Tag Archives: Antarctic

Unstable polar glaciers lose ice ever faster

As oceans warm, Antarctica’s ice sheets are at growing risk, with polar glaciers losing ice at rates to match the height of global monuments.

LONDON, 31 May, 2019 – Almost a quarter of all the glaciers in West Antarctica have been pronounced “unstable”. This means, in the simplest terms, that they are losing ice to the ocean faster than they can gain it from falling snow.

In the last 25 years most of the largest flows have accelerated the loss of ice fivefold.

And in places some glaciers, including those known as Pine Island and Thwaites, have “thinned” by 122 metres. That means that the thickness of the ice between the surface and the bedrock over which glaciers flow has fallen by almost the height of the Great Pyramid of Cheops in Egypt, and far more than the Statue of Liberty in New York or the tower of Big Ben in London.

The conclusions are based on climate simulation matched against 800 million measurements of the Antarctic ice sheet recorded by the altimeters aboard four orbiting satellites put up by the European Space Agency between 1992 and 2017. The conclusion is published in the journal Geophysical Research Letters.

“A wave of thinning has spread rapidly across some of Antarctica’s most vulnerable glaciers, and their losses are driving up sea levels around the planet”

Antarctic research is challenging. The continent is enormous – nearly twice the size of Australia – and frozen: 99.4% of it is covered by ice, to huge depths. It is also defined as a desert.

Snowfalls are low, but over millions of years these have built up to a reservoir of about nine-tenths of the planet’s fresh water, in the form of snow and ice.

It is also the coldest place on Earth and – even more of a problem for climate scientists – no observations or measurements of anything in Antarctica date back much further than the beginning of the 19th century. Most of the on-the-ground science is possible only in the Antarctic summer.

The latest study confirms a succession of alarming finds. The West Antarctic ice sheet is not just losing ice, it is doing so at ever-faster speeds. Scientists have already suggested that the rate of loss for the Pine Island and Thwaites glaciers could be irreversible. So much has already been lost that the bedrock, crushed by its burden of ice for aeons, is actually beginning to bounce up in response.

Huge ice losses

“In parts of Antarctica the ice sheet has thinned by extraordinary amounts, and we set out to show how much was due to changes in climate and how much was due to weather,” said Andrew Shepherd of the University of Leeds, UK, who led the research.

Changes in snowfall tended, they found, to be reflected over changes in height over large areas for a few years. But the most pronounced changes have persisted for decades: it’s the climate that is changing things, not the weather.

“Knowing how much snow has fallen has really helped us to detect the underlying change in glacier ice within the satellite record. We can see clearly now that a wave of thinning has spread rapidly across some of Antarctica’s most vulnerable glaciers, and their losses are driving up sea levels around the planet”, Professor Shepherd says.

“Altogether, ice losses from East and West Antarctica have contributed 4.6mm to global sea level rise since 1992.” – Climate News Network

As oceans warm, Antarctica’s ice sheets are at growing risk, with polar glaciers losing ice at rates to match the height of global monuments.

LONDON, 31 May, 2019 – Almost a quarter of all the glaciers in West Antarctica have been pronounced “unstable”. This means, in the simplest terms, that they are losing ice to the ocean faster than they can gain it from falling snow.

In the last 25 years most of the largest flows have accelerated the loss of ice fivefold.

And in places some glaciers, including those known as Pine Island and Thwaites, have “thinned” by 122 metres. That means that the thickness of the ice between the surface and the bedrock over which glaciers flow has fallen by almost the height of the Great Pyramid of Cheops in Egypt, and far more than the Statue of Liberty in New York or the tower of Big Ben in London.

The conclusions are based on climate simulation matched against 800 million measurements of the Antarctic ice sheet recorded by the altimeters aboard four orbiting satellites put up by the European Space Agency between 1992 and 2017. The conclusion is published in the journal Geophysical Research Letters.

“A wave of thinning has spread rapidly across some of Antarctica’s most vulnerable glaciers, and their losses are driving up sea levels around the planet”

Antarctic research is challenging. The continent is enormous – nearly twice the size of Australia – and frozen: 99.4% of it is covered by ice, to huge depths. It is also defined as a desert.

Snowfalls are low, but over millions of years these have built up to a reservoir of about nine-tenths of the planet’s fresh water, in the form of snow and ice.

It is also the coldest place on Earth and – even more of a problem for climate scientists – no observations or measurements of anything in Antarctica date back much further than the beginning of the 19th century. Most of the on-the-ground science is possible only in the Antarctic summer.

The latest study confirms a succession of alarming finds. The West Antarctic ice sheet is not just losing ice, it is doing so at ever-faster speeds. Scientists have already suggested that the rate of loss for the Pine Island and Thwaites glaciers could be irreversible. So much has already been lost that the bedrock, crushed by its burden of ice for aeons, is actually beginning to bounce up in response.

Huge ice losses

“In parts of Antarctica the ice sheet has thinned by extraordinary amounts, and we set out to show how much was due to changes in climate and how much was due to weather,” said Andrew Shepherd of the University of Leeds, UK, who led the research.

Changes in snowfall tended, they found, to be reflected over changes in height over large areas for a few years. But the most pronounced changes have persisted for decades: it’s the climate that is changing things, not the weather.

“Knowing how much snow has fallen has really helped us to detect the underlying change in glacier ice within the satellite record. We can see clearly now that a wave of thinning has spread rapidly across some of Antarctica’s most vulnerable glaciers, and their losses are driving up sea levels around the planet”, Professor Shepherd says.

“Altogether, ice losses from East and West Antarctica have contributed 4.6mm to global sea level rise since 1992.” – Climate News Network

Sea level rise may double forecast for 2100

Scientists say global sea level rise could far exceed predictions because of faster melting in Greenland and Antarctica.

LONDON, 22 May, 2019 − If you are among the many millions of people who live near the world’s coasts, it will probably be worth your while to read this: sea level rise could be much greater than we expect.

A team of international scientists led by the University of Bristol, UK, has looked again at the estimates of how much the world’s oceans are likely to rise during this century. It concludes that the figure could be far higher than previous studies suggested.

In an extreme case, the members say, sea level rise over the next 80 years could mean that by 2100 the oceans will have risen by around six feet (two metres) − roughly twice the level thought likely till now, with “pretty unimaginable” consequences

In its fifth assessment report, published in 2013, the Intergovernmental Panel on Climate Change (IPCC) said the continued warming of the Earth, if there were no major reductions in greenhouse gas emissions, would see the seas rising by between 52cm and 98cm by 2100.

Sombre prospect

Many climate scientists have argued that this was a conservative estimate. The possibility that the eventual figure could be around double the forecast, threatening hundreds of millions of people with having to leave their homes, is sobering. It is published in the Proceedings of the National Academy of Sciences (PNAS).

The Bristol team used a different way of trying to gauge the possible effect of the way the ice is melting in Greenland, West and East Antarctica, not relying simply on projections from numerical models.

Their method used a technique called a structured expert judgement study, which involved 22 ice sheet experts in estimating plausible ranges for future sea level rise caused by the projected melting of the ice sheets in each of the three areas studied, under low and high future global temperature rise scenarios.

If emissions continue on their current path, the business-as-usual scenario, the researchers say, then the world’s seas would be very likely to rise by between 62cm and 238cm by 2100. This would be in a world that had warmed by around 5°C, one of the worst-case scenarios for global warming.

 

“I think that a 5% probability, crikey − I think that’s a serious risk. If we see something like that in the next 80 years we are looking at social breakdown on scales that are pretty unimaginable”

“For 2100, the ice sheet contribution is very likely in the range of 7-178cm but once you add in glaciers and ice caps outside the ice sheets and thermal expansion of the seas, you tip well over two metres,” said the lead author, Jonathan Bamber, of the University of Bristol.

He added: “Such a rise in global sea level could result in land loss of 1.79 million sq km, including critical regions of food production, and potential displacement of up to 187 million people.”

For temperature rises expected up to 2°C Greenland’s ice sheet makes the single biggest contribution to sea level rise. But as temperatures climb further the much larger Antarctic ice sheets become involved.

“When you start to look at these lower-likelihood but still plausible values, then the experts believe that there is a small but statistically significant probability that West Antarctica will transition to a very unstable state, and parts of East Antarctica will start contributing as well,” said Professor Bamber.

“But it’s only at these higher probabilities for 5°C that we see those types of behaviours kicking in.”

Mass exodus

Globally important food-growing areas such as the Nile delta would be liable to vanish beneath the waves, and large parts of Bangladesh. Major global cities including London, New York, Rio de Janeiro and Shanghai would face significant threats.

“To put this into perspective, the Syrian refugee crisis resulted in about a million refugees coming into Europe,” said Professor Bamber.

Polar science is making striking advances in understanding what is happening to the Greenland and Antarctic ice sheets. New satellite measurements are showing ice mass loss happening faster than models expected, and there is also something called the marine ice-cliff instability hypothesis, which assumes that coastal ice cliffs can rapidly collapse after ice shelves disintegrate, as a result of surface and sub-shelf melting caused by global warming.

Serious risk

The chances of sea level rise as devastating as this are small, the Bristol team say − about 5%. But they should be taken seriously.

“If I said to you that there was a one in 20 chance that if you crossed the road you would be squashed you wouldn’t go near it,” Professor Bamber said.

