Category Archives: Polar

Arctic’s coldest sea ice is vulnerable to melting

Every year an ice floe as big as Austria simply vanishes. That’s climate change, as the Arctic’s coldest sea ice risks melting.

LONDON, 6 July, 2021 − The frozen world is dwindling fast. New research suggests that the cryosphere − the area of the planet covered by snow and ice − is dwindling by around 87,000 square kilometres every year. This is an area bigger than Austria, almost as big as Hungary, or Jordan. Even the Arctic’s coldest sea ice is threatened.

A second, separate study warns that what glacier scientists call the Last Ice Refuge − the tract of Arctic Ocean that will stay frozen when the rest of it becomes open water during some summers in the next decades − is itself at risk: the coldest and most secure reaches of sea ice just north of Greenland and Canada could be vulnerable to summer melt.

That the polar regions and the high-altitude frozen rivers and lakes are at risk is not news: climate scientists have been warning for decades of accelerating melt in Antarctica, ever-higher losses of ice mass from Greenland, and a loss of northern polar sea ice so comprehensive that by 2050, much of the Arctic Ocean could be clear blue water most summers.

The cryosphere matters: it is a reservoir of two-thirds of the planet’s fresh water. Its gleaming white surface acts as planetary insulation: most of the sunlight that falls upon it is reflected back into space. As the ice thins and retreats, the exposed darker ocean below it warms up, to accelerate global heating and trigger yet more ice loss.

“In years when you replenish the ice cover in this region with older, thicker ice, that doesn’t seem to help as much as you might expect”

Scientists from Lanzhou University in China report in the journal Earth’s Future that they tried to look at the picture of change on a planetary scale. The cryosphere has always expanded and shrunk with the seasons in both hemispheres. Scientists calculated the daily extent of all the world’s snow and ice cover and then averaged it to get yearly estimates.

The Arctic is perhaps the fastest-warming zone on the planet and the northern hemisphere cover has been losing 102,000 sq kms a year, every year. This is an area bigger than Iceland, or Eritrea. The southern hemisphere ice however has been expanding by about 14,000 sq kms a year − think of the Bahamas − to offset a little of the loss.

The researchers also found that much of the cryosphere was now frozen for shorter periods: the day of first freezing now happens about 3.6 days later than it did in 1979, and the ice thaws 5.7 days earlier than it did 40 years ago.

But until now, one stretch of Arctic sea ice had shown no particular signs of change. When glaciologists repeatedly warned that the Arctic could be ice-free in summer by mid-century, they meant that the region would be down to its last million sq km of ice floe. This would be the last stronghold of the frozen world: the last place where seals, walruses and polar bears could find the surfaces they needed for survival.

Essential Refuge

But researchers aboard the German icebreaker Polarstern observed that the ice cover of the Wandel Sea off Greenland and Canada in the summer of 2020 was at a record low. This was a surprise, because at the beginning of the season it had been as dense as ever.

Permanent ice is a matter of life and death to the Arctic’s apex mammal predators: seals haul out onto the ice, to become potential prey for polar bears. Walruses use the ice as a platform for foraging. As the summer sea ice thins and shrinks a little more every year over the rest of the Arctic, the Last Ice Refuge becomes ever more important for their survival as species. The big question is: were the weather conditions unusual, or was this a sign of global heating?

“During the winter and spring of 2020 you had patches of older, thicker ice that had drifted into there, but there was enough thinner, newer ice that melted to expose open ocean,” said Axel Schweiger of the University of Washington in the US, who led the research.

“That began a cycle of absorbing heat energy to melt more ice, in spite of the fact that there was some thick ice. So in years when you replenish the ice cover in this region with older, thicker ice, that doesn’t seem to help as much as you might expect.” − Climate News Network

Every year an ice floe as big as Austria simply vanishes. That’s climate change, as the Arctic’s coldest sea ice risks melting.

LONDON, 6 July, 2021 − The frozen world is dwindling fast. New research suggests that the cryosphere − the area of the planet covered by snow and ice − is dwindling by around 87,000 square kilometres every year. This is an area bigger than Austria, almost as big as Hungary, or Jordan. Even the Arctic’s coldest sea ice is threatened.

A second, separate study warns that what glacier scientists call the Last Ice Refuge − the tract of Arctic Ocean that will stay frozen when the rest of it becomes open water during some summers in the next decades − is itself at risk: the coldest and most secure reaches of sea ice just north of Greenland and Canada could be vulnerable to summer melt.

That the polar regions and the high-altitude frozen rivers and lakes are at risk is not news: climate scientists have been warning for decades of accelerating melt in Antarctica, ever-higher losses of ice mass from Greenland, and a loss of northern polar sea ice so comprehensive that by 2050, much of the Arctic Ocean could be clear blue water most summers.

The cryosphere matters: it is a reservoir of two-thirds of the planet’s fresh water. Its gleaming white surface acts as planetary insulation: most of the sunlight that falls upon it is reflected back into space. As the ice thins and retreats, the exposed darker ocean below it warms up, to accelerate global heating and trigger yet more ice loss.

“In years when you replenish the ice cover in this region with older, thicker ice, that doesn’t seem to help as much as you might expect”

Scientists from Lanzhou University in China report in the journal Earth’s Future that they tried to look at the picture of change on a planetary scale. The cryosphere has always expanded and shrunk with the seasons in both hemispheres. Scientists calculated the daily extent of all the world’s snow and ice cover and then averaged it to get yearly estimates.

The Arctic is perhaps the fastest-warming zone on the planet and the northern hemisphere cover has been losing 102,000 sq kms a year, every year. This is an area bigger than Iceland, or Eritrea. The southern hemisphere ice however has been expanding by about 14,000 sq kms a year − think of the Bahamas − to offset a little of the loss.

The researchers also found that much of the cryosphere was now frozen for shorter periods: the day of first freezing now happens about 3.6 days later than it did in 1979, and the ice thaws 5.7 days earlier than it did 40 years ago.

But until now, one stretch of Arctic sea ice had shown no particular signs of change. When glaciologists repeatedly warned that the Arctic could be ice-free in summer by mid-century, they meant that the region would be down to its last million sq km of ice floe. This would be the last stronghold of the frozen world: the last place where seals, walruses and polar bears could find the surfaces they needed for survival.

Essential Refuge

But researchers aboard the German icebreaker Polarstern observed that the ice cover of the Wandel Sea off Greenland and Canada in the summer of 2020 was at a record low. This was a surprise, because at the beginning of the season it had been as dense as ever.

Permanent ice is a matter of life and death to the Arctic’s apex mammal predators: seals haul out onto the ice, to become potential prey for polar bears. Walruses use the ice as a platform for foraging. As the summer sea ice thins and shrinks a little more every year over the rest of the Arctic, the Last Ice Refuge becomes ever more important for their survival as species. The big question is: were the weather conditions unusual, or was this a sign of global heating?

“During the winter and spring of 2020 you had patches of older, thicker ice that had drifted into there, but there was enough thinner, newer ice that melted to expose open ocean,” said Axel Schweiger of the University of Washington in the US, who led the research.

“That began a cycle of absorbing heat energy to melt more ice, in spite of the fact that there was some thick ice. So in years when you replenish the ice cover in this region with older, thicker ice, that doesn’t seem to help as much as you might expect.” − Climate News Network

Polar concerns rise as ice now melts ever faster

An Antarctic glacier gathers pace. In the north, the Arctic ice thins faster. Racing climate heat is feeding polar concerns.

LONDON, 15 June, 2021 − An Antarctic glacier has begun to move more quickly towards the open ocean, as the shelf of sea ice that once held it back starts to collapse. The water in that one glacier is enough to raise global sea levels by half a metre. And that’s not all that’s raising polar concerns across the scientific world.

At the other end of the Earth global heating is accelerating the loss of Arctic ice. A new study reports that the thinning of sea ice in three separate coastal regions could now be happening twice as fast.

Both findings are linked to the inexorable rise in global average temperatures as the profligate use of fossil fuels heightens the ratio of greenhouse gases in the planet’s atmosphere.

Antarctic scientists have been worrying about warming in Antarctica for years. And they have been anxiously watching the Pine Island glacier in West Antarctica for decades.

