Tag Archives: Ice melt

‘Upside-down rivers’ speed polar ice loss

polar ice

Researchers move closer to understanding the invisible dynamics that drive the loss of polar ice shelves – but what it means for global warming is still uncertain.

LONDON, October 16, 2019 – Scientists in the US believe they have now identified the machinery that drives the break-up of great chunks of polar ice shelves. What they call “upside down rivers” of warm, less dense, less saline water, tens of miles long and miles wide, find weaknesses in the massive ice shelves.

And because global temperature rise is causing polar currents to get warmer, the effect could be to accelerate the collapse of great tracts of ice shelf, and allow glacial flow to speed up – resulting in rising sea levels.

Call it subversion: these unexpected channels of water rise from underneath to concentrate their effect on fracture zones that form as land-bound glaciers flow slowly onto the marine surface.

“Warm water circulation is attacking the undersides of these ice shelves at their weakest points,” says Earth scientist Karen Alley, who did her research at the University of Colorado in Boulder, but is now at the College of Wooster in Ohio, US. “These effects matter. Exactly how much, we don’t yet know. But we need to.”

Frozen sheets

The research could explain the persistent appearance, at roughly the same place every year, of polynyas. These are great pools of open sea water in the ice shelves, and scientists have been puzzling for decades about the mechanisms that make them possible.

About 80% of Antarctica is bounded by frozen sheets of sea ice, many of them anchored by bumps and chasms on the sea floor, and this is what slows the flow of ice from high ground to ocean.

But satellite studies have long exposed crevasses in this ice, formed at what scientists call “shear margins” – weak points in flowing ice.

Once part of the floating shelf, these fracture zones are more vulnerable to plumes of more buoyant – that is, less saline and warmer – water that flow as “basal channels” to create long wrinkles or sags in the shelf.

Dr Alley and her colleagues report in Science Advances journal that they pieced together this picture of polar dynamism far below the surface by combing satellite data to expose patterns of surface change made possible only by some consistent erosion by warmer current.

Climate – winds, rainfall, heat and drought patterns – is driven by the temperature gradient. Large-scale weather systems happen because the poles are cold and the tropics are hot, and this difference powers the stratospheric jet stream and the most profound ocean flow.

So climate scientists are intensely interested in change in both Greenland and the Antarctic.

“Now we’re seeing a new process, where warm water cuts into the ice shelf from below”

Other teams have already established that ice shelves are melting ever faster in the coldest places on the planet, that this melting is happening ever faster, that the ice is being attacked from below, and that this can only accelerate sea-level rise in a world subject to global heating driven by human use of fossil fuels that deposit huge volumes of greenhouse gases in the atmosphere.

The latest study focused on Antarctica, but the findings could also be applied to Greenland, which has the greatest reserve of Arctic ice, and where ice loss is accelerating even faster.

Report co-author Ted Scambos, senior research scientist in the Earth Science and Observation Centre at the University of Colorado at Boulder, says: “Now we’re seeing a new process, where warm water cuts into the ice shelf from below.

“Like scoring a plate of glass, the trough renders the shelf weak and, in a few decades, it’s gone, freeing the ice sheet to ride out faster into the ocean.” – Climate News Network

Researchers move closer to understanding the invisible dynamics that drive the loss of polar ice shelves – but what it means for global warming is still uncertain.

LONDON, October 16, 2019 – Scientists in the US believe they have now identified the machinery that drives the break-up of great chunks of polar ice shelves. What they call “upside down rivers” of warm, less dense, less saline water, tens of miles long and miles wide, find weaknesses in the massive ice shelves.

And because global temperature rise is causing polar currents to get warmer, the effect could be to accelerate the collapse of great tracts of ice shelf, and allow glacial flow to speed up – resulting in rising sea levels.

Call it subversion: these unexpected channels of water rise from underneath to concentrate their effect on fracture zones that form as land-bound glaciers flow slowly onto the marine surface.

“Warm water circulation is attacking the undersides of these ice shelves at their weakest points,” says Earth scientist Karen Alley, who did her research at the University of Colorado in Boulder, but is now at the College of Wooster in Ohio, US. “These effects matter. Exactly how much, we don’t yet know. But we need to.”

Frozen sheets

The research could explain the persistent appearance, at roughly the same place every year, of polynyas. These are great pools of open sea water in the ice shelves, and scientists have been puzzling for decades about the mechanisms that make them possible.

About 80% of Antarctica is bounded by frozen sheets of sea ice, many of them anchored by bumps and chasms on the sea floor, and this is what slows the flow of ice from high ground to ocean.

But satellite studies have long exposed crevasses in this ice, formed at what scientists call “shear margins” – weak points in flowing ice.

Once part of the floating shelf, these fracture zones are more vulnerable to plumes of more buoyant – that is, less saline and warmer – water that flow as “basal channels” to create long wrinkles or sags in the shelf.

Dr Alley and her colleagues report in Science Advances journal that they pieced together this picture of polar dynamism far below the surface by combing satellite data to expose patterns of surface change made possible only by some consistent erosion by warmer current.

Climate – winds, rainfall, heat and drought patterns – is driven by the temperature gradient. Large-scale weather systems happen because the poles are cold and the tropics are hot, and this difference powers the stratospheric jet stream and the most profound ocean flow.

So climate scientists are intensely interested in change in both Greenland and the Antarctic.

“Now we’re seeing a new process, where warm water cuts into the ice shelf from below”

Other teams have already established that ice shelves are melting ever faster in the coldest places on the planet, that this melting is happening ever faster, that the ice is being attacked from below, and that this can only accelerate sea-level rise in a world subject to global heating driven by human use of fossil fuels that deposit huge volumes of greenhouse gases in the atmosphere.

The latest study focused on Antarctica, but the findings could also be applied to Greenland, which has the greatest reserve of Arctic ice, and where ice loss is accelerating even faster.

Report co-author Ted Scambos, senior research scientist in the Earth Science and Observation Centre at the University of Colorado at Boulder, says: “Now we’re seeing a new process, where warm water cuts into the ice shelf from below.

“Like scoring a plate of glass, the trough renders the shelf weak and, in a few decades, it’s gone, freeing the ice sheet to ride out faster into the ocean.” – Climate News Network

Penguins in peril as winds change and heat rises

New weather patterns in the warming Antarctic are leaving thousands of penguins in peril, prompting calls for them to be specially protected.

LONDON, 10 October, 2019 – A species that has come to symbolise Antarctica’s wealth of wildlife now faces mortal danger: climate change is putting emperor penguins in peril.

British scientists say the continent is warming with unparalleled speed, meaning the birds may soon have almost nowhere to breed. Some researchers think the number of emperors could be cut by more than half by 2100.

Philip Trathan, head of conservation biology at the British Antarctic Survey in Cambridge, says: “The current rate of warming in parts of the Antarctic is greater than anything in the recent glaciological record.

“Though emperor penguins have experienced periods of warming and cooling over their evolutionary history, the current rates of warming are unprecedented.

“Currently, we have no idea how the emperors will adjust to the loss of their primary breeding habitat – sea ice. They are not agile, and climbing ashore across steep coastal land forms will be difficult.

Numbers fluctuate

“For breeding, they depend upon sea ice, and in a warming world there is a high probability that this will decrease. Without it, they will have little or no breeding habitat.”

It is not the first time scientists have sounded the alarm for the emperors. This time, though, they are urging potentially far-reaching action.

In a study published in the journal Biological Conservation, an international team of researchers, led by Dr Trathan, recommends new steps to protect and conserve the penguins (Aptenodytes forsteri).

Satellite images in 2012 suggested there were almost 600,000 of the birds in the Antarctic, roughly double the number estimated in 1992. The researchers involved in this latest report reviewed over 150 studies on the species and its environment as well as its behaviour and character in relation to its breeding biology.

“Some colonies of emperor penguins may not survive the coming decades, so we must work to give as much protection as we can to the species”

Current climate change projections indicate that rising temperatures and changing wind patterns will damage the sea ice on which the emperors breed, with some studies showing populations likely to fall by more than 50% over this century.

Before breeding, both males and females must build their body reserves so that females can lay their single egg, and for males to fast while undertaking the entire egg incubation during the Antarctic winter.

Emperors are unique amongst birds because they breed on seasonal Antarctic sea ice which they need while incubating their eggs and raising their chicks.

They also need stable sea ice after they have completed breeding, during the time when they undergo their annual moult. They cannot enter the water then as their feathers are no longer waterproof, leaving them unable to enter the sea.

So the researchers are recommending that the IUCN status for the species be raised from “near-threatened” to “vulnerable” on the IUCN Red List.  They say improvements in climate change forecasting of impacts on Antarctic wildlife would help, and recommend that the emperors should be listed by the Antarctic Treaty as a specially protected species.

Wider appeal

Better protection will let scientists coordinate research into the penguins’ resilience to a range of different threats and stressors.

Dr Peter Fretwell, remote sensing specialist at BAS and a co-author of the study, says: “Some colonies of emperor penguins may not survive the coming decades, so we must work to give as much protection as we can to the species to give them the best chance.”

