Category Archives: Polar

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

Arctic soils may produce huge methane leak

Arctic soils tell an ominous story. Change in the high latitudes could be swifter and more devastating than anyone had imagined.

LONDON, 9 May, 2019 − The permafrost may be about to spring an unwelcome surprise, with Arctic soils thought to be thawing faster than anyone had predicted. This threatens to release vast quantities of frozen methane into the atmosphere and transform the northern landscape.

One-fourth of all the land in the northern half of the globe is defined as permafrost. This long-frozen soil is home to the detritus of life over many thousands of years: the remains of plants, animals and microbes. The permanently frozen soils of the region hold, so far in a harmless state, 1,600 billion tonnes of carbon: twice as much as exists in the atmosphere.

And as the Arctic warms, this could release ever-greater volumes of a potent greenhouse gas, to accelerate global warming still further, and the consequent collapse of the soil, the flooding and the landslides could change not just the habitat but even the contours of the high latitudes.

“We are watching this sleeping giant wake up right in front of our eyes,” said Merritt Turetsky, an ecologist at the University of Guelph in Canada.

“Let’s keep that carbon where it belongs – safely frozen in the stunning soils of the north”

“We work in areas where permafrost contains a lot of ice, and our field sites are being destroyed by abrupt collapse of this ice, not gradually over decades, but very quickly over months to years.”

And Miriam Jones, of the US Geological Survey, said: “This abrupt thaw is changing forested ecosystems to thaw lakes and wetlands, resulting in a wholesale transformation of the landscape that not only impacts carbon feedbacks to climate but is also altering wildlife habitat and damaging infrastructure.”

The two scientists are among 14 researchers who argue in the journal Nature that the thaw is happening far faster than anyone had predicted. The Arctic is warming at a rate faster than almost anywhere else on Earth.

So far the thaw affects less than one-fifth of the entire permafrost, but even this relatively small area has the potential to double what climate scientists call “feedback” – the release of hitherto stored greenhouse gases to fuel yet faster warming.

Growing urgency

It is the latest in a series of increasingly urgent warnings about the rate of change in the Arctic.

Stable climate patterns are maintained by stable temperatures. As the polar north warms twice as fast as the average for the rest of the world, the all-important difference between tropics and polar regions begins to accelerate the advance of spring, and delay the next freeze to bring weather extremes and ever higher sea level rises which could soon start to exact a toll on human economies on an unprecedented scale.

Researchers have been warning for years about the consequences of thaw and the release of ever more carbon into the greenhouse atmosphere.

But it is only in recent months that climate scientists have begun to see the effect of ice melt at depth upon the soils that – for now – support Arctic roads, buildings and pipelines as well as a huge natural ecosystem of plants and animals adapted by thousands of years of evolution to long winters and brief flowering summers.

Goal in jeopardy

Put simply: 195 nations met in Paris in 2015 and agreed  to contain average global warming to “well below” 2°C above the long-term level for most of human history. Accelerating thaw in the Arctic puts that goal at risk.

The researchers call for better and more reliable observation of change in the region, more investment in on-the-ground measurement of change, more information about the extent of carbon emissions from the soils, better models of global change in the region, and better reporting of change.

“We can’t prevent abrupt thawing of the permafrost, but we can try to forecast where and when it is likely to happen, to enable decision makers and communities to protect people and resources”, the scientists write.

“Reducing global emissions might be the surest way to slow further release of permafrost carbon into the atmosphere. Let’s keep that carbon where it belongs – safely frozen in the stunning soils of the north.” − Climate News Network

Arctic soils tell an ominous story. Change in the high latitudes could be swifter and more devastating than anyone had imagined.

LONDON, 9 May, 2019 − The permafrost may be about to spring an unwelcome surprise, with Arctic soils thought to be thawing faster than anyone had predicted. This threatens to release vast quantities of frozen methane into the atmosphere and transform the northern landscape.

One-fourth of all the land in the northern half of the globe is defined as permafrost. This long-frozen soil is home to the detritus of life over many thousands of years: the remains of plants, animals and microbes. The permanently frozen soils of the region hold, so far in a harmless state, 1,600 billion tonnes of carbon: twice as much as exists in the atmosphere.

And as the Arctic warms, this could release ever-greater volumes of a potent greenhouse gas, to accelerate global warming still further, and the consequent collapse of the soil, the flooding and the landslides could change not just the habitat but even the contours of the high latitudes.

“We are watching this sleeping giant wake up right in front of our eyes,” said Merritt Turetsky, an ecologist at the University of Guelph in Canada.

“Let’s keep that carbon where it belongs – safely frozen in the stunning soils of the north”

“We work in areas where permafrost contains a lot of ice, and our field sites are being destroyed by abrupt collapse of this ice, not gradually over decades, but very quickly over months to years.”

And Miriam Jones, of the US Geological Survey, said: “This abrupt thaw is changing forested ecosystems to thaw lakes and wetlands, resulting in a wholesale transformation of the landscape that not only impacts carbon feedbacks to climate but is also altering wildlife habitat and damaging infrastructure.”

