Tag Archives: Ice melt

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

Pathway to global climate catastrophe is clear

Global climate catastrophe could be nearer than we think. New research suggests how it could happen.

LONDON, 8 June, 2021 − Here is a set of circumstances that could trigger global climate catastrophe. The Greenland ice sheet could begin a process of irreversible melting.

As it does, greater quantities of fresh water would flood into the Arctic Ocean, to further slow the already slowing Atlantic meridional overturning circulation, that great flow of water sometimes called the Gulf Stream that  distributes warmth from the tropics.

But as the Atlantic flow weakens, so rises the probability of increased and sustained drought and dieback in the Amazon rainforest: the entire region could begin to tip inexorably into savannah.

And the Southern Ocean would begin to warm: it could warm enough to hasten the disintegration of the West Antarctic ice sheet, to accelerate the rise of global sea levels and intensify the whole machinery of global heating.

Alarmingly, this process could begin to happen while global temperatures are still not much higher than they are now: 1.5°C has been repeatedly described as the limit beyond which global average temperatures should not rise, but the official global agreed target is a limit of 2°C.

In fact, the chance of a cascade of domino effects − of tipping points that trigger other climate tipping points − could begin somewhere between those two figures, and the probability rises thereafter.

No way back

And, researchers warn, when they say irreversible, they mean it. Once the Greenland ice sheet starts to slide into the sea, there will be no stopping it. The only question is how swiftly all these things could happen.

“Once triggered, the actual tipping process might take several years up to millennia, depending on the respective response times of the system,” the scientists write in the journal Earth System Dynamics.

It’s a scenario, not a prediction. It’s a calculation of possibilities and probabilities inherent in the process of global warming and climate change. It’s an identification of the way atmospheric warming driven by greenhouse gas emissions from human economies can and might change the climate system that drives planetary weather.

“We provide risk analysis, not a prediction, yet our findings still raise concern,” said Ricarda Winkelmann, of the Potsdam Institute for Climate Impact Research, one of the authors.

She and her colleagues base their study on computer simulations of planetary response to temperature rise. And one third of those simulations suggest that if the world reaches 2°C, then one of those elements could begin to tip towards irreversible change, and at the same time trigger other tipping points.

“We’re shifting the odds, and not to our favour − the risk is clearly increasing the more we heat our planet,” said her colleague and co-author Jonathan Donges. “It rises substantially between 1°C and 3°C.

“Rapidly reducing greenhouse gas emissions is indispensable to limit the risks of crossing tipping points in the climate system”

“If greenhouse gas emissions and the resulting climate change cannot be halted, the upper level of this warming range could most likely be crossed by the end of this century. With even higher temperatures, more tipping cascades are to be expected, with long-term devastating effects.”

Climate science has been concerned with the idea of tipping points − temperatures beyond which climate change might be irreversible − for decades. There have been repeated findings that some of these might be nearer than anybody had suspected.

Greenland is in effect the reservoir of most of the Northern hemisphere’s ice − enough to raise sea levels by seven metres − and it is melting at an ever-accelerating rate.

Researchers have again and again identified a possible faltering of the Atlantic current, to warn of a paradoxical consequence: if the Gulf Stream slows, then average temperatures in western Europe could actually fall in a globally-heating world.

The Amazon rainforest − a vital part of the planet’s climate machinery since the end of the last Ice Age − has been hit not just by human degradation but by drought and forest fire, and could be about to slide into permanent savannah.

Overshoot nears

And scientists in Antarctica have been warning for a decade of thinning ice sheets, and accelerating glaciers.

The planet has already warmed by more than a degree Celsius in the last century or so. There is a high chance that some time this decade the annual average planetary temperature could pass the 1.5°C threshold, if only temporarily.

Right now, although 195 nations in Paris in 2015 committed themselves to a target of “well below” 2°C by 2100, the world is heading for a temperature rise by the end of the century of more than 3°C.

The authors concede that their results contain a lot of uncertainties: there is more research to be done. But that doesn’t mean there is no urgency.

“Our analysis is conservative in the sense that several interactions and tipping elements are not yet considered”, said Professor Winkelmann. It would hence be a daring bet to hope that the uncertainties play out in a good way, given what is at stake.

“From a precautionary perspective, rapidly reducing greenhouse gas emissions is indispensable to limit the risks of crossing tipping points in the climate system, and potentially causing domino effects.” − Climate News Network

Global climate catastrophe could be nearer than we think. New research suggests how it could happen.

LONDON, 8 June, 2021 − Here is a set of circumstances that could trigger global climate catastrophe. The Greenland ice sheet could begin a process of irreversible melting.

As it does, greater quantities of fresh water would flood into the Arctic Ocean, to further slow the already slowing Atlantic meridional overturning circulation, that great flow of water sometimes called the Gulf Stream that  distributes warmth from the tropics.

But as the Atlantic flow weakens, so rises the probability of increased and sustained drought and dieback in the Amazon rainforest: the entire region could begin to tip inexorably into savannah.

