West Antarctic ice sheet has not reached its tipping point towards irreversible collapse – yet, new research finds
There is a limited window of time before large-scale, irreversible ice loss in the Antarctic starts, according to new research from Northumbria University
Peer-Reviewed PublicationIMAGE: ICE SHEET BREAKING AWAY view more
CREDIT: TIPACC
- In the first study of its kind, researchers from Northumbria University examined the current state of the Antarctic ice sheet, which reveals no evidence that a tipping point towards large-scale, irreversible collapse has been crossed – yet.
- However, researchers found even with no additional global warming, an irreversible collapse of some regions of the West Antarctic ice sheet is possible.
- While ice loss in Antarctica is expected to continue, authors say these studies give slight hope it might be possible to avoid or delay the tipping point, but with urgent action.
There is a limited window of time before large-scale, irreversible ice loss in the Antarctic starts, according to new research from Northumbria University.
For the first time, two collaborative papers published today in The Cryosphere journal, examined whether the Antarctic ice sheet has already reached a tipping point towards permanent unstoppable retreat.
The ongoing ice loss in Antarctica has raised concerns that the West Antarctic ice sheet might already be destabilised and ‘past the point of no return’.
However, researchers have now systematically analysed this question and found there is no evidence that it has already reached its tipping point.
The modelling study – carried out by Northumbria University and several research institutions across Europe – used three different computer models to run a series of simulations to conduct a thorough inspection looking for signs of irreversible retreat of the Antarctic ice sheet in its present form.
Authors of the study say whilst ice loss in Antarctica will continue in the future, these results give slight hope that it might still be possible to avoid or delay crossing the tipping point, if urgent action is taken.
Dr Emily Hill, Research Fellow at Northumbria University and report co-author, said: “The implications are profound. We used three different numerical models which all showed that we have not yet crossed a tipping point that leads to irreversible ice loss in Antarctica.
“Using several models makes our findings even more convincing, and it is reassuring to know that we haven’t yet passed the point of no return.”
However, the researchers also ran hypothetical simulations to investigate how the ice sheet might evolve if current climate conditions stay as they are. They found that even with no additional global warming, an irreversible collapse of some marine regions of West Antarctica’s ice sheet is possible in the future.
One of their models shows the earliest that this could happen is within 300-500 years under current conditions, warning that accelerating climate change is likely to shorten this timescale further.
Antarctica’s ice masses store enough water to raise sea levels by several metres around the globe and remain one of the greatest uncertainties in future projections of the effects of climate change.
Dr Ronja Reese, Vice-Chancellor’s Fellow at Northumbria University and report co-author, said: “Accelerated ice loss at the margins of the ice sheet could signal a collapse of larger marine regions. Our experiments show that an irreversible collapse in some marine regions in West Antarctica is possible for the current climate conditions.
“Importantly, this collapse is not happening yet, as our first study shows, and it evolves over thousands of years. But we would expect that further climate warming in the future will speed this up substantially.”
The research forms part of a major £4 million EU-funded study on Tipping Points in Antarctic Climate Components (TiPACCs) bringing together experts from the UK, Norway, Germany and France to investigate the likelihood of abrupt changes in the movement of ice in the Antarctic region.
Petra Langebroek, Research Director at the Norwegian Research Centre (NORCE), and Scientific Coordinator of the European TiPACCs Project, said: “I am very proud to see this work published. This tight collaboration across different European institutes has resulted in major progress in our understanding of Antarctic ice sheet stability and tipping points.
“This is somewhat good news. We have not yet crossed these tipping point in Antarctica, which – in theory – means that the ongoing ice loss can be reduced or even stopped. Unfortunately, our research also shows that with ongoing climate change, we are headed to crossing tipping points in West Antarctica.”
Northumbria University is home to one of the world’s leading groups in the studies of the interactions between ice sheets and oceans. The team of researchers are working to explore the future of ice sheets and glaciers worldwide in a warming world. This involves understanding the causes of ongoing changes in Antarctica, Greenland and alpine areas, as well as assessing future changes and resulting impacts on human environments globally.