Glaciers move at the proverbial glacial pace towards the sea, to be held in check, in the polar oceans, by vast shelves of sea ice. Between 2017 and 2020 the ice shelves have undergone a series of collapses and lost one fifth of their area, possibly because the glacier has been accelerating.

“The thickness of the sea ice is a sensitive indicator of the health of the Arctic”

“We may not have the luxury of waiting for slow changes on Pine Island; things could actually go much quicker than expected,” said Ian Joughin, of the University of Washington in the US.

“The processes we’d been studying in this region were leading to an irreversible collapse, but at a fairly measured pace. Things could be much more abrupt if we lose the rest of that ice shelf.”

He and his colleagues report in the journal Science Advances that the Pine Island glacier has already become Antarctica’s biggest contributor to sea level rise. The pace of flow remained fairly steady from 2009 to 2017, but they found that data from Europe’s Copernicus Sentinel satellite system showed an acceleration of 12% in the past three years.

The Pine Island glacier contains roughly 180 trillion tonnes of ice, enough to raise global sea levels by 0.5 metres. Researchers had calculated that it might take a century or more for slowly-warming polar waters to thin the ice shelves to the point where they could no longer stem the glacier flow. But it now seems that the big player in the shelf ice collapse is the glacier itself, as the flow rate increases.

“The loss of Pine Island’s ice shelf now looks possibly like it could occur in the next decade or two, as opposed to the melt-driven sub-surface change playing out over more than 100 or more years,” said Pierre Dutrieux of the British Antarctic Survey, a co-author. “So it’s a potentially much more rapid and abrupt change.”

Snow fall dwindles

Abrupt change, too, may be on the way in the Arctic Ocean. British researchers used a new computer simulation to explore measurements from Europe’s CryoSat-2 satellite. The scientists report in the journal The Cryosphere that the thinning of ice in the Laptev and Kara Seas north of Siberia, and the Chukchi Sea between Siberia and Alaska, has stepped up by 70%, 98% and 110% respectively.

Sea ice diminishes each summer and forms again each winter; each successive summer reveals an ever-greater loss, as the ice itself thins and the area covered by ice dwindles.

Calculations of ice thickness have always allowed for the falls of fresh winter snow. But since the formation of sea ice has been later every year, there has been less time for the snow to accumulate. Such things make a difference.

“The thickness of the sea ice is a sensitive indicator of the health of the Arctic,” said Robbie Mallett, of University College London.

“It is important as thicker ice acts as an insulating blanket, stopping the ocean from warming up the atmosphere in winter, and protecting the ocean from sunshine in summer. Thinner ice is also less likely to survive the summer melt.” − Climate News Network

An Antarctic glacier gathers pace. In the north, the Arctic ice thins faster. Racing climate heat is feeding polar concerns.

LONDON, 15 June, 2021 − An Antarctic glacier has begun to move more quickly towards the open ocean, as the shelf of sea ice that once held it back starts to collapse. The water in that one glacier is enough to raise global sea levels by half a metre. And that’s not all that’s raising polar concerns across the scientific world.

At the other end of the Earth global heating is accelerating the loss of Arctic ice. A new study reports that the thinning of sea ice in three separate coastal regions could now be happening twice as fast.

Both findings are linked to the inexorable rise in global average temperatures as the profligate use of fossil fuels heightens the ratio of greenhouse gases in the planet’s atmosphere.

Antarctic scientists have been worrying about warming in Antarctica for years. And they have been anxiously watching the Pine Island glacier in West Antarctica for decades.

Glaciers move at the proverbial glacial pace towards the sea, to be held in check, in the polar oceans, by vast shelves of sea ice. Between 2017 and 2020 the ice shelves have undergone a series of collapses and lost one fifth of their area, possibly because the glacier has been accelerating.

“The thickness of the sea ice is a sensitive indicator of the health of the Arctic”

“We may not have the luxury of waiting for slow changes on Pine Island; things could actually go much quicker than expected,” said Ian Joughin, of the University of Washington in the US.

“The processes we’d been studying in this region were leading to an irreversible collapse, but at a fairly measured pace. Things could be much more abrupt if we lose the rest of that ice shelf.”

He and his colleagues report in the journal Science Advances that the Pine Island glacier has already become Antarctica’s biggest contributor to sea level rise. The pace of flow remained fairly steady from 2009 to 2017, but they found that data from Europe’s Copernicus Sentinel satellite system showed an acceleration of 12% in the past three years.

The Pine Island glacier contains roughly 180 trillion tonnes of ice, enough to raise global sea levels by 0.5 metres. Researchers had calculated that it might take a century or more for slowly-warming polar waters to thin the ice shelves to the point where they could no longer stem the glacier flow. But it now seems that the big player in the shelf ice collapse is the glacier itself, as the flow rate increases.

“The loss of Pine Island’s ice shelf now looks possibly like it could occur in the next decade or two, as opposed to the melt-driven sub-surface change playing out over more than 100 or more years,” said Pierre Dutrieux of the British Antarctic Survey, a co-author. “So it’s a potentially much more rapid and abrupt change.”

Snow fall dwindles

Abrupt change, too, may be on the way in the Arctic Ocean. British researchers used a new computer simulation to explore measurements from Europe’s CryoSat-2 satellite. The scientists report in the journal The Cryosphere that the thinning of ice in the Laptev and Kara Seas north of Siberia, and the Chukchi Sea between Siberia and Alaska, has stepped up by 70%, 98% and 110% respectively.

Sea ice diminishes each summer and forms again each winter; each successive summer reveals an ever-greater loss, as the ice itself thins and the area covered by ice dwindles.

Calculations of ice thickness have always allowed for the falls of fresh winter snow. But since the formation of sea ice has been later every year, there has been less time for the snow to accumulate. Such things make a difference.

“The thickness of the sea ice is a sensitive indicator of the health of the Arctic,” said Robbie Mallett, of University College London.

“It is important as thicker ice acts as an insulating blanket, stopping the ocean from warming up the atmosphere in winter, and protecting the ocean from sunshine in summer. Thinner ice is also less likely to survive the summer melt.” − Climate News Network

Polar cod face new threat from Arctic oil pollution

Already struggling to survive in warming Arctic seas, the polar cod are now at risk from rising oil pollution.

LONDON, 2 June, 2021 – They are small – on average around 25cm long. But polar cod (Boreogadus saida) are a vital part of the Arctic food chain, a major ingredient in the diet of seals, narwhals and a wide variety of seabirds.

The Arctic is warming faster than any other area on the planet, and a study published in 2020 found that declines in winter sea ice cover in the Barents Sea region of the Arctic, plus warmer sea temperatures, were causing declines in polar cod reproduction rates.

The latest research indicates that the polar cod is now under threat not only from warming Arctic seas, but because of oil pollution as well, as the region’s rapidly diminishing ice cover allows more shipping traffic and commercial activity.

Morgan Lizabeth Bender is a researcher in the department of Arctic and Marine Biology at the University of Tromsø (UiT) in northern Norway. Her research has found that when the polar cod is exposed to a combination of warmer waters and only very slight levels of oil pollution, its development is interrupted, with abnormalities common.

“Polar cod is a somewhat difficult species that hasn’t been researched that much,” Dr Bender told the Science Norway website. “The fish are a difficult species to find and to take care of in the lab. However, this species has a very important ecological role.”

“Increased water temperature can increase the harmful effects of oil exposure”

The fish, monitored during the breeding process, were sorted into aquariums – some at a current Arctic water temperature of 0.5°C, others at a warmer 2.8°C to mimic an Arctic affected by climate change.

The aquariums contained either pure water or water contaminated by minuscule amounts of crude oil. “The pollution level would be the equivalent of about five drops of oil in an Olympic-size swimming pool,” says Dr Bender.

Though the study found that polar cod eggs in the warmer water hatched much faster than those in the colder water, at first there was little difference between survival rates in the various aquariums.

But then something strange started happening to the fry – the young fish – that were exposed to oil.

“When they first hatched, there wasn’t much difference,” says Dr Bender. “But as their jaw, face and eyes started to develop, we saw very clearly that they weren’t forming properly.”

