Tag Archives: Sea levels

Half a degree may make heat impact far worse

Half a degree of warming doesn’t sound like much. But there is fresh evidence that it could make a huge difference to rainfall and drought.

LONDON, 4 April, 2019 − Japanese scientists have found new evidence that a global average temperature rise as small as half a degree could have a drastic effect.

They conclude that the world cannot afford to delay action to reduce greenhouse gas emissions and slow global warming to 1.5°C by 2100 – the “ideal target” enshrined in the promise by 195 nations to limit warming to well below 2°C above the long-term average for most of human history.

The evidence is this: a shift of even 0.5°C could make a dramatic difference to the risks of devastating droughts and calamitous floods.

If governments keep to the letter of the Paris Agreement of 2015 but not the spirit, and let warming rise to the maximum of 2°, then there will be more intense rainfall across North America, Europe and Asia, and more intense droughts around the Mediterranean.

And although the average intensity of each flood or drought would increase measurably, the intensity of the most extreme event could be even more intense: 10 times greater. That is: the worst imaginable floods 80 years from now would be ten times worse than the worst today.

“Such drastic changes between flood and drought conditions pose a major challenge . . . risks could be substantially reduced by achieving a 1.5°C target”

At the heart of research like this is a new way of looking at future climate projections devised – by researchers all over the world – on a range of possible outcomes for a planet that has recognised climate change, vowed to respond, but failed to take sufficiently energetic steps.

The planet is already warmer by 1°C on average than it was a century ago. Since the Paris Agreement researchers have warned that on present form, and with the present state of commitment nationally and internationally, global average temperatures will top an increase of at least 3°C by the century’s close.

This would be catastrophic. But since then, a slew of fresh studies has defined fresh shades of potential catastrophe even at 2°C maximum, and delivered evidence that a limit of overall warming to the target of 1.5°C would save not just economic damage but even lost lands.

They have demonstrated that just half a degree more would see sea levels rise by 10cms, to threaten the existence of already vulnerable small island states and low-lying coastal floodplains, to put at risk the survival of the coral reefs, and the Arctic ice.

The latest study simply addressed a phenomenon known in the scientific language as the event-to-event hydrological intensification index. This awkward mouthful of syllables masks the crude consequence of average warming: if the overall temperature rises, then so do the extremes of temperature. That is what is meant by average: the mean of all the extremes.

Harder rain

But if average temperatures rise, so does the capacity of the air to hold moisture, which means that when it does rain, then it will rain harder. And when it doesn’t, the groundwater will evaporate more easily.

So landscapes such as the US south-west, already prone to heat and drought, can expect more heat waves, more forest fires and more intense and prolonged drought, while the northeast could see more flooding.

And the latest study in the journal Scientific Reports, by researchers at the University of Tokyo, looked at the difference of outcomes between 1.5°C and 2°C in an already rapidly-warming world, to find that when it came to rainfall – and the attendant floods, droughts, mudslides, harvest failures and water shortages – even half a degree beyond the ideal could make the very bad 10 times worse.

“The high damage potential of such drastic changes between flood and drought conditions poses a major challenge to adaptation,” the researchers conclude, “and the findings suggest that risks could be substantially reduced by achieving a 1.5°C target.” − Climate News Network

Half a degree of warming doesn’t sound like much. But there is fresh evidence that it could make a huge difference to rainfall and drought.

LONDON, 4 April, 2019 − Japanese scientists have found new evidence that a global average temperature rise as small as half a degree could have a drastic effect.

They conclude that the world cannot afford to delay action to reduce greenhouse gas emissions and slow global warming to 1.5°C by 2100 – the “ideal target” enshrined in the promise by 195 nations to limit warming to well below 2°C above the long-term average for most of human history.

The evidence is this: a shift of even 0.5°C could make a dramatic difference to the risks of devastating droughts and calamitous floods.

If governments keep to the letter of the Paris Agreement of 2015 but not the spirit, and let warming rise to the maximum of 2°, then there will be more intense rainfall across North America, Europe and Asia, and more intense droughts around the Mediterranean.