The two scientists are among 14 researchers who argue in the journal Nature that the thaw is happening far faster than anyone had predicted. The Arctic is warming at a rate faster than almost anywhere else on Earth.

So far the thaw affects less than one-fifth of the entire permafrost, but even this relatively small area has the potential to double what climate scientists call “feedback” – the release of hitherto stored greenhouse gases to fuel yet faster warming.

Growing urgency

It is the latest in a series of increasingly urgent warnings about the rate of change in the Arctic.

Stable climate patterns are maintained by stable temperatures. As the polar north warms twice as fast as the average for the rest of the world, the all-important difference between tropics and polar regions begins to accelerate the advance of spring, and delay the next freeze to bring weather extremes and ever higher sea level rises which could soon start to exact a toll on human economies on an unprecedented scale.

Researchers have been warning for years about the consequences of thaw and the release of ever more carbon into the greenhouse atmosphere.

But it is only in recent months that climate scientists have begun to see the effect of ice melt at depth upon the soils that – for now – support Arctic roads, buildings and pipelines as well as a huge natural ecosystem of plants and animals adapted by thousands of years of evolution to long winters and brief flowering summers.

Goal in jeopardy

Put simply: 195 nations met in Paris in 2015 and agreed  to contain average global warming to “well below” 2°C above the long-term level for most of human history. Accelerating thaw in the Arctic puts that goal at risk.

The researchers call for better and more reliable observation of change in the region, more investment in on-the-ground measurement of change, more information about the extent of carbon emissions from the soils, better models of global change in the region, and better reporting of change.

“We can’t prevent abrupt thawing of the permafrost, but we can try to forecast where and when it is likely to happen, to enable decision makers and communities to protect people and resources”, the scientists write.

“Reducing global emissions might be the surest way to slow further release of permafrost carbon into the atmosphere. Let’s keep that carbon where it belongs – safely frozen in the stunning soils of the north.” − 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

Arctic leaks of laughing gas may add to heat

Laughing gas from the thawing Alaskan permafrost is no laughing matter. Nitrous oxide is one of the most potent greenhouse gases.

LONDON, 22 April, 2019 − US scientists have identified yet another hazard linked to the thawing permafrost: laughing gas. A series of flights over the North Slope of Alaska has detected unexpected levels of emissions of the greenhouse gas nitrous oxide from the rapidly warming soils.

Nitrous oxide, which chemists know also as laughing gas, is an estimated 300 times more potent as a climate warming agent than the principal greenhouse gas, carbon dioxide. It was present in data recordings at levels at least 12 times higher than all previous estimates.

And it is long-lived: it survives in the atmosphere for around 120 years, according to a separate new study of the microbiology of nitrous oxide. And if it gets even higher, into the stratosphere, it can be converted by the action of oxygen and sunlight into another oxide of nitrogen, to quietly destroy the ozone layer.

Oxides of nitrogen are at least as damaging to stratospheric ozone – an invisible screen that absorbs potentially lethal ultraviolet radiation from the sun – as the man-made chlorofluorocarbons banned by an international protocol three decades ago.

“Much smaller increases in nitrous oxide would entail the same kind of climate change that a large plume of CO2 would cause”

Nitrogen is an inert gas which makes up almost four-fifths of the planet’s atmosphere. It is vital to life: growing plants build their tissues by absorbing carbon dioxide from the atmosphere with the aid of photosynthesis. But they must also absorb nitrogen from plant decay and animal waste, through their roots, with help from soil microbes.

The process is natural, but too slow to help deliver the cereals, tubers and pulses needed to feed seven billion humans and their livestock. For more than 100 years, nations have been making nitrogenous fertiliser in factories and applying it generously to soils to boost harvest yields.

As a consequence, nitrous oxide is now the third most significant greenhouse gas, and the news that it is rising from the permafrost could be troubling.

The permafrost is home to enormous stores of carbon: as soil microbes become warmer and more active, they start to break down long-frozen and partly-decomposed plant material to release both carbon dioxide and potent quantities of methane. The implication is that nitrous oxide could add to the mix, and accelerate warming still further.

Study’s revelation

“Much smaller increases in nitrous oxide would entail the same kind of climate change that a large plume of CO2 would cause,” said Jordan Wilkerson, a Harvard graduate student who led the research, now published in the journal Atmospheric Chemistry and Physics.

“We don’t know how much more it’s going to increase and we didn’t know it was significant at all until this study came out.”

The research is based on data collected from a series of low-level flights over four different areas of the North Slope of Alaska, and the scientists used a routine technique to determine the balance of gases getting into the atmosphere from what had once been permafrost.

The point of the flights was to measure levels of carbon dioxide, methane and water vapour, but the raw data included information about nitrous oxide as well: information recovered and examined only years later.

