Tag Archives: Ice melt

Ancient sea level rises may have been fairly minimal

Maybe ancient sea level rises were not so dramatic. But they’d still have been pretty frightening.

LONDON, 12 August, 2021 − Earth scientists have measured the rising tides of a warmer world more than 100 millennia ago and found a glimmer of good news: ancient sea level rises during a warm spell in the last Ice Age were quite possibly only about 1.2 metres higher than they are today.

Since, between 128,000 and 117,000 years ago, the world was perhaps as much as 2°C warmer than it would become for most of human history, this really is encouraging. Right now, climate scientists project a rise of somewhere between 60cm and 1.5m later this century, as global temperature levels rise 2°C or more above those normal before the Industrial Revolution.

But until now, geological orthodoxy has proposed that during the last “interglacial” or sudden warming, sea levels rose by six metres or possibly even nine metres. This could only happen if the Antarctic or Greenland ice sheets had collapsed.

And although these are indeed already losing ice at an accelerating rate, it doesn’t seem possible for such a colossal quantity of ice to melt in only a handful of decades.

Missing factor

So there was a mismatch between the predictions of the world’s scientists and the apparent evidence from the past.

Now a new study in the Proceedings of the National Academy of Sciences offers a solution: calculations about past sea level heights may have been perhaps too gloomy because they did not fully factor in sea level’s other great uncertainty — the movement of the continents lapped by the sea.

This bedevils all predictions about sea level rise. Seas rise and fall with global temperatures, but so do landmasses. Right now, although sea level is creeping up at a rate measured in millimetres per year, the land under a number of great coastal cities is sinking dramatically, as humans build  ever more massive cities and abstract ever more groundwater. So predictions warn that millions could be at risk of coastal flooding.

But there is another, deeper reason for the uncertainty: as rising temperatures remove the massive burden of ice from glaciated land, and wind and rain erode mountains, so the subterranean rocks in the Earth’s mantle, far below the crust, respond by inching upwards. Even the seemingly solid rocks are elastic, subsiding under pressure and rising when the mass is removed.

“Models of ice sheets are still in their toddlerhood”

All this means that, unless researchers can make an accurate estimate of land movement as well, sea level estimates are riven with uncertainties.

So a team from Columbia University in the US has looked at evidence of sea level rise and fall preserved in fossilised reefs and dunes in just one 1200km chain of islands − the Bahamas in the Atlantic − to come up with a new set of projections.

In the next 100 years, sea levels will rise by about 1.2 metres. This could be too modest: sea levels could just possibly rise by perhaps 5.3 metres, but this doesn’t seem likely. And a nine-metre rise is highly improbable.

“To get to nine metres of sea level rise, you’d have to melt large parts of Greenland and Antarctica,” said Blake Dyer, of the university’s Lamont-Doherty Earth Observatory.

Tricky calculation

“This suggests that didn’t happen. So maybe we should feel not so bad about the future. On the other hand, our lower estimate is bad, and our upper one is really bad.”

At the heart of the puzzle is a phenomenon known to geophysicists as isostasy: vast tracts of continental landmass have been heaving up and down, imperceptibly, over periods of tens of thousands of years, in response to ice and erosion.

So calculating sea level rise and fall when the thing on which sea level measurements are recorded − the land − is itself always shifting becomes tricky. That has always been why climate projections of sea levels contain a range of forecasts, rather than a hard number.

The argument is that changes recorded along the north-south lie of the Bahamas would provide a new and more sophisticated way of reconstructing sea heights in the relatively recent past.

Melting not guaranteed

The study doesn’t settle the question: estimates of past sea level change on a dramatic scale come from many parts of the planet, and glaciologists still have to reconstruct the rate at which the northern ice, for instance, may have retreated while the southern ice cap continued to advance during the last interglacial: that too would have limited sea level rise.

“This is still a question. Models of ice sheets are still in their toddlerhood,” said Maureen Raymo, director of the Earth Observatory and a co-author.

Human carbon emissions are now heating the globe far more rapidly and evenly than during the last interglacial, so there is no guarantee of any melting at different rates in two hemispheres

“That makes it more difficult to apply the results to today. The easy thing to say would be, ‘Oh we showed that sea levels were not so bad, and that’s terrific.’  The harder answer, the more honest answer, is that maybe things were different then, and we’re not in the clear.” − Climate News Network

Maybe ancient sea level rises were not so dramatic. But they’d still have been pretty frightening.

LONDON, 12 August, 2021 − Earth scientists have measured the rising tides of a warmer world more than 100 millennia ago and found a glimmer of good news: ancient sea level rises during a warm spell in the last Ice Age were quite possibly only about 1.2 metres higher than they are today.