The UK was one of the countries which notified the Antarctic Treaty Consultative Meeting at its 2019 meeting in July that emperor penguins were threatened by the loss of their breeding habitat and that further protection was needed.

A similar paper has also been submitted to this year’s Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR), which meets in the Tasmanian capital, Hobart, later this month. – Climate News Network 

New weather patterns in the warming Antarctic are leaving thousands of penguins in peril, prompting calls for them to be specially protected.

LONDON, 10 October, 2019 – A species that has come to symbolise Antarctica’s wealth of wildlife now faces mortal danger: climate change is putting emperor penguins in peril.

British scientists say the continent is warming with unparalleled speed, meaning the birds may soon have almost nowhere to breed. Some researchers think the number of emperors could be cut by more than half by 2100.

Philip Trathan, head of conservation biology at the British Antarctic Survey in Cambridge, says: “The current rate of warming in parts of the Antarctic is greater than anything in the recent glaciological record.

“Though emperor penguins have experienced periods of warming and cooling over their evolutionary history, the current rates of warming are unprecedented.

“Currently, we have no idea how the emperors will adjust to the loss of their primary breeding habitat – sea ice. They are not agile, and climbing ashore across steep coastal land forms will be difficult.

Numbers fluctuate

“For breeding, they depend upon sea ice, and in a warming world there is a high probability that this will decrease. Without it, they will have little or no breeding habitat.”

It is not the first time scientists have sounded the alarm for the emperors. This time, though, they are urging potentially far-reaching action.

In a study published in the journal Biological Conservation, an international team of researchers, led by Dr Trathan, recommends new steps to protect and conserve the penguins (Aptenodytes forsteri).

Satellite images in 2012 suggested there were almost 600,000 of the birds in the Antarctic, roughly double the number estimated in 1992. The researchers involved in this latest report reviewed over 150 studies on the species and its environment as well as its behaviour and character in relation to its breeding biology.

“Some colonies of emperor penguins may not survive the coming decades, so we must work to give as much protection as we can to the species”

Current climate change projections indicate that rising temperatures and changing wind patterns will damage the sea ice on which the emperors breed, with some studies showing populations likely to fall by more than 50% over this century.

Before breeding, both males and females must build their body reserves so that females can lay their single egg, and for males to fast while undertaking the entire egg incubation during the Antarctic winter.

Emperors are unique amongst birds because they breed on seasonal Antarctic sea ice which they need while incubating their eggs and raising their chicks.

They also need stable sea ice after they have completed breeding, during the time when they undergo their annual moult. They cannot enter the water then as their feathers are no longer waterproof, leaving them unable to enter the sea.

So the researchers are recommending that the IUCN status for the species be raised from “near-threatened” to “vulnerable” on the IUCN Red List.  They say improvements in climate change forecasting of impacts on Antarctic wildlife would help, and recommend that the emperors should be listed by the Antarctic Treaty as a specially protected species.

Wider appeal

Better protection will let scientists coordinate research into the penguins’ resilience to a range of different threats and stressors.

Dr Peter Fretwell, remote sensing specialist at BAS and a co-author of the study, says: “Some colonies of emperor penguins may not survive the coming decades, so we must work to give as much protection as we can to the species to give them the best chance.”

The UK was one of the countries which notified the Antarctic Treaty Consultative Meeting at its 2019 meeting in July that emperor penguins were threatened by the loss of their breeding habitat and that further protection was needed.

A similar paper has also been submitted to this year’s Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR), which meets in the Tasmanian capital, Hobart, later this month. – Climate News Network 

Extreme sea level events ‘will hit once a year by 2050’

This story originally appeared in The Guardian. It is republished here as part of the Climate News Network’s partnership with Covering Climate Now, a global collaboration of more than 250 news outlets to strengthen coverage of the climate story.

Extreme sea level events that used to occur once a century will strike every year on many coasts by 2050, no matter whether climate heating emissions are curbed or not, according to a landmark report by the world’s scientists.

25 September, 2019 − The stark assessment of the climate crisis in the world’s oceans and ice caps concludes that many serious impacts are already inevitable, from more intense storms to melting permafrost and dwindling marine life.

But far worse impacts will hit without urgent action to cut fossil fuel emissions, including eventual sea level rise of more than 4 metres in the worst case, an outcome that would redraw the map of the world and harm billions of people.

The report from the Intergovernmental Panel on Climate Change (IPCC), and approved by its 193 member nations, says that “all people on Earth depend directly or indirectly on the ocean” and ice caps and glaciers to regulate the climate and provide water and oxygen. But it finds unprecedented and dangerous changes being driven by global heating.

Sea level rise is accelerating as losses from Greenland and Antarctica increase, and the ocean is getting hotter, more acidic and less oxygenated. All these trends will continue to the end of the century, the IPCC report said.

Half the world’s megacities, and almost 2 billion people, live on coasts. Even if heating is restricted to just 2C, scientists expect the impact of sea level rise to cause several trillion dollars of damage a year, and result in many millions of migrants.

“The future for low-lying coastal communities looks extremely bleak,” said Prof Jonathan Bamber at Bristol University in the UK, who is not one of the report’s authors. “But the consequences will be felt by all of us. There is plenty to be concerned about for the future of humanity and social order from the headlines in this report.”

The new IPCC projections of likely sea level rise by 2100 are higher than those it made in 2014, due to unexpectedly fast melting in Antarctica. Without cuts in carbon emissions, the ocean is expected to rise between 61cm and 110cm, about 10cm more than the earlier estimate. A 10cm rise means 10 million additional people exposed to flooding, research shows.

The IPCC considers the likely range of sea level rise but not the worst-case scenario. Recent expert analysis led by Bamber concluded that up to 238cm of sea level rise remains possible by 2100, drowning many megacities around the world. “This cannot be ruled out,” said Zita Sebesvari at the United Nations University, a lead author of the IPCC report.

Even if huge cuts in emissions begin immediately, between 29cm and 59cm of sea level rise is already inevitable because the ice caps and glaciers melt slowly. Sea level will rise for centuries without action, Sebesvari warned. “The dramatic thing about sea level rise is if we accept 1 metre happening by 2100, we accept we will get about 4 metres by 2300. That is simply not an option we can risk.”

Extreme sea level impacts will be felt in many places very soon and well before 2050, Sebesvari said. The IPCC report states: “Extreme sea level events that [occur] once per century in the recent past are projected to occur at least once per year at many locations by 2050 in all scenarios.”

The heating oceans are causing more intense tropical storms to batter coasts, the IPCC report found, with stronger winds and greater deluges of rain. For example, Hurricane Harvey’s unprecedented deluge, which caused catastrophic flooding, was made three times more likely by climate change.

Ocean heating also harms kelp forests and other important ecosystems, with the marine heatwaves that sear through them like underwater wildfires having doubled in frequency in the last 40 years. They are projected to increase by at least 20 times by 2100, the IPCC reported.

Extreme El Niño events, which see heatwaves in some regions and floods in others, are projected to occur twice as often this century whether emissions are cut or not, the report said. Coral reefs, vital nurseries for marine life, will suffer major losses and local extinctions. Across the ocean, heat, acidification and lower oxygen is set to cut fisheries by a quarter and all marine life by 15% if emissions are not slashed.

The IPCC report also records the large reduction in Arctic ice. This loss exacerbates global heating, because the exposed darker ocean absorbs more heat from the sun than highly reflective ice. On Monday, scientists announced that the Arctic sea ice in 2019 shrank to its second lowest extent in the 41-year satellite record.

The world’s high mountain glaciers, upon which almost 2 billion people rely for water, are also melting fast, the IPCC found, while landslides are expected to increase. A third of the great Himalayan range is already doomed, with two-thirds projected to vanish if emissions are not cut.

One of the most worrying alarms sounded by the IPCC report is about melting tundra and increasing wildfires in northern latitudes: “Widespread permafrost thaw is projected for this century and beyond.” A quarter is already near certain to melt, it said, and 70% or more would go if emissions are not curbed. In the latter case, hundreds of billions of tonnes of carbon dioxide and methane could be released, supercharging the climate emergency.

“That risks taking us beyond the point where climate change could be easily constrained,” said Richard Black, at the UK’s Energy and Climate Intelligence Unit. “Nevertheless, the IPCC’s 2018 report concluded that governments can shrink emissions quickly enough to keep global warming to 1.5C if they choose. None can claim to be unaware of both the dangers of untrammelled climate change nor the feasibility of preventing it.”

Anne Hidalgo, the mayor of Paris and chair of the C40 Cities climate coalition, said the IPCC report was shocking. “Around 1.9 billion people and over half of the world’s megacities are all in grave danger if we don’t act immediately. Several cities, home to hundreds of thousands of people, are already disappearing underwater. This is what the climate crisis looks like now.”

Taehyun Park, of Greenpeace East Asia, said: “The science is both chilling and compelling. The impacts on our oceans are on a much larger scale and happening way faster than predicted. It will require unprecedented political action to prevent the most severe consequences to our planet.”