“Even a 1% probability means that a one in a hundred year flood is something that could happen in your lifetime. I think that a 5% probability, crikey − I think that’s a serious risk.

“If we see something like that in the next 80 years we are looking at social breakdown on scales that are pretty unimaginable.” − Climate News Network

Scientists say global sea level rise could far exceed predictions because of faster melting in Greenland and Antarctica.

LONDON, 22 May, 2019 − If you are among the many millions of people who live near the world’s coasts, it will probably be worth your while to read this: sea level rise could be much greater than we expect.

A team of international scientists led by the University of Bristol, UK, has looked again at the estimates of how much the world’s oceans are likely to rise during this century. It concludes that the figure could be far higher than previous studies suggested.

In an extreme case, the members say, sea level rise over the next 80 years could mean that by 2100 the oceans will have risen by around six feet (two metres) − roughly twice the level thought likely till now, with “pretty unimaginable” consequences

In its fifth assessment report, published in 2013, the Intergovernmental Panel on Climate Change (IPCC) said the continued warming of the Earth, if there were no major reductions in greenhouse gas emissions, would see the seas rising by between 52cm and 98cm by 2100.

Sombre prospect

Many climate scientists have argued that this was a conservative estimate. The possibility that the eventual figure could be around double the forecast, threatening hundreds of millions of people with having to leave their homes, is sobering. It is published in the Proceedings of the National Academy of Sciences (PNAS).

The Bristol team used a different way of trying to gauge the possible effect of the way the ice is melting in Greenland, West and East Antarctica, not relying simply on projections from numerical models.

Their method used a technique called a structured expert judgement study, which involved 22 ice sheet experts in estimating plausible ranges for future sea level rise caused by the projected melting of the ice sheets in each of the three areas studied, under low and high future global temperature rise scenarios.

If emissions continue on their current path, the business-as-usual scenario, the researchers say, then the world’s seas would be very likely to rise by between 62cm and 238cm by 2100. This would be in a world that had warmed by around 5°C, one of the worst-case scenarios for global warming.

 

“I think that a 5% probability, crikey − I think that’s a serious risk. If we see something like that in the next 80 years we are looking at social breakdown on scales that are pretty unimaginable”

“For 2100, the ice sheet contribution is very likely in the range of 7-178cm but once you add in glaciers and ice caps outside the ice sheets and thermal expansion of the seas, you tip well over two metres,” said the lead author, Jonathan Bamber, of the University of Bristol.

He added: “Such a rise in global sea level could result in land loss of 1.79 million sq km, including critical regions of food production, and potential displacement of up to 187 million people.”

For temperature rises expected up to 2°C Greenland’s ice sheet makes the single biggest contribution to sea level rise. But as temperatures climb further the much larger Antarctic ice sheets become involved.

“When you start to look at these lower-likelihood but still plausible values, then the experts believe that there is a small but statistically significant probability that West Antarctica will transition to a very unstable state, and parts of East Antarctica will start contributing as well,” said Professor Bamber.

“But it’s only at these higher probabilities for 5°C that we see those types of behaviours kicking in.”

Mass exodus

Globally important food-growing areas such as the Nile delta would be liable to vanish beneath the waves, and large parts of Bangladesh. Major global cities including London, New York, Rio de Janeiro and Shanghai would face significant threats.

“To put this into perspective, the Syrian refugee crisis resulted in about a million refugees coming into Europe,” said Professor Bamber.

Polar science is making striking advances in understanding what is happening to the Greenland and Antarctic ice sheets. New satellite measurements are showing ice mass loss happening faster than models expected, and there is also something called the marine ice-cliff instability hypothesis, which assumes that coastal ice cliffs can rapidly collapse after ice shelves disintegrate, as a result of surface and sub-shelf melting caused by global warming.

Serious risk

The chances of sea level rise as devastating as this are small, the Bristol team say − about 5%. But they should be taken seriously.

“If I said to you that there was a one in 20 chance that if you crossed the road you would be squashed you wouldn’t go near it,” Professor Bamber said.

“Even a 1% probability means that a one in a hundred year flood is something that could happen in your lifetime. I think that a 5% probability, crikey − I think that’s a serious risk.

“If we see something like that in the next 80 years we are looking at social breakdown on scales that are pretty unimaginable.” − Climate News Network

Heat makes ocean winds and waves fiercer

The seas are rising. Ocean winds and waves are growing in speed and force. The oceans could be feeling the heat.

LONDON, 1 May, 2019 − The great swells of the Pacific are beginning to swell even more as fiercer ocean winds and waves leave their mark. The breakers that crash on the storm beaches now do so with greater force. The white horses are gathering pace.

A 33-year-study of data from 31 satellites and 80 ocean buoys has confirmed suspicions. The extreme ocean winds are now fiercer, and the waves are getting measurably higher.

It is a given of global warming that as average planetary temperatures rise, then more energy is available for storm, rainfall and drought.

In the past century, because of ever-increasing combustion of fossil fuels that release growing quantities of greenhouse gases, average global temperatures have crept higher by 1°C and in three decades the speed of extreme winds in the Southern Ocean has increased by 8%, or 1.5 metres per second. Extreme waves have increased by 30cms, or 5%, over the same period.

“These changes have impacts that are felt all over the world. Storm waves can increase coastal erosion, putting coastal settlements and infrastructures at risk”

“Although increases of 5 and 8% might not seem like much, if sustained into the future such changes to our climate will have major impacts,” said Ian Young, an engineer at the University of Melbourne in Australia

He and a colleague report in the journal Science that they reached their conclusion on the basis of 4 billion observations made between 1985 and 2018.

“Flooding events are caused by storm surge and associated breaking waves. The increased sea level makes these events more serious and more frequent,” said Professor Young. “Increases in wave height, and changes in other properties such as wave direction, will further increase the probability of coastal flooding.”

Sea levels have been creeping ever higher, in large part because of the retreat of most of the planet’s great glaciers and the ever-increasing meltwater from Greenland and West Antarctica, and also as a simple matter of physics: as the oceans warm, the waters become less dense and sea levels rise.

Difficult measurements

Surfers and pleasure-seekers began to worry about the impact of global warming and climate change on wave patterns years ago. But seemingly simple phenomena such as the effects wave height and wind speed have in the open oceans on a world-wide basis are harder to measure.

Spanish oceanographers reported earlier this year that they were sure that ocean waves were gathering in force and strength, and European engineers have warned of the impact of more intense storms backed up by rising seas on the Atlantic ports and coastlines of the continent.

But there are problems: precision measurements have been made only recently. Oceanographers cannot be sure that they are not witnessing a natural cycle of ocean change, in which storm intensities slowly vary over a pattern of decades.

Since 1985 earth observation satellites have been equipped with altimeters to measure wave height and wind speed, radiometers to measure wind speed, and scatterometers to record wind speed and direction. The next problem has been calibrating data from a range of different satellites, and indeed the slightly different stories told by instruments on the same satellite.

Worse to come

But the Australian engineers report that they are now 90% confident that they can measure ocean change: violent storms now arrive with higher wave crests and more dangerous winds than they did in 1985, and although this is true worldwide, the effect is most pronounced in the great ocean that swirls around Antarctica.

The next challenge is to make estimates of how much more violent the worst sea storms are likely to become later in the century, as planetary average temperatures – and sea levels – continue to rise.

“These changes have impacts that are felt all over the world. Storm waves can increase coastal erosion, putting coastal settlements and infrastructures at risk,” Professor Young said.

“We need a better understanding of how much this change is due to long-term climate change, and how much is due to multi-decadal fluctuations or cycles.” − Climate News Network

The seas are rising. Ocean winds and waves are growing in speed and force. The oceans could be feeling the heat.

LONDON, 1 May, 2019 − The great swells of the Pacific are beginning to swell even more as fiercer ocean winds and waves leave their mark. The breakers that crash on the storm beaches now do so with greater force. The white horses are gathering pace.

A 33-year-study of data from 31 satellites and 80 ocean buoys has confirmed suspicions. The extreme ocean winds are now fiercer, and the waves are getting measurably higher.

It is a given of global warming that as average planetary temperatures rise, then more energy is available for storm, rainfall and drought.

In the past century, because of ever-increasing combustion of fossil fuels that release growing quantities of greenhouse gases, average global temperatures have crept higher by 1°C and in three decades the speed of extreme winds in the Southern Ocean has increased by 8%, or 1.5 metres per second. Extreme waves have increased by 30cms, or 5%, over the same period.

“These changes have impacts that are felt all over the world. Storm waves can increase coastal erosion, putting coastal settlements and infrastructures at risk”

“Although increases of 5 and 8% might not seem like much, if sustained into the future such changes to our climate will have major impacts,” said Ian Young, an engineer at the University of Melbourne in Australia

He and a colleague report in the journal Science that they reached their conclusion on the basis of 4 billion observations made between 1985 and 2018.

“Flooding events are caused by storm surge and associated breaking waves. The increased sea level makes these events more serious and more frequent,” said Professor Young. “Increases in wave height, and changes in other properties such as wave direction, will further increase the probability of coastal flooding.”

Sea levels have been creeping ever higher, in large part because of the retreat of most of the planet’s great glaciers and the ever-increasing meltwater from Greenland and West Antarctica, and also as a simple matter of physics: as the oceans warm, the waters become less dense and sea levels rise.