Since, between 128,000 and 117,000 years ago, the world was perhaps as much as 2°C warmer than it would become for most of human history, this really is encouraging. Right now, climate scientists project a rise of somewhere between 60cm and 1.5m later this century, as global temperature levels rise 2°C or more above those normal before the Industrial Revolution.

But until now, geological orthodoxy has proposed that during the last “interglacial” or sudden warming, sea levels rose by six metres or possibly even nine metres. This could only happen if the Antarctic or Greenland ice sheets had collapsed.

And although these are indeed already losing ice at an accelerating rate, it doesn’t seem possible for such a colossal quantity of ice to melt in only a handful of decades.

Missing factor

So there was a mismatch between the predictions of the world’s scientists and the apparent evidence from the past.

Now a new study in the Proceedings of the National Academy of Sciences offers a solution: calculations about past sea level heights may have been perhaps too gloomy because they did not fully factor in sea level’s other great uncertainty — the movement of the continents lapped by the sea.

This bedevils all predictions about sea level rise. Seas rise and fall with global temperatures, but so do landmasses. Right now, although sea level is creeping up at a rate measured in millimetres per year, the land under a number of great coastal cities is sinking dramatically, as humans build  ever more massive cities and abstract ever more groundwater. So predictions warn that millions could be at risk of coastal flooding.

But there is another, deeper reason for the uncertainty: as rising temperatures remove the massive burden of ice from glaciated land, and wind and rain erode mountains, so the subterranean rocks in the Earth’s mantle, far below the crust, respond by inching upwards. Even the seemingly solid rocks are elastic, subsiding under pressure and rising when the mass is removed.

“Models of ice sheets are still in their toddlerhood”

All this means that, unless researchers can make an accurate estimate of land movement as well, sea level estimates are riven with uncertainties.

So a team from Columbia University in the US has looked at evidence of sea level rise and fall preserved in fossilised reefs and dunes in just one 1200km chain of islands − the Bahamas in the Atlantic − to come up with a new set of projections.

In the next 100 years, sea levels will rise by about 1.2 metres. This could be too modest: sea levels could just possibly rise by perhaps 5.3 metres, but this doesn’t seem likely. And a nine-metre rise is highly improbable.

“To get to nine metres of sea level rise, you’d have to melt large parts of Greenland and Antarctica,” said Blake Dyer, of the university’s Lamont-Doherty Earth Observatory.

Tricky calculation

“This suggests that didn’t happen. So maybe we should feel not so bad about the future. On the other hand, our lower estimate is bad, and our upper one is really bad.”

At the heart of the puzzle is a phenomenon known to geophysicists as isostasy: vast tracts of continental landmass have been heaving up and down, imperceptibly, over periods of tens of thousands of years, in response to ice and erosion.

So calculating sea level rise and fall when the thing on which sea level measurements are recorded − the land − is itself always shifting becomes tricky. That has always been why climate projections of sea levels contain a range of forecasts, rather than a hard number.

The argument is that changes recorded along the north-south lie of the Bahamas would provide a new and more sophisticated way of reconstructing sea heights in the relatively recent past.

Melting not guaranteed

The study doesn’t settle the question: estimates of past sea level change on a dramatic scale come from many parts of the planet, and glaciologists still have to reconstruct the rate at which the northern ice, for instance, may have retreated while the southern ice cap continued to advance during the last interglacial: that too would have limited sea level rise.

“This is still a question. Models of ice sheets are still in their toddlerhood,” said Maureen Raymo, director of the Earth Observatory and a co-author.

Human carbon emissions are now heating the globe far more rapidly and evenly than during the last interglacial, so there is no guarantee of any melting at different rates in two hemispheres

“That makes it more difficult to apply the results to today. The easy thing to say would be, ‘Oh we showed that sea levels were not so bad, and that’s terrific.’  The harder answer, the more honest answer, is that maybe things were different then, and we’re not in the clear.” − Climate News Network

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

Melting tropical glaciers sound an early warning

Climate change means melting tropical glaciers are losing frozen landscapes of great beauty − and high value to millions.

LONDON, 5 July, 2021 − The world’s remotest water towers are in retreat. The snows of Kilimanjaro in Africa are diminishing: between 1986 and 2017 the area of ice that crowns the most famous mountain in Tanzania has decreased by 71%. A tropical glacier near Puncak Jaya in Papua in Indonesia has lost 93% of its ice in the 38 years from 1980 to 2018. Melting tropical glaciers are together sounding an ominous warning.

The frozen summit of Huascarán, the highest peak in the tropics, in Peru has decreased in area by 19% between 1970 and 2003. In 1976, US scientists first took cores from the ice cap of Quelccaya in the Peruvian Andes: by 2020, around 46% had gone.

The darkening summits of the highest tropical mountains have a message for the world about the rate of climate change. “These are in the most remote parts of our planet − they’re not next to big cities, so you don’t have a local pollution effect,” said Lonnie Thompson of Ohio University.

