” likely has only one full Antarctic summer in it making a trend hard to define. Nevertheless, even if it’s true that the trend is reversing, this only would show that there is cyclic behavior, not impending doom.
It costs 30 bucks to see the data that might support the conclusions of the summary. I don’t think it’s worth it.
The Warmists want Antarctica to melt and they will find ways to melt it. In fact, the Warmists may destroy Antarctica …..15 foreign species have been introduced to the continent …16 if you count Bad Man himself….about 75,000 visitors are expected in a year of cruise ships……clearly, Bad Man must leave Antarctica in its pristine condition…or else.
So what are the consequences of this expansion of sea ice around the cooling Antarctica?
One of them is increased downwelling-formation of cold deep water at the continent’s periphery. As one might expect.
https://ptolemy2.wordpress.com/2022/01/13/antarctic-formation-of-cold-saline-deep-water-is-accelerating/
What? Nature fixing itself? No, they can’t have this. It makes a mockery of “climate change” and puts them out of bu$ine$$
Nothing other than their models likely shows the sea ice controls the on-land ice sheets. They observe increasing sea ice aprons and claim they see future Antarctic ice sheet loss. If they saw reduction in sea ice apron they would of course see future Antarctic ice sheet loss. There is only every one answer – it’s worse than we could every imagine (or model).