Lower survival rates

The research found that the fry were very sensitive to even the slightest amount of oil pollution: death rates were highest among fry exposed to both warmer water and oil.

When the fry became large enough to start feeding, only 8% survived in the contaminated warmer water and 23% in the contaminated cold water.

Marine scientists say that polar cod numbers have shown a downward trend since 2010, despite the fact that they are not a fished species.

Sonnich Meier, of the Norwegian Institute of Marine Research, has been examining the impact of both global warming and oil pollution on Arctic fish species for a number of years.

“Polar cod is one of the fish species that is hardest hit by climate change in the Arctic,” he says. “The study shows that increased water temperature can increase the harmful effects of oil exposure.” – Climate News Network

Already struggling to survive in warming Arctic seas, the polar cod are now at risk from rising oil pollution.

LONDON, 2 June, 2021 – They are small – on average around 25cm long. But polar cod (Boreogadus saida) are a vital part of the Arctic food chain, a major ingredient in the diet of seals, narwhals and a wide variety of seabirds.

The Arctic is warming faster than any other area on the planet, and a study published in 2020 found that declines in winter sea ice cover in the Barents Sea region of the Arctic, plus warmer sea temperatures, were causing declines in polar cod reproduction rates.

The latest research indicates that the polar cod is now under threat not only from warming Arctic seas, but because of oil pollution as well, as the region’s rapidly diminishing ice cover allows more shipping traffic and commercial activity.

Morgan Lizabeth Bender is a researcher in the department of Arctic and Marine Biology at the University of Tromsø (UiT) in northern Norway. Her research has found that when the polar cod is exposed to a combination of warmer waters and only very slight levels of oil pollution, its development is interrupted, with abnormalities common.

“Polar cod is a somewhat difficult species that hasn’t been researched that much,” Dr Bender told the Science Norway website. “The fish are a difficult species to find and to take care of in the lab. However, this species has a very important ecological role.”

“Increased water temperature can increase the harmful effects of oil exposure”

The fish, monitored during the breeding process, were sorted into aquariums – some at a current Arctic water temperature of 0.5°C, others at a warmer 2.8°C to mimic an Arctic affected by climate change.

The aquariums contained either pure water or water contaminated by minuscule amounts of crude oil. “The pollution level would be the equivalent of about five drops of oil in an Olympic-size swimming pool,” says Dr Bender.

Though the study found that polar cod eggs in the warmer water hatched much faster than those in the colder water, at first there was little difference between survival rates in the various aquariums.

But then something strange started happening to the fry – the young fish – that were exposed to oil.

“When they first hatched, there wasn’t much difference,” says Dr Bender. “But as their jaw, face and eyes started to develop, we saw very clearly that they weren’t forming properly.”

Lower survival rates

The research found that the fry were very sensitive to even the slightest amount of oil pollution: death rates were highest among fry exposed to both warmer water and oil.

When the fry became large enough to start feeding, only 8% survived in the contaminated warmer water and 23% in the contaminated cold water.

Marine scientists say that polar cod numbers have shown a downward trend since 2010, despite the fact that they are not a fished species.

Sonnich Meier, of the Norwegian Institute of Marine Research, has been examining the impact of both global warming and oil pollution on Arctic fish species for a number of years.

“Polar cod is one of the fish species that is hardest hit by climate change in the Arctic,” he says. “The study shows that increased water temperature can increase the harmful effects of oil exposure.” – Climate News Network

Faster Greenland ice melt could be unstoppable

A rapid thaw could destroy a whole ice sheet if the faster Greenland ice melt scientists have found spreads across the island.

LONDON, 24 May, 2021 − Researchers say the faster Greenland ice melt affecting part of the island could mean a large area is on the verge of irreversible loss. Their new study shows that the central western region of the ice sheet is near what climate scientists call “a tipping point.”

That is, once the ice starts to slide away, most of it will tip into the sea, to raise global sea levels and potentially to trigger the collapse of the great Atlantic Ocean current that enhances the climate of north-west Europe.

“We have found evidence that the central western part of the Greenland ice sheet has been destabilising and is now close to a critical transition,” said Niklas Boers, of the Potsdam Institute for Climate Impact Research. “Our results suggest there will be substantially enhanced melting in the future − which is quite worrying.”

Dr Boers and his colleague Martin Rypdal of the Arctic University of Norway report in the Proceedings of the National Academy of Sciences that they looked at data since 1880 of melt rates and ice-sheet altitude shifts of a region called the Jakobshavn basin in the central western region of the northern hemisphere’s biggest single block of ice − a block big enough to raise global sea levels by seven metres, were it all to melt.

And what they saw was something alarming: evidence that surface melting is beginning to accelerate. The conclusion, for now, is tentative.

“It’s high time we dramatically and substantially reduce greenhouse gas emissions from burning fossil fuels”

“We might be seeing the beginning of a large scale destabilisation, but at the moment we cannot tell, unfortunately,” Dr Boers said. “So far the signals we see are only regional, but that might simply be due to the scarcity of accurate and long-term data for other parts of the ice sheet.”

The region is home to the Jakobshavn glacier, which began to accelerate its flow to the sea this century, but the alarm is consistent with other studies of the mass of ice piled up on Greenland.

For most of the last 10,000 years or so, the summer loss of ice through melt and glacial flow has been replaced by winter snow. But in recent years, other research teams have warned, repeatedly, that the rate of  melting of Greenland’s surface ice has increased, in ways that really could threaten the stability of the entire sheet. Last year, ice loss reached a new record.

Greenland’s ice sheet is high: colder, therefore, at altitude. As the surface melts, the elevation becomes lower, and therefore increasingly warmer. So once the high ground surface begins to melt away, it could reach a level below which there is no obvious reason why the process should stop.

Climate computer simulations predict a threshold of global average temperature change that could, in effect, start a process in which the loss of the entire ice sheet would become inevitable. The loss would happen over hundreds of years, or perhaps thousands, but once begun it would continue inexorably.

Extreme Arctic warming

Global sea levels would rise at ever faster rates, and the arrival of so much fresh water in the north Atlantic would be enough to interfere with the ocean circulation.

For years oceanographers have been warning that the existing current, which takes warm tropical water as far north as the Arctic, could weaken, or fail, with unpredictable and uncomfortable consequences for north European nations.

The only way to stop Greenland’s accelerated melt, once it reaches a critical point, would be to lower the temperature of the whole planet back to that which was normal more than 200 years ago. That is unlikely to happen. Instead, for the moment, the evidence is that average temperatures worldwide could rise by 3°C or more by 2100. The Arctic, however, is likely to become much, much warmer.

“So practically, the current and near-future mass loss will be irreversible,” said Dr Boers, “That’s why it’s high time we dramatically and substantially reduce greenhouse gas emissions from burning fossil fuels and restabilise the ice sheet and our climate.” − Climate News Network

A rapid thaw could destroy a whole ice sheet if the faster Greenland ice melt scientists have found spreads across the island.

LONDON, 24 May, 2021 − Researchers say the faster Greenland ice melt affecting part of the island could mean a large area is on the verge of irreversible loss. Their new study shows that the central western region of the ice sheet is near what climate scientists call “a tipping point.”

That is, once the ice starts to slide away, most of it will tip into the sea, to raise global sea levels and potentially to trigger the collapse of the great Atlantic Ocean current that enhances the climate of north-west Europe.

“We have found evidence that the central western part of the Greenland ice sheet has been destabilising and is now close to a critical transition,” said Niklas Boers, of the Potsdam Institute for Climate Impact Research. “Our results suggest there will be substantially enhanced melting in the future − which is quite worrying.”

Dr Boers and his colleague Martin Rypdal of the Arctic University of Norway report in the Proceedings of the National Academy of Sciences that they looked at data since 1880 of melt rates and ice-sheet altitude shifts of a region called the Jakobshavn basin in the central western region of the northern hemisphere’s biggest single block of ice − a block big enough to raise global sea levels by seven metres, were it all to melt.

And what they saw was something alarming: evidence that surface melting is beginning to accelerate. The conclusion, for now, is tentative.