And although the average intensity of each flood or drought would increase measurably, the intensity of the most extreme event could be even more intense: 10 times greater. That is: the worst imaginable floods 80 years from now would be ten times worse than the worst today.

“Such drastic changes between flood and drought conditions pose a major challenge . . . risks could be substantially reduced by achieving a 1.5°C target”

At the heart of research like this is a new way of looking at future climate projections devised – by researchers all over the world – on a range of possible outcomes for a planet that has recognised climate change, vowed to respond, but failed to take sufficiently energetic steps.

The planet is already warmer by 1°C on average than it was a century ago. Since the Paris Agreement researchers have warned that on present form, and with the present state of commitment nationally and internationally, global average temperatures will top an increase of at least 3°C by the century’s close.

This would be catastrophic. But since then, a slew of fresh studies has defined fresh shades of potential catastrophe even at 2°C maximum, and delivered evidence that a limit of overall warming to the target of 1.5°C would save not just economic damage but even lost lands.

They have demonstrated that just half a degree more would see sea levels rise by 10cms, to threaten the existence of already vulnerable small island states and low-lying coastal floodplains, to put at risk the survival of the coral reefs, and the Arctic ice.

The latest study simply addressed a phenomenon known in the scientific language as the event-to-event hydrological intensification index. This awkward mouthful of syllables masks the crude consequence of average warming: if the overall temperature rises, then so do the extremes of temperature. That is what is meant by average: the mean of all the extremes.

Harder rain

But if average temperatures rise, so does the capacity of the air to hold moisture, which means that when it does rain, then it will rain harder. And when it doesn’t, the groundwater will evaporate more easily.

So landscapes such as the US south-west, already prone to heat and drought, can expect more heat waves, more forest fires and more intense and prolonged drought, while the northeast could see more flooding.

And the latest study in the journal Scientific Reports, by researchers at the University of Tokyo, looked at the difference of outcomes between 1.5°C and 2°C in an already rapidly-warming world, to find that when it came to rainfall – and the attendant floods, droughts, mudslides, harvest failures and water shortages – even half a degree beyond the ideal could make the very bad 10 times worse.

“The high damage potential of such drastic changes between flood and drought conditions poses a major challenge to adaptation,” the researchers conclude, “and the findings suggest that risks could be substantially reduced by achieving a 1.5°C target.” − 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

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

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

Warming may mean sea levels 30 cms higher

Warmer oceans mean higher tides, bigger storm surges and heavier rainstorms. With ocean temperatures rising ever faster, sea levels 30 cms higher are possible by 2100.

LONDON, 14 January, 2019 − The world’s oceans are warming increasingly fast. The planet could face sea levels 30 cms higher in 80 years.

While 2018 was probably only the fourth warmest year for global surface temperatures, it is likely to have been the hottest year ever for the oceans. The previous such year was 2017, and before that 2016.

And if global warming follows the pattern predicted by computer simulations, then at present rates the extra temperature of the oceans will cause a thermal expansion – warm water is always less dense than cold water – by 30 centimetres by the end of the century.

That is 30cms of sea level rise on top of all the extra rising sea water delivered by melting ice caps and glaciers on the world’s continents.

“The need to slow or stop the rates of climate change and prepare for the expected impacts is increasingly evident”

The planet is 71% ocean and the clear blue water absorbs an estimated 93% of all the excess heat trapped by the greenhouse gases emitted by humans as they burn fossil fuels to power the global economy.

And a quartet of scientists from China and the US calculate that if the world goes on burning fossil fuels under the notorious business-as-usual scenario, then by the end of the century the top 2,000 metres of the high seas will have warmed by 0.78°C, causing 30cms of sea level rise simply by ocean expansion.

These warmer waters, inevitably, will in turn and less directly accelerate the already increasingly rapid melting of Greenland’s glaciers and surface ice, and eat away at the floating ice shelves that for the moment slow the great glaciers of the Antarctic continent.

Warmer sea waters are linked to the propagation of hurricanes, typhoons or tropical cyclones; to ever heavier and more devastating rainstorms; and to prolonged droughts, heat waves and forest fires.