Difficult measurements

Surfers and pleasure-seekers began to worry about the impact of global warming and climate change on wave patterns years ago. But seemingly simple phenomena such as the effects wave height and wind speed have in the open oceans on a world-wide basis are harder to measure.

Spanish oceanographers reported earlier this year that they were sure that ocean waves were gathering in force and strength, and European engineers have warned of the impact of more intense storms backed up by rising seas on the Atlantic ports and coastlines of the continent.

But there are problems: precision measurements have been made only recently. Oceanographers cannot be sure that they are not witnessing a natural cycle of ocean change, in which storm intensities slowly vary over a pattern of decades.

Since 1985 earth observation satellites have been equipped with altimeters to measure wave height and wind speed, radiometers to measure wind speed, and scatterometers to record wind speed and direction. The next problem has been calibrating data from a range of different satellites, and indeed the slightly different stories told by instruments on the same satellite.

Worse to come

But the Australian engineers report that they are now 90% confident that they can measure ocean change: violent storms now arrive with higher wave crests and more dangerous winds than they did in 1985, and although this is true worldwide, the effect is most pronounced in the great ocean that swirls around Antarctica.

The next challenge is to make estimates of how much more violent the worst sea storms are likely to become later in the century, as planetary average temperatures – and sea levels – continue to rise.

“These changes have impacts that are felt all over the world. Storm waves can increase coastal erosion, putting coastal settlements and infrastructures at risk,” Professor Young said.

“We need a better understanding of how much this change is due to long-term climate change, and how much is due to multi-decadal fluctuations or cycles.” − Climate News Network

Fast Arctic melt could cost $70 trillion

Polar change, notably the fast Arctic melt, could impose huge costs on world economies. New evidence shows how rapidly the frozen north is changing.

LONDON, 26 April, 2019 – The northern reaches of the planet are undergoing very rapid change: the fast Arctic melt means the region is warming at twice the speed of the planetary average.

The loss of sea ice and land snow could tip the planet into a new and unprecedented cycle of climatic change and add yet another $70 trillion (£54 tn) to the estimated economic cost of global warming.

In yet another sombre statement of the challenge presented by climate change, driven by ever-increasing emissions of greenhouse gases from the fossil fuels that power the global economy, British, European and US researchers took a look at two manifestations of warming.

One is the growing levels of ancient carbon now being released into the atmosphere as the Arctic permafrost begins to melt. The other is the reduced reflection of solar radiation back into space as what had once been an expanse of snow and ice melts, to expose ever greater areas of light-absorbing blue sea, dark rock and scrubby tundra.

Abrupt surprises

The concern is with what the scientists like to call “non-linear transitions”. The fear is not that global warming will simply get more pronounced as more snow and ice disappears. The fear is that at some point the melting will reach a threshold that could tip the planet into a new climate regime that would be irreversible, and for which there has been no parallel in human history.

And if so, the costs in terms of climate disruption, heat waves, rising sea levels, harvest failures, more violent storms and more devastating floods and so on could start to soar.

The scientists report in the journal Nature Communications that if the nations of the world were to keep a promise made in Paris in 2015 to contain planetary warming to “well below” 2°C above the average for most of human history by the year 2100, the extra cost of Arctic ice loss would still tip $24 tn.

But on the evidence of national plans tabled so far, the world seems on course to hit 3°C by the century’s end, and the extra cost to the global economies is estimated at almost $70 tn.

“What we are witnessing is a major transport current faltering, which is bringing the world one step closer to a sea ice-free summer in the Arctic”

If the world goes on burning more and more fossil fuels – this is called the business-as-usual scenario – then global temperatures could rise to 4°C above the historic average by 2100. The bill for what the scientists call “the most expensive and least desirable scenario” is set at $2197 tn. And, they stress, their forecast $70 tn is just the extra cost of the melting Arctic.

They have not factored in all the other much-feared potential “tipping points” such as the loss of the tropical rainforests that absorb so much of the atmospheric carbon, the collapse of the great Atlantic current that distributes equatorial heat to temperate climates, the loss of the West Antarctic ice sheet, and other irreversible changes.

As they see it, even to contain global warming to 1.5°C by 2100 could cost a global $600 trillion.

And although the thawing of the permafrost and the opening of the Arctic Ocean would deliver mining and shipping opportunities, any such rewards would be dwarfed by the cost of the emissions from the thawing permafrost, and the reduction of what scientists call albedo: the reflectivity of pristine ice and snow that helps keep the Arctic frozen.

Model-based estimates

Research of this kind is based on vast numbers of simulations of the global economies under a range of scenarios, and the calculations of cost remain just that, estimates based on models of what nations might or might not do. The price economies must pay will be real enough, but the advanced accounting of what has yet to happen remains academic.

But the changes in the Arctic are far from academic, according to a series of new studies of what has been happening, and is happening right now.

●Researchers in California report in the Proceedings of the National Academy of Sciences that they have now reconstructed change in the Greenland ice sheet between 1972 and 2018, to estimate the loss of ice.

Fifty years ago, the northern hemisphere’s greatest sheet of ice was losing 47 billion tonnes of ice every year, and by the next decade 50 bn tonnes annually.

Sea levels raised

Since then the losses have risen almost six-fold, and since 2010 the island has been losing ice at the rate of 290 billion tonnes a year. So far, ice from Greenland alone has raised sea levels by almost 14 mm.

●German scientists have looked at the results of 15 years of observations by the Grace satellite system – the acronym stands for Gravity Recovery and Climate Experiment – which ended in 2018. They calculate that between April 2002 and June 2017, Greenland lost about 260 bn tonnes of ice each year, and Antarctica 140 bn tonnes.

They warn in the journal Nature Climate Change that melting at this rate could accelerate sea level rise to 10 mm a year – faster than at any time in the last 5,000 years – as a direct consequence of a warming climate.

●And the traffic of sea ice across the Arctic ocean has begun to falter, according to German oceanographers. The Transpolar Drift is a slow flow of new sea ice from the Siberian Arctic across the pole to the Fram Strait east of Greenland.

Melting too early

It has its place in the history of polar exploration: in 1893 the Norwegian explorer Fridtjof Nansen deliberately sailed his ship the Fram into the ice pack off Siberia and went with the floes across the Arctic.

The Drift is a kind of frozen ocean conveyor that carries nutrients, algae and sediments across the pole. But, researchers say in the journal Scientific Reports, this flow has started to vary. Most of the young ice off the Siberian coast now melts before it can leave its “nursery”. Once, half the ice from the Russian shelf completed the journey. Now, only one-fifth does.

“What we are witnessing is a major transport current faltering, which is bringing the world one step closer to a sea ice-free summer in the Arctic,” said Thomas Krumpen of the Alfred Wegener Institute, who led the study.

“The ice now leaving the Arctic through the Fram Strait is, on average, 30% thinner than it was 15 years ago.” – Climate News Network

Polar change, notably the fast Arctic melt, could impose huge costs on world economies. New evidence shows how rapidly the frozen north is changing.

LONDON, 26 April, 2019 – The northern reaches of the planet are undergoing very rapid change: the fast Arctic melt means the region is warming at twice the speed of the planetary average.

The loss of sea ice and land snow could tip the planet into a new and unprecedented cycle of climatic change and add yet another $70 trillion (£54 tn) to the estimated economic cost of global warming.

In yet another sombre statement of the challenge presented by climate change, driven by ever-increasing emissions of greenhouse gases from the fossil fuels that power the global economy, British, European and US researchers took a look at two manifestations of warming.

One is the growing levels of ancient carbon now being released into the atmosphere as the Arctic permafrost begins to melt. The other is the reduced reflection of solar radiation back into space as what had once been an expanse of snow and ice melts, to expose ever greater areas of light-absorbing blue sea, dark rock and scrubby tundra.

Abrupt surprises

The concern is with what the scientists like to call “non-linear transitions”. The fear is not that global warming will simply get more pronounced as more snow and ice disappears. The fear is that at some point the melting will reach a threshold that could tip the planet into a new climate regime that would be irreversible, and for which there has been no parallel in human history.

And if so, the costs in terms of climate disruption, heat waves, rising sea levels, harvest failures, more violent storms and more devastating floods and so on could start to soar.

The scientists report in the journal Nature Communications that if the nations of the world were to keep a promise made in Paris in 2015 to contain planetary warming to “well below” 2°C above the average for most of human history by the year 2100, the extra cost of Arctic ice loss would still tip $24 tn.

But on the evidence of national plans tabled so far, the world seems on course to hit 3°C by the century’s end, and the extra cost to the global economies is estimated at almost $70 tn.

“What we are witnessing is a major transport current faltering, which is bringing the world one step closer to a sea ice-free summer in the Arctic”

If the world goes on burning more and more fossil fuels – this is called the business-as-usual scenario – then global temperatures could rise to 4°C above the historic average by 2100. The bill for what the scientists call “the most expensive and least desirable scenario” is set at $2197 tn. And, they stress, their forecast $70 tn is just the extra cost of the melting Arctic.

They have not factored in all the other much-feared potential “tipping points” such as the loss of the tropical rainforests that absorb so much of the atmospheric carbon, the collapse of the great Atlantic current that distributes equatorial heat to temperate climates, the loss of the West Antarctic ice sheet, and other irreversible changes.