And the Southern Ocean would begin to warm: it could warm enough to hasten the disintegration of the West Antarctic ice sheet, to accelerate the rise of global sea levels and intensify the whole machinery of global heating.

Alarmingly, this process could begin to happen while global temperatures are still not much higher than they are now: 1.5°C has been repeatedly described as the limit beyond which global average temperatures should not rise, but the official global agreed target is a limit of 2°C.

In fact, the chance of a cascade of domino effects − of tipping points that trigger other climate tipping points − could begin somewhere between those two figures, and the probability rises thereafter.

No way back

And, researchers warn, when they say irreversible, they mean it. Once the Greenland ice sheet starts to slide into the sea, there will be no stopping it. The only question is how swiftly all these things could happen.

“Once triggered, the actual tipping process might take several years up to millennia, depending on the respective response times of the system,” the scientists write in the journal Earth System Dynamics.

It’s a scenario, not a prediction. It’s a calculation of possibilities and probabilities inherent in the process of global warming and climate change. It’s an identification of the way atmospheric warming driven by greenhouse gas emissions from human economies can and might change the climate system that drives planetary weather.

“We provide risk analysis, not a prediction, yet our findings still raise concern,” said Ricarda Winkelmann, of the Potsdam Institute for Climate Impact Research, one of the authors.

She and her colleagues base their study on computer simulations of planetary response to temperature rise. And one third of those simulations suggest that if the world reaches 2°C, then one of those elements could begin to tip towards irreversible change, and at the same time trigger other tipping points.

“We’re shifting the odds, and not to our favour − the risk is clearly increasing the more we heat our planet,” said her colleague and co-author Jonathan Donges. “It rises substantially between 1°C and 3°C.

“Rapidly reducing greenhouse gas emissions is indispensable to limit the risks of crossing tipping points in the climate system”

“If greenhouse gas emissions and the resulting climate change cannot be halted, the upper level of this warming range could most likely be crossed by the end of this century. With even higher temperatures, more tipping cascades are to be expected, with long-term devastating effects.”

Climate science has been concerned with the idea of tipping points − temperatures beyond which climate change might be irreversible − for decades. There have been repeated findings that some of these might be nearer than anybody had suspected.

Greenland is in effect the reservoir of most of the Northern hemisphere’s ice − enough to raise sea levels by seven metres − and it is melting at an ever-accelerating rate.

Researchers have again and again identified a possible faltering of the Atlantic current, to warn of a paradoxical consequence: if the Gulf Stream slows, then average temperatures in western Europe could actually fall in a globally-heating world.

The Amazon rainforest − a vital part of the planet’s climate machinery since the end of the last Ice Age − has been hit not just by human degradation but by drought and forest fire, and could be about to slide into permanent savannah.

Overshoot nears

And scientists in Antarctica have been warning for a decade of thinning ice sheets, and accelerating glaciers.

The planet has already warmed by more than a degree Celsius in the last century or so. There is a high chance that some time this decade the annual average planetary temperature could pass the 1.5°C threshold, if only temporarily.

Right now, although 195 nations in Paris in 2015 committed themselves to a target of “well below” 2°C by 2100, the world is heading for a temperature rise by the end of the century of more than 3°C.

The authors concede that their results contain a lot of uncertainties: there is more research to be done. But that doesn’t mean there is no urgency.

“Our analysis is conservative in the sense that several interactions and tipping elements are not yet considered”, said Professor Winkelmann. It would hence be a daring bet to hope that the uncertainties play out in a good way, given what is at stake.

“From a precautionary perspective, rapidly reducing greenhouse gas emissions is indispensable to limit the risks of crossing tipping points in the climate system, and potentially causing domino effects.” − 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

Faster glacier melting raises hunger threat

The world’s upland icecaps are in retreat. Faster glacier melting could slow to a trickle streams that once fed foaming rivers.

LONDON, 5 May, 2021 − Glacial retreat − the rate at which mountain ice is turning to running water − has accelerated. In the last two decades, the world’s 220,000 glaciers have lost ice at the rate of 267 billion tonnes a year on average, and this faster glacier melting could soon imperil downstream food and water supplies.

To make sense of this almost unimaginable volume, think of a country the size of Switzerland. And then submerge it six metres deep in water. And then go on doing that every year for 20 years.

European scientists report in the journal Nature that, on the basis of satellite data, they assembled a global snapshot of the entire world’s stock of land-borne ice, excluding Antarctica and Greenland. And then they began to measure the impact of global heating driven by profligate fossil fuel use on the lofty, frozen beauty of the Alps, the Hindu Kush, the Andes, the Himalayas and the mountains of Alaska.

They found not just loss, but a loss that was accelerating sharply. Between 2000 and 2004, the glaciers together surrendered 227 billion tons of ice a year on average. By 2015 to 2019, the annual loss had risen to 298 billion tonnes. The run-off from the retreating glaciers alone caused more than one-fifth of observed sea level rise this century.

“The world really needs to act now to prevent the worst case climate change scenario”

Right now an estimated 200 million people live on land that is likely to be flooded by high tides at the close of this century. Altogether, one billion people could face water shortages and failed harvests within the next three decades, in many instances because of glacier loss.