Oceans are indicator

“If you want to see where global warming is happening, look in our oceans. Ocean heating is a very important indicator of climate change, and we have robust evidence that it is warming more rapidly than we thought,” said Zeke Hausfather, of the Energy and Resources Group at the University of California, Berkeley, and a co-author of the study in the journal Science.

“While 2018 will be the fourth warmest year on record on the surface, it will most certainly be the warmest year on record in the oceans, as was 2017 and 2016 before that. The global warming signal is a lot easier to detect if it is changing in the oceans than on the surface.”

The research is based on readings from Project Argo, a fleet of nearly 4,000 floating robots that periodically dive to 2,000 metres depth to measure ocean temperatures, chemistry, salinity and so on. The latest predictions are backed up by other recent studies.

One has calculated the heat that must have been absorbed by the oceans over the last 150 years. Another has already confirmed the latest study’s other conclusion, that the so-called “hiatus” in global warming never really happened: the heat not registered in global average air temperatures was taken up by the oceans.

Heat uptake continues

Ocean temperatures matter to climate calculations. What happens to air temperatures can be affected briefly by any number of natural cycles. An El Niño event may make one year conspicuously warmer than the next; a sequence of explosive volcanic eruptions may darken the skies and, for a year or so, lower the global temperatures. But the vast body of water that defines the blue planet is largely impervious to brief surface changes.

And, the researchers calculate, it will go on absorbing heat. By 2100, once again under the business-as-usual scenario, the five great oceans could between them have warmed by a total of 2,020 zettajoules: a joule is a basic unit of energy, and one zettajoule adds up to a billion trillion joules.

“This level of warming,” the scientists say, “would have major impacts on ocean ecosystems and sea level rise through thermal expansion.” They identify, they say, a clear need to go on trying to refine climate models and to improve their observations of ocean change.

“In addition, the need to slow or stop the rates of climate change and prepare for the expected impacts is increasingly evident.” − Climate News Network

Warmer oceans mean higher tides, bigger storm surges and heavier rainstorms. With ocean temperatures rising ever faster, sea levels 30 cms higher are possible by 2100.

LONDON, 14 January, 2019 − The world’s oceans are warming increasingly fast. The planet could face sea levels 30 cms higher in 80 years.

While 2018 was probably only the fourth warmest year for global surface temperatures, it is likely to have been the hottest year ever for the oceans. The previous such year was 2017, and before that 2016.

And if global warming follows the pattern predicted by computer simulations, then at present rates the extra temperature of the oceans will cause a thermal expansion – warm water is always less dense than cold water – by 30 centimetres by the end of the century.

That is 30cms of sea level rise on top of all the extra rising sea water delivered by melting ice caps and glaciers on the world’s continents.

“The need to slow or stop the rates of climate change and prepare for the expected impacts is increasingly evident”

The planet is 71% ocean and the clear blue water absorbs an estimated 93% of all the excess heat trapped by the greenhouse gases emitted by humans as they burn fossil fuels to power the global economy.

And a quartet of scientists from China and the US calculate that if the world goes on burning fossil fuels under the notorious business-as-usual scenario, then by the end of the century the top 2,000 metres of the high seas will have warmed by 0.78°C, causing 30cms of sea level rise simply by ocean expansion.

These warmer waters, inevitably, will in turn and less directly accelerate the already increasingly rapid melting of Greenland’s glaciers and surface ice, and eat away at the floating ice shelves that for the moment slow the great glaciers of the Antarctic continent.

Warmer sea waters are linked to the propagation of hurricanes, typhoons or tropical cyclones; to ever heavier and more devastating rainstorms; and to prolonged droughts, heat waves and forest fires.

Oceans are indicator

“If you want to see where global warming is happening, look in our oceans. Ocean heating is a very important indicator of climate change, and we have robust evidence that it is warming more rapidly than we thought,” said Zeke Hausfather, of the Energy and Resources Group at the University of California, Berkeley, and a co-author of the study in the journal Science.

“While 2018 will be the fourth warmest year on record on the surface, it will most certainly be the warmest year on record in the oceans, as was 2017 and 2016 before that. The global warming signal is a lot easier to detect if it is changing in the oceans than on the surface.”