As they see it, even to contain global warming to 1.5°C by 2100 could cost a global $600 trillion.

And although the thawing of the permafrost and the opening of the Arctic Ocean would deliver mining and shipping opportunities, any such rewards would be dwarfed by the cost of the emissions from the thawing permafrost, and the reduction of what scientists call albedo: the reflectivity of pristine ice and snow that helps keep the Arctic frozen.

Model-based estimates

Research of this kind is based on vast numbers of simulations of the global economies under a range of scenarios, and the calculations of cost remain just that, estimates based on models of what nations might or might not do. The price economies must pay will be real enough, but the advanced accounting of what has yet to happen remains academic.

But the changes in the Arctic are far from academic, according to a series of new studies of what has been happening, and is happening right now.

●Researchers in California report in the Proceedings of the National Academy of Sciences that they have now reconstructed change in the Greenland ice sheet between 1972 and 2018, to estimate the loss of ice.

Fifty years ago, the northern hemisphere’s greatest sheet of ice was losing 47 billion tonnes of ice every year, and by the next decade 50 bn tonnes annually.

Sea levels raised

Since then the losses have risen almost six-fold, and since 2010 the island has been losing ice at the rate of 290 billion tonnes a year. So far, ice from Greenland alone has raised sea levels by almost 14 mm.

●German scientists have looked at the results of 15 years of observations by the Grace satellite system – the acronym stands for Gravity Recovery and Climate Experiment – which ended in 2018. They calculate that between April 2002 and June 2017, Greenland lost about 260 bn tonnes of ice each year, and Antarctica 140 bn tonnes.

They warn in the journal Nature Climate Change that melting at this rate could accelerate sea level rise to 10 mm a year – faster than at any time in the last 5,000 years – as a direct consequence of a warming climate.

●And the traffic of sea ice across the Arctic ocean has begun to falter, according to German oceanographers. The Transpolar Drift is a slow flow of new sea ice from the Siberian Arctic across the pole to the Fram Strait east of Greenland.

Melting too early

It has its place in the history of polar exploration: in 1893 the Norwegian explorer Fridtjof Nansen deliberately sailed his ship the Fram into the ice pack off Siberia and went with the floes across the Arctic.

The Drift is a kind of frozen ocean conveyor that carries nutrients, algae and sediments across the pole. But, researchers say in the journal Scientific Reports, this flow has started to vary. Most of the young ice off the Siberian coast now melts before it can leave its “nursery”. Once, half the ice from the Russian shelf completed the journey. Now, only one-fifth does.

“What we are witnessing is a major transport current faltering, which is bringing the world one step closer to a sea ice-free summer in the Arctic,” said Thomas Krumpen of the Alfred Wegener Institute, who led the study.

“The ice now leaving the Arctic through the Fram Strait is, on average, 30% thinner than it was 15 years ago.” – Climate News Network

Glaciers’ global melt may leave Alps bare

High mountain ice is vital to millions. As the world warms, the glaciers’ global melt could see the frozen peaks vanish.

LONDON, 12 April, 2019 – Many of the planet’s most scenic – and most valued – high-altitude landscapes are likely to look quite different within the next 80 years: the glaciers’ global melt will have left just bare rock.

By the century’s end, Europe’s famous Alps – the chain of snow- and ice-covered peaks that have become a playground of the wealthy and a source of income and pleasure for generations – will have lost more than nine-tenths of all its glacier ice.

And in the last 50 years, the world’s glaciers – in Asia, the Americas, Europe, Africa and the sub-Arctic mountains – have lost more than nine trillion tonnes of ice as global temperatures creep ever upwards in response to profligate combustion of fossil fuels.

And as meltwater has trickled down the mountains, the seas have risen by 27mm, thanks entirely to glacial retreat.

“Present mass-loss rates indicate that glaciers could almost disappear in some mountain ranges in this century”

In two separate studies, Swiss scientists have tried to audit a profit and loss account for the world’s frozen high-altitude rivers, and found a steady downhill trend.

Glacial ice is a source of security and even wealth: in the poorest regions the annual summer melt of winter snow and ice banked at altitude can guarantee both energy as hydropower and water for crops in the valleys and floodplains.

In wealthy regions, the white peaks and slopes become sources of income as tourist attractions and centres for winter sport – as well as reliable sources of power and water.

Swiss focus

In the journal The Cryosphere, a team from the Swiss Federal Institute of Technology, almost always known simply as ETH Zurich, looked into the future of the nation’s own landscape, and beyond.

They made computer models of the annual flow of ice and its melting patterns and took 2017 as the reference year: a year when the Alpine glaciers bore 100 cubic kilometres of ice. And then they started simulating the future.

If humankind kept the promise made by 195 nations in Paris in 2015, to drastically reduce fossil fuel use, lower emissions of carbon dioxide, restore the forests and keep global warming to no more than 2°C above historic levels, then the stores of high ice would be reduced by more than a third over the next eight decades. If humankind went on expanding its use of fossil fuels at the present rates, then half of all the ice would be lost by 2050 and 95% by 2100.

Time lag

But there will be losses in all scenarios: warming so far has seen to that. Ice reflects radiation and keeps itself cold, so change lags behind atmospheric temperature.

“The future evolution of glaciers will strongly depend on how the climate will evolve,” said Harry Zekollari, once of ETH and now at Delft University of Technology in the Netherlands, who led the research. “In the case of a more limited warming, a far more substantial part of the glaciers could be saved.”

The Alpine glaciers were made world-famous first by Romantic painters and poets of the 19th century, among them JMW Turner and Lord Byron. But their contribution to rising sea levels is, in a global context, negligible.

When Swiss researchers and their Russian, Canadian and European partners looked at the big picture, they found that the mass loss of ice from the mountains of AlaskaCanada, parts of Asia and the Andes matched the increasing flow of water from the melting Greenland ice cap, and exceeded the flow of melting water from the Antarctic continent.

Europe’s modest melt

They report in Nature that glaciers separate from the Greenland and Antarctic sheets covered 706,000 square kilometres of the planet, with a total volume of 170,000 cubic kilometres, or 40 centimetres of potential sea level rise.

And in the five decades from 1961 to 2016, according to careful study of satellite imagery and historic observations, the seas have already risen by 27mm as a consequence of increasing rates of glacial retreat. This is already between 25% and 30% of observed sea level rise so far.

Europe did not figure much in the reckoning. “Globally, we lose three times the ice volume stored in the entirety of the European Alps – every single year,” said Michael Zemp, a glaciologist at the University of Zurich.

He and his colleagues warn: “Present mass-loss rates indicate that glaciers could almost disappear in some mountain ranges in this century, while heavily glacierised regions will continue to contribute to sea level rise beyond 2100.” – Climate News Network

High mountain ice is vital to millions. As the world warms, the glaciers’ global melt could see the frozen peaks vanish.

LONDON, 12 April, 2019 – Many of the planet’s most scenic – and most valued – high-altitude landscapes are likely to look quite different within the next 80 years: the glaciers’ global melt will have left just bare rock.

By the century’s end, Europe’s famous Alps – the chain of snow- and ice-covered peaks that have become a playground of the wealthy and a source of income and pleasure for generations – will have lost more than nine-tenths of all its glacier ice.

And in the last 50 years, the world’s glaciers – in Asia, the Americas, Europe, Africa and the sub-Arctic mountains – have lost more than nine trillion tonnes of ice as global temperatures creep ever upwards in response to profligate combustion of fossil fuels.

And as meltwater has trickled down the mountains, the seas have risen by 27mm, thanks entirely to glacial retreat.

“Present mass-loss rates indicate that glaciers could almost disappear in some mountain ranges in this century”

In two separate studies, Swiss scientists have tried to audit a profit and loss account for the world’s frozen high-altitude rivers, and found a steady downhill trend.

Glacial ice is a source of security and even wealth: in the poorest regions the annual summer melt of winter snow and ice banked at altitude can guarantee both energy as hydropower and water for crops in the valleys and floodplains.

In wealthy regions, the white peaks and slopes become sources of income as tourist attractions and centres for winter sport – as well as reliable sources of power and water.

Swiss focus

In the journal The Cryosphere, a team from the Swiss Federal Institute of Technology, almost always known simply as ETH Zurich, looked into the future of the nation’s own landscape, and beyond.

They made computer models of the annual flow of ice and its melting patterns and took 2017 as the reference year: a year when the Alpine glaciers bore 100 cubic kilometres of ice. And then they started simulating the future.

If humankind kept the promise made by 195 nations in Paris in 2015, to drastically reduce fossil fuel use, lower emissions of carbon dioxide, restore the forests and keep global warming to no more than 2°C above historic levels, then the stores of high ice would be reduced by more than a third over the next eight decades. If humankind went on expanding its use of fossil fuels at the present rates, then half of all the ice would be lost by 2050 and 95% by 2100.

Time lag

But there will be losses in all scenarios: warming so far has seen to that. Ice reflects radiation and keeps itself cold, so change lags behind atmospheric temperature.

“The future evolution of glaciers will strongly depend on how the climate will evolve,” said Harry Zekollari, once of ETH and now at Delft University of Technology in the Netherlands, who led the research. “In the case of a more limited warming, a far more substantial part of the glaciers could be saved.”