“It’s high time we dramatically and substantially reduce greenhouse gas emissions from burning fossil fuels”

“We might be seeing the beginning of a large scale destabilisation, but at the moment we cannot tell, unfortunately,” Dr Boers said. “So far the signals we see are only regional, but that might simply be due to the scarcity of accurate and long-term data for other parts of the ice sheet.”

The region is home to the Jakobshavn glacier, which began to accelerate its flow to the sea this century, but the alarm is consistent with other studies of the mass of ice piled up on Greenland.

For most of the last 10,000 years or so, the summer loss of ice through melt and glacial flow has been replaced by winter snow. But in recent years, other research teams have warned, repeatedly, that the rate of  melting of Greenland’s surface ice has increased, in ways that really could threaten the stability of the entire sheet. Last year, ice loss reached a new record.

Greenland’s ice sheet is high: colder, therefore, at altitude. As the surface melts, the elevation becomes lower, and therefore increasingly warmer. So once the high ground surface begins to melt away, it could reach a level below which there is no obvious reason why the process should stop.

Climate computer simulations predict a threshold of global average temperature change that could, in effect, start a process in which the loss of the entire ice sheet would become inevitable. The loss would happen over hundreds of years, or perhaps thousands, but once begun it would continue inexorably.

Extreme Arctic warming

Global sea levels would rise at ever faster rates, and the arrival of so much fresh water in the north Atlantic would be enough to interfere with the ocean circulation.

For years oceanographers have been warning that the existing current, which takes warm tropical water as far north as the Arctic, could weaken, or fail, with unpredictable and uncomfortable consequences for north European nations.

The only way to stop Greenland’s accelerated melt, once it reaches a critical point, would be to lower the temperature of the whole planet back to that which was normal more than 200 years ago. That is unlikely to happen. Instead, for the moment, the evidence is that average temperatures worldwide could rise by 3°C or more by 2100. The Arctic, however, is likely to become much, much warmer.

“So practically, the current and near-future mass loss will be irreversible,” said Dr Boers, “That’s why it’s high time we dramatically and substantially reduce greenhouse gas emissions from burning fossil fuels and restabilise the ice sheet and our climate.” − Climate News Network

2°C more heat may mean catastrophic sea level rise

The Paris Agreement to limit global heat could prevent catastrophic sea level rise, if states keep their promises to cut carbon.

LONDON, 7 May, 2021 − Climate scientists warn that − unless the world acts to limit global heating − the Antarctic ice sheet could begin irreversible collapse. The ice on the Antarctic continent could raise global sea levels by more than 47 metres, higher than a ten-storey building, and enough to unleash catastrophic sea level rise.

Global warming of just 3°C above the long-term average for most of human history would bring on a sea level rise from south polar melting of at least 0.5cms a year from about 2060 onwards.

Right now, greenhouse gas emissions continue to increase as nations burn ever more coal, oil and gas to power economic growth, and the world is on course for temperatures significantly above 3°C.

Researchers calculate in the journal Nature that any global warming that exceeds the target of no more than 2°C by 2100, agreed by almost all of the world’s nations in Paris in 2015, will put the ice shelves that ring the southern continent at risk of melting.

“Unstoppable, catastrophic sea level rise from Antarctica [may] be triggered if the Paris Agreement temperature targets are exceeded”

The mass and extent of sea ice acts as a buttress to flow from higher ground. If the sea ice melts, then the flow of glacial ice to the sea will accelerate.

“Ice-sheet collapse is irreversible over thousands of years, and if the Antarctic ice sheet collapse becomes unstable it could continue to retreat for centuries,” said Daniel Gilford of Rutgers University in the US, one of the research team. “That’s regardless of whether emissions mitigation strategies such as removing carbon dioxide from the atmosphere are employed.”

The finding is based on computer simulation backed up by detailed knowledge of at least some of the more prominent glaciers in West Antarctica, and of the response of the sea ice offshore to warmer winds and ocean currents.

Nor can it be a surprise to climate scientists: they have been warning for years of the potential loss of shelf-ice, they have already warned that ice loss could become irreversible, and they have measured the rates of loss often enough to be confident that this is accelerating.

On course for 3°C

The ice in Antarctica sits on a landmass bigger than the entire US and European Union combined: the burden of ice adds up to 30 million cubic kilometres, and some of it flows as vast glaciers 50kms wide and 2000 metres deep. And there has been concern for years that some flows are accelerating.

The Paris Agreement actually settled on the phrase “well below 2°C” as the global ambition for 2100. The national plans declared so far to reduce emissions commit the planet to a warming of 3°C or more.

The fear is that at 3°C nothing could prevent eventual ice sheet attrition over the following centuries. The latest research confirms that fear with a more than usually forthright scientific conclusion.

“These results demonstrate the possibility that unstoppable, catastrophic sea level rise from Antarctica will be triggered if the Paris Agreement temperature targets are exceeded,” the scientists write. − Climate News Network

The Paris Agreement to limit global heat could prevent catastrophic sea level rise, if states keep their promises to cut carbon.

LONDON, 7 May, 2021 − Climate scientists warn that − unless the world acts to limit global heating − the Antarctic ice sheet could begin irreversible collapse. The ice on the Antarctic continent could raise global sea levels by more than 47 metres, higher than a ten-storey building, and enough to unleash catastrophic sea level rise.

Global warming of just 3°C above the long-term average for most of human history would bring on a sea level rise from south polar melting of at least 0.5cms a year from about 2060 onwards.

Right now, greenhouse gas emissions continue to increase as nations burn ever more coal, oil and gas to power economic growth, and the world is on course for temperatures significantly above 3°C.

Researchers calculate in the journal Nature that any global warming that exceeds the target of no more than 2°C by 2100, agreed by almost all of the world’s nations in Paris in 2015, will put the ice shelves that ring the southern continent at risk of melting.

“Unstoppable, catastrophic sea level rise from Antarctica [may] be triggered if the Paris Agreement temperature targets are exceeded”

The mass and extent of sea ice acts as a buttress to flow from higher ground. If the sea ice melts, then the flow of glacial ice to the sea will accelerate.

“Ice-sheet collapse is irreversible over thousands of years, and if the Antarctic ice sheet collapse becomes unstable it could continue to retreat for centuries,” said Daniel Gilford of Rutgers University in the US, one of the research team. “That’s regardless of whether emissions mitigation strategies such as removing carbon dioxide from the atmosphere are employed.”

The finding is based on computer simulation backed up by detailed knowledge of at least some of the more prominent glaciers in West Antarctica, and of the response of the sea ice offshore to warmer winds and ocean currents.

Nor can it be a surprise to climate scientists: they have been warning for years of the potential loss of shelf-ice, they have already warned that ice loss could become irreversible, and they have measured the rates of loss often enough to be confident that this is accelerating.

On course for 3°C

The ice in Antarctica sits on a landmass bigger than the entire US and European Union combined: the burden of ice adds up to 30 million cubic kilometres, and some of it flows as vast glaciers 50kms wide and 2000 metres deep. And there has been concern for years that some flows are accelerating.

The Paris Agreement actually settled on the phrase “well below 2°C” as the global ambition for 2100. The national plans declared so far to reduce emissions commit the planet to a warming of 3°C or more.

The fear is that at 3°C nothing could prevent eventual ice sheet attrition over the following centuries. The latest research confirms that fear with a more than usually forthright scientific conclusion.

“These results demonstrate the possibility that unstoppable, catastrophic sea level rise from Antarctica will be triggered if the Paris Agreement temperature targets are exceeded,” the scientists write. − Climate News Network

Human activity alters Earth’s spin on its axis

The planet may not catch fire, but climate change really has altered the Earth’s spin on its axis as it rounds the sun.

LONDON, 29 April, 2021 − Human action has altered Earth’s spin on its axis. Climate change since 1990 has altered both the rate and the direction of the drift of the north and south poles.

Chinese researchers report in the journal Geophysical Research Letters that on the basis of their calculations, the dramatic melting of the Antarctic and Greenland ice caps and the Andean glaciers of South America has shifted the weight of the global water storage system and affected the planetary drift of the poles.

This glacial loss has been compounded by massive increases in the use of groundwater − most of the planet’s fresh water is in fact stored in subterranean aquifers − which have helped to accelerate the rate of change.