The research is based on readings from Project Argo, a fleet of nearly 4,000 floating robots that periodically dive to 2,000 metres depth to measure ocean temperatures, chemistry, salinity and so on. The latest predictions are backed up by other recent studies.

One has calculated the heat that must have been absorbed by the oceans over the last 150 years. Another has already confirmed the latest study’s other conclusion, that the so-called “hiatus” in global warming never really happened: the heat not registered in global average air temperatures was taken up by the oceans.

Heat uptake continues

Ocean temperatures matter to climate calculations. What happens to air temperatures can be affected briefly by any number of natural cycles. An El Niño event may make one year conspicuously warmer than the next; a sequence of explosive volcanic eruptions may darken the skies and, for a year or so, lower the global temperatures. But the vast body of water that defines the blue planet is largely impervious to brief surface changes.

And, the researchers calculate, it will go on absorbing heat. By 2100, once again under the business-as-usual scenario, the five great oceans could between them have warmed by a total of 2,020 zettajoules: a joule is a basic unit of energy, and one zettajoule adds up to a billion trillion joules.

“This level of warming,” the scientists say, “would have major impacts on ocean ecosystems and sea level rise through thermal expansion.” They identify, they say, a clear need to go on trying to refine climate models and to improve their observations of ocean change.

“In addition, the need to slow or stop the rates of climate change and prepare for the expected impacts is increasingly evident.” − Climate News Network

Ocean warming speeds vary with depth

The world’s oceans are a vast reservoir of heat, a slow register of natural climate change − and ocean warming speeds differ widely.

LONDON, 10 January, 2019 − Climate scientists who have found a new way to chart temperature change in the world’s seas over time say ocean warming speeds are much slower in deep water than on the surface.

Planet Earth is mostly ocean. Human-linked changes have started to raise global temperatures to what could be alarming levels and, as the thermometer rises, so will sea levels. So detailed understanding of temperature and ocean is vital. But two separate studies confirm that the connection is far from simple.

One study of the Atlantic confirms that in the last 150 years, the oceans have taken up 90% of the excess energy released by the combustion of fossil fuels to drive human economic growth and power − and to fuel potentially-catastrophic global warming and runaway climate change.

But what the oceans will actually do with that colossal burst of heat has yet to be fully explored. And a separate examination of the deep history of the Pacific Ocean confirms that change may be inexorable, but it is also very slow: the deeper parts of the Pacific are still registering the onset of the so-called “Little Ice Age” several centuries ago.

“These waters are so old and haven’t been near the surface in so long, they still ‘remember’ what was going on hundreds of years ago”

Both studies are reminders that oceanography is still a relatively new science and researchers still have a lot to learn about the fine detail of the ways in which temperature, atmosphere and ocean interact to affect climate over the world’s continents.

But repeated research has confirmed that the oceans are warming in response to human-triggered changes on land, that this warming presents several different kinds of hazard  to marine life, and that there is a link between overall ocean temperatures and the behaviour of the ocean’s currents, a link that plays out in dramatic shifts in regional climates.

So the rewards for a more precise understanding are considerable. But understanding starts with accurate and comprehensive data, and systematic measurement of ocean temperatures began only with the voyage of the British research ship HMS Challenger in 1871.

So Laure Zanna, a physicist at the University of Oxford and her colleagues, report in the Proceedings of the National Academy of Sciences that they deployed sophisticated mathematical techniques to calculate the heat uptake of the oceans and the way the blue planet has responded since 1871.

Huge heat uptake

Altogether, in the last 150 years, the deep waters have absorbed 436 zettajoules: a joule is the unit of energy required to deliver one watt for one second and a zettajoule is a number followed by 21 zeroes. This is an enormous amount of heat, roughly 1,000 times the energy consumed by 7 billion humans in the course of a year.

The researchers’ results so far show that roughly half the observed warming of the last 60 years – and the associated sea level rise – is linked to changes in ocean circulation. They were able to reconstruct two considerable bouts of warming, over the years 1920 to 1945 and between 1990 and 2015. What they have yet to do is sort out what this means for the behaviour of the oceans over the decades to come.