The Alpine glaciers were made world-famous first by Romantic painters and poets of the 19th century, among them JMW Turner and Lord Byron. But their contribution to rising sea levels is, in a global context, negligible.

When Swiss researchers and their Russian, Canadian and European partners looked at the big picture, they found that the mass loss of ice from the mountains of AlaskaCanada, parts of Asia and the Andes matched the increasing flow of water from the melting Greenland ice cap, and exceeded the flow of melting water from the Antarctic continent.

Europe’s modest melt

They report in Nature that glaciers separate from the Greenland and Antarctic sheets covered 706,000 square kilometres of the planet, with a total volume of 170,000 cubic kilometres, or 40 centimetres of potential sea level rise.

And in the five decades from 1961 to 2016, according to careful study of satellite imagery and historic observations, the seas have already risen by 27mm as a consequence of increasing rates of glacial retreat. This is already between 25% and 30% of observed sea level rise so far.

Europe did not figure much in the reckoning. “Globally, we lose three times the ice volume stored in the entirety of the European Alps – every single year,” said Michael Zemp, a glaciologist at the University of Zurich.

He and his colleagues warn: “Present mass-loss rates indicate that glaciers could almost disappear in some mountain ranges in this century, while heavily glacierised regions will continue to contribute to sea level rise beyond 2100.” – Climate News Network

More acidic seas devour marine food web

As more acidic seas spread across the globe, conditions for survival start to change. That could close vast volumes of ocean for vital forms of life.

LONDON, 13 March, 2019 – By the close of the century, parts of the Southern Ocean could become impoverished as more acidic seas displace abundant marine food resources. Tiny sea snails that form the basis of the food supply for one of the world’s richest ecosystems could disappear because the depth at which they can form their shells will have shifted.

Right now, in Antarctic waters, creatures known as pteropods can exploit the calcium carbonate dissolved in the oceans down to a depth of 1000 metres to grow their shells.

But as atmospheric carbon dioxide levels soar, as a consequence of profligate use of fossil fuels by humankind, the chemistry of the oceans will shift towards the acidic.

The ratios of two kinds of carbonate – calcite and aragonite – will alter. And by 2100, there won’t be enough aragonite.

“A pocket of corrosive water will sit just below the surface, making life difficult for these communities of primarily surface-dwelling organisms”

Right now, pteropods flourish in the top 300 metres of the ocean. By 2100, the survival zone for the pteropods will end at a depth of 83 metres.

And, scientists warn in the journal Nature Climate Change, this could “change food web dynamics and have cascading effects on global ocean ecosystems.” In other words, the larger fish and marine mammals that feed on the smaller creatures that in turn depend on a basic diet of pteropods will have nothing to eat.

And that can only be bad news for global fisheries.

All shelled marine creatures – the tiny coccolithophores that die and leave their shells as chalk, the clams and molluscs, the foraminifera that float on the surface or coat the rocks and the seafloor, and the corals that are the basis for rich tropical ecosystems, all depend on the right levels of calcite and aragonite to form their exoskeletons.

The oceans are the biggest living space on the planet: the waves cover 70% of all living space and the depth of the deepest trenches is far greater than the highest terrestrial mountain ranges.

Origin of life

The oceans are the crucible in which life first emerged, and the oceans ultimately provided the sediments from which humankind has built its cities.

US and Norwegian scientists chose one species with precise needs in one reach of ocean as an indicator or what climate change driven by ever greater levels of the greenhouse gas carbon dioxide could do to an ocean ecosystem.

They found that what they called the “aragonite saturation horizon” became dramatically shallower as the seas became more acidic.

“These calcifying organisms will struggle to build and maintain their shells as acidification proceeds,” said Nicole Lovenduski, of the University of Colorado at Boulder, one of the researchers.

Inevitable result

“In the future, a pocket of corrosive water will sit just below the surface, making life difficult for these communities of primarily surface-dwelling organisms.”

As the world warms, acidification of the oceans becomes inevitable. Researchers have repeatedly warned that such change can only diminish ocean life, harm the coral reefs and kelp forests that shelter the rich biodiversity of sea creatures, change the behaviour of fish and some kinds of shrimp and threaten the shellfish harvest.

But for the first time, scientists have been able to model the impact of atmospheric change on the ocean chemistry in one zone at precise depths. The message is that right now, the pteropods have plenty of sea space for survival. But the aragonite saturation horizon may have already begun to shift in some places: perhaps as early as 2006, or as late as 2038. Once change begins, it will continue.

“If emissions were curbed tomorrow, this suddenly shallow horizon would still appear, even if possibly delayed,” said Dr Lovenduski. “And that, inevitably, along with lack of time for organisms to adapt, is most concerning.” – Climate News Network

As more acidic seas spread across the globe, conditions for survival start to change. That could close vast volumes of ocean for vital forms of life.

LONDON, 13 March, 2019 – By the close of the century, parts of the Southern Ocean could become impoverished as more acidic seas displace abundant marine food resources. Tiny sea snails that form the basis of the food supply for one of the world’s richest ecosystems could disappear because the depth at which they can form their shells will have shifted.

Right now, in Antarctic waters, creatures known as pteropods can exploit the calcium carbonate dissolved in the oceans down to a depth of 1000 metres to grow their shells.

But as atmospheric carbon dioxide levels soar, as a consequence of profligate use of fossil fuels by humankind, the chemistry of the oceans will shift towards the acidic.

The ratios of two kinds of carbonate – calcite and aragonite – will alter. And by 2100, there won’t be enough aragonite.

“A pocket of corrosive water will sit just below the surface, making life difficult for these communities of primarily surface-dwelling organisms”

Right now, pteropods flourish in the top 300 metres of the ocean. By 2100, the survival zone for the pteropods will end at a depth of 83 metres.

And, scientists warn in the journal Nature Climate Change, this could “change food web dynamics and have cascading effects on global ocean ecosystems.” In other words, the larger fish and marine mammals that feed on the smaller creatures that in turn depend on a basic diet of pteropods will have nothing to eat.

And that can only be bad news for global fisheries.

All shelled marine creatures – the tiny coccolithophores that die and leave their shells as chalk, the clams and molluscs, the foraminifera that float on the surface or coat the rocks and the seafloor, and the corals that are the basis for rich tropical ecosystems, all depend on the right levels of calcite and aragonite to form their exoskeletons.

The oceans are the biggest living space on the planet: the waves cover 70% of all living space and the depth of the deepest trenches is far greater than the highest terrestrial mountain ranges.

Origin of life

The oceans are the crucible in which life first emerged, and the oceans ultimately provided the sediments from which humankind has built its cities.

US and Norwegian scientists chose one species with precise needs in one reach of ocean as an indicator or what climate change driven by ever greater levels of the greenhouse gas carbon dioxide could do to an ocean ecosystem.

They found that what they called the “aragonite saturation horizon” became dramatically shallower as the seas became more acidic.

“These calcifying organisms will struggle to build and maintain their shells as acidification proceeds,” said Nicole Lovenduski, of the University of Colorado at Boulder, one of the researchers.

Inevitable result

“In the future, a pocket of corrosive water will sit just below the surface, making life difficult for these communities of primarily surface-dwelling organisms.”

As the world warms, acidification of the oceans becomes inevitable. Researchers have repeatedly warned that such change can only diminish ocean life, harm the coral reefs and kelp forests that shelter the rich biodiversity of sea creatures, change the behaviour of fish and some kinds of shrimp and threaten the shellfish harvest.

But for the first time, scientists have been able to model the impact of atmospheric change on the ocean chemistry in one zone at precise depths. The message is that right now, the pteropods have plenty of sea space for survival. But the aragonite saturation horizon may have already begun to shift in some places: perhaps as early as 2006, or as late as 2038. Once change begins, it will continue.

“If emissions were curbed tomorrow, this suddenly shallow horizon would still appear, even if possibly delayed,” said Dr Lovenduski. “And that, inevitably, along with lack of time for organisms to adapt, is most concerning.” – Climate News Network

Melting polar ice sheets will alter weather

Sea level rise and melting polar ice sheets may not cause a climate catastrophe, but they will certainly change weather patterns unpredictably.

LONDON, 15 February, 2019 – The global weather is about to get worse. The melting polar ice sheets will mean rainfall and windstorms could become more violent, and hot spells and ice storms could become more extreme.

This is because the ice sheets of Greenland and Antarctica are melting, to affect what were once stable ocean currents and airflow patterns around the globe.

Planetary surface temperatures could rise by 3°C or even 4°C by the end of the century. Global sea levels will rise in ways that would “enhance global temperature variability”, but this might not be as high as earlier studies have predicted. That is because the ice cliffs of Antarctica might not be so much at risk of disastrous collapse that would set the glaciers accelerating to the sea.

The latest revision of evidence from the melting ice sheets in two hemispheres – and there is plenty of evidence that melting is happening at ever greater rates – is based on two studies of what could happen to the world’s greatest reservoirs of frozen freshwater if nations pursue current policies, fossil fuel combustion continues to increase, and global average temperatures creep up to unprecedented levels.