It sounds like the plot of a science fiction film. It was in fact the plot of a British 1961 science fiction film, The Day the Earth Caught Fire. In that fantasia, Cold War superpower nuclear tests unintentionally alter the planet’s axis of rotation and trigger dramatic changes in climate.

In fact, in the real-life, here-and-now version of planetary rotational shift, climate change driven by economic growth powered by profligate fossil fuel use is the cause. And the superpowers have yet to decide upon a course correction.

Polar speed-up

There is a second difference: the axis of the rotational poles has always shifted, from year to year, in response to the distribution of ice and groundwater, and the oceanic currents; and from aeon to aeon in response to the movements of the continents, and the sloshing of molten iron at the Earth’s core.

What has happened since 1990 is that water loss from both the glaciated land surface and the soil beneath the inhabited surface has been so pronounced that it has tilted the North Pole away from Canada and towards Russia, and accelerated the rate at which this is happening.

Since 1990, geographic North has been tilting, in geodetic language, towards longitude 26°E at the rate of 3.28 milliseconds of arc per year. One millisecond of arc is about 3 cms.

The story has been pieced together by data from a US-German satellite system known as GRACE (short for Gravity Recovery and Climate Experiment), which has been recording ice loss and water storage for most of this century.

“The faster ice-melting under global warming was the most likely cause of the directional change of the polar drift in the 1990s”

The researchers, from the Chinese Academy of Sciences, already had access to 176 years of precision measurement of the polar axial shift. In fact, the loss of ice from both the north and south polar regions has been colossal, and has been happening at speed.

Groundwater, too, has been abstracted at accelerating rates and the study notes that while in 1989 India pumped 194 billion cubic metres from the soil, by 2010 this had reached 351 billion cubic metres. There had, too, been dramatic changes in the water levels of vast inland lakes such as the Aral Sea.

The planet is always in a state of change: the magnetic poles are on the move and scientists have confirmed that climate over very long periods is affected by changes in planetary orbit.

Other teams of researchers had separately confirmed that climate change − and the redistribution of water around the planet − must have altered the length of the day by millionths of a second in the course of a year. But the new research has established something more immediately measurable: the alteration of the pattern of rotational tilt.

“The faster ice-melting under global warming was the most likely cause of the directional change of the polar drift in the 1990s,” the researchers conclude. − Climate News Network

The planet may not catch fire, but climate change really has altered the Earth’s spin on its axis as it rounds the sun.

LONDON, 29 April, 2021 − Human action has altered Earth’s spin on its axis. Climate change since 1990 has altered both the rate and the direction of the drift of the north and south poles.

Chinese researchers report in the journal Geophysical Research Letters that on the basis of their calculations, the dramatic melting of the Antarctic and Greenland ice caps and the Andean glaciers of South America has shifted the weight of the global water storage system and affected the planetary drift of the poles.

This glacial loss has been compounded by massive increases in the use of groundwater − most of the planet’s fresh water is in fact stored in subterranean aquifers − which have helped to accelerate the rate of change.

It sounds like the plot of a science fiction film. It was in fact the plot of a British 1961 science fiction film, The Day the Earth Caught Fire. In that fantasia, Cold War superpower nuclear tests unintentionally alter the planet’s axis of rotation and trigger dramatic changes in climate.

In fact, in the real-life, here-and-now version of planetary rotational shift, climate change driven by economic growth powered by profligate fossil fuel use is the cause. And the superpowers have yet to decide upon a course correction.

Polar speed-up

There is a second difference: the axis of the rotational poles has always shifted, from year to year, in response to the distribution of ice and groundwater, and the oceanic currents; and from aeon to aeon in response to the movements of the continents, and the sloshing of molten iron at the Earth’s core.

What has happened since 1990 is that water loss from both the glaciated land surface and the soil beneath the inhabited surface has been so pronounced that it has tilted the North Pole away from Canada and towards Russia, and accelerated the rate at which this is happening.

Since 1990, geographic North has been tilting, in geodetic language, towards longitude 26°E at the rate of 3.28 milliseconds of arc per year. One millisecond of arc is about 3 cms.

The story has been pieced together by data from a US-German satellite system known as GRACE (short for Gravity Recovery and Climate Experiment), which has been recording ice loss and water storage for most of this century.

“The faster ice-melting under global warming was the most likely cause of the directional change of the polar drift in the 1990s”

The researchers, from the Chinese Academy of Sciences, already had access to 176 years of precision measurement of the polar axial shift. In fact, the loss of ice from both the north and south polar regions has been colossal, and has been happening at speed.

Groundwater, too, has been abstracted at accelerating rates and the study notes that while in 1989 India pumped 194 billion cubic metres from the soil, by 2010 this had reached 351 billion cubic metres. There had, too, been dramatic changes in the water levels of vast inland lakes such as the Aral Sea.

The planet is always in a state of change: the magnetic poles are on the move and scientists have confirmed that climate over very long periods is affected by changes in planetary orbit.

Other teams of researchers had separately confirmed that climate change − and the redistribution of water around the planet − must have altered the length of the day by millionths of a second in the course of a year. But the new research has established something more immediately measurable: the alteration of the pattern of rotational tilt.

“The faster ice-melting under global warming was the most likely cause of the directional change of the polar drift in the 1990s,” the researchers conclude. − Climate News Network

Loss of Arctic sea ice can spoil French wine harvest

What happens in the Arctic may not stay there. Loss of Arctic sea ice can dump the polar blizzards elsewhere.

LONDON, 19 April, 2021 − Once again, scientists have linked a weather-related catastrophe directly to human-induced climate change. Extreme frost and springtime snowfalls in Western Europe can be pinned to the dramatic loss of Arctic sea ice.

So, paradoxically, global heating may have had the unexpected effect of wiping out around one third of the French wine harvest for this coming year, after temperatures so low that growers were forced to light bonfires in their vineyards to save the first buds from the chill.

“Climate change doesn’t always manifest in the most obvious ways,” said Alun Hubbard, of the Arctic University of Norway. “It’s easy to extrapolate models to show that winters are getting warmer and to forecast a virtually snow-free future in Europe, but our most recent study shows that is too simplistic. We should be beware of making broad, sweeping statements about the impacts of climate change.”

Professor Hubbard and colleagues report in the journal Nature Geoscience that they measured telltale isotope signatures in water vapour from Finland in February 2018 during an episode of freezing snow in Europe, in an anticyclone dubbed “the Beast from the East” by meteorologists and the media.

“The abrupt changes being witnessed across the Arctic now really are affecting the entire planet”

They found that the Barents Sea north of Scandinavia was anomalously warm. And 60% of the sea’s surface was free of ice, and the same sea lost 140 billion tonnes of water to evaporation during this too-warm February. This enormous atmospheric burden of water vapour provided, they calculate, 88% of the snow that was to fall over northern Europe that month.

Then they looked at the pattern over the years from 1979 to 2020, to find that, for every square metre of ice that vanished in the month of March − itself part of a pattern of Arctic temperature rise − evaporation across the Barents Sea increased by 70 kg, and this could be matched with increases in Europe’s maximum snowfall.

“Our analysis directly links Arctic sea ice loss with increased evaporation and extreme snow fall,” they write, and warn that by 2080 an ice-free Barents Sea “will be a major source of winter moisture for continental Europe.”

The Beast from the East brought much of Europe to a halt, at an economic cost of an estimated $1bn (£0.72bn) a day. It is still rare for researchers to directly link any particular weather event with climate change driven by profligate use of fossil fuels − that is because climate is what forecasters can reasonably expect, but weather is what actually happens − but some scientists have begun to do so with increasing confidence. And this time, they can explain why.

Natural complexity

The ice cover over the Barents Sea has fallen by 54% since 1979, at the rate of 11,200 sq kms a year, and snow mass across Eurasia has increased. The latest study confirms the link: the isotope signature of Barents water was repeated in the European snows that arrived with the Beast from the East.

“What we’re finding is that sea ice is effectively a lid on the ocean. And with its long term reduction across the Arctic, we’re seeing increasing amounts of moisture enter the atmosphere during winter, which directly impacts our weather further south, causing extremely heavy snowfalls,” said Hannah Bailey of the University of Oulu in Finland, who led the research.