Arctic in change

The weight of the finding is uncertain. One-fourth of the northern hemisphere is home to permafrost – 23 million square kilometres − and the flights covered only 310 square kilometres in all, and only in the month of August. What could be true for one part of the frozen landscape may not apply to all of it.

And thanks to global warming driven by fossil fuel emissions from the world’s power stations, vehicle exhausts and factory chimneys, the Arctic is changing.

Shrubs and trees are beginning to invade the frozen north. Green things consume nitrogen, and the greening of the Arctic might actually decrease nitrous oxide emissions.

Once again, the study is a reminder of how much more work is needed to understand the chemistry, biology and geophysics of climate change. − Climate News Network

Laughing gas from the thawing Alaskan permafrost is no laughing matter. Nitrous oxide is one of the most potent greenhouse gases.

LONDON, 22 April, 2019 − US scientists have identified yet another hazard linked to the thawing permafrost: laughing gas. A series of flights over the North Slope of Alaska has detected unexpected levels of emissions of the greenhouse gas nitrous oxide from the rapidly warming soils.

Nitrous oxide, which chemists know also as laughing gas, is an estimated 300 times more potent as a climate warming agent than the principal greenhouse gas, carbon dioxide. It was present in data recordings at levels at least 12 times higher than all previous estimates.

And it is long-lived: it survives in the atmosphere for around 120 years, according to a separate new study of the microbiology of nitrous oxide. And if it gets even higher, into the stratosphere, it can be converted by the action of oxygen and sunlight into another oxide of nitrogen, to quietly destroy the ozone layer.

Oxides of nitrogen are at least as damaging to stratospheric ozone – an invisible screen that absorbs potentially lethal ultraviolet radiation from the sun – as the man-made chlorofluorocarbons banned by an international protocol three decades ago.

“Much smaller increases in nitrous oxide would entail the same kind of climate change that a large plume of CO2 would cause”

Nitrogen is an inert gas which makes up almost four-fifths of the planet’s atmosphere. It is vital to life: growing plants build their tissues by absorbing carbon dioxide from the atmosphere with the aid of photosynthesis. But they must also absorb nitrogen from plant decay and animal waste, through their roots, with help from soil microbes.

The process is natural, but too slow to help deliver the cereals, tubers and pulses needed to feed seven billion humans and their livestock. For more than 100 years, nations have been making nitrogenous fertiliser in factories and applying it generously to soils to boost harvest yields.

As a consequence, nitrous oxide is now the third most significant greenhouse gas, and the news that it is rising from the permafrost could be troubling.

The permafrost is home to enormous stores of carbon: as soil microbes become warmer and more active, they start to break down long-frozen and partly-decomposed plant material to release both carbon dioxide and potent quantities of methane. The implication is that nitrous oxide could add to the mix, and accelerate warming still further.

Study’s revelation

“Much smaller increases in nitrous oxide would entail the same kind of climate change that a large plume of CO2 would cause,” said Jordan Wilkerson, a Harvard graduate student who led the research, now published in the journal Atmospheric Chemistry and Physics.

“We don’t know how much more it’s going to increase and we didn’t know it was significant at all until this study came out.”

The research is based on data collected from a series of low-level flights over four different areas of the North Slope of Alaska, and the scientists used a routine technique to determine the balance of gases getting into the atmosphere from what had once been permafrost.

The point of the flights was to measure levels of carbon dioxide, methane and water vapour, but the raw data included information about nitrous oxide as well: information recovered and examined only years later.

Arctic in change

The weight of the finding is uncertain. One-fourth of the northern hemisphere is home to permafrost – 23 million square kilometres − and the flights covered only 310 square kilometres in all, and only in the month of August. What could be true for one part of the frozen landscape may not apply to all of it.

And thanks to global warming driven by fossil fuel emissions from the world’s power stations, vehicle exhausts and factory chimneys, the Arctic is changing.

Shrubs and trees are beginning to invade the frozen north. Green things consume nitrogen, and the greening of the Arctic might actually decrease nitrous oxide emissions.

Once again, the study is a reminder of how much more work is needed to understand the chemistry, biology and geophysics of climate change. − 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

Ice melt makes Arctic soils slip more often

As warm summers loosen the grip of the polar ice, the Arctic soils begin to shift. And they are now shifting faster than ever before.

LONDON, 9 April, 2019 − Global warming is about to change the face of the frozen polar landmass, where the Arctic soils are slipping and sliding at record speed. Once-firm ground has begun to shift.

Researchers who closely examined landslips and slumps on Banks Island in the Canadian Arctic Archipelago have found a sixty-fold increase in ground movement in the last 30 years.

In 1984, summer temperatures accounted for just 60 events of the kind glaciologists know as retrogressive thaw slumps or collapses of surface soil as the permafrost ice begins to melt. In 2014, there were more than 4,000 such slumps, including about 300 in an area protected as a natural park.

And on Banks Island alone, even under a relatively conservative scenario, this number could grow to 10,000 a decade by 2075, to precipitate as many as 30,000 active landslides in any future year.