As well as cutting fossil fuel emissions, preparing for the inevitable impacts is also vital, said Sebesvari, especially in poorer nations that lack the funds to build sea walls, move settlements or restore protective coastal marshes.

“Action is needed now to secure the coast for our children and coming generations,” she said. The pressure now being exerted by the global school strikes for climate was important, she said. “I have very strong motivation. I have two kids and we are really being tested by our kids on our actions.”

* * * * * * *

Damian Carrington is The Guardian’s environment editor.

This story originally appeared in The Guardian. It is republished here as part of the Climate News Network’s partnership with Covering Climate Now, a global collaboration of more than 250 news outlets to strengthen coverage of the climate story.

Extreme sea level events that used to occur once a century will strike every year on many coasts by 2050, no matter whether climate heating emissions are curbed or not, according to a landmark report by the world’s scientists.

25 September, 2019 − The stark assessment of the climate crisis in the world’s oceans and ice caps concludes that many serious impacts are already inevitable, from more intense storms to melting permafrost and dwindling marine life.

But far worse impacts will hit without urgent action to cut fossil fuel emissions, including eventual sea level rise of more than 4 metres in the worst case, an outcome that would redraw the map of the world and harm billions of people.

The report from the Intergovernmental Panel on Climate Change (IPCC), and approved by its 193 member nations, says that “all people on Earth depend directly or indirectly on the ocean” and ice caps and glaciers to regulate the climate and provide water and oxygen. But it finds unprecedented and dangerous changes being driven by global heating.

Sea level rise is accelerating as losses from Greenland and Antarctica increase, and the ocean is getting hotter, more acidic and less oxygenated. All these trends will continue to the end of the century, the IPCC report said.

Half the world’s megacities, and almost 2 billion people, live on coasts. Even if heating is restricted to just 2C, scientists expect the impact of sea level rise to cause several trillion dollars of damage a year, and result in many millions of migrants.

“The future for low-lying coastal communities looks extremely bleak,” said Prof Jonathan Bamber at Bristol University in the UK, who is not one of the report’s authors. “But the consequences will be felt by all of us. There is plenty to be concerned about for the future of humanity and social order from the headlines in this report.”

The new IPCC projections of likely sea level rise by 2100 are higher than those it made in 2014, due to unexpectedly fast melting in Antarctica. Without cuts in carbon emissions, the ocean is expected to rise between 61cm and 110cm, about 10cm more than the earlier estimate. A 10cm rise means 10 million additional people exposed to flooding, research shows.

The IPCC considers the likely range of sea level rise but not the worst-case scenario. Recent expert analysis led by Bamber concluded that up to 238cm of sea level rise remains possible by 2100, drowning many megacities around the world. “This cannot be ruled out,” said Zita Sebesvari at the United Nations University, a lead author of the IPCC report.

Even if huge cuts in emissions begin immediately, between 29cm and 59cm of sea level rise is already inevitable because the ice caps and glaciers melt slowly. Sea level will rise for centuries without action, Sebesvari warned. “The dramatic thing about sea level rise is if we accept 1 metre happening by 2100, we accept we will get about 4 metres by 2300. That is simply not an option we can risk.”

Extreme sea level impacts will be felt in many places very soon and well before 2050, Sebesvari said. The IPCC report states: “Extreme sea level events that [occur] once per century in the recent past are projected to occur at least once per year at many locations by 2050 in all scenarios.”

The heating oceans are causing more intense tropical storms to batter coasts, the IPCC report found, with stronger winds and greater deluges of rain. For example, Hurricane Harvey’s unprecedented deluge, which caused catastrophic flooding, was made three times more likely by climate change.

Ocean heating also harms kelp forests and other important ecosystems, with the marine heatwaves that sear through them like underwater wildfires having doubled in frequency in the last 40 years. They are projected to increase by at least 20 times by 2100, the IPCC reported.

Extreme El Niño events, which see heatwaves in some regions and floods in others, are projected to occur twice as often this century whether emissions are cut or not, the report said. Coral reefs, vital nurseries for marine life, will suffer major losses and local extinctions. Across the ocean, heat, acidification and lower oxygen is set to cut fisheries by a quarter and all marine life by 15% if emissions are not slashed.

The IPCC report also records the large reduction in Arctic ice. This loss exacerbates global heating, because the exposed darker ocean absorbs more heat from the sun than highly reflective ice. On Monday, scientists announced that the Arctic sea ice in 2019 shrank to its second lowest extent in the 41-year satellite record.

The world’s high mountain glaciers, upon which almost 2 billion people rely for water, are also melting fast, the IPCC found, while landslides are expected to increase. A third of the great Himalayan range is already doomed, with two-thirds projected to vanish if emissions are not cut.

One of the most worrying alarms sounded by the IPCC report is about melting tundra and increasing wildfires in northern latitudes: “Widespread permafrost thaw is projected for this century and beyond.” A quarter is already near certain to melt, it said, and 70% or more would go if emissions are not curbed. In the latter case, hundreds of billions of tonnes of carbon dioxide and methane could be released, supercharging the climate emergency.

“That risks taking us beyond the point where climate change could be easily constrained,” said Richard Black, at the UK’s Energy and Climate Intelligence Unit. “Nevertheless, the IPCC’s 2018 report concluded that governments can shrink emissions quickly enough to keep global warming to 1.5C if they choose. None can claim to be unaware of both the dangers of untrammelled climate change nor the feasibility of preventing it.”

Anne Hidalgo, the mayor of Paris and chair of the C40 Cities climate coalition, said the IPCC report was shocking. “Around 1.9 billion people and over half of the world’s megacities are all in grave danger if we don’t act immediately. Several cities, home to hundreds of thousands of people, are already disappearing underwater. This is what the climate crisis looks like now.”

Taehyun Park, of Greenpeace East Asia, said: “The science is both chilling and compelling. The impacts on our oceans are on a much larger scale and happening way faster than predicted. It will require unprecedented political action to prevent the most severe consequences to our planet.”

As well as cutting fossil fuel emissions, preparing for the inevitable impacts is also vital, said Sebesvari, especially in poorer nations that lack the funds to build sea walls, move settlements or restore protective coastal marshes.

“Action is needed now to secure the coast for our children and coming generations,” she said. The pressure now being exerted by the global school strikes for climate was important, she said. “I have very strong motivation. I have two kids and we are really being tested by our kids on our actions.”

* * * * * * *

Damian Carrington is The Guardian’s environment editor.

Humans cause Antarctic ice melt, study finds

Yes, it’s us. Human activities are to blame for at least part of what’s melting the West Antarctic Ice Sheet, scientists say.

LONDON, 13 August, 2019 − A team of British and American scientists has found what it says is unequivocal evidence that humans are responsible for significant Antarctic ice melt.

They say their study provides the first evidence of a direct link between global warming from human activities and the melting of the West Antarctic Ice Sheet (WAIS).

The discovery is fundamentally important to international efforts to limit climate change, as a small number of scientists still argue that global warming results from natural rather than human causes. That argument should from now on be harder to sustain.

Ice loss in West Antarctica has increased substantially in the last few decades, and is continuing. Scientists have known for some time that the loss is caused by melting driven from the ocean, and that varying winds in the region cause transitions between relatively warm and cool ocean conditions around key glaciers. But until now it was unclear how these naturally-occurring wind variations could cause the ice loss.

“We knew this region was affected by natural climate cycles. Now we have evidence that a century-long change underlies these cycles, and that it is caused by human activities”

The UK-US team report in the journal Nature Geoscience that, as well as the natural wind variations, which last about a decade, there has been a much longer-term change in the winds that can be linked with human activities.

This result is important for another reason as well: continued ice loss from the WAIS could cause tens of centimetres of sea level rise by the year 2100.

The researchers combined satellite observations and climate model simulations to understand how winds over the ocean near West Antarctica have changed since the 1920s in response to rising greenhouse gas concentrations.

Their investigation shows that human-induced climate change has caused the longer-term change in the winds, and that warm ocean conditions have gradually become more prevalent as a result.

The team’s members are from the British Antarctic Survey (BAS), Columbia University’s Lamont-Doherty Earth Observatory in New York, and the University of Washington.

Galloping speed-up

BAS is one of the organisations researching a huge West Antarctic ice mass in the International Thwaites Glacier Collaboration, aimed at finding out how soon it and its neighbour, the Pine Island glacier, may collapse, with implications for sea levels worldwide.

The fact that melting at both poles has been accelerating fast has been known for some time, though not the reason. Since 1979 Antarctica’s ice loss has grown six times faster, and Greenland’s four times since the turn of the century.

One British scientist, Professor Martin Siegert, has said what is happening in the Antarctic means the world “will be locked into substantial global changes” unless it alters course radically by 2030.

The lead author of the new study, Paul Holland from BAS, said the impact of human-induced climate change on the WAIS was not simple: “Our results imply that a combination of human activity and natural climate variations have caused ice loss in this region, accounting for around 4.5 cm of sea level rise per century.”

Act now

The team also looked at model simulations of future winds. Professor Holland added: “An important finding is that if high greenhouse gas emissions continue in future, the winds keep changing and there could be a further increase in ice melting.