“It might seem counter-intuitive, but nature is complex and what happens in the Arctic doesn’t stay in the Arctic.”

And Professor Hubbard said: “This study illustrates that the abrupt changes being witnessed across the Arctic now really are affecting the entire planet.” − Climate News Network

What happens in the Arctic may not stay there. Loss of Arctic sea ice can dump the polar blizzards elsewhere.

LONDON, 19 April, 2021 − Once again, scientists have linked a weather-related catastrophe directly to human-induced climate change. Extreme frost and springtime snowfalls in Western Europe can be pinned to the dramatic loss of Arctic sea ice.

So, paradoxically, global heating may have had the unexpected effect of wiping out around one third of the French wine harvest for this coming year, after temperatures so low that growers were forced to light bonfires in their vineyards to save the first buds from the chill.

“Climate change doesn’t always manifest in the most obvious ways,” said Alun Hubbard, of the Arctic University of Norway. “It’s easy to extrapolate models to show that winters are getting warmer and to forecast a virtually snow-free future in Europe, but our most recent study shows that is too simplistic. We should be beware of making broad, sweeping statements about the impacts of climate change.”

Professor Hubbard and colleagues report in the journal Nature Geoscience that they measured telltale isotope signatures in water vapour from Finland in February 2018 during an episode of freezing snow in Europe, in an anticyclone dubbed “the Beast from the East” by meteorologists and the media.

“The abrupt changes being witnessed across the Arctic now really are affecting the entire planet”

They found that the Barents Sea north of Scandinavia was anomalously warm. And 60% of the sea’s surface was free of ice, and the same sea lost 140 billion tonnes of water to evaporation during this too-warm February. This enormous atmospheric burden of water vapour provided, they calculate, 88% of the snow that was to fall over northern Europe that month.

Then they looked at the pattern over the years from 1979 to 2020, to find that, for every square metre of ice that vanished in the month of March − itself part of a pattern of Arctic temperature rise − evaporation across the Barents Sea increased by 70 kg, and this could be matched with increases in Europe’s maximum snowfall.

“Our analysis directly links Arctic sea ice loss with increased evaporation and extreme snow fall,” they write, and warn that by 2080 an ice-free Barents Sea “will be a major source of winter moisture for continental Europe.”

The Beast from the East brought much of Europe to a halt, at an economic cost of an estimated $1bn (£0.72bn) a day. It is still rare for researchers to directly link any particular weather event with climate change driven by profligate use of fossil fuels − that is because climate is what forecasters can reasonably expect, but weather is what actually happens − but some scientists have begun to do so with increasing confidence. And this time, they can explain why.

Natural complexity

The ice cover over the Barents Sea has fallen by 54% since 1979, at the rate of 11,200 sq kms a year, and snow mass across Eurasia has increased. The latest study confirms the link: the isotope signature of Barents water was repeated in the European snows that arrived with the Beast from the East.

“What we’re finding is that sea ice is effectively a lid on the ocean. And with its long term reduction across the Arctic, we’re seeing increasing amounts of moisture enter the atmosphere during winter, which directly impacts our weather further south, causing extremely heavy snowfalls,” said Hannah Bailey of the University of Oulu in Finland, who led the research.

“It might seem counter-intuitive, but nature is complex and what happens in the Arctic doesn’t stay in the Arctic.”

And Professor Hubbard said: “This study illustrates that the abrupt changes being witnessed across the Arctic now really are affecting the entire planet.” − Climate News Network

Climate heating may speed up to unexpected levels

When the ice thaws, ocean levels rise. And four new studies show climate heating can happen fast.

LONDON, 15 April, 2021 − If climate heating continues apace and the planet goes on warming, then up to a third of Antarctica’s ice shelf could tip into the sea.

And tip is the operative word, according to a separate study: at least one Antarctic glacier could be about to tip into rapid and irreversible retreat if temperatures go on rising.

And rise they could: evidence from the past in a third research programme confirms that at the end of the last Ice Age, Greenland’s temperature rose by somewhere between 5°C and 16°C in just decades, in line with a cascade of climate change events.

And ominously a fourth study of climate change 14,600 years ago confirmed that as the ice retreated, sea levels rose at 10 times the current rate, to 3.6 metres in just a century, and up to 18 metres in a 500-year sequence.

Each study is, on its own, an examination of the complexities of the planetary climate machine and the role of the polar ice sheets in climate change. But the message of the four together is a stark one: climate change is happening, could accelerate and could happen at unexpected speeds.

Unstable at 4°C

The Antarctic ice sheet floats on the sea: were it all to melt, sea levels globally would remain much the same. But the ice sheet plays an important role in stabilising the massive reserves of ice on the continental surface.

“Ice shelves are important buffers preventing glaciers on land from flowing freely into the ocean and contributing to sea level rise,” warned Ella Gilbert, a meteorologist at the University of Reading in the UK. “When they collapse, it’s like a giant cork being removed from a bottle, allowing unimaginable amounts of water from glaciers to pour into the sea.”

She and colleagues report in the journal Geophysical Research Letters that their detailed study of the vulnerable platforms of floating ice around the continent revealed that half a million square kilometres of shelf − 34% in total, including two-thirds of all the ice off the Antarctic Peninsula − would become unstable if global temperatures rose by 4°C, under the business-as-usual scenario in which nations went on burning ever-greater quantities of fossil fuel.

If however the world kept to the limit it agreed in Paris in 2015, that would halve the area at risk and perhaps avoid significant sea level rise. But already, just two Antarctic glaciers are responsible for around 10% of sea level rise at the current rate, and researchers have been warning for years that the Pine Island and Thwaites glaciers in West Antarctica could be at risk.

Now researchers in the UK report in the journal The Cryosphere that their computer simulation had identified a series of tipping points for the Pine Island flow.

“Ice shelves are important buffers preventing glaciers on land from contributing to sea level rise. When they collapse, it’s like a giant cork being removed from a bottle, allowing unimaginable amounts of water to pour into the sea”

The third of these, triggered by ocean temperatures that had warmed just 1.2°C, would lead to irretrievable retreat of the entire glacier. Hilmar Gudmundsson, a glaciologist at the UK’s Northumbria University and one of the authors, called the research a “major step forward” in the understanding of the dynamics of the region.

“But the findings of this study also concern me”, he said. “Should the glacier enter unstable irreversible retreat, the impact on sea level could be measured in metres, and as this study shows, once the retreat starts it might be impossible to halt it.”

Rapid polar melt is part of the pattern of climate history. Danish researchers report in Nature Communications that, on the evidence preserved in Greenland ice cores, they identified a series of 30 abrupt climate changes at the close of the Last Ice Age, affecting North Atlantic ocean currents, wind and rainfall patterns and the spread of sea ice: a set of physical processes that changed together, like a row of cascading dominoes.

The precise order of events was difficult to ascertain, but during that sequence the temperature of Greenland soared by 5°C to 16°C in decades to centuries. The question remains open: could such things happen today?

“The results emphasise the importance of trying to limit climate change by, for example, cutting anthropogenic emissions of CO2 and other greenhouse gases, both to reduce the predictable, gradual climate change and to reduce the risk of future abrupt climate change,” said Sune Olander Rasmussen, at the Niels Bohr Institute in Copenhagen, one of the authors.

Greenland’s future role

“If you do not want the dominoes to topple over, you are better off not to push the table they stand on too much.”

And another study in the same journal by British scientists reports on a close study of geological evidence to decipher the pattern of events during the largest and most rapid pulse of sea level rise at the close of the last Ice Age.

Their study suggested that although the sea levels rose 18 metres in about 500 years − a rate of about 3.6 metres a century − it all happened with relatively little help from a melting Antarctica. As the great glaciers retreated from North America, Europe and Asia, so the oceans rose.

“The next big question is to work out what triggered the ice melt, and what impact the massive influx of meltwater had on ocean currents in the North Atlantic,” said Pippa Whitehouse of the University of Durham, one of the researchers.

“This is very much on our minds today − any disruption to the Gulf Stream, for example due to melting of the Greenland Ice Sheet, will have significant consequences for the UK climate.” − Climate News Network

When the ice thaws, ocean levels rise. And four new studies show climate heating can happen fast.