“We can encourage our politicians to take the necessary measures to help reduce our greenhouse emissions, so that future warming is as limited as possible”

Researchers report in the journal Nature Communications that massive amounts of sediment released by the slumps have choked river valleys and changed the colour of 288 lakes. Once a thaw slump begins, soils once held stable by the frost can go on sliding or slipping.

Nobody can be sure of the impact on the natural ecosystems, but the island is home to arctic foxes, caribou, polar bears, wolves, musk oxen, arctic hare, lemmings, ermine, seal and even grizzly bears.

It also provides feeding grounds for lesser snow geese, black brants, eiders, peregrine falcons, snowy owls, rough-legged hawks and ravens.

And, the scientists say, a small local Inuit population based on the island can confirm the ground truth of satellite records: ground slumps increasingly make it difficult to go hunting or fishing.

Methane risk

The study is hardly the first to suggest that global warming will change the high Arctic, but it may be the first to put firm estimates to the increasing scale of damage through time. The implication is that what happens on Banks Island could also happen at the same latitudes anywhere.

Climate scientists have been increasingly alarmed at the hazards of permafrost thaw, if only because locked in the frozen soils are millennia of plant remains, all of which could decay into methane and accelerate global warming to melt yet more permafrost and drive global average temperatures ever higher.

Geographers have already warned that what had once been hard ground beneath roads, buildings, factories, airfields and housing has already begun to slump, to devastate infrastructure and even threaten oil and gas piping.

“We cannot stop thousands of thaw slumps once they start,” said Antoni Lewkowicz of the University of Ottawa, who led the research. “We can only make changes in our own lives to reduce our carbon footprint and we can encourage our politicians to take the necessary measures to help reduce our greenhouse emissions, so that future warming is as limited as possible.” − Climate News Network

As warm summers loosen the grip of the polar ice, the Arctic soils begin to shift. And they are now shifting faster than ever before.

LONDON, 9 April, 2019 − Global warming is about to change the face of the frozen polar landmass, where the Arctic soils are slipping and sliding at record speed. Once-firm ground has begun to shift.

Researchers who closely examined landslips and slumps on Banks Island in the Canadian Arctic Archipelago have found a sixty-fold increase in ground movement in the last 30 years.

In 1984, summer temperatures accounted for just 60 events of the kind glaciologists know as retrogressive thaw slumps or collapses of surface soil as the permafrost ice begins to melt. In 2014, there were more than 4,000 such slumps, including about 300 in an area protected as a natural park.

And on Banks Island alone, even under a relatively conservative scenario, this number could grow to 10,000 a decade by 2075, to precipitate as many as 30,000 active landslides in any future year.

“We can encourage our politicians to take the necessary measures to help reduce our greenhouse emissions, so that future warming is as limited as possible”

Researchers report in the journal Nature Communications that massive amounts of sediment released by the slumps have choked river valleys and changed the colour of 288 lakes. Once a thaw slump begins, soils once held stable by the frost can go on sliding or slipping.

Nobody can be sure of the impact on the natural ecosystems, but the island is home to arctic foxes, caribou, polar bears, wolves, musk oxen, arctic hare, lemmings, ermine, seal and even grizzly bears.

It also provides feeding grounds for lesser snow geese, black brants, eiders, peregrine falcons, snowy owls, rough-legged hawks and ravens.

And, the scientists say, a small local Inuit population based on the island can confirm the ground truth of satellite records: ground slumps increasingly make it difficult to go hunting or fishing.

Methane risk

The study is hardly the first to suggest that global warming will change the high Arctic, but it may be the first to put firm estimates to the increasing scale of damage through time. The implication is that what happens on Banks Island could also happen at the same latitudes anywhere.

Climate scientists have been increasingly alarmed at the hazards of permafrost thaw, if only because locked in the frozen soils are millennia of plant remains, all of which could decay into methane and accelerate global warming to melt yet more permafrost and drive global average temperatures ever higher.

Geographers have already warned that what had once been hard ground beneath roads, buildings, factories, airfields and housing has already begun to slump, to devastate infrastructure and even threaten oil and gas piping.

“We cannot stop thousands of thaw slumps once they start,” said Antoni Lewkowicz of the University of Ottawa, who led the research. “We can only make changes in our own lives to reduce our carbon footprint and we can encourage our politicians to take the necessary measures to help reduce our greenhouse emissions, so that future warming is as limited as possible.” − Climate News Network

Gulf Stream slowdown may bring later cold

The Gulf Stream is weakening, and Europe could expect a prolonged cold spell as the world warms – but not the day after tomorrow.

LONDON, 25 March, 2019 – As the Gulf Stream weakens in a rapidly warming world, north-western Europe could paradoxically become cooler. There is, however, a time lag between those two climate change-related events, and US scientists now think they know how long that could be.
It could be as much as 400 years.