Watch this video to learn more about the TiPACCSs study into tipping points in Antarctica.
NOTES TO EDITORS
Notes to editors
Pre-prints of the papers are available as follows:
1The stability of present-day Antarctic grounding lines – Part 2: Onset of irreversible retreat of Amundsen Sea glaciers under current climate on centennial timescales cannot be excluded. Ronja Reese, Julius Garbe, Emily A. Hill, Benoît Urruty, Kaitlin A. Naughten, Olivier Gagliardini, Gaël Durand, Fabien Gillet-Chaulet, G. Hilmar Gudmundsson, David Chandler, Petra M. Langebroek, and Ricarda Winkelmann. https://tc.copernicus.org/preprints/tc-2022-105/
2The stability of present-day Antarctic grounding lines – Part 1: No indication of marine ice sheet instability in the current geometry. Emily A. Hill, Benoît Urruty, Ronja Reese, Julius Garbe, Olivier Gagliardini, Gaël Durand, Fabien Gillet-Chaulet, G. Hilmar Gudmundsson, Ricarda Winkelmann, Mondher Chekki2, David Chandler, and Petra M. Langebroek. https://tc.copernicus.org/preprints/tc-2022-104/
3 Other research partners include: l'Institut des Géosciences de l'Environnement (IGE) at the Univ. Grenoble Alpes, Potsdam Institute for Climate Impact Research (PIK) and Norwegian Research Centre (NORCE)
JOURNAL
The Cryosphere
METHOD OF RESEARCH
Computational simulation/modeling
SUBJECT OF RESEARCH
Not applicable
ARTICLE TITLE
The stability of present-day Antarctic grounding lines – Part 1: No indication of marine ice sheet instability in the current geometry.
ARTICLE PUBLICATION DATE
7-Sep-2023
Stability inspection for West Antarctica shows: marine ice sheet is not destabilized yet, but possibly on a path to tipping
Antarctica’s vast ice masses seem far away, yet they store enough water to raise global sea levels by several meters. A team of experts from European research institutes has now provided the first systematic stability inspection of the ice sheet’s current state. Their diagnosis: While they found no indication of irreversible, self-reinforcing retreat of the ice sheet in West Antarctica yet, global warming to date could already be enough to trigger the slow but certain loss of ice over the next hundreds to thousands of years.
“With more and more ice being lost in Antarctica over the last years, concerns have been raised whether a tipping point has already been crossed and an irreversible, long-term collapse of the West Antarctic Ice Sheet has already been initiated,” explains Ronja Reese from the Potsdam Institute for Climate Impact Research (PIK) and the Northumbria University, Newcastle. “The results of our studies deliver two messages: First, while a number of glaciers in Antarctica are retreating at the moment, we find no indication of irreversible, self-reinforcing retreat yet, which is reassuring. However, our calculations also clearly indicate that an onset of an irreversible retreat of the ice sheet in West Antarctica is possible if the current state of the climate is sustained.”
The main driver of ice loss in West Antarctica is relatively warm ocean water that amplifies melting underneath the ice shelves, which are the floating extensions of the grounded ice sheet. Melting of these ice shelves can enhance ice loss as it speeds up the grounded sections of the ice sheet. That is why the Antarctic margin with its grounding lines – the zone where the grounded and the floating ice are connected – is a key indicator of ice sheet health. An accelerated retreat of the grounding lines could indicate a forthcoming collapse of large marine regions of West Antarctica’s ice sheet - those parts of the ice sheet that are grounded below sea level.