LONDON, 15 April, 2021 − If climate heating continues apace and the planet goes on warming, then up to a third of Antarctica’s ice shelf could tip into the sea.

And tip is the operative word, according to a separate study: at least one Antarctic glacier could be about to tip into rapid and irreversible retreat if temperatures go on rising.

And rise they could: evidence from the past in a third research programme confirms that at the end of the last Ice Age, Greenland’s temperature rose by somewhere between 5°C and 16°C in just decades, in line with a cascade of climate change events.

And ominously a fourth study of climate change 14,600 years ago confirmed that as the ice retreated, sea levels rose at 10 times the current rate, to 3.6 metres in just a century, and up to 18 metres in a 500-year sequence.

Each study is, on its own, an examination of the complexities of the planetary climate machine and the role of the polar ice sheets in climate change. But the message of the four together is a stark one: climate change is happening, could accelerate and could happen at unexpected speeds.

Unstable at 4°C

The Antarctic ice sheet floats on the sea: were it all to melt, sea levels globally would remain much the same. But the ice sheet plays an important role in stabilising the massive reserves of ice on the continental surface.

“Ice shelves are important buffers preventing glaciers on land from flowing freely into the ocean and contributing to sea level rise,” warned Ella Gilbert, a meteorologist at the University of Reading in the UK. “When they collapse, it’s like a giant cork being removed from a bottle, allowing unimaginable amounts of water from glaciers to pour into the sea.”

She and colleagues report in the journal Geophysical Research Letters that their detailed study of the vulnerable platforms of floating ice around the continent revealed that half a million square kilometres of shelf − 34% in total, including two-thirds of all the ice off the Antarctic Peninsula − would become unstable if global temperatures rose by 4°C, under the business-as-usual scenario in which nations went on burning ever-greater quantities of fossil fuel.

If however the world kept to the limit it agreed in Paris in 2015, that would halve the area at risk and perhaps avoid significant sea level rise. But already, just two Antarctic glaciers are responsible for around 10% of sea level rise at the current rate, and researchers have been warning for years that the Pine Island and Thwaites glaciers in West Antarctica could be at risk.

Now researchers in the UK report in the journal The Cryosphere that their computer simulation had identified a series of tipping points for the Pine Island flow.

“Ice shelves are important buffers preventing glaciers on land from contributing to sea level rise. When they collapse, it’s like a giant cork being removed from a bottle, allowing unimaginable amounts of water to pour into the sea”

The third of these, triggered by ocean temperatures that had warmed just 1.2°C, would lead to irretrievable retreat of the entire glacier. Hilmar Gudmundsson, a glaciologist at the UK’s Northumbria University and one of the authors, called the research a “major step forward” in the understanding of the dynamics of the region.

“But the findings of this study also concern me”, he said. “Should the glacier enter unstable irreversible retreat, the impact on sea level could be measured in metres, and as this study shows, once the retreat starts it might be impossible to halt it.”

Rapid polar melt is part of the pattern of climate history. Danish researchers report in Nature Communications that, on the evidence preserved in Greenland ice cores, they identified a series of 30 abrupt climate changes at the close of the Last Ice Age, affecting North Atlantic ocean currents, wind and rainfall patterns and the spread of sea ice: a set of physical processes that changed together, like a row of cascading dominoes.

The precise order of events was difficult to ascertain, but during that sequence the temperature of Greenland soared by 5°C to 16°C in decades to centuries. The question remains open: could such things happen today?

“The results emphasise the importance of trying to limit climate change by, for example, cutting anthropogenic emissions of CO2 and other greenhouse gases, both to reduce the predictable, gradual climate change and to reduce the risk of future abrupt climate change,” said Sune Olander Rasmussen, at the Niels Bohr Institute in Copenhagen, one of the authors.

Greenland’s future role

“If you do not want the dominoes to topple over, you are better off not to push the table they stand on too much.”

And another study in the same journal by British scientists reports on a close study of geological evidence to decipher the pattern of events during the largest and most rapid pulse of sea level rise at the close of the last Ice Age.

Their study suggested that although the sea levels rose 18 metres in about 500 years − a rate of about 3.6 metres a century − it all happened with relatively little help from a melting Antarctica. As the great glaciers retreated from North America, Europe and Asia, so the oceans rose.

“The next big question is to work out what triggered the ice melt, and what impact the massive influx of meltwater had on ocean currents in the North Atlantic,” said Pippa Whitehouse of the University of Durham, one of the researchers.

“This is very much on our minds today − any disruption to the Gulf Stream, for example due to melting of the Greenland Ice Sheet, will have significant consequences for the UK climate.” − Climate News Network

Antarctic warming speed-up alarms researchers

The world’s largest reservoir of snow and ice could be melting faster than ever. Two new studies highlight Antarctic warming.

LONDON, 4 March, 2021 − Antarctic warming is accelerating: at least one of the southern continent’s ice shelves has been melting faster than ever. The polar summer of 2019-20 set a new record for temperatures above freezing point over the George VI ice shelf off the Antarctic Peninsula.

The finding is ominous: the ice shelves form a natural buttress that slows the rate of glacier flow from the continental bedrock. The faster the glaciers flow into the sea, the higher the hazard of sea level rise.

And a second study confirms that this is already happening in West Antarctica: researchers looked at 25 years of satellite observation of 14 glaciers in the Getz sector to find that meltwater is flowing into the Amundsen Sea ever faster. Between 1994 and 2018, these glaciers lost 315 billion tonnes of ice, enough to raise global sea levels by almost 1mm.

Melting rates in Antarctica have been a source of alarm for years. The latest studies confirm the picture of continuing melt.

“The high rates of increased glacier speed − coupled with ice thinning − confirm the Getz basin is losing more ice than it gains through snowfall”

US scientists report in the journal The Cryosphere that they too used satellite observation − 41 years of it − to measure summer meltwater on the ice and in the near-surface snow of the northern part of the George VI ice shelf. They identified the most widespread melt and the greatest total of melt days of any season during the 2019-2020 summer.

Air temperatures were above freezing for up to 90 hours, allowing pools of meltwater to collect on the shelf. At its peak 23% of the region was covered with water: the equivalent, in glaciology’s favourite popular measure, of 250,000 Olympic swimming pools.

“When the temperature is above zero degrees Celsius, that limits refreezing and also leads to further melting,” said Alison Banwell, of the University of Colorado at Boulder, who led the study. “Water absorbs more radiation than snow and ice, and that leads to even more melting.”

Remote and untrodden

The Getz shelf is one of the biggest of a sector of the West Antarctic known as Marie Byrd Land. A new report in Nature Communications confirms that all 14 measured glaciers there have picked up speed and reach the ocean ever more swiftly.

Three of them have accelerated by more than 44%. And over the years the loss of ice has been the equivalent of 126 million Olympic swimming pools − all of it now adding to global sea level rise.

“The Getz region of Antarctica is so remote that humans have never set foot on most of this part of the continent,” said Heather Selley, of the University of Leeds, UK, first author. “Satellite radar altimetry records have shown substantial thinning of the ice sheet.

“However, the high rates of increased glacier speed − coupled with ice thinning − now confirm the Getz basin is in dynamic imbalance, meaning that it is losing more ice than it gains through snowfall.” − Climate News Network

The world’s largest reservoir of snow and ice could be melting faster than ever. Two new studies highlight Antarctic warming.

LONDON, 4 March, 2021 − Antarctic warming is accelerating: at least one of the southern continent’s ice shelves has been melting faster than ever. The polar summer of 2019-20 set a new record for temperatures above freezing point over the George VI ice shelf off the Antarctic Peninsula.

The finding is ominous: the ice shelves form a natural buttress that slows the rate of glacier flow from the continental bedrock. The faster the glaciers flow into the sea, the higher the hazard of sea level rise.

And a second study confirms that this is already happening in West Antarctica: researchers looked at 25 years of satellite observation of 14 glaciers in the Getz sector to find that meltwater is flowing into the Amundsen Sea ever faster. Between 1994 and 2018, these glaciers lost 315 billion tonnes of ice, enough to raise global sea levels by almost 1mm.