They know this because the world has warmed and cooled before, and as the difference between tropics and Arctic narrows, there is a change in the so-called Atlantic conveyor, an important part of the climate machine.

This vast Atlantic current carries a steady flow of warm water to the far north, making north-western Europe up to 5°C warmer than its latitude would otherwise dictate. Then, as it meets colder, denser Arctic waters, it dives, to carry its burden of surface carbon to the depths, and then flows southwards again.

This phenomenon, known as the Atlantic Meridional Overturning Circulation, or AMOC, is in effect Europe’s bespoke heating system: Britain’s chief scientific adviser once calculated that it delivers to the UK alone the warmth of 27,000 power stations.

“There are some precursors in the ocean, so we should be watching the ocean”

But evidence from climate history shows that this heating has been turned off a number of times. Europe was plunged into a cold snap 13,000 years ago during a period known as the Younger Dryas and then warmed up about 11,000 years ago.

New and sophisticated studies of fossil carbon show that anybody taking notes at the time might have observed the warning signs. About 400 years before the abrupt shift to a frosty spell, the Atlantic current weakened. And it started to strengthen again about four centuries before the world warmed.

The study, published in the journal Nature Communications, confirms what climate scientists have always known: any sudden catastrophic return of the Ice Ages – dramatised in Hollywood’s notorious 2004 climate change movie The Day After Tomorrow – won’t happen at action movie pace. But it will happen over decades, and now seemingly with several centuries of advance notice.

“Our reconstructions indicate that there are clear climate precursors provided by the ocean state – like warning signs, so to speak,” said Francesco Muschitiello, then of the Lamont-Doherty Earth Observatory at Columbia University, US, and now at the University of Cambridge in the UK, who led the research.

Timing established

Climate scientists have clear dates for the timing of the Younger Dryas event: ice cores from the Arctic show both that Greenland’s temperature fell by 6°C or more at the beginning of the cycle, and that it rose by at least 8°C at its end.

To time the changes in the ocean current, they used carbon-dating techniques to identify a pattern of change in the marine sediments in the Norwegian Sea.

Since marine sediments settle very slowly, over very long periods of time, they needed a more precise “clock” to help calibrate their calculations: they found this in the fossilised ancient plants in a Scandinavian lake.

The isotope carbon-14 is pulled directly from the atmosphere each season by growing foliage. It decays at a predictable rate, and the amount of surviving C14 delivered a reliable clock. The identification of two volcanic ash layers from eruptions in Iceland, in both lake and seabed, provided yet more confidence in the timings. From these factors, the researchers were able to identify a slowdown in the transport of carbon from surface to the deep – and thus a slowdown in the current.

Long wait

The research confirms a link between ocean circulation patterns and northern hemisphere climate shifts: it provides evidence of what could be a considerable interval between the two.

Researchers have repeatedly warned that the Atlantic current seemed to be slowing, in response to global warming driven by profligate fossil fuel use by humankind, and that the consequences of continued slowdown could be very uncomfortable for hundreds of millions.

If the evidence from the Younger Dryas provides a sure parallel to today’s conditions, then Europeans might have time to prepare.

“It is clear that there are some precursors in the ocean, so we should be watching the ocean,” said Dr Muschitiello. “The mere fact that AMOC has been slowing down, that should be a concern based on what we have found.” – Climate News Network

The Gulf Stream is weakening, and Europe could expect a prolonged cold spell as the world warms – but not the day after tomorrow.

LONDON, 25 March, 2019 – As the Gulf Stream weakens in a rapidly warming world, north-western Europe could paradoxically become cooler. There is, however, a time lag between those two climate change-related events, and US scientists now think they know how long that could be.
It could be as much as 400 years.

They know this because the world has warmed and cooled before, and as the difference between tropics and Arctic narrows, there is a change in the so-called Atlantic conveyor, an important part of the climate machine.

This vast Atlantic current carries a steady flow of warm water to the far north, making north-western Europe up to 5°C warmer than its latitude would otherwise dictate. Then, as it meets colder, denser Arctic waters, it dives, to carry its burden of surface carbon to the depths, and then flows southwards again.

This phenomenon, known as the Atlantic Meridional Overturning Circulation, or AMOC, is in effect Europe’s bespoke heating system: Britain’s chief scientific adviser once calculated that it delivers to the UK alone the warmth of 27,000 power stations.

“There are some precursors in the ocean, so we should be watching the ocean”

But evidence from climate history shows that this heating has been turned off a number of times. Europe was plunged into a cold snap 13,000 years ago during a period known as the Younger Dryas and then warmed up about 11,000 years ago.

New and sophisticated studies of fossil carbon show that anybody taking notes at the time might have observed the warning signs. About 400 years before the abrupt shift to a frosty spell, the Atlantic current weakened. And it started to strengthen again about four centuries before the world warmed.

The study, published in the journal Nature Communications, confirms what climate scientists have always known: any sudden catastrophic return of the Ice Ages – dramatised in Hollywood’s notorious 2004 climate change movie The Day After Tomorrow – won’t happen at action movie pace. But it will happen over decades, and now seemingly with several centuries of advance notice.