Evolving over 10,000 years, triggered today: irreversible ice-loss and sea-level rise
Using state-of-the-art ice sheet models, the researchers not only conducted a thorough inspection of signs of irreversible retreat of marine sectors of the Antarctic ice sheet at present, they also ran simulations to investigate how the ice sheet would evolve over the next 10,000 years if current conditions remained unchanged. These hypothetical experiments indicate that even with no additional warming beyond what we have already experienced today, an irreversible collapse of some marine regions of West Antarctica’s ice sheet is possible. Because the ice reacts to changes in temperature very slowly, the authors find that collapse occurs in their simulations at the earliest in 300 to 500 years from now, under current climate forcing. A full collapse would take centuries to millennia.
“The thing with sea-level rise from Antarctica is not that changes would happen overnight as an immediate threat to coastal communities. The process of melting would happen over hundreds or thousands of years. However, the cause could be human actions today, as they have the power to trigger and commit a future of 10,000 years to several meters of global sea-level rise. And stronger warming in the future would even speed up this process,” Julius Garbe from PIK stresses.
Changes in ice discharge from Antarctica remain one of the greatest uncertainties in future projections of global sea-level rise. “The Antarctic ice is our ultimate heritage of the past, millions of years old and often coined ‘eternal’ ice. But our work shows: while current ice loss may still be reversible, a destabilization of marine sectors of the ice sheet could initiate a long-term ice loss that is slow but certain. Climate change today could already be enough to tip the scales, that is concerning. Yet, with West Antarctica not destabilized yet there is still a chance to mitigate at least some of the risk by ambitious climate action,” Ricarda Winkelmann from PIK concludes.
Emily A. Hill, Benoît Urruty, Ronja Reese, Julius Garbe, Olivier Gagliardini, Gaël Durand, Fabien Gillet-Chaulet, G. Hilmar Gudmundsson, Ricarda Winkelmann, Mondher Chekki, David Chandler, Petra M. Langebroek (2023): The stability of present-day Antarctic grounding lines – Part 1: No indication of marine ice sheet instability in the current geometry, The Cryosphere, 17, 3739–3759 [DOI: 10.5194/tc-17-3739-2023]
Ronja Reese, Julius Garbe, Emily A. Hill, Benoît Urruty, Kaitlin A. Naughten, Olivier Gagliardini, Gaël Durand, Fabien Gillet-Chaulet, G. Hilmar Gudmundsson, David Chandler, Petra M. Langebroek, Ricarda Winkelmann (2023): The stability of present-day Antarctic grounding lines – Part 2: Onset of irreversible retreat of Amundsen Sea glaciers under current climate on centennial timescales cannot be excluded, The Cryosphere, 17, 3761–3783 [DOI: 10.5194/tc-17-3761-2023]
Weblink to the articles: https://tc.copernicus.org/articles/17/3739/2023/ and https://tc.copernicus.org/articles/17/3761/2023/
Video explaining the results in more detail: https://www.youtube.com/watch?v=wsSD_vuBz-s
JOURNAL
The Cryosphere
METHOD OF RESEARCH
Computational simulation/modeling
SUBJECT OF RESEARCH
Not applicable
ARTICLE TITLE
The stability of present-day Antarctic grounding lines – Part 1 + 2
ARTICLE PUBLICATION DATE
7-Sep-2023
Heatwaves hitting Antarctica too
The world's coldest, dryest continent experienced both record heat and record snowfall in 2022
IMAGE: RAJASHREE TRI DATTA view more
CREDIT: CU BOULDER
The world saw another year full of extreme weather events resulting from climate change in 2022, from intense storms to soaring temperatures and rising sea levels. Antarctica was no exception, according to new research published this week.
In the 33rd annual State of the Climate report, an international assessment of the global climate published Sept. 6 in the Bulletin of the American Meteorological Society, CU Boulder researchers report that the planet’s coldest and driest continent experienced both an unprecedented heatwave and extreme precipitation last year.
“My hope is that the public starts to see both the fragility and complexity of these polar regions,” said Rajashree Tri Datta, a research associate in the Department of Atmospheric and Oceanic Sciences who contributed to sections of the report related to Antarctica and the Southern Ocean.