“These glaciers are sentinels, they’re early warning systems for the planet and they are all saying the same thing.”

Millennial climate records

He and colleagues report in the journal Global and Planetary Change that they analysed the impact of warming on what they call “rapidly retreating high-altitude, low-latitude glaciers” in four separate regions of the planet: Africa, the Andes in Peru and Bolivia, the Tibetan Plateau and Himalayas of Asia, and the mountains of Papua province in Indonesia on the island known as New Guinea in the southwestern Pacific.

Each of the sample glaciers has yielded cores of ice that preserve, in their snow chemistry and trapped pollen, a record of many thousands of years of subtle climate change. And, since 1972, Earth observation satellites such as Nasa’s Landsat mission have monitored their surfaces.

In a world now heating as a response to greenhouse gas emissions into the atmosphere, where once snow had fallen, there is now rain to wash away the high-altitude ice. Glaciers serve as sources of fresh water for farmers and villagers in the tropical mountain zones: they also provide the river melt for many millions downstream.

The latest research confirms something climate scientists already knew: that almost everywhere, mountain ice is in retreat, with potentially devastating consequences for local economies. And the culprit is climate change driven by profligate fossil fuel combustion.

“These glaciers are sentinels, they’re early warning systems for the planet and they are all saying the same thing”

The Ohio researchers say: “Since the beginning of the 21st century the rates of ice loss have been at historically unprecedented levels.”

Within two or three years, the high snows near Puncak Jaya − these have powerful religious and cultural significance for the local people − will have gone.

But, the scientists argue, it is not too late to slow or stop the rate of greenhouse gas emissions into the atmosphere, and to slow or stop the retreat of many tropical glaciers.

“The science doesn’t change the trajectory we’re on,” said Professor Thompson. “Regardless of how clear the science is, we need something to happen to change that trajectory.” − Climate News Network

Climate change means melting tropical glaciers are losing frozen landscapes of great beauty − and high value to millions.

LONDON, 5 July, 2021 − The world’s remotest water towers are in retreat. The snows of Kilimanjaro in Africa are diminishing: between 1986 and 2017 the area of ice that crowns the most famous mountain in Tanzania has decreased by 71%. A tropical glacier near Puncak Jaya in Papua in Indonesia has lost 93% of its ice in the 38 years from 1980 to 2018. Melting tropical glaciers are together sounding an ominous warning.

The frozen summit of Huascarán, the highest peak in the tropics, in Peru has decreased in area by 19% between 1970 and 2003. In 1976, US scientists first took cores from the ice cap of Quelccaya in the Peruvian Andes: by 2020, around 46% had gone.

The darkening summits of the highest tropical mountains have a message for the world about the rate of climate change. “These are in the most remote parts of our planet − they’re not next to big cities, so you don’t have a local pollution effect,” said Lonnie Thompson of Ohio University.

“These glaciers are sentinels, they’re early warning systems for the planet and they are all saying the same thing.”

Millennial climate records

He and colleagues report in the journal Global and Planetary Change that they analysed the impact of warming on what they call “rapidly retreating high-altitude, low-latitude glaciers” in four separate regions of the planet: Africa, the Andes in Peru and Bolivia, the Tibetan Plateau and Himalayas of Asia, and the mountains of Papua province in Indonesia on the island known as New Guinea in the southwestern Pacific.

Each of the sample glaciers has yielded cores of ice that preserve, in their snow chemistry and trapped pollen, a record of many thousands of years of subtle climate change. And, since 1972, Earth observation satellites such as Nasa’s Landsat mission have monitored their surfaces.

In a world now heating as a response to greenhouse gas emissions into the atmosphere, where once snow had fallen, there is now rain to wash away the high-altitude ice. Glaciers serve as sources of fresh water for farmers and villagers in the tropical mountain zones: they also provide the river melt for many millions downstream.

The latest research confirms something climate scientists already knew: that almost everywhere, mountain ice is in retreat, with potentially devastating consequences for local economies. And the culprit is climate change driven by profligate fossil fuel combustion.

“These glaciers are sentinels, they’re early warning systems for the planet and they are all saying the same thing”

The Ohio researchers say: “Since the beginning of the 21st century the rates of ice loss have been at historically unprecedented levels.”

Within two or three years, the high snows near Puncak Jaya − these have powerful religious and cultural significance for the local people − will have gone.

But, the scientists argue, it is not too late to slow or stop the rate of greenhouse gas emissions into the atmosphere, and to slow or stop the retreat of many tropical glaciers.

“The science doesn’t change the trajectory we’re on,” said Professor Thompson. “Regardless of how clear the science is, we need something to happen to change that trajectory.” − 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

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