Glacial ice in the high mountains represents so much water stored, to be released in the summer melt to nourish crops downstream. The fastest melt is in Alaska, Iceland and the Alps, but global warming is also affecting the Pamirs, the Hindu Kush and other peaks in Central Asia.

“The situation in the Himalayas is particularly worrying,” said Romain Hugonnet, of the Swiss Federal Institute of Technology, known as ETH Zurich, and the University of Toulouse.

“During the dry season, glacial meltwater is an important source that feeds major waterways such as the Ganges, Brahmaputra and Indus rivers. Right now, this increased melting acts as a buffer for people living in the region, but if Himalayan glacier shrinkage keeps accelerating, populous countries like India and Bangladesh could face food and water shortages in a few decades.”

Climate change link

Such news could hardly be a shock to geographers and climate scientists: researchers have been warning for years that as many as half of the planet’s mountain glaciers could be gone by the century’s end. Europe’s Alps could by 2100 have lost nine-tenths of all the continent’s flowing ice.

Researchers have also identified the consequent risk to water supplies for millions, and confirmed an “irrefutable” link between human-induced climate change and glacier loss. So the latest research is an update, and a check on subtle changes in rates of loss, based on imagery from Nasa’s Terra satellite, which has been orbiting the planet every 100 minutes since 1999.

The scientists found that melt rates in Greenland, Iceland and Scandinavia all slowed in the first two decades of the century, perhaps because of a change in temperatures and precipitation in the North Atlantic. Conversely, glaciers in the Karakoram range that had once seemed anomalously stable had now started to melt.

“Our findings are important on a political level,” said Daniel Farinotti, also of ETH Zurich. “The world really needs to act now to prevent the worst case climate change scenario.” − Climate News Network

The world’s upland icecaps are in retreat. Faster glacier melting could slow to a trickle streams that once fed foaming rivers.

LONDON, 5 May, 2021 − Glacial retreat − the rate at which mountain ice is turning to running water − has accelerated. In the last two decades, the world’s 220,000 glaciers have lost ice at the rate of 267 billion tonnes a year on average, and this faster glacier melting could soon imperil downstream food and water supplies.

To make sense of this almost unimaginable volume, think of a country the size of Switzerland. And then submerge it six metres deep in water. And then go on doing that every year for 20 years.

European scientists report in the journal Nature that, on the basis of satellite data, they assembled a global snapshot of the entire world’s stock of land-borne ice, excluding Antarctica and Greenland. And then they began to measure the impact of global heating driven by profligate fossil fuel use on the lofty, frozen beauty of the Alps, the Hindu Kush, the Andes, the Himalayas and the mountains of Alaska.

They found not just loss, but a loss that was accelerating sharply. Between 2000 and 2004, the glaciers together surrendered 227 billion tons of ice a year on average. By 2015 to 2019, the annual loss had risen to 298 billion tonnes. The run-off from the retreating glaciers alone caused more than one-fifth of observed sea level rise this century.

“The world really needs to act now to prevent the worst case climate change scenario”

Right now an estimated 200 million people live on land that is likely to be flooded by high tides at the close of this century. Altogether, one billion people could face water shortages and failed harvests within the next three decades, in many instances because of glacier loss.

Glacial ice in the high mountains represents so much water stored, to be released in the summer melt to nourish crops downstream. The fastest melt is in Alaska, Iceland and the Alps, but global warming is also affecting the Pamirs, the Hindu Kush and other peaks in Central Asia.

“The situation in the Himalayas is particularly worrying,” said Romain Hugonnet, of the Swiss Federal Institute of Technology, known as ETH Zurich, and the University of Toulouse.

“During the dry season, glacial meltwater is an important source that feeds major waterways such as the Ganges, Brahmaputra and Indus rivers. Right now, this increased melting acts as a buffer for people living in the region, but if Himalayan glacier shrinkage keeps accelerating, populous countries like India and Bangladesh could face food and water shortages in a few decades.”

Climate change link

Such news could hardly be a shock to geographers and climate scientists: researchers have been warning for years that as many as half of the planet’s mountain glaciers could be gone by the century’s end. Europe’s Alps could by 2100 have lost nine-tenths of all the continent’s flowing ice.

Researchers have also identified the consequent risk to water supplies for millions, and confirmed an “irrefutable” link between human-induced climate change and glacier loss. So the latest research is an update, and a check on subtle changes in rates of loss, based on imagery from Nasa’s Terra satellite, which has been orbiting the planet every 100 minutes since 1999.

The scientists found that melt rates in Greenland, Iceland and Scandinavia all slowed in the first two decades of the century, perhaps because of a change in temperatures and precipitation in the North Atlantic. Conversely, glaciers in the Karakoram range that had once seemed anomalously stable had now started to melt.

“Our findings are important on a political level,” said Daniel Farinotti, also of ETH Zurich. “The world really needs to act now to prevent the worst case climate change scenario.” − 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