While Antarctica may seem isolated from the rest of the world, changes to the icy continent could significantly impact the rest of the world.
“Most of the planet’s fresh water is held on the ice sheet of Antarctica. What happens there ends up affecting coasts across the world, and what affects coasts across the world impacts everything from agriculture to migration patterns,” Datta said.
In recent years, scientists have observed rapid sea ice decline and enhanced warming there. Regions of Antarctica, such as the West Antarctic Ice Sheet, have started to lose ice rapidly, contributing to sea level rise.
Datta and her team report that for six days last March, a large region of East Antarctica experienced temperatures exceeding 18 degrees Fahrenheit (10 degrees Celsius) above the historic March average from 1991 to 2020. The temperature recorded at a weather station in the interior of East Antarctica reached a record-breaking 14.7 F (-9.6C) on March 16, 2022, more than 79 F (44 C) higher than the average March temperature at that location.
Normally, March marks the transition from summer to winter in Antarctica, and the temperature drops rapidly. Following the heatwave, the Conger Ice shelf, a floating tongue of ice the size of Rome, collapsed in East Antarctica. This ice shelf had become increasingly vulnerable over the years. The collapse of floating ice shelves can often hasten the loss of upstream glaciers, resulting in ice loss and sea level rise.
As people around the world also experienced more frequent and intense heatwaves in 2022, Datta said the team’s research provides an opportunity to communicate with the public about climate change in Antarctica in a way that resonates with them.
“They know what a heatwave means. They experience it in their daily lives, and it is impacting Antarctica as well, although in very different ways” Datta said.
Unprecedented snowfall too
East Antarctica also saw an unprecedented amount of snowfall last March, tripling the month’s mean precipitation in some locations compared with the March average between 1991 and 2020. As a result, the annual balance of snow and ice retained on the surface of the ice sheet reached the highest value in the 40 years since the observational data became available.
“The strong precipitation this year is very interesting, because it offsets the ice loss around the margins of Antarctica,” Datta said. “The snowfall this year actually protected the world against sea level rise.”
Weather phenomena called atmospheric rivers—much like those that fueled record flooding in California this year—contributed to both the heatwave and the record precipitation, Datta said. These storms pull moisture from lower latitudes and delivered warm air and a large amount of precipitation to Antarctica in 2022.
While precipitation in Antarctica typically takes the form of snow, changes in these atmospheric rivers could bring enough heat to contribute to more surface melt or bring rain instead in the future, driving sea levels higher and impacting billions of people around the world, she said. Greenland, which is much warmer than Antarctica, is already experiencing many of these impacts.
The State of the Climate report, a collaboration of more than 570 international scientists, also reported that Earth’s greenhouse gas concentrations reached a new record last year. The global annual average atmospheric carbon dioxide concentration was 50% greater than the pre-industrial level, the highest measured amount in modern observational records. The amount of heat stored in the ocean continued to increase, as did global sea levels, reaching about 4 inches on average above the 1993 mean.
In another section of the report, Twila Moon, the deputy lead scientist at the National Snow and Ice Data Center at CU Boulder, reported that weather pattern shifts are also affecting the planet’s other pole.
"Observations over the past forty-plus years show a transition to a wetter Arctic, with seasonal shifts and widespread disturbances influencing the flora, fauna, physical systems, and peoples of the Arctic," Moon and her team wrote.
"The report adds pieces to the larger puzzle of how climate change can impact Antarctica,” Datta said. “Many of these dramatic events in 2022, and further research into their causes and effects, can arm us with a better understanding of our potential future.”
JOURNAL
Bulletin of the American Meteorological Society
METHOD OF RESEARCH
Data/statistical analysis
SUBJECT OF RESEARCH
Not applicable
ARTICLE TITLE
Antarctica and the S. Ocean: The Antarctic Heatwave of March 2022
ARTICLE PUBLICATION DATE
6-Sep-2023
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