“The technique is only applicable to tracers like man-made carbon that are passively transported by ocean circulation,” Professor Zanna said. “However, heat does not behave in this manner as it affects circulation by changing the density of seawater. We were pleasantly surprised by how well the approach works. It opens up an exciting new way to study ocean warming in addition to using direct measurements.”

What the research also underlines is that the oceans have a long memory: so extensive and so deep are the five oceans that the surface waters may respond to 20th century greenhouse gas emissions while the deepest trenches contain water that last warmed more than 1,000 years ago in the reign of Charlemagne, the first Holy Roman Emperor.

Still adjusting

US oceanographers report in the journal Science that they matched predictions from computer models and modern data and ancient evidence with readings from the Challenger expedition to show that two kilometres under the waves, the Pacific Ocean is still adjusting to cooling that began with the onset of the Little Ice Age centuries ago.

Such studies count as basic research: as a way of testing techniques and establishing ground rules from which more discovery could follow. They also offer new ways to understand oceans as registers of climate change over long intervals.

“These waters are so old and haven’t been near the surface in so long, they still ‘remember’ what was going on hundreds of years ago when Europe experienced some of its coldest winters in history,” said Jake Gebbie, of the Woods Hole Oceanographic Institution.

“The close correspondence between prediction and observed trends gave us confidence that this is a real phenomenon.” − Climate News Network

The world’s oceans are a vast reservoir of heat, a slow register of natural climate change − and ocean warming speeds differ widely.

LONDON, 10 January, 2019 − Climate scientists who have found a new way to chart temperature change in the world’s seas over time say ocean warming speeds are much slower in deep water than on the surface.

Planet Earth is mostly ocean. Human-linked changes have started to raise global temperatures to what could be alarming levels and, as the thermometer rises, so will sea levels. So detailed understanding of temperature and ocean is vital. But two separate studies confirm that the connection is far from simple.

One study of the Atlantic confirms that in the last 150 years, the oceans have taken up 90% of the excess energy released by the combustion of fossil fuels to drive human economic growth and power − and to fuel potentially-catastrophic global warming and runaway climate change.

But what the oceans will actually do with that colossal burst of heat has yet to be fully explored. And a separate examination of the deep history of the Pacific Ocean confirms that change may be inexorable, but it is also very slow: the deeper parts of the Pacific are still registering the onset of the so-called “Little Ice Age” several centuries ago.

“These waters are so old and haven’t been near the surface in so long, they still ‘remember’ what was going on hundreds of years ago”

Both studies are reminders that oceanography is still a relatively new science and researchers still have a lot to learn about the fine detail of the ways in which temperature, atmosphere and ocean interact to affect climate over the world’s continents.

But repeated research has confirmed that the oceans are warming in response to human-triggered changes on land, that this warming presents several different kinds of hazard  to marine life, and that there is a link between overall ocean temperatures and the behaviour of the ocean’s currents, a link that plays out in dramatic shifts in regional climates.

So the rewards for a more precise understanding are considerable. But understanding starts with accurate and comprehensive data, and systematic measurement of ocean temperatures began only with the voyage of the British research ship HMS Challenger in 1871.

So Laure Zanna, a physicist at the University of Oxford and her colleagues, report in the Proceedings of the National Academy of Sciences that they deployed sophisticated mathematical techniques to calculate the heat uptake of the oceans and the way the blue planet has responded since 1871.

Huge heat uptake

Altogether, in the last 150 years, the deep waters have absorbed 436 zettajoules: a joule is the unit of energy required to deliver one watt for one second and a zettajoule is a number followed by 21 zeroes. This is an enormous amount of heat, roughly 1,000 times the energy consumed by 7 billion humans in the course of a year.

The researchers’ results so far show that roughly half the observed warming of the last 60 years – and the associated sea level rise – is linked to changes in ocean circulation. They were able to reconstruct two considerable bouts of warming, over the years 1920 to 1945 and between 1990 and 2015. What they have yet to do is sort out what this means for the behaviour of the oceans over the decades to come.