Melting rates in Antarctica have been a source of alarm for years. The latest studies confirm the picture of continuing melt.

“The high rates of increased glacier speed − coupled with ice thinning − confirm the Getz basin is losing more ice than it gains through snowfall”

US scientists report in the journal The Cryosphere that they too used satellite observation − 41 years of it − to measure summer meltwater on the ice and in the near-surface snow of the northern part of the George VI ice shelf. They identified the most widespread melt and the greatest total of melt days of any season during the 2019-2020 summer.

Air temperatures were above freezing for up to 90 hours, allowing pools of meltwater to collect on the shelf. At its peak 23% of the region was covered with water: the equivalent, in glaciology’s favourite popular measure, of 250,000 Olympic swimming pools.

“When the temperature is above zero degrees Celsius, that limits refreezing and also leads to further melting,” said Alison Banwell, of the University of Colorado at Boulder, who led the study. “Water absorbs more radiation than snow and ice, and that leads to even more melting.”

Remote and untrodden

The Getz shelf is one of the biggest of a sector of the West Antarctic known as Marie Byrd Land. A new report in Nature Communications confirms that all 14 measured glaciers there have picked up speed and reach the ocean ever more swiftly.

Three of them have accelerated by more than 44%. And over the years the loss of ice has been the equivalent of 126 million Olympic swimming pools − all of it now adding to global sea level rise.

“The Getz region of Antarctica is so remote that humans have never set foot on most of this part of the continent,” said Heather Selley, of the University of Leeds, UK, first author. “Satellite radar altimetry records have shown substantial thinning of the ice sheet.

“However, the high rates of increased glacier speed − coupled with ice thinning − now confirm the Getz basin is in dynamic imbalance, meaning that it is losing more ice than it gains through snowfall.” − Climate News Network

Scientists say world’s huge ice loss is speeding up

The frozen world is shrinking at a “staggering” rate. New research takes a measure of the world’s huge ice loss.

LONDON, 27 January, 2021 − Planet Earth is losing its frozen mantle faster than ever as the world’s huge ice loss intensifies. Between 1994 and 2017, the polar regions and the mountain glaciers said farewell to a total of 28 million million tonnes of ice. This is a quantity large enough to conceal the entire United Kingdom under an ice sheet 100 metres thick.

More alarmingly, scientists warn, the rate of loss has been accelerating. Over the course of the 23-year survey of the planet’s ice budget, there has been a 65% increase in the flow of meltwater from the glaciers, ice shelves and ice sheets.

Early in the last decade of the last century, ice loss was counted at 0.8 trillion tonnes a year. By 2017, this had increased to 1.3 trillion tonnes a year, says a new study in the journal The Cryosphere.

The finding should come as no great surprise. Thanks to profligate combustion of fossil fuels and the clearance of forests and grasslands, the planet is warming: 2020 has been awarded the unwelcome title of equal place as warmest year ever recorded, and the last six years have been the six warmest since records began.

“The vast majority of Earth’s ice loss is a direct consequence of climate warming.”

Researchers warned last year that the melting rate of Greenland’s ice sheet − the biggest in the northern hemisphere − would soon hit a 12,000 year high. A second group warned in the same month that ice loss from Antarctica would soon become irreversible.

The latest research, based on satellite data, confirms all fears. “Although every region we studied lost ice, losses from the Antarctic and Greenland ice sheets have accelerated the most,” said Thomas Slater, of the University of Leeds in the UK, who led the research.

“The ice sheets are now following the worst case climate warning scenarios set out by the Intergovernmental Panel on Climate Change. Sea level rise on this scale will have very serious impacts on coastal communities this century.”

The scientists measured loss from the land-based ice sheets of Greenland and Antarctica, from the shelf ice around Antarctica and from the drifting sea ice in the Arctic and Southern Oceans, as well as the retreat of 215,000 mountain glaciers worldwide.

‘Staggering’ loss

During the 23-year-survey, thanks to rising air and ocean temperatures, the Arctic Ocean lost 7.6 trillion tonnes, the Antarctic ice shelves 6.5 trillion tonnes. Melting sea ice will not affect sea levels, but it will expose greater areas of ocean to radiation, which would otherwise be reflected back into space. So the loss of sea ice can only lead to even more warming.

The researchers claim theirs is the first full global survey, but they also concede it can only be incomplete: they did not take the measure of fallen snow on land, nor of the icy soils of the permafrost, and they did not try to measure the loss of winter ice on lakes and rivers − but they note that the duration of ice on lakes has fallen by 12 days in the last two centuries, thanks to atmospheric warming.

However, they could put a measure on ice losses from land − 6.1 trillion tonnes from mountain glaciers worldwide, 3.8 trillion tonnes from the Greenland ice sheet, 2.5 trillion tonnes from the Antarctic surface − enough to raise global sea levels by 35mm.

Scientific studies tend to be presented without emotive language. But the researchers call their total of lost ice “staggering”. And they warn: “There can be little doubt that the vast majority of Earth’s ice loss is a direct consequence of climate warming.” − Climate News Network

The frozen world is shrinking at a “staggering” rate. New research takes a measure of the world’s huge ice loss.

LONDON, 27 January, 2021 − Planet Earth is losing its frozen mantle faster than ever as the world’s huge ice loss intensifies. Between 1994 and 2017, the polar regions and the mountain glaciers said farewell to a total of 28 million million tonnes of ice. This is a quantity large enough to conceal the entire United Kingdom under an ice sheet 100 metres thick.

More alarmingly, scientists warn, the rate of loss has been accelerating. Over the course of the 23-year survey of the planet’s ice budget, there has been a 65% increase in the flow of meltwater from the glaciers, ice shelves and ice sheets.

Early in the last decade of the last century, ice loss was counted at 0.8 trillion tonnes a year. By 2017, this had increased to 1.3 trillion tonnes a year, says a new study in the journal The Cryosphere.

The finding should come as no great surprise. Thanks to profligate combustion of fossil fuels and the clearance of forests and grasslands, the planet is warming: 2020 has been awarded the unwelcome title of equal place as warmest year ever recorded, and the last six years have been the six warmest since records began.

“The vast majority of Earth’s ice loss is a direct consequence of climate warming.”

Researchers warned last year that the melting rate of Greenland’s ice sheet − the biggest in the northern hemisphere − would soon hit a 12,000 year high. A second group warned in the same month that ice loss from Antarctica would soon become irreversible.

The latest research, based on satellite data, confirms all fears. “Although every region we studied lost ice, losses from the Antarctic and Greenland ice sheets have accelerated the most,” said Thomas Slater, of the University of Leeds in the UK, who led the research.

“The ice sheets are now following the worst case climate warning scenarios set out by the Intergovernmental Panel on Climate Change. Sea level rise on this scale will have very serious impacts on coastal communities this century.”

The scientists measured loss from the land-based ice sheets of Greenland and Antarctica, from the shelf ice around Antarctica and from the drifting sea ice in the Arctic and Southern Oceans, as well as the retreat of 215,000 mountain glaciers worldwide.

‘Staggering’ loss

During the 23-year-survey, thanks to rising air and ocean temperatures, the Arctic Ocean lost 7.6 trillion tonnes, the Antarctic ice shelves 6.5 trillion tonnes. Melting sea ice will not affect sea levels, but it will expose greater areas of ocean to radiation, which would otherwise be reflected back into space. So the loss of sea ice can only lead to even more warming.

The researchers claim theirs is the first full global survey, but they also concede it can only be incomplete: they did not take the measure of fallen snow on land, nor of the icy soils of the permafrost, and they did not try to measure the loss of winter ice on lakes and rivers − but they note that the duration of ice on lakes has fallen by 12 days in the last two centuries, thanks to atmospheric warming.

However, they could put a measure on ice losses from land − 6.1 trillion tonnes from mountain glaciers worldwide, 3.8 trillion tonnes from the Greenland ice sheet, 2.5 trillion tonnes from the Antarctic surface − enough to raise global sea levels by 35mm.

Scientific studies tend to be presented without emotive language. But the researchers call their total of lost ice “staggering”. And they warn: “There can be little doubt that the vast majority of Earth’s ice loss is a direct consequence of climate warming.” − Climate News Network