“Our reconstructions indicate that there are clear climate precursors provided by the ocean state – like warning signs, so to speak,” said Francesco Muschitiello, then of the Lamont-Doherty Earth Observatory at Columbia University, US, and now at the University of Cambridge in the UK, who led the research.

Timing established

Climate scientists have clear dates for the timing of the Younger Dryas event: ice cores from the Arctic show both that Greenland’s temperature fell by 6°C or more at the beginning of the cycle, and that it rose by at least 8°C at its end.

To time the changes in the ocean current, they used carbon-dating techniques to identify a pattern of change in the marine sediments in the Norwegian Sea.

Since marine sediments settle very slowly, over very long periods of time, they needed a more precise “clock” to help calibrate their calculations: they found this in the fossilised ancient plants in a Scandinavian lake.

The isotope carbon-14 is pulled directly from the atmosphere each season by growing foliage. It decays at a predictable rate, and the amount of surviving C14 delivered a reliable clock. The identification of two volcanic ash layers from eruptions in Iceland, in both lake and seabed, provided yet more confidence in the timings. From these factors, the researchers were able to identify a slowdown in the transport of carbon from surface to the deep – and thus a slowdown in the current.

Long wait

The research confirms a link between ocean circulation patterns and northern hemisphere climate shifts: it provides evidence of what could be a considerable interval between the two.

Researchers have repeatedly warned that the Atlantic current seemed to be slowing, in response to global warming driven by profligate fossil fuel use by humankind, and that the consequences of continued slowdown could be very uncomfortable for hundreds of millions.

If the evidence from the Younger Dryas provides a sure parallel to today’s conditions, then Europeans might have time to prepare.

“It is clear that there are some precursors in the ocean, so we should be watching the ocean,” said Dr Muschitiello. “The mere fact that AMOC has been slowing down, that should be a concern based on what we have found.” – Climate News Network

Greenland’s winter rain melts icecap faster

Its huge icecap is thawing faster because Greenland’s winter rain means its snows are being washed away, or falling at higher altitudes.

LONDON, 8 March, 2019 − The largest body of ice in the northern hemisphere faces a problem scientists had not identified before: Greenland’s winter rain is accelerating the loss of its vast store of ice.

Two new studies have identified mechanisms for ever-faster melting of the ice. One is that the snowline keeps shifting, to alter the levels of radiation absorbed by the ice sheet that masks the Greenland bedrock.

The other is that ever more snow and ice is simply washed away by the rainfall – even in the Arctic winter. That is because global warming has raised Greenland’s summer temperatures as much as 1.8°C, and by up to 3°C in the winter months.

Reports of winter rain over an icecap large enough – if it were all washed into the ocean – to raise global sea levels by more than seven metres are a surprise: glaciologists expect some melting of the polar ice caps each summer, to be replaced each winter by snowfall that insulates the ice below and then endures for much of the following summer.

Meltwater matters more

Such icecaps are thought to shed most of their mass as glaciers deliver ice downstream to the coast, and icebergs calve and float south.

But research in the journal The Cryosphere tells a different and unexpected story: direct meltwater now running off Greenland into the sea accounts for seven-tenths of the 270 billion tonnes of ice that Greenland loses each year. And increasingly, rainy weather is the trigger that sets off the rivulets of meltwater streaming to the coast.

German and US researchers took data from 20 Greenland weather stations between 1979 and 2012, and matched this with satellite imagery that could distinguish snow from liquid water. In the data they identified more than 300 episodes of melting in which the initial trigger was the arrival of rain.

And during the 33 years of data, they found that melting associated with rainfall doubled during the summer months, and tripled in winter. Nearly a third of all the flow of water from Greenland was initiated by rainfall.

“Suddenly the snowline was just gone. In a couple of days it had moved 30 kilometres or so up the ice sheet”

Warm air can melt ice but, more potently, warming air can turn what might have been snow into rain. Liquid water carries considerable heat, to soak into the snow and melt it. And the clouds that bring the rain have a way of conserving the warmth in the air.

Some of the meltwater will refreeze as surface ice, darkened by dust and colonised by algae, to absorb solar radiation more efficiently than snow, and to melt more easily and much earlier in the summer.

“If it rains in the winter, that preconditions the ice to be more vulnerable in the summer,” said Marco Tedesco of Columbia University’s Lamont-Doherty Earth Observatory, one of the authors. “We are starting to realise you have to look at all the seasons.”

Most of the winter rainfall is in the island’s south and southwest, spilled by warm ocean winds from the south, and these may have become more common because warming has been linked to changes in the stratospheric jet stream.

Loss not gain

Marilena Oltmanns, of Germany’s Geomar Centre for Ocean Research, called the discovery “a surprise to see. The ice should be gaining mass in winter when it snows, but an increasing part of the mass gain from precipitation is lost by melt.”