“The technique is only applicable to tracers like man-made carbon that are passively transported by ocean circulation,” Professor Zanna said. “However, heat does not behave in this manner as it affects circulation by changing the density of seawater. We were pleasantly surprised by how well the approach works. It opens up an exciting new way to study ocean warming in addition to using direct measurements.”

What the research also underlines is that the oceans have a long memory: so extensive and so deep are the five oceans that the surface waters may respond to 20th century greenhouse gas emissions while the deepest trenches contain water that last warmed more than 1,000 years ago in the reign of Charlemagne, the first Holy Roman Emperor.

Still adjusting

US oceanographers report in the journal Science that they matched predictions from computer models and modern data and ancient evidence with readings from the Challenger expedition to show that two kilometres under the waves, the Pacific Ocean is still adjusting to cooling that began with the onset of the Little Ice Age centuries ago.

Such studies count as basic research: as a way of testing techniques and establishing ground rules from which more discovery could follow. They also offer new ways to understand oceans as registers of climate change over long intervals.

“These waters are so old and haven’t been near the surface in so long, they still ‘remember’ what was going on hundreds of years ago when Europe experienced some of its coldest winters in history,” said Jake Gebbie, of the Woods Hole Oceanographic Institution.

“The close correspondence between prediction and observed trends gave us confidence that this is a real phenomenon.” − Climate News Network

London’s melting ice shows world’s plight

How do you raise awareness of climate change? A novel approach in the UK this winter, shipped in from Greenland, is London’s melting ice.

LONDON, 18 December, 2018 – They stand on the bank of the river Thames, outside the world-famous Tate Modern art venue – London’s melting ice, 24 large blocks, some transparent, some opaque, all different shapes, all gently melting in the not so cold air. Another six stands of ice sit in a square in the heart of London’s financial district.

Ice Watch is the idea of Danish-Icelandic artist Olafur Eliasson and Minik Rosing, a Greenland geologist.

“These blocks tell their own story and I suggest you listen to what they have to say”, Eliasson tells London’s Evening Standard newspaper. “Their melting into the ocean is our world melting.”

The blocks on display in London – weighing a total of more than 100 tonnes – were collected from the cold waters of Nuup Kangerlua fjord near Nuuk, Greenland’s capital.

They had originally been part of Greenland’s ice sheet, which covers about 80% of the island and is the largest ice mass in the northern hemisphere. The blocks were transported to London in containers usually used for exports of frozen fish.

“You can’t live in a perennial state of shock. This is what Ice Watch is about”

Glaciologists say rising air and sea temperatures have caused the pace of melting of the ice sheet to go into overdrive in recent times. There are fears that if the sheet continues to melt at its present rate global sea levels could rise by several metres, flooding coastal cities and large tracts of land.

Visitors can touch the mini-icebergs in London and put their ears to the cold surfaces to listen to the crackling noises as the ice melts, with minuscule air pockets trapped within the blocks cracking open.

Dirt and other material trapped within the ice are evidence of life and changes in the atmosphere stretching back over thousands of years. “Smell, look – and witness the ecological changes our world is undergoing”, says Eliasson.

The artist says that while the facts about climate change and how great a threat it is to the world’s future are clear, people still need to be encouraged to take action.

“We need to communicate the facts of climate change to hearts as well as heads, to emotions as well as minds”, says Eliasson.

Fear is ineffective

“When it comes to people’s choices for or against taking climate action, we are inclined to stick to what we have, here and now, rather than make changes. Inducing fear does not seem an effective strategy.

“You can’t live in a perennial state of shock. This is what Ice Watch is about. I am hopeful that we can push for change. To do so, we have to make use of all the tools at hand, including art.”

Minik Rosing, who has undertaken extensive geological work on the Greenland ice sheet, says the melting of the area’s ice has raised global sea levels by 2.5 millimetres. “Earth is changing at an ever-increasing speed”, he says.

A similar Ice Watch installation has already been staged in Paris. Eliasson has long been involved in climate-related issues. Fifteen years ago his Weather Project exhibition was displayed at Tate Modern.

Ice Watch will be in place in London till December 20 – or until the ice melts completely. – Climate News Network

How do you raise awareness of climate change? A novel approach in the UK this winter, shipped in from Greenland, is London’s melting ice.