“However, if emissions of greenhouse gases are curtailed, there is little change in the winds from present-day conditions. This shows that curbing greenhouse gas emissions now could reduce the future sea level contribution from this region.”

One co-author, Professor Pierre Dutrieux from Lamont-Doherty Earth Observatory, said: “We knew this region was affected by natural climate cycles lasting about a decade, but these didn’t necessarily explain the ice loss. Now we have evidence that a century-long change underlies these cycles, and that it is caused by human activities.”

Another co-author, Professor Eric Steig from the University of Washington, said: “These results solve a long-standing puzzle.  We have known for some time that varying winds near the West Antarctic Ice Sheet have contributed to the ice loss, but it has not been clear why the ice sheet is changing now.

“Our work with ice cores drilled in the Antarctic Ice Sheet have shown, for example, that wind conditions have been similar in the past. But the ice core data also suggest a subtle long-term trend in the winds. This new work corroborates that evidence and, furthermore, explains why that trend has occurred.” − Climate News Network

Yes, it’s us. Human activities are to blame for at least part of what’s melting the West Antarctic Ice Sheet, scientists say.

LONDON, 13 August, 2019 − A team of British and American scientists has found what it says is unequivocal evidence that humans are responsible for significant Antarctic ice melt.

They say their study provides the first evidence of a direct link between global warming from human activities and the melting of the West Antarctic Ice Sheet (WAIS).

The discovery is fundamentally important to international efforts to limit climate change, as a small number of scientists still argue that global warming results from natural rather than human causes. That argument should from now on be harder to sustain.

Ice loss in West Antarctica has increased substantially in the last few decades, and is continuing. Scientists have known for some time that the loss is caused by melting driven from the ocean, and that varying winds in the region cause transitions between relatively warm and cool ocean conditions around key glaciers. But until now it was unclear how these naturally-occurring wind variations could cause the ice loss.

“We knew this region was affected by natural climate cycles. Now we have evidence that a century-long change underlies these cycles, and that it is caused by human activities”

The UK-US team report in the journal Nature Geoscience that, as well as the natural wind variations, which last about a decade, there has been a much longer-term change in the winds that can be linked with human activities.

This result is important for another reason as well: continued ice loss from the WAIS could cause tens of centimetres of sea level rise by the year 2100.

The researchers combined satellite observations and climate model simulations to understand how winds over the ocean near West Antarctica have changed since the 1920s in response to rising greenhouse gas concentrations.

Their investigation shows that human-induced climate change has caused the longer-term change in the winds, and that warm ocean conditions have gradually become more prevalent as a result.

The team’s members are from the British Antarctic Survey (BAS), Columbia University’s Lamont-Doherty Earth Observatory in New York, and the University of Washington.

Galloping speed-up

BAS is one of the organisations researching a huge West Antarctic ice mass in the International Thwaites Glacier Collaboration, aimed at finding out how soon it and its neighbour, the Pine Island glacier, may collapse, with implications for sea levels worldwide.

The fact that melting at both poles has been accelerating fast has been known for some time, though not the reason. Since 1979 Antarctica’s ice loss has grown six times faster, and Greenland’s four times since the turn of the century.

One British scientist, Professor Martin Siegert, has said what is happening in the Antarctic means the world “will be locked into substantial global changes” unless it alters course radically by 2030.

The lead author of the new study, Paul Holland from BAS, said the impact of human-induced climate change on the WAIS was not simple: “Our results imply that a combination of human activity and natural climate variations have caused ice loss in this region, accounting for around 4.5 cm of sea level rise per century.”

Act now

The team also looked at model simulations of future winds. Professor Holland added: “An important finding is that if high greenhouse gas emissions continue in future, the winds keep changing and there could be a further increase in ice melting.

“However, if emissions of greenhouse gases are curtailed, there is little change in the winds from present-day conditions. This shows that curbing greenhouse gas emissions now could reduce the future sea level contribution from this region.”

One co-author, Professor Pierre Dutrieux from Lamont-Doherty Earth Observatory, said: “We knew this region was affected by natural climate cycles lasting about a decade, but these didn’t necessarily explain the ice loss. Now we have evidence that a century-long change underlies these cycles, and that it is caused by human activities.”

Another co-author, Professor Eric Steig from the University of Washington, said: “These results solve a long-standing puzzle.  We have known for some time that varying winds near the West Antarctic Ice Sheet have contributed to the ice loss, but it has not been clear why the ice sheet is changing now.

“Our work with ice cores drilled in the Antarctic Ice Sheet have shown, for example, that wind conditions have been similar in the past. But the ice core data also suggest a subtle long-term trend in the winds. This new work corroborates that evidence and, furthermore, explains why that trend has occurred.” − Climate News Network

Artificial snow could save world’s coasts

In theory, artificial snow could save the ice caps and limit sea level rise. But rescuing civilisation this way would sacrifice Antarctica.

LONDON, 2 August, 2019 − German scientists have proposed a startling new way of slowing sea level rise and saving New York, Shanghai, Amsterdam and Miami from 3.3 metres of ocean flooding − by using artificial snow.

They suggest the rising seas could be halted by turning West Antarctica, one of the last undisturbed places on Earth, into an industrial snow complex, complete with a sophisticated distribution system.

An estimated 12,000 high-performance wind turbines could be used to generate the 145 Gigawatts of power (one Gigawatt supplies the energy for about 750,000 US homes) needed to lift Antarctic ocean water to heights of, on average, 640 metres, heat it, desalinate it and then spray it over 52,000 square kilometres of the West Antarctic ice sheet in the form of artificial snow, at the rate of several hundred billion tonnes a year, for decades.

Such action could slow or halt the apparently-inevitable collapse of the ice sheet: were this to melt entirely – and right now it is melting at the rate of 361 billion tonnes a year – the world’s oceans would rise by 3.3 metres.

“The fundamental trade-off is whether we as humanity want to sacrifice Antarctica to save the currently inhabited coastal regions and cultural heritage that we have built and are building on our shores,” said Anders Levermann of the Potsdam Institute for Climate Impact Research.

“The apparent absurdity of the endeavour to let it snow in Antarctica to stop an ice instability reflects the breathtaking dimension of the sea level problem”

“It is about global metropolises, from New York to Shanghai, which in the long term will be below sea level if nothing is done. The West Antarctic ice sheet is one of the tipping elements in our climate system. Ice loss is accelerating and might not stop until the West Antarctic ice sheet is practically gone.”

The Potsdam scientists report in the journal Science Advances that their simulations of ice loss from West Antarctica and the measures needed to halt such loss are not an alternative to other steps. Their calculations would be valid “only under a simultaneous drastic reduction” of the global carbon dioxide emissions that drive global heating, and sea level rise, in the first place.

That is, the world would need to abandon fossil fuels, agree to switch to renewable energy, and then use that renewable energy to in effect destroy the Antarctic’s unique ecosystem but save the great cities of the world from the advancing waves later in this millennium.

The researchers acknowledge that the solution is somewhere between impractical and impossible (in their words, it would have to be undertaken “under the difficult circumstances of the Antarctic climate”). But the mere fact that they could write such a proposal is itself an indicator of the accelerating seriousness of the planetary predicament.

In Paris in 2015, 195 nations agreed to take steps to limit global temperature rise to “well below” 2°C above the level that obtained for most of human history. Such steps for the most part have yet to be taken.

3°C rise possible

Carbon dioxide emissions are increasing, the Arctic ice cap is diminishing, the oceans are warming and the loss of ice in Antarctica is increasing.

By 2100, on present trends, the world will be at least 3°C above the historic average.

“The apparent absurdity of the endeavour to let it snow in Antarctica to stop an ice instability reflects the breathtaking dimension of the sea level problem,” Professor Levermann said.

“Yet as scientists we feel it is our duty to inform society about each and every potential option to counter the problems ahead.

“As unbelievable as it might seem, in order to prevent an unprecedented risk, humankind might have to make an unprecedented effort, too.” − Climate News Network

In theory, artificial snow could save the ice caps and limit sea level rise. But rescuing civilisation this way would sacrifice Antarctica.

LONDON, 2 August, 2019 − German scientists have proposed a startling new way of slowing sea level rise and saving New York, Shanghai, Amsterdam and Miami from 3.3 metres of ocean flooding − by using artificial snow.

They suggest the rising seas could be halted by turning West Antarctica, one of the last undisturbed places on Earth, into an industrial snow complex, complete with a sophisticated distribution system.

An estimated 12,000 high-performance wind turbines could be used to generate the 145 Gigawatts of power (one Gigawatt supplies the energy for about 750,000 US homes) needed to lift Antarctic ocean water to heights of, on average, 640 metres, heat it, desalinate it and then spray it over 52,000 square kilometres of the West Antarctic ice sheet in the form of artificial snow, at the rate of several hundred billion tonnes a year, for decades.

Such action could slow or halt the apparently-inevitable collapse of the ice sheet: were this to melt entirely – and right now it is melting at the rate of 361 billion tonnes a year – the world’s oceans would rise by 3.3 metres.