“Even if we do include ice-cliff instability … the most likely contribution to sea level rise would be less than half a metre by 2100”

“Under current global government policies, we are heading towards 3 or 4 degrees of warming above pre-industrial levels, causing a significant amount of melt water from the Greenland and Antarctic ice sheets to enter Earth’s oceans. According to our models, this melt water will cause significant disruptions to ocean currents and change levels of warming around the world,” said Nick Golledge, a south polar researcher at Victoria University, in New Zealand.

He and colleagues from Canada, the US, Germany and the UK report in Nature that they matched satellite observations of what is happening to the ice sheets with detailed simulations of the complex effects of melting over time, and according to the human response so far to warnings of climate change.

In Paris in 2015, leaders from 195 nations vowed to contain global warming to “well below” an average rise of 2°C by 2100. But promises have yet to become concerted and coherent action, and researchers warn that on present policies, a 3°C rise seems inevitable.

Sea levels have already risen by about 14 cms in the last century: the worst scenarios have proposed a devastating rise of 130 cms by 2100. The fastest increase in the rise of sea levels is likely to happen between 2065 and 2075.

Gulf Stream weakens

As warmer melt water gets into the North Atlantic, that major ocean current the Gulf Stream is likely to be weakened. Air temperatures are likely to rise over eastern Canada, central America and the high Arctic. Northwestern Europe – scientists have been warning of this for years – will become cooler.

In the Antarctic, a lens of warm fresh water will form over the surface, allowing uprising warm ocean water to spread and cause what could be further Antarctic melting.

But how bad this could be is re-examined in a second, companion paper in Nature. Tamsin Edwards, now at King’s College London, Dr Golledge and others took a fresh look at an old scare: that the vast cliffs of ice – some of them 100 metres above sea level – around the Antarctic could become unstable and collapse, accelerating the retreat of the ice behind them.

They used geophysical techniques to analyse dramatic episodes of ice loss that must have happened 3 million years ago and 125,000 years ago, and they went back to the present patterns of melt. These losses, in their calculations, did not cause unstoppable ice loss in the past, and may not affect the future much either.

Instability less important

“We’ve shown that ice-cliff instability doesn’t appear to be an essential mechanism in reproducing past sea level changes and so this suggests ‘the jury’s still out’ when it comes to including it in future predictions,” said Dr Edwards.

“Even if we do include ice-cliff instability, our more thorough assessment shows the most likely contribution to sea level rise would be less than half a metre by 2100.”

At worst, there is a one in 20 chance that enough of Antarctica’s glacial burden will melt to raise sea levels by 39 cms. More likely, both studies conclude, under high levels of greenhouse gas concentrations, south polar ice will only melt to raise sea levels worldwide by about 15 cms. – Climate News Network

Sea level rise and melting polar ice sheets may not cause a climate catastrophe, but they will certainly change weather patterns unpredictably.

LONDON, 15 February, 2019 – The global weather is about to get worse. The melting polar ice sheets will mean rainfall and windstorms could become more violent, and hot spells and ice storms could become more extreme.

This is because the ice sheets of Greenland and Antarctica are melting, to affect what were once stable ocean currents and airflow patterns around the globe.

Planetary surface temperatures could rise by 3°C or even 4°C by the end of the century. Global sea levels will rise in ways that would “enhance global temperature variability”, but this might not be as high as earlier studies have predicted. That is because the ice cliffs of Antarctica might not be so much at risk of disastrous collapse that would set the glaciers accelerating to the sea.

The latest revision of evidence from the melting ice sheets in two hemispheres – and there is plenty of evidence that melting is happening at ever greater rates – is based on two studies of what could happen to the world’s greatest reservoirs of frozen freshwater if nations pursue current policies, fossil fuel combustion continues to increase, and global average temperatures creep up to unprecedented levels.

“Even if we do include ice-cliff instability … the most likely contribution to sea level rise would be less than half a metre by 2100”

“Under current global government policies, we are heading towards 3 or 4 degrees of warming above pre-industrial levels, causing a significant amount of melt water from the Greenland and Antarctic ice sheets to enter Earth’s oceans. According to our models, this melt water will cause significant disruptions to ocean currents and change levels of warming around the world,” said Nick Golledge, a south polar researcher at Victoria University, in New Zealand.

He and colleagues from Canada, the US, Germany and the UK report in Nature that they matched satellite observations of what is happening to the ice sheets with detailed simulations of the complex effects of melting over time, and according to the human response so far to warnings of climate change.

In Paris in 2015, leaders from 195 nations vowed to contain global warming to “well below” an average rise of 2°C by 2100. But promises have yet to become concerted and coherent action, and researchers warn that on present policies, a 3°C rise seems inevitable.

Sea levels have already risen by about 14 cms in the last century: the worst scenarios have proposed a devastating rise of 130 cms by 2100. The fastest increase in the rise of sea levels is likely to happen between 2065 and 2075.

Gulf Stream weakens

As warmer melt water gets into the North Atlantic, that major ocean current the Gulf Stream is likely to be weakened. Air temperatures are likely to rise over eastern Canada, central America and the high Arctic. Northwestern Europe – scientists have been warning of this for years – will become cooler.

In the Antarctic, a lens of warm fresh water will form over the surface, allowing uprising warm ocean water to spread and cause what could be further Antarctic melting.

But how bad this could be is re-examined in a second, companion paper in Nature. Tamsin Edwards, now at King’s College London, Dr Golledge and others took a fresh look at an old scare: that the vast cliffs of ice – some of them 100 metres above sea level – around the Antarctic could become unstable and collapse, accelerating the retreat of the ice behind them.

They used geophysical techniques to analyse dramatic episodes of ice loss that must have happened 3 million years ago and 125,000 years ago, and they went back to the present patterns of melt. These losses, in their calculations, did not cause unstoppable ice loss in the past, and may not affect the future much either.

Instability less important

“We’ve shown that ice-cliff instability doesn’t appear to be an essential mechanism in reproducing past sea level changes and so this suggests ‘the jury’s still out’ when it comes to including it in future predictions,” said Dr Edwards.

“Even if we do include ice-cliff instability, our more thorough assessment shows the most likely contribution to sea level rise would be less than half a metre by 2100.”

At worst, there is a one in 20 chance that enough of Antarctica’s glacial burden will melt to raise sea levels by 39 cms. More likely, both studies conclude, under high levels of greenhouse gas concentrations, south polar ice will only melt to raise sea levels worldwide by about 15 cms. – Climate News Network

Permafrost thaws as global warming sets in

Global warming is at work far below the surface, at depths seemingly insulated from the greenhouse effect. This is bad news for the permafrost.

LONDON, 29 January, 2019 – Even in the coldest places – 10 metres below the surface of the polar wastes – global warming has begun to work. A new study of the frozen soils in both hemispheres shows that between 2007 and 2016, they warmed by an average of 0.3°C.

This remained true within the Arctic and Antarctic zones, in the highest mountain regions of Europe and Asia, and even in the Siberian tundra, where the temperatures at depth rose by almost a whole degree.

New research into the permafrost, defined as territory where soil has been frozen for at least two consecutive years, suggests that much of it may not be permanently frozen for much longer.

Climate scientists have repeatedly warned that along with the tilth, clays and sediments the icy structures store vast amounts of carbon in the form of yet-to-be-decomposed plant material.

So the thawing permafrost could surrender even more warming agents in the form of greenhouse gases, and accelerate global warming even further.

“The permafrost isn’t simply warming on a local and regional scale, but worldwide and at virtually the same pace as climate warming”

Researchers based in Potsdam, Germany report in the journal Nature Communications that they and colleagues in the Global Terrestrial Network for Permafrost monitored and measured soil temperatures in boreholes at 154 locations; more than 120 of them over a 10-year cycle. In a dozen locations the temperatures actually fell, and at 40 locations there was virtually no change.

The most dramatic warming was in the Arctic, where soils that were more than 90% permafrost increased temperatures by 0.3°C, and the Siberian north, where temperatures rose by 0.9°C or more. Air temperatures over those regions had risen by an average of 0.6°C in the same decade. In those Arctic regions with less than 90% permafrost, the frozen ground had warmed by 0.2°C.

“In these regions there is more and more snowfall, which insulates the permafrost in two ways, following the igloo principle,” said Boris Biskaborn of the Alfred Wegener Institute, at the Helmholtz Centre for Polar and Marine Research, who led the study.

“In winter snow protects the soil from extreme cold, which on average produces a warming effect. In spring it reflects the sunlight, and prevents the soils from being exposed to too much warmth, at least until the snow has completely melted away.”

Widespread impact

The scientists also report that soil temperature rises were recorded in the Alps of Europe, the mountain ranges of Scandinavia, and in the Himalayas.

Other scientists have already this year identified potential disaster for many settlements in the Arctic regions: the once-hard-frozen topsoils are in danger of thawing, and since these support industrial buildings, oil and gas pipelines, road surfaces, and even whole towns, the danger of severe damage to infrastructure is growing.

And, the researchers warn, even if the world sticks to its promise, made by 195 nations in Paris in 2015, and contains global warming to no more than 2°C over pre-industrial levels by 2100, there is still a likelihood that the permafrost will disappear over a large area, to surrender more greenhouse gases, and trigger more warming.