But research in the journal Science Advances in the same week pinpoints another related factor in setting the rate of melting in Greenland: the snowline.

This varies significantly from year to year. Once again, snow tends to reflect radiation, and with darker ice to absorb it the new study suggests that even Greenland’s icy mountains conform to simple physics.

Researchers flew drones inland across the bare ice to identify the snowline. A pause during a few days of high winds brought a big surprise.

No specific studies

“Suddenly the snowline was just gone. In a couple of days it had moved 30 kilometres or so up the ice sheet and was now out of the range of our drones.

“That was the first moment we thought we should investigate the effects of snowline movement on melt,” said Jonathan Ryan, of Brown University in Rhode Island, who led the study.

And Laurence Smith, a researcher based at Brown University, and one of the authors, said: “People who study alpine glaciers have recognised the importance of snowlines for years, but no one has explicitly studied them in Greenland before.

“This study shows for the first time that simple partitioning between bare ice and snow matters more when it comes to melting than a whole host of other processes that receive more attention.” − Climate News Network

Its huge icecap is thawing faster because Greenland’s winter rain means its snows are being washed away, or falling at higher altitudes.

LONDON, 8 March, 2019 − The largest body of ice in the northern hemisphere faces a problem scientists had not identified before: Greenland’s winter rain is accelerating the loss of its vast store of ice.

Two new studies have identified mechanisms for ever-faster melting of the ice. One is that the snowline keeps shifting, to alter the levels of radiation absorbed by the ice sheet that masks the Greenland bedrock.

The other is that ever more snow and ice is simply washed away by the rainfall – even in the Arctic winter. That is because global warming has raised Greenland’s summer temperatures as much as 1.8°C, and by up to 3°C in the winter months.

Reports of winter rain over an icecap large enough – if it were all washed into the ocean – to raise global sea levels by more than seven metres are a surprise: glaciologists expect some melting of the polar ice caps each summer, to be replaced each winter by snowfall that insulates the ice below and then endures for much of the following summer.

Meltwater matters more

Such icecaps are thought to shed most of their mass as glaciers deliver ice downstream to the coast, and icebergs calve and float south.

But research in the journal The Cryosphere tells a different and unexpected story: direct meltwater now running off Greenland into the sea accounts for seven-tenths of the 270 billion tonnes of ice that Greenland loses each year. And increasingly, rainy weather is the trigger that sets off the rivulets of meltwater streaming to the coast.

German and US researchers took data from 20 Greenland weather stations between 1979 and 2012, and matched this with satellite imagery that could distinguish snow from liquid water. In the data they identified more than 300 episodes of melting in which the initial trigger was the arrival of rain.

And during the 33 years of data, they found that melting associated with rainfall doubled during the summer months, and tripled in winter. Nearly a third of all the flow of water from Greenland was initiated by rainfall.

“Suddenly the snowline was just gone. In a couple of days it had moved 30 kilometres or so up the ice sheet”

Warm air can melt ice but, more potently, warming air can turn what might have been snow into rain. Liquid water carries considerable heat, to soak into the snow and melt it. And the clouds that bring the rain have a way of conserving the warmth in the air.

Some of the meltwater will refreeze as surface ice, darkened by dust and colonised by algae, to absorb solar radiation more efficiently than snow, and to melt more easily and much earlier in the summer.

“If it rains in the winter, that preconditions the ice to be more vulnerable in the summer,” said Marco Tedesco of Columbia University’s Lamont-Doherty Earth Observatory, one of the authors. “We are starting to realise you have to look at all the seasons.”

Most of the winter rainfall is in the island’s south and southwest, spilled by warm ocean winds from the south, and these may have become more common because warming has been linked to changes in the stratospheric jet stream.

Loss not gain

Marilena Oltmanns, of Germany’s Geomar Centre for Ocean Research, called the discovery “a surprise to see. The ice should be gaining mass in winter when it snows, but an increasing part of the mass gain from precipitation is lost by melt.”

But research in the journal Science Advances in the same week pinpoints another related factor in setting the rate of melting in Greenland: the snowline.

This varies significantly from year to year. Once again, snow tends to reflect radiation, and with darker ice to absorb it the new study suggests that even Greenland’s icy mountains conform to simple physics.

Researchers flew drones inland across the bare ice to identify the snowline. A pause during a few days of high winds brought a big surprise.

No specific studies

“Suddenly the snowline was just gone. In a couple of days it had moved 30 kilometres or so up the ice sheet and was now out of the range of our drones.

“That was the first moment we thought we should investigate the effects of snowline movement on melt,” said Jonathan Ryan, of Brown University in Rhode Island, who led the study.

And Laurence Smith, a researcher based at Brown University, and one of the authors, said: “People who study alpine glaciers have recognised the importance of snowlines for years, but no one has explicitly studied them in Greenland before.