“The fundamental trade-off is whether we as humanity want to sacrifice Antarctica to save the currently inhabited coastal regions and cultural heritage that we have built and are building on our shores,” said Anders Levermann of the Potsdam Institute for Climate Impact Research.

“The apparent absurdity of the endeavour to let it snow in Antarctica to stop an ice instability reflects the breathtaking dimension of the sea level problem”

“It is about global metropolises, from New York to Shanghai, which in the long term will be below sea level if nothing is done. The West Antarctic ice sheet is one of the tipping elements in our climate system. Ice loss is accelerating and might not stop until the West Antarctic ice sheet is practically gone.”

The Potsdam scientists report in the journal Science Advances that their simulations of ice loss from West Antarctica and the measures needed to halt such loss are not an alternative to other steps. Their calculations would be valid “only under a simultaneous drastic reduction” of the global carbon dioxide emissions that drive global heating, and sea level rise, in the first place.

That is, the world would need to abandon fossil fuels, agree to switch to renewable energy, and then use that renewable energy to in effect destroy the Antarctic’s unique ecosystem but save the great cities of the world from the advancing waves later in this millennium.

The researchers acknowledge that the solution is somewhere between impractical and impossible (in their words, it would have to be undertaken “under the difficult circumstances of the Antarctic climate”). But the mere fact that they could write such a proposal is itself an indicator of the accelerating seriousness of the planetary predicament.

In Paris in 2015, 195 nations agreed to take steps to limit global temperature rise to “well below” 2°C above the level that obtained for most of human history. Such steps for the most part have yet to be taken.

3°C rise possible

Carbon dioxide emissions are increasing, the Arctic ice cap is diminishing, the oceans are warming and the loss of ice in Antarctica is increasing.

By 2100, on present trends, the world will be at least 3°C above the historic average.

“The apparent absurdity of the endeavour to let it snow in Antarctica to stop an ice instability reflects the breathtaking dimension of the sea level problem,” Professor Levermann said.

“Yet as scientists we feel it is our duty to inform society about each and every potential option to counter the problems ahead.

“As unbelievable as it might seem, in order to prevent an unprecedented risk, humankind might have to make an unprecedented effort, too.” − Climate News Network

Ancient water-saving can help modern Peru

Ancient water-saving methods may help Lima, Peru’s capital, through its water crisis, caused by climate change and population growth.

LONDON, 2 July, 2019 − There’s plenty to learn in modern Peru from the designers of ancient water-saving methods, scientists are finding. Our forebears could even keep the capital’s taps running through the summer heat.

Lima, Peru’s desert capital, a city of 12 million people, expects to run out of water by 2025. It already faces a crisis each summer as the supply from the mountains dwindles to a trickle. Yet the quantity of rain in the wet season can be overwhelming.

Between the Andes and the Pacific ocean, Lima sits on a coastal plain where the average rainfall is a tiny 9 mm a year, and it has to rely on the snow melt from the mountains and glaciers to provide summer drinking water and the needs of industry and farming.

But with the glaciers disappearing because of climate change, and the population increasing, the city will soon become untenable for many of the poor in summer, unless water supplies can be improved.

A group of scientists has found that reviving systems developed 1,400 years ago by local people before the Inca empire existed could harvest water from the winter rainy season in the mountains to ensure Lima’s summer supplies.

“You’d be forgiven for wondering how ancient methods could apply to modern-day problems. However we have lots to learn from our ancestors’ creative problem-solving skills”

Researchers from Imperial College London and their colleagues at the Regional Initiative for Hydrological Monitoring of Andean Ecosystems studied a water system in Huamantanga, in the central Andes, one of the last of its kind.

The local people still use a method developed in 600 AD by Peruvian civilisations that created systems in the mountains to divert excess rainwater from source streams through ponds and canals onto mountain slopes and down through fissures in the rocks.

The water would take weeks or even months to trickle through the system and resurface downstream – just in time for the dry season.

The researchers used dye tracers and hydrological monitoring to study the system from the wet to dry seasons of 2014–2015 and 2015–2016. Social scientists involved also worked with Huamantanga’s local people to understand the practice and help map the landscape.

Big increase

They found the water took between two weeks and eight months to re-emerge, with an average time of 45 days. From these timescales, they calculated that, if governments upscale the systems to cater for today’s population size, they could reroute and delay 35% of wet season water, equivalent to 99 million cubic metres per year of water flowing through Lima’s natural terrain.

This could increase the water available in the dry season by up to 33% in the early months, and an average of 7.5% for the rest of the summer.

The method could essentially extend the wet season, providing more drinking water and longer crop-growing periods for local farmers.

The study, published in the journal Nature Sustainability, is the first to examine the pre-Inca system in this much detail to find answers to modern problems. The authors say their research shows how indigenous systems could complement modern engineering solutions for water security in coastal Peru.

Lead author Dr Boris Ochoa-Tocachi, from Imperial’s Department of Civil and Environmental Engineering, said: “With the advent of modern science, you’d be forgiven for wondering how ancient methods could apply to modern-day problems. However, it turns out that we have lots to learn from our ancestors’ creative problem-solving skills.”

Growing too fast

Senior author Dr Wouter Buytaert, from the same department, said: “Like many tropical cities, Lima’s population is growing fast – too fast for water reserves to keep up during dry seasons. Upscaling existing pre-Inca systems could help relieve Peru’s wet months of water and quench its dry ones.”

The seasonal variability typical of coastal Peru is worsened by human impacts. Apart from glacier melting caused by global warming, humans also contribute to erosion, which renders soil too weak to support dams big enough to hold all the water needed in the summer.

Climate change also makes wet seasons wetter, and dry seasons drier − making the need for effective water storage in Peru even more urgent.

The authors say combining pre-Inca systems with classic structures, such as smaller dams, could also help to improve adaptability and water supply in an unpredictable climate. − Climate News Network

Ancient water-saving methods may help Lima, Peru’s capital, through its water crisis, caused by climate change and population growth.

LONDON, 2 July, 2019 − There’s plenty to learn in modern Peru from the designers of ancient water-saving methods, scientists are finding. Our forebears could even keep the capital’s taps running through the summer heat.

Lima, Peru’s desert capital, a city of 12 million people, expects to run out of water by 2025. It already faces a crisis each summer as the supply from the mountains dwindles to a trickle. Yet the quantity of rain in the wet season can be overwhelming.

Between the Andes and the Pacific ocean, Lima sits on a coastal plain where the average rainfall is a tiny 9 mm a year, and it has to rely on the snow melt from the mountains and glaciers to provide summer drinking water and the needs of industry and farming.

But with the glaciers disappearing because of climate change, and the population increasing, the city will soon become untenable for many of the poor in summer, unless water supplies can be improved.

A group of scientists has found that reviving systems developed 1,400 years ago by local people before the Inca empire existed could harvest water from the winter rainy season in the mountains to ensure Lima’s summer supplies.

“You’d be forgiven for wondering how ancient methods could apply to modern-day problems. However we have lots to learn from our ancestors’ creative problem-solving skills”

Researchers from Imperial College London and their colleagues at the Regional Initiative for Hydrological Monitoring of Andean Ecosystems studied a water system in Huamantanga, in the central Andes, one of the last of its kind.

The local people still use a method developed in 600 AD by Peruvian civilisations that created systems in the mountains to divert excess rainwater from source streams through ponds and canals onto mountain slopes and down through fissures in the rocks.

The water would take weeks or even months to trickle through the system and resurface downstream – just in time for the dry season.

The researchers used dye tracers and hydrological monitoring to study the system from the wet to dry seasons of 2014–2015 and 2015–2016. Social scientists involved also worked with Huamantanga’s local people to understand the practice and help map the landscape.

Big increase

They found the water took between two weeks and eight months to re-emerge, with an average time of 45 days. From these timescales, they calculated that, if governments upscale the systems to cater for today’s population size, they could reroute and delay 35% of wet season water, equivalent to 99 million cubic metres per year of water flowing through Lima’s natural terrain.

This could increase the water available in the dry season by up to 33% in the early months, and an average of 7.5% for the rest of the summer.

The method could essentially extend the wet season, providing more drinking water and longer crop-growing periods for local farmers.

The study, published in the journal Nature Sustainability, is the first to examine the pre-Inca system in this much detail to find answers to modern problems. The authors say their research shows how indigenous systems could complement modern engineering solutions for water security in coastal Peru.

Lead author Dr Boris Ochoa-Tocachi, from Imperial’s Department of Civil and Environmental Engineering, said: “With the advent of modern science, you’d be forgiven for wondering how ancient methods could apply to modern-day problems. However, it turns out that we have lots to learn from our ancestors’ creative problem-solving skills.”

Growing too fast

Senior author Dr Wouter Buytaert, from the same department, said: “Like many tropical cities, Lima’s population is growing fast – too fast for water reserves to keep up during dry seasons. Upscaling existing pre-Inca systems could help relieve Peru’s wet months of water and quench its dry ones.”

The seasonal variability typical of coastal Peru is worsened by human impacts. Apart from glacier melting caused by global warming, humans also contribute to erosion, which renders soil too weak to support dams big enough to hold all the water needed in the summer.