“All this data tells us that the permafrost isn’t simply warming on a local and regional scale, but worldwide and at virtually the same pace as climate warming, which is producing a substantial warming of the air and increased snow thickness, especially in the Arctic,” said Guido Grosse, who heads permafrost research in Potsdam. “These two factors produce a warming of the once permanently frozen ground.” – Climate News Network

Global warming is at work far below the surface, at depths seemingly insulated from the greenhouse effect. This is bad news for the permafrost.

LONDON, 29 January, 2019 – Even in the coldest places – 10 metres below the surface of the polar wastes – global warming has begun to work. A new study of the frozen soils in both hemispheres shows that between 2007 and 2016, they warmed by an average of 0.3°C.

This remained true within the Arctic and Antarctic zones, in the highest mountain regions of Europe and Asia, and even in the Siberian tundra, where the temperatures at depth rose by almost a whole degree.

New research into the permafrost, defined as territory where soil has been frozen for at least two consecutive years, suggests that much of it may not be permanently frozen for much longer.

Climate scientists have repeatedly warned that along with the tilth, clays and sediments the icy structures store vast amounts of carbon in the form of yet-to-be-decomposed plant material.

So the thawing permafrost could surrender even more warming agents in the form of greenhouse gases, and accelerate global warming even further.

“The permafrost isn’t simply warming on a local and regional scale, but worldwide and at virtually the same pace as climate warming”

Researchers based in Potsdam, Germany report in the journal Nature Communications that they and colleagues in the Global Terrestrial Network for Permafrost monitored and measured soil temperatures in boreholes at 154 locations; more than 120 of them over a 10-year cycle. In a dozen locations the temperatures actually fell, and at 40 locations there was virtually no change.

The most dramatic warming was in the Arctic, where soils that were more than 90% permafrost increased temperatures by 0.3°C, and the Siberian north, where temperatures rose by 0.9°C or more. Air temperatures over those regions had risen by an average of 0.6°C in the same decade. In those Arctic regions with less than 90% permafrost, the frozen ground had warmed by 0.2°C.

“In these regions there is more and more snowfall, which insulates the permafrost in two ways, following the igloo principle,” said Boris Biskaborn of the Alfred Wegener Institute, at the Helmholtz Centre for Polar and Marine Research, who led the study.

“In winter snow protects the soil from extreme cold, which on average produces a warming effect. In spring it reflects the sunlight, and prevents the soils from being exposed to too much warmth, at least until the snow has completely melted away.”

Widespread impact

The scientists also report that soil temperature rises were recorded in the Alps of Europe, the mountain ranges of Scandinavia, and in the Himalayas.

Other scientists have already this year identified potential disaster for many settlements in the Arctic regions: the once-hard-frozen topsoils are in danger of thawing, and since these support industrial buildings, oil and gas pipelines, road surfaces, and even whole towns, the danger of severe damage to infrastructure is growing.

And, the researchers warn, even if the world sticks to its promise, made by 195 nations in Paris in 2015, and contains global warming to no more than 2°C over pre-industrial levels by 2100, there is still a likelihood that the permafrost will disappear over a large area, to surrender more greenhouse gases, and trigger more warming.

“All this data tells us that the permafrost isn’t simply warming on a local and regional scale, but worldwide and at virtually the same pace as climate warming, which is producing a substantial warming of the air and increased snow thickness, especially in the Arctic,” said Guido Grosse, who heads permafrost research in Potsdam. “These two factors produce a warming of the once permanently frozen ground.” – Climate News Network

Polar ice loss speeds up by leaps and bounds

North and south, polar ice loss is happening faster than ever. Researchers now have a measure of the accelerating flow into the ocean.

LONDON, 22 January, 2019 – In the last few decades the speed of polar ice loss at both ends of the planet has begun to gallop away at rates which will have a marked effect on global sea levels.

Antarctica is now losing ice mass six times faster than it did 40 years ago. In the decade that began in 1979, the great white continent surrendered 40 billion tons of ice a year to raise global sea levels. By the decade 2009 to 2017, this mass loss had soared to 252 billion tons a year.

And in Greenland, the greatest concentration of terrestrial ice in the northern hemisphere has also accelerated its rate of ice loss fourfold in this century.

Satellite studies confirm that in 2003, around 102 billion tons of ice turned to flowing water or broke off into the ocean as floating bergs. By 2013, this figure had climbed to 393 billion tons a year.

“That’s just the tip of the iceberg, so to speak. As the Antarctic Ice Sheet continues to melt away, we expect multi-metre sea level rise from Antarctica in the coming centuries”

Scientists report in the Proceedings of the National Academy of Sciences that they studied high resolution aerial photographs, satellite radar readings and historic Landsat imagery to survey 18 south polar regions encompassing 176 basins and surrounding islands of Antarctica to take the most precise measurement of ice loss so far.

Most of the loss is attributed to the contact with ever-warmer ocean waters as they lap the ice shelves or eat away at grounded glaciers. Since 1979 it has contributed 14mm to global sea level rise. The researchers stress that their reading of the profit-and-loss accounts of polar ice is the longest study so far.

“That’s just the tip of the iceberg, so to speak,” said Eric Rignot, of the University of California Irvine. “As the Antarctic Ice Sheet continues to melt away, we expect multi-metre sea level rise from Antarctica in the coming centuries.” If all the ice on the continent were to melt, it would raise global sea levels by 57 metres.

Growing concern

For more than a decade scientists have been concerned with the rate of warming, the acceleration of glacial flow and the loss of shelf ice off West Antarctica. The latest study indicates that East Antarctica, home to a far greater volume of ice, is also losing mass.

Accelerating glacier movement across Greenland towards the sea has also concerned climate scientists worried about icemelt for years. The island’s bedrock bears a burden of ice sufficient to raise global sea levels by seven metres.

Researchers who have used data from the GRACE satellites – the acronym stands for Gravity Recovery and Climate Experiment – since 2002 also report in the same journal that the largest sustained loss of ice on Greenland came from the island’s southwest. They think that within two decades the region could become a major contributor to global sea level rise. But why the loss has accelerated is uncertain.

“Whichever this was, it couldn’t be explained by glaciers, because there aren’t many there,” said Michael Bevis of Ohio State University. “It had to be surface mass – the ice was melting inland from the coastline.”

Puzzling picture

Once again, warming atmosphere and ocean are linked to ice loss in the Arctic region, a change driven by global warming as a consequence of ever-higher ratios of greenhouse gases in the atmosphere, fed by ever-higher rates of combustion of fossil fuels.

Melting rates have been uneven: the unexplained acceleration between 2003 and 2013 was followed by an equally puzzling pause. Natural atmospheric cycles such as the North Atlantic Oscillation must be part of the explanation.

“These oscillations have been happening forever. So why only now are they causing this massive melt? It is because the atmosphere is, at its baseline, warmer. The transient warming driven by the North Atlantic Oscillation was riding on top of more sustained global warming,” Professor Bevis said.

“We are going to see faster and faster sea level rise for the foreseeable future. Once you hit that tipping point, the only question is: how severe does it get?” – Climate News Network

North and south, polar ice loss is happening faster than ever. Researchers now have a measure of the accelerating flow into the ocean.

LONDON, 22 January, 2019 – In the last few decades the speed of polar ice loss at both ends of the planet has begun to gallop away at rates which will have a marked effect on global sea levels.

Antarctica is now losing ice mass six times faster than it did 40 years ago. In the decade that began in 1979, the great white continent surrendered 40 billion tons of ice a year to raise global sea levels. By the decade 2009 to 2017, this mass loss had soared to 252 billion tons a year.

And in Greenland, the greatest concentration of terrestrial ice in the northern hemisphere has also accelerated its rate of ice loss fourfold in this century.

Satellite studies confirm that in 2003, around 102 billion tons of ice turned to flowing water or broke off into the ocean as floating bergs. By 2013, this figure had climbed to 393 billion tons a year.

“That’s just the tip of the iceberg, so to speak. As the Antarctic Ice Sheet continues to melt away, we expect multi-metre sea level rise from Antarctica in the coming centuries”

Scientists report in the Proceedings of the National Academy of Sciences that they studied high resolution aerial photographs, satellite radar readings and historic Landsat imagery to survey 18 south polar regions encompassing 176 basins and surrounding islands of Antarctica to take the most precise measurement of ice loss so far.

Most of the loss is attributed to the contact with ever-warmer ocean waters as they lap the ice shelves or eat away at grounded glaciers. Since 1979 it has contributed 14mm to global sea level rise. The researchers stress that their reading of the profit-and-loss accounts of polar ice is the longest study so far.

“That’s just the tip of the iceberg, so to speak,” said Eric Rignot, of the University of California Irvine. “As the Antarctic Ice Sheet continues to melt away, we expect multi-metre sea level rise from Antarctica in the coming centuries.” If all the ice on the continent were to melt, it would raise global sea levels by 57 metres.

Growing concern

For more than a decade scientists have been concerned with the rate of warming, the acceleration of glacial flow and the loss of shelf ice off West Antarctica. The latest study indicates that East Antarctica, home to a far greater volume of ice, is also losing mass.

Accelerating glacier movement across Greenland towards the sea has also concerned climate scientists worried about icemelt for years. The island’s bedrock bears a burden of ice sufficient to raise global sea levels by seven metres.