“This study shows for the first time that simple partitioning between bare ice and snow matters more when it comes to melting than a whole host of other processes that receive more attention.” − Climate News Network

Pacific climate wobble speeds Arctic ice melt

Thanks to a natural sea temperature cycle, a Pacific climate wobble, the Arctic Ocean could be ice-free in the summer in a decade or two.

LONDON, 6 March, 2019 – Sunlit skies and bright blue water could come earlier to the Arctic – much earlier, thanks to a distant Pacific climate wobble.

Scientists now think that the Arctic Ocean could be effectively ice-free within the next 20 years, opening it to sea lanes across the polar waters between Europe, the US and east Asia.

Climate researchers have repeatedly warned, in the last two decades, that because of global warming the ice sheet that masks the Arctic Ocean has been thinning and could in effect vanish altogether in summertime by 2050.

New research has brought forward the prediction date. And this time the effective agency is not just global warming driven by profligate combustion of fossil fuels worldwide, but a natural cyclic phenomenon known to oceanographers as the interdecadal Pacific oscillation, or IPO.

“The trajectory is towards becoming ice-free in the summer …  there’s more chance of it being on the earlier end of that window than the later end”

Over a cycle of between one to three decades, the average ocean temperatures of the north Pacific shift up or down by about 0.5°C.

And a new study in the journal Geophysical Research Letters pinpoints the state of the present cycle: the Pacific ended its cold phase and started to warm up about five years ago.

James Screen of the University of Exeter, UK, and a colleague used computer modelling to merge the continuous upward rise in global average temperatures as a consequence of the build-up of greenhouse gases in the atmosphere with the pattern of predicted natural change in ocean surface temperatures to identify the moment when the summer ice will have melted.

The phrase “ice-free” is not a simple one, because some sea ice always remains, but oceanographers and glaciologists have their own definition: it happens when the area of summer sea ice falls below a million square kilometres.

Dramatic change likely

And this is now likely to happen some time between 2030 and 2050. Any argument is not about if, but when. The Arctic is just about the fastest-warming region of the planet, and in 2016 polar sea ice in both hemispheres  reached a record low: an area of ice the size of Mexico was lost.

Temperatures in the Arctic were recorded as up to 20°C above the average for some of the winter months. The long-term consequences are unpredictable, but since both ocean current and air movement are driven by the difference between equatorial and polar temperatures, dramatic climate change is likely to follow.

“The trajectory is towards becoming ice-free in the summer, but there is uncertainty as to when that is going to occur,” Dr Screen said.

“You can hedge your bets. The shift in the IPO means there’s more chance of it being on the earlier end of that window than the later end.” – Climate News Network

Thanks to a natural sea temperature cycle, a Pacific climate wobble, the Arctic Ocean could be ice-free in the summer in a decade or two.

LONDON, 6 March, 2019 – Sunlit skies and bright blue water could come earlier to the Arctic – much earlier, thanks to a distant Pacific climate wobble.

Scientists now think that the Arctic Ocean could be effectively ice-free within the next 20 years, opening it to sea lanes across the polar waters between Europe, the US and east Asia.

Climate researchers have repeatedly warned, in the last two decades, that because of global warming the ice sheet that masks the Arctic Ocean has been thinning and could in effect vanish altogether in summertime by 2050.

New research has brought forward the prediction date. And this time the effective agency is not just global warming driven by profligate combustion of fossil fuels worldwide, but a natural cyclic phenomenon known to oceanographers as the interdecadal Pacific oscillation, or IPO.

“The trajectory is towards becoming ice-free in the summer …  there’s more chance of it being on the earlier end of that window than the later end”

Over a cycle of between one to three decades, the average ocean temperatures of the north Pacific shift up or down by about 0.5°C.

And a new study in the journal Geophysical Research Letters pinpoints the state of the present cycle: the Pacific ended its cold phase and started to warm up about five years ago.

James Screen of the University of Exeter, UK, and a colleague used computer modelling to merge the continuous upward rise in global average temperatures as a consequence of the build-up of greenhouse gases in the atmosphere with the pattern of predicted natural change in ocean surface temperatures to identify the moment when the summer ice will have melted.

The phrase “ice-free” is not a simple one, because some sea ice always remains, but oceanographers and glaciologists have their own definition: it happens when the area of summer sea ice falls below a million square kilometres.

Dramatic change likely

And this is now likely to happen some time between 2030 and 2050. Any argument is not about if, but when. The Arctic is just about the fastest-warming region of the planet, and in 2016 polar sea ice in both hemispheres  reached a record low: an area of ice the size of Mexico was lost.

Temperatures in the Arctic were recorded as up to 20°C above the average for some of the winter months. The long-term consequences are unpredictable, but since both ocean current and air movement are driven by the difference between equatorial and polar temperatures, dramatic climate change is likely to follow.

“The trajectory is towards becoming ice-free in the summer, but there is uncertainty as to when that is going to occur,” Dr Screen said.

“You can hedge your bets. The shift in the IPO means there’s more chance of it being on the earlier end of that window than the later end.” – 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