Climate change also makes wet seasons wetter, and dry seasons drier − making the need for effective water storage in Peru even more urgent.

The authors say combining pre-Inca systems with classic structures, such as smaller dams, could also help to improve adaptability and water supply in an unpredictable climate. − Climate News Network

Ice-free Greenland possible in 1,000 years

Look far enough ahead and in a millennium an ice-free Greenland is a possibility, scientists say. Sea levels too will be a lot higher by then.

LONDON, 25 June, 2019 − US scientists have just established that the long-term future may bring an ice-free Greenland, if melting continues at the current rate. By the year 3,000 it could simply be green, with rocky outcrops. Greenland’s icy mountains will have vanished.

By the end of this century, the island – the largest body of ice in the northern hemisphere, and home to 8% of the world’s fresh water in frozen form – will have lost 4.5% of its ice cover, and sea levels will have risen by up to 33cm.

And if melting continues, and the world goes on burning fossil fuels under climate science’s notorious “business as usual scenario”, then within another thousand years the entire cover will have run into the sea, which by then will have risen – just because of melting in Greenland – by more than seven metres, to wash away cities such as Miami, Los Angeles, Copenhagen, Shanghai and New Orleans.

“How Greenland will look in the future – in a couple of hundred years or in 1,000 years – whether there will be Greenland, or at least a Greenland similar to today, it’s up to us”, said Andy Aschwanden, of the University of Fairbanks, Alaska geophysical institute.

He and colleagues from the US and Denmark report in the journal Science Advances that they used new radar data that gave a picture of the thickness of the ice and the bedrock beneath it to estimate the total mass of ice.

“We project that Greenland will very likely become ice-free within a millennium without substantial reduction in greenhouse gas emissions”

They then selected three possible climate outcomes, depending on national and political responses to the climate emergency, considered the rates at which glaciers had begun to flow, the levels of summer and even winter ice melt, and the warming of the oceans, and ran 500 computer simulations to form a picture of the future.

Researchers have been warning for years that the rate of ice loss in Greenland is accelerating. Ice is being lost from the ice sheet surface, in some places at such speed that the bedrock beneath, once crushed by the weight of ice, is beginning to rise.

The great frozen rivers that carry ice to the sea to form summer icebergs are themselves gathering pace: one of these in 2014 was recorded as having quadrupled in speed, to move at almost 50 metres a day.

Research in polar regions is always difficult, and conclusions are necessarily tentative. On-the-ground studies are limited in summer and all but impossible in winter. The dynamic of ice loss changes, depending on conditions both in the atmosphere and the surrounding ocean.

Greenhouse gas increase

But the Fairbanks study is consistent with a huge body of other research. And the same computer simulations confirm that what happens depends ultimately on whether the world continues to heat up as a consequence of the profligate consumption of fossil fuels that increase the ratio of greenhouse gases in the atmosphere.

If carbon dioxide emissions are sharply reduced, the scientists say, the picture changes. Instead, the island could lose only up to a quarter of its ice cover by the end of this millennium, with a corresponding sea level rise of up to 1.88 metres.

Another, less hopeful scenario foresees a loss of up to 57% and sea level rise of up to 4.17 metres. In the worst case, the range of possible ice loss is from 72% to the lot, with the oceans higher by up to 7.28 metres, all of it from the existing ice mass of Greenland.

“We project that Greenland will very likely become ice-free within a millennium without substantial reduction in greenhouse gas emissions”, the researchers conclude. − Climate News Network

Look far enough ahead and in a millennium an ice-free Greenland is a possibility, scientists say. Sea levels too will be a lot higher by then.

LONDON, 25 June, 2019 − US scientists have just established that the long-term future may bring an ice-free Greenland, if melting continues at the current rate. By the year 3,000 it could simply be green, with rocky outcrops. Greenland’s icy mountains will have vanished.

By the end of this century, the island – the largest body of ice in the northern hemisphere, and home to 8% of the world’s fresh water in frozen form – will have lost 4.5% of its ice cover, and sea levels will have risen by up to 33cm.

And if melting continues, and the world goes on burning fossil fuels under climate science’s notorious “business as usual scenario”, then within another thousand years the entire cover will have run into the sea, which by then will have risen – just because of melting in Greenland – by more than seven metres, to wash away cities such as Miami, Los Angeles, Copenhagen, Shanghai and New Orleans.

“How Greenland will look in the future – in a couple of hundred years or in 1,000 years – whether there will be Greenland, or at least a Greenland similar to today, it’s up to us”, said Andy Aschwanden, of the University of Fairbanks, Alaska geophysical institute.

He and colleagues from the US and Denmark report in the journal Science Advances that they used new radar data that gave a picture of the thickness of the ice and the bedrock beneath it to estimate the total mass of ice.

“We project that Greenland will very likely become ice-free within a millennium without substantial reduction in greenhouse gas emissions”

They then selected three possible climate outcomes, depending on national and political responses to the climate emergency, considered the rates at which glaciers had begun to flow, the levels of summer and even winter ice melt, and the warming of the oceans, and ran 500 computer simulations to form a picture of the future.

Researchers have been warning for years that the rate of ice loss in Greenland is accelerating. Ice is being lost from the ice sheet surface, in some places at such speed that the bedrock beneath, once crushed by the weight of ice, is beginning to rise.

The great frozen rivers that carry ice to the sea to form summer icebergs are themselves gathering pace: one of these in 2014 was recorded as having quadrupled in speed, to move at almost 50 metres a day.

Research in polar regions is always difficult, and conclusions are necessarily tentative. On-the-ground studies are limited in summer and all but impossible in winter. The dynamic of ice loss changes, depending on conditions both in the atmosphere and the surrounding ocean.

Greenhouse gas increase

But the Fairbanks study is consistent with a huge body of other research. And the same computer simulations confirm that what happens depends ultimately on whether the world continues to heat up as a consequence of the profligate consumption of fossil fuels that increase the ratio of greenhouse gases in the atmosphere.

If carbon dioxide emissions are sharply reduced, the scientists say, the picture changes. Instead, the island could lose only up to a quarter of its ice cover by the end of this millennium, with a corresponding sea level rise of up to 1.88 metres.

Another, less hopeful scenario foresees a loss of up to 57% and sea level rise of up to 4.17 metres. In the worst case, the range of possible ice loss is from 72% to the lot, with the oceans higher by up to 7.28 metres, all of it from the existing ice mass of Greenland.

“We project that Greenland will very likely become ice-free within a millennium without substantial reduction in greenhouse gas emissions”, the researchers conclude. − Climate News Network

Himalayan melt rate doubles in 40 years

The pace of glacier thawing on the roof of the world has doubled in 40 years, scientists say, with the Himalayan melt rate affected by climate heating.

LONDON, 20 June, 2019 − The Himalayan melt rate is now thawing glaciers on whose water many millions of lives depend twice as fast as just four decades ago, researchers say. One scientist thinks the glaciers may have lost a quarter of their mass in the last 40 years.

A new, comprehensive study shows the glaciers’ melting, caused by rising temperatures, has accelerated significantly since the turn of the century. The study, which draws on 40 years of satellite observations across India, China, Nepal and Bhutan, shows the glaciers have been losing the equivalent of more than 20 inches (about half a metre) of ice each year since 2000, twice the amount of melting recorded from 1975 to 2000.

The study, published in the journal Science Advances, is the latest to show the threat that climate change represents to the water supplies of hundreds of millions of people living downstream across much of Asia.

“This is the clearest picture yet of how fast Himalayan glaciers are melting over this time interval, and why,” said the lead author, Joshua Maurer, a Ph D candidate at Columbia University’s Lamont-Doherty Earth Observatory. While not specifically calculated in the study, the glaciers may have lost as much as a quarter of their mass over the last four decades, he said.

With around 600 billion tons of ice today, the Himalayas are sometimes called the Earth’s third pole. Many recent studies have suggested that the glaciers are dwindling, including one in February this year projecting that up to two-thirds of the current ice cover could be gone by 2100.

Wider picture

Until now, though, observations have usually focused on individual glaciers or specific regions, or on shorter lengths of time, and have sometimes produced contradictory results, on both the degree of ice loss and its causes. The new study incorporates data from across the region, stretching from early satellite observations to the present.

This shows the melting is consistent over time and in different areas, and that rising temperatures are to blame: they vary from place to place, but from 2000 to 2016 they have averaged 1°C (1.8°F) higher than those from 1975 to 2000.

Maurer and his co-authors analysed repeat satellite images of about 650 glaciers spanning 2,000 kilometres. Many of the 20th-century observations came from recently declassified photographic images taken by US spy satellites.

The researchers created an automated system to turn these into three-dimensional models that could show the changing elevations of glaciers over time. They then compared these images with post-2000 optical data from more sophisticated satellites, which show elevation changes more directly.

“This is the clearest picture yet of how fast Himalayan glaciers are melting over this time interval, and why”

They found that from 1975 to 2000, glaciers across the region lost an average of about 0.25 metres (10 inches) of ice each year in the face of slight warming. Following a more pronounced warming trend which started in the 1990s, from 2000 the loss accelerated to about half a metre annually.