Researchers who have used data from the GRACE satellites – the acronym stands for Gravity Recovery and Climate Experiment – since 2002 also report in the same journal that the largest sustained loss of ice on Greenland came from the island’s southwest. They think that within two decades the region could become a major contributor to global sea level rise. But why the loss has accelerated is uncertain.

“Whichever this was, it couldn’t be explained by glaciers, because there aren’t many there,” said Michael Bevis of Ohio State University. “It had to be surface mass – the ice was melting inland from the coastline.”

Puzzling picture

Once again, warming atmosphere and ocean are linked to ice loss in the Arctic region, a change driven by global warming as a consequence of ever-higher ratios of greenhouse gases in the atmosphere, fed by ever-higher rates of combustion of fossil fuels.

Melting rates have been uneven: the unexplained acceleration between 2003 and 2013 was followed by an equally puzzling pause. Natural atmospheric cycles such as the North Atlantic Oscillation must be part of the explanation.

“These oscillations have been happening forever. So why only now are they causing this massive melt? It is because the atmosphere is, at its baseline, warmer. The transient warming driven by the North Atlantic Oscillation was riding on top of more sustained global warming,” Professor Bevis said.

“We are going to see faster and faster sea level rise for the foreseeable future. Once you hit that tipping point, the only question is: how severe does it get?” – Climate News Network

Underwater walls might avert sea level rise

Could a vast underwater wall in front of an unstable glacier prevent dangerous sea level rise? Or should everyone just move further inland?

LONDON, 10 October, 2018 – Two climate scientists believe they have a long-term solution to dangerous sea level rise by targeting the most vulnerable glaciers, especially those that could trigger a massive collapse of the ice sheets behind them.

A submarine wall big enough and wide enough could halt the flow of increasingly warm ocean water below the front of each glacier. The combination of warmer air temperatures and warmer waters that accompany human-triggered climate change is dangerous: it could for instance accelerate the already alarming retreat of the Thwaites Glacier in West Antarctica, which alone shores up enough ice to raise global sea levels by up to 3 metres.

The scientists don’t propose an immediate start. But they do want to explore ways of halting sea level rise driven by global warming that could soon be costing the world $50 trillion a year in economic losses, that could submerge small island states and turn 1 million people a year into climate migrants.

“We are not advocating that glacial geoengineering be attempted any time soon”, they warn in the journal The Cryosphere.

Their simplest option – a series of pillars to shore up a targeted glacier and keep it “grounded” – would require engineering comparable in scale to the excavation of the Suez canal, would be undertaken in the world’s harshest environment, and would have just a one in three chance of success.

“In the long run we need plans to deal with the committed climate changes that are already in the pipeline, one of which may be an ice sheet collapse”

The researchers – John Moore, of Beijing Normal University in China, who also holds a post at the University of Lapland in Finland, and Michael Wolovick, of Princeton University in the US – have made this case before: they and others argued in March in Nature for what they call “managed collapse.”

In the latest study, they look at the challenge in greater detail. And they warn that even if targeted geoengineering of individual glaciers worked, it would only do so if humans stopped tipping ever more greenhouse gases into the atmosphere to fuel yet more global warming.

Nor do they argue that a submarine curtain wall to halt warming water across the front of the Thwaites glacier – up to 100 kms wide – is currently feasible. “But in the long run we need plans to deal with the committed climate changes that are already in the pipeline, one of which may be an ice sheet collapse.”

And one of these is the Thwaites Glacier in Antarctica: another is the Jakobshaven Isbrae in Greenland. Both could be cases of what the scientists call marine ice sheet instability: as a glacier retreats from its grounding line, the ice lifts off the bedrock and begins to float.

If the bedrock slopes down towards the centre of the ice sheet, and warmer ocean currents wash beneath it, then the ice starts to stretch and thin, and retreat further. At some point, it would become much easier for thawing ice to flow into the sea, and start what could become a runaway collapse. Engineers could devise a way of slowing or halting the process.

Huge impact

The scientists argue that even a rise of 0.6m to 1.2 metres by 2100 could cause up to $50 trillion in economic damage, and the resultant flooding could force up to 200 million to 500 million people out of their homes at least for a few days or weeks: around a million or so every year would never go back.

Climate scientists have been arguing about geoengineering solutions – the so-called technofix – to climate change for more than a decade. Global answers, such as blocking sunlight with stratospheric soot and sulphate aerosols, or whitening the polar ice to make it more reflective, remain contentious.

But the Cryosphere proposals are much more limited, and the immediate dangers of sea level rise are not contested. Ice sheet collapse in Antarctica, for instance, could raise sea levels by more than 3 metres and even by as much as 19 metres over the next two or three centuries.

The researchers’ calculations suggest that in theory an engineering solution that blocked even 50% of the warm water getting under a glacier could offer a 70% chance of delaying or stopping ice sheet collapse.

Left behind

Countries already spend on coastal protection: their solution would require international co-operation at the highest political level, and intensive scientific research.

“Managing sea level rise at the source has the advantage of benefiting the entire world, while a strategy that relies only on local coastal protection is more of an every-nation-for-itself approach that may leave many poor countries behind,” they write.

“Perhaps, after careful consideration, we may conclude that glacial geoengineering is unworkable and the right answer is to invest heavily in coastal protection and retreat inland where that is not practical or economical.

“However, we owe it to the 400 million people who live within 5m of sea level to at least consider the alternatives.” – Climate News Network

Could a vast underwater wall in front of an unstable glacier prevent dangerous sea level rise? Or should everyone just move further inland?

LONDON, 10 October, 2018 – Two climate scientists believe they have a long-term solution to dangerous sea level rise by targeting the most vulnerable glaciers, especially those that could trigger a massive collapse of the ice sheets behind them.

A submarine wall big enough and wide enough could halt the flow of increasingly warm ocean water below the front of each glacier. The combination of warmer air temperatures and warmer waters that accompany human-triggered climate change is dangerous: it could for instance accelerate the already alarming retreat of the Thwaites Glacier in West Antarctica, which alone shores up enough ice to raise global sea levels by up to 3 metres.

The scientists don’t propose an immediate start. But they do want to explore ways of halting sea level rise driven by global warming that could soon be costing the world $50 trillion a year in economic losses, that could submerge small island states and turn 1 million people a year into climate migrants.

“We are not advocating that glacial geoengineering be attempted any time soon”, they warn in the journal The Cryosphere.

Their simplest option – a series of pillars to shore up a targeted glacier and keep it “grounded” – would require engineering comparable in scale to the excavation of the Suez canal, would be undertaken in the world’s harshest environment, and would have just a one in three chance of success.

“In the long run we need plans to deal with the committed climate changes that are already in the pipeline, one of which may be an ice sheet collapse”

The researchers – John Moore, of Beijing Normal University in China, who also holds a post at the University of Lapland in Finland, and Michael Wolovick, of Princeton University in the US – have made this case before: they and others argued in March in Nature for what they call “managed collapse.”

In the latest study, they look at the challenge in greater detail. And they warn that even if targeted geoengineering of individual glaciers worked, it would only do so if humans stopped tipping ever more greenhouse gases into the atmosphere to fuel yet more global warming.

Nor do they argue that a submarine curtain wall to halt warming water across the front of the Thwaites glacier – up to 100 kms wide – is currently feasible. “But in the long run we need plans to deal with the committed climate changes that are already in the pipeline, one of which may be an ice sheet collapse.”

And one of these is the Thwaites Glacier in Antarctica: another is the Jakobshaven Isbrae in Greenland. Both could be cases of what the scientists call marine ice sheet instability: as a glacier retreats from its grounding line, the ice lifts off the bedrock and begins to float.

If the bedrock slopes down towards the centre of the ice sheet, and warmer ocean currents wash beneath it, then the ice starts to stretch and thin, and retreat further. At some point, it would become much easier for thawing ice to flow into the sea, and start what could become a runaway collapse. Engineers could devise a way of slowing or halting the process.

Huge impact

The scientists argue that even a rise of 0.6m to 1.2 metres by 2100 could cause up to $50 trillion in economic damage, and the resultant flooding could force up to 200 million to 500 million people out of their homes at least for a few days or weeks: around a million or so every year would never go back.

Climate scientists have been arguing about geoengineering solutions – the so-called technofix – to climate change for more than a decade. Global answers, such as blocking sunlight with stratospheric soot and sulphate aerosols, or whitening the polar ice to make it more reflective, remain contentious.

But the Cryosphere proposals are much more limited, and the immediate dangers of sea level rise are not contested. Ice sheet collapse in Antarctica, for instance, could raise sea levels by more than 3 metres and even by as much as 19 metres over the next two or three centuries.

The researchers’ calculations suggest that in theory an engineering solution that blocked even 50% of the warm water getting under a glacier could offer a 70% chance of delaying or stopping ice sheet collapse.

Left behind

Countries already spend on coastal protection: their solution would require international co-operation at the highest political level, and intensive scientific research.

“Managing sea level rise at the source has the advantage of benefiting the entire world, while a strategy that relies only on local coastal protection is more of an every-nation-for-itself approach that may leave many poor countries behind,” they write.

“Perhaps, after careful consideration, we may conclude that glacial geoengineering is unworkable and the right answer is to invest heavily in coastal protection and retreat inland where that is not practical or economical.

“However, we owe it to the 400 million people who live within 5m of sea level to at least consider the alternatives.” – Climate News Network