Recent yearly losses have averaged about 8 billion tons of water, Maurer says. On most glaciers the melting has been concentrated mainly at lower elevations, where some ice surfaces are losing as much as 5 metres (16 feet) a year.

Despite suggestions that changes in precipitation, or increasing deposits of soot from growing fossil fuel burning in Asia, might be affecting the glaciers rather than climate heating, Maurer believes rising temperature is the main cause of the melting.

“It looks just like what we would expect if warming were the dominant driver of ice loss,” he said. At least one recent study has found a similar process at work in Alaska.

Alpine parallel

Ice loss in the Himalayas resembles the much more closely studied European Alps, where temperatures started going up a little earlier, in the 1980s. Glaciers there began melting soon after that, and rapid ice loss has continued since. The Himalayas are generally not melting as fast as the Alps, but their changes are similar, the researchers say.

Their study does not include the huge adjoining ranges of high-mountain Asia such as the Pamir, Hindu Kush or Tian Shan, but other studies suggest similar melting is under way there as well.

About 800 million people depend in part on seasonal runoff from Himalayan glaciers for irrigation, hydropower and drinking water. The faster melting appears so far to be increasing runoff during warm seasons, but scientists think this will slow within decades as the glaciers lose mass, eventually leading to water shortages.

In many high mountain areas meltwater lakes are building up rapidly behind natural dams of rocky debris, threatening downstream communities with outburst floods. On Everest, the long-lost bodies of climbers who failed to return from the summits are emerging from the melting ice. − Climate News Network

The pace of glacier thawing on the roof of the world has doubled in 40 years, scientists say, with the Himalayan melt rate affected by climate heating.

LONDON, 20 June, 2019 − The Himalayan melt rate is now thawing glaciers on whose water many millions of lives depend twice as fast as just four decades ago, researchers say. One scientist thinks the glaciers may have lost a quarter of their mass in the last 40 years.

A new, comprehensive study shows the glaciers’ melting, caused by rising temperatures, has accelerated significantly since the turn of the century. The study, which draws on 40 years of satellite observations across India, China, Nepal and Bhutan, shows the glaciers have been losing the equivalent of more than 20 inches (about half a metre) of ice each year since 2000, twice the amount of melting recorded from 1975 to 2000.

The study, published in the journal Science Advances, is the latest to show the threat that climate change represents to the water supplies of hundreds of millions of people living downstream across much of Asia.

“This is the clearest picture yet of how fast Himalayan glaciers are melting over this time interval, and why,” said the lead author, Joshua Maurer, a Ph D candidate at Columbia University’s Lamont-Doherty Earth Observatory. While not specifically calculated in the study, the glaciers may have lost as much as a quarter of their mass over the last four decades, he said.

With around 600 billion tons of ice today, the Himalayas are sometimes called the Earth’s third pole. Many recent studies have suggested that the glaciers are dwindling, including one in February this year projecting that up to two-thirds of the current ice cover could be gone by 2100.

Wider picture

Until now, though, observations have usually focused on individual glaciers or specific regions, or on shorter lengths of time, and have sometimes produced contradictory results, on both the degree of ice loss and its causes. The new study incorporates data from across the region, stretching from early satellite observations to the present.

This shows the melting is consistent over time and in different areas, and that rising temperatures are to blame: they vary from place to place, but from 2000 to 2016 they have averaged 1°C (1.8°F) higher than those from 1975 to 2000.

Maurer and his co-authors analysed repeat satellite images of about 650 glaciers spanning 2,000 kilometres. Many of the 20th-century observations came from recently declassified photographic images taken by US spy satellites.

The researchers created an automated system to turn these into three-dimensional models that could show the changing elevations of glaciers over time. They then compared these images with post-2000 optical data from more sophisticated satellites, which show elevation changes more directly.

“This is the clearest picture yet of how fast Himalayan glaciers are melting over this time interval, and why”

They found that from 1975 to 2000, glaciers across the region lost an average of about 0.25 metres (10 inches) of ice each year in the face of slight warming. Following a more pronounced warming trend which started in the 1990s, from 2000 the loss accelerated to about half a metre annually.

Recent yearly losses have averaged about 8 billion tons of water, Maurer says. On most glaciers the melting has been concentrated mainly at lower elevations, where some ice surfaces are losing as much as 5 metres (16 feet) a year.

Despite suggestions that changes in precipitation, or increasing deposits of soot from growing fossil fuel burning in Asia, might be affecting the glaciers rather than climate heating, Maurer believes rising temperature is the main cause of the melting.

“It looks just like what we would expect if warming were the dominant driver of ice loss,” he said. At least one recent study has found a similar process at work in Alaska.

Alpine parallel

Ice loss in the Himalayas resembles the much more closely studied European Alps, where temperatures started going up a little earlier, in the 1980s. Glaciers there began melting soon after that, and rapid ice loss has continued since. The Himalayas are generally not melting as fast as the Alps, but their changes are similar, the researchers say.

Their study does not include the huge adjoining ranges of high-mountain Asia such as the Pamir, Hindu Kush or Tian Shan, but other studies suggest similar melting is under way there as well.

About 800 million people depend in part on seasonal runoff from Himalayan glaciers for irrigation, hydropower and drinking water. The faster melting appears so far to be increasing runoff during warm seasons, but scientists think this will slow within decades as the glaciers lose mass, eventually leading to water shortages.

In many high mountain areas meltwater lakes are building up rapidly behind natural dams of rocky debris, threatening downstream communities with outburst floods. On Everest, the long-lost bodies of climbers who failed to return from the summits are emerging from the melting ice. − Climate News Network

Siberia expects mass migration as it warms

Scientists mapping the effects of increased temperature and rainfall across Siberia say it could expect mass migration in a warmer world.

LONDON, 7 June, 2019 − Siberia, currently one of the most sparsely populated places in the northern hemisphere, could become a target for mass migration as the climate warms.

By 2080, scientists report, melting permafrost and warming summer and winter temperatures will mean that agriculture could thrive and support between five and seven times the current population.

Lands to the south are becoming far less able to feed and sustain their existing populations, as heat makes crops harder to grow and cities untenable, and mass migration northward is likely, the scientists predict.

Their study, which is produced by the Krasnoyarsk Federal Research Centre in Siberia and the US National Institute of Aerospace, says the current problem of falling population in Russia will be reversed as conditions in Siberia become much better for growing food, and both summers and winters more pleasant to live in. It is published in the journal Environmental Research Letters.

With 13 million square kilometres of land area, Asian Russia – east of the Urals, towards the Pacific – accounts for 77% of Russian territory. Its population, however, accounts for just 27% of the country’s people and is concentrated along the forest-steppe in the south, with its comfortable climate and fertile soil.

“In a future, warmer climate, food security, in terms of crop distribution and production capability, is predicted to become more favourable”

The findings have a certain irony, because at the close of the Communist era the Soviet government was not keen to take any action on climate change: it saw the warming of Siberia as a chance for the USSR to grow more wheat and challenge US dominance of the world’s grain supply.

The scientists warn, however, that mass migration will not be that simple. The melting of the permafrost threatens what little infrastructure there is in the region. Before a larger population could provide for itself, investments need to be made in new roads, railways and power supplies to support it.

They say warming in the region already exceeds earlier estimates. Depending on how much carbon dioxide humans continue to pump into the atmosphere, the scientists predict mid-winter temperatures over Asian Russia will increase between 3.4°C and 9.1°C by 2080. Increases in mid-summer will be between 1.9°C and 5.7°C, they say.

Permafrost, which currently covers 65% of the region, would fall to 40% by 2080, and crucially there will be increases in rainfall of between 60 mm and 140 mm, making the unfrozen area much more favourable for crops.

Migration ‘probable’

Using something called Ecological Landscape Potential, or ELP, to gauge the potential for land to support human populations, the scientists came to the conclusion that mass migration north was probable.

“We found the ELP would increase over most of Asian Russia, which would lead to a five- to seven-fold increase in the capacity of the territory to sustain and become attractive to human populations, which would then lead to migrations from less sustainable lands to Asian Russia during this century,” they say.

Dr Elena Parfenova, from the Krasnoyarsk centre, said: “In a future, warmer climate, food security, in terms of crop distribution and production capability, is predicted to become more favourable to support settlements in what is currently an extremely cold Asian Russia.”

She said that obviously people would flock first to the already developed areas in the south, but most of the area of Siberia and the Far East “have poorly developed infrastructure. The rapidity that these developments occur is dependent on investments in infrastructure and agriculture, which is dependent on the decisions that will be made in the near future.” − Climate News Network

Scientists mapping the effects of increased temperature and rainfall across Siberia say it could expect mass migration in a warmer world.

LONDON, 7 June, 2019 − Siberia, currently one of the most sparsely populated places in the northern hemisphere, could become a target for mass migration as the climate warms.

By 2080, scientists report, melting permafrost and warming summer and winter temperatures will mean that agriculture could thrive and support between five and seven times the current population.

Lands to the south are becoming far less able to feed and sustain their existing populations, as heat makes crops harder to grow and cities untenable, and mass migration northward is likely, the scientists predict.

Their study, which is produced by the Krasnoyarsk Federal Research Centre in Siberia and the US National Institute of Aerospace, says the current problem of falling population in Russia will be reversed as conditions in Siberia become much better for growing food, and both summers and winters more pleasant to live in. It is published in the journal Environmental Research Letters.

With 13 million square kilometres of land area, Asian Russia – east of the Urals, towards the Pacific – accounts for 77% of Russian territory. Its population, however, accounts for just 27% of the country’s people and is concentrated along the forest-steppe in the south, with its comfortable climate and fertile soil.

“In a future, warmer climate, food security, in terms of crop distribution and production capability, is predicted to become more favourable”

The findings have a certain irony, because at the close of the Communist era the Soviet government was not keen to take any action on climate change: it saw the warming of Siberia as a chance for the USSR to grow more wheat and challenge US dominance of the world’s grain supply.

The scientists warn, however, that mass migration will not be that simple. The melting of the permafrost threatens what little infrastructure there is in the region. Before a larger population could provide for itself, investments need to be made in new roads, railways and power supplies to support it.

They say warming in the region already exceeds earlier estimates. Depending on how much carbon dioxide humans continue to pump into the atmosphere, the scientists predict mid-winter temperatures over Asian Russia will increase between 3.4°C and 9.1°C by 2080. Increases in mid-summer will be between 1.9°C and 5.7°C, they say.

Permafrost, which currently covers 65% of the region, would fall to 40% by 2080, and crucially there will be increases in rainfall of between 60 mm and 140 mm, making the unfrozen area much more favourable for crops.

Migration ‘probable’

Using something called Ecological Landscape Potential, or ELP, to gauge the potential for land to support human populations, the scientists came to the conclusion that mass migration north was probable.

“We found the ELP would increase over most of Asian Russia, which would lead to a five- to seven-fold increase in the capacity of the territory to sustain and become attractive to human populations, which would then lead to migrations from less sustainable lands to Asian Russia during this century,” they say.

Dr Elena Parfenova, from the Krasnoyarsk centre, said: “In a future, warmer climate, food security, in terms of crop distribution and production capability, is predicted to become more favourable to support settlements in what is currently an extremely cold Asian Russia.”

She said that obviously people would flock first to the already developed areas in the south, but most of the area of Siberia and the Far East “have poorly developed infrastructure. The rapidity that these developments occur is dependent on investments in infrastructure and agriculture, which is dependent on the decisions that will be made in the near future.” − Climate News Network

Arctic sea ice loss affects the jet stream

The jet stream affects northern hemisphere climates. And global warming affects the behaviour of the jet stream. Prepare for yet more extremes of seasonal weather.

LONDON, 6 June, 2019 − Did you shiver in a winter ice storm? Could you wilt in a protracted heatwave this summer? German scientists have just identified the guilty agency and delivered the evidence implicating the jet stream.

Blame it on Arctic warming, they conclude: the retreat of the sea ice over the polar ocean has distorted the pattern of flow of the stratospheric winds usually known as the jet stream.

It is not a new idea. But this time, scientists have employed artificial intelligence and a machine-learning programme to accurately model the changes in the jet stream and then link these to changes in the chemistry of the upper atmosphere, and increasing patterns of twisting waves in the high altitude winds which then distort seasonal weather in the northern hemisphere mid-latitudes. They describe their research in the journal Scientific Reports.

“Our study shows that the changes in the jet stream are at least partly due to the loss of Arctic sea ice. If the ice cover continues to dwindle, we believe that both the frequency and intensity of the extreme weather events previously observed in the middle latitudes will increase,” said Markus Rex, who heads atmospheric research at the Alfred Wegener Institute in Potsdam, Germany.

Cold bouts explained

“In addition, our findings confirm that the more frequently occurring cold phases in winter in the USA, Europe and Asia are by no means a contradiction to global warming; rather they are part of anthropogenic climate change.”

The jet stream – exploited by jet aircraft on the trans-Atlantic routes – is made up of westerly winds that, at an altitude of 10 kilometres, stream around the planet in the mid-latitudes, at speeds of up to 500 km an hour, and push weather systems from west to east.

But researchers have already observed this: they have been changing, in response to global warming and in particular to the rapid warming of the Arctic, as greenhouse gas ratios in the atmosphere rise, and go on rising, in response to profligate human combustion of fossil fuels.

Rather than stick to a course more or less parallel to the Equator, these winds have been observed describing dramatic waves.

“If the ice cover continues to dwindle, we believe that both the frequency and intensity of the extreme weather events previously observed in the middle latitudes will increase”

These twists of direction have been linked to blasts of Arctic air into regions that could normally expect relatively mild winters: in particular to the ferocious cold that hit the US Midwest in January 2019.

These winds have also weakened and been linked to prolonged drought and extremes of heat that hit Europe in 2003, 2006, 2015 and 2018.

But association is not the same as demonstration of cause-and-effect. The Potsdam scientists wanted surer evidence. And their new climate simulations now include a machine-learning component that accounts for ozone chemistry at high altitudes.

And what their new model found was that as the Arctic sea ice retreats, the atmospheric waves have warmed the polar stratosphere in ways that have been amplified by the behaviour of the ozone layer.

Ozone response

Since what powers the jet stream is the difference between the cold Arctic and the warm tropics, the jet stream has weakened, and begun to meander, like a river flowing across a flood plain towards the sea.

In effect, the new study introduces a new piece to the climate puzzle: the response of the ozone layer and its role in the play of winds around the planet. The pay-off could be a clearer picture of things to come.

“We are now for the first time employing artificial intelligence in climate modelling, helping us arrive at more realistic model systems,” said Professor Rex.

“This holds tremendous potential for future climate models, which we believe will deliver more reliable climate projections and therefore a more robust basis for political decision-making.” − Climate News Network

The jet stream affects northern hemisphere climates. And global warming affects the behaviour of the jet stream. Prepare for yet more extremes of seasonal weather.

LONDON, 6 June, 2019 − Did you shiver in a winter ice storm? Could you wilt in a protracted heatwave this summer? German scientists have just identified the guilty agency and delivered the evidence implicating the jet stream.

Blame it on Arctic warming, they conclude: the retreat of the sea ice over the polar ocean has distorted the pattern of flow of the stratospheric winds usually known as the jet stream.

It is not a new idea. But this time, scientists have employed artificial intelligence and a machine-learning programme to accurately model the changes in the jet stream and then link these to changes in the chemistry of the upper atmosphere, and increasing patterns of twisting waves in the high altitude winds which then distort seasonal weather in the northern hemisphere mid-latitudes. They describe their research in the journal Scientific Reports.

“Our study shows that the changes in the jet stream are at least partly due to the loss of Arctic sea ice. If the ice cover continues to dwindle, we believe that both the frequency and intensity of the extreme weather events previously observed in the middle latitudes will increase,” said Markus Rex, who heads atmospheric research at the Alfred Wegener Institute in Potsdam, Germany.

Cold bouts explained

“In addition, our findings confirm that the more frequently occurring cold phases in winter in the USA, Europe and Asia are by no means a contradiction to global warming; rather they are part of anthropogenic climate change.”

The jet stream – exploited by jet aircraft on the trans-Atlantic routes – is made up of westerly winds that, at an altitude of 10 kilometres, stream around the planet in the mid-latitudes, at speeds of up to 500 km an hour, and push weather systems from west to east.

But researchers have already observed this: they have been changing, in response to global warming and in particular to the rapid warming of the Arctic, as greenhouse gas ratios in the atmosphere rise, and go on rising, in response to profligate human combustion of fossil fuels.

Rather than stick to a course more or less parallel to the Equator, these winds have been observed describing dramatic waves.

“If the ice cover continues to dwindle, we believe that both the frequency and intensity of the extreme weather events previously observed in the middle latitudes will increase”

These twists of direction have been linked to blasts of Arctic air into regions that could normally expect relatively mild winters: in particular to the ferocious cold that hit the US Midwest in January 2019.

These winds have also weakened and been linked to prolonged drought and extremes of heat that hit Europe in 2003, 2006, 2015 and 2018.

But association is not the same as demonstration of cause-and-effect. The Potsdam scientists wanted surer evidence. And their new climate simulations now include a machine-learning component that accounts for ozone chemistry at high altitudes.

And what their new model found was that as the Arctic sea ice retreats, the atmospheric waves have warmed the polar stratosphere in ways that have been amplified by the behaviour of the ozone layer.

Ozone response

Since what powers the jet stream is the difference between the cold Arctic and the warm tropics, the jet stream has weakened, and begun to meander, like a river flowing across a flood plain towards the sea.

In effect, the new study introduces a new piece to the climate puzzle: the response of the ozone layer and its role in the play of winds around the planet. The pay-off could be a clearer picture of things to come.

“We are now for the first time employing artificial intelligence in climate modelling, helping us arrive at more realistic model systems,” said Professor Rex.

“This holds tremendous potential for future climate models, which we believe will deliver more reliable climate projections and therefore a more robust basis for political decision-making.” − Climate News Network