LONDON, 18 December, 2018 – They stand on the bank of the river Thames, outside the world-famous Tate Modern art venue – London’s melting ice, 24 large blocks, some transparent, some opaque, all different shapes, all gently melting in the not so cold air. Another six stands of ice sit in a square in the heart of London’s financial district.

Ice Watch is the idea of Danish-Icelandic artist Olafur Eliasson and Minik Rosing, a Greenland geologist.

“These blocks tell their own story and I suggest you listen to what they have to say”, Eliasson tells London’s Evening Standard newspaper. “Their melting into the ocean is our world melting.”

The blocks on display in London – weighing a total of more than 100 tonnes – were collected from the cold waters of Nuup Kangerlua fjord near Nuuk, Greenland’s capital.

They had originally been part of Greenland’s ice sheet, which covers about 80% of the island and is the largest ice mass in the northern hemisphere. The blocks were transported to London in containers usually used for exports of frozen fish.

“You can’t live in a perennial state of shock. This is what Ice Watch is about”

Glaciologists say rising air and sea temperatures have caused the pace of melting of the ice sheet to go into overdrive in recent times. There are fears that if the sheet continues to melt at its present rate global sea levels could rise by several metres, flooding coastal cities and large tracts of land.

Visitors can touch the mini-icebergs in London and put their ears to the cold surfaces to listen to the crackling noises as the ice melts, with minuscule air pockets trapped within the blocks cracking open.

Dirt and other material trapped within the ice are evidence of life and changes in the atmosphere stretching back over thousands of years. “Smell, look – and witness the ecological changes our world is undergoing”, says Eliasson.

The artist says that while the facts about climate change and how great a threat it is to the world’s future are clear, people still need to be encouraged to take action.

“We need to communicate the facts of climate change to hearts as well as heads, to emotions as well as minds”, says Eliasson.

Fear is ineffective

“When it comes to people’s choices for or against taking climate action, we are inclined to stick to what we have, here and now, rather than make changes. Inducing fear does not seem an effective strategy.

“You can’t live in a perennial state of shock. This is what Ice Watch is about. I am hopeful that we can push for change. To do so, we have to make use of all the tools at hand, including art.”

Minik Rosing, who has undertaken extensive geological work on the Greenland ice sheet, says the melting of the area’s ice has raised global sea levels by 2.5 millimetres. “Earth is changing at an ever-increasing speed”, he says.

A similar Ice Watch installation has already been staged in Paris. Eliasson has long been involved in climate-related issues. Fifteen years ago his Weather Project exhibition was displayed at Tate Modern.

Ice Watch will be in place in London till December 20 – or until the ice melts completely. – Climate News Network

Greenland’s icecap melt picks up speed

Recent melting of Greenland’s icecap has been more intense than ever. And all the signs are that it could get worse.

LONDON, 13 December, 2018 – Greenland’s icecap – the largest single store of frozen freshwater in the northern hemisphere – is melting faster than ever, according to two separate studies using two different approaches.

Surface meltwater started flowing over the surface and percolating through the ice at a greater rate in the mid-19th century and accelerated dramatically during the 20th and the first decades of the 21st century, according to a new study of ice cores taken more than 2,000 metres above sea level.

And a 25-year record of European Space Agency satellite data confirms the alarming picture: the elevation of the Greenland ice sheet was changing in the mid-1990s, and the pace of thinning stepped up after 2003. Greenland’s bedrock carries enough ice to raise global sea levels by around seven metres.

“Melting of the Greenland Ice Sheet has gone into overdrive. As a result, Greenland melt is adding to sea level more than at any time in the last three and a half centuries, if not thousands of years,” said Luke Trusel, a glaciologist at Rowan University in the US.

“And increasing melt began around the same time as we started altering the atmosphere in the mid 1800s.”

“The melting and sea level rise we’ve observed will already be dwarfed by what may be expected in the future”

His co-author Sarah Das of the Woods Hole Oceanographic Institution said: “From a historical perspective, today’s melt rates are off the charts, and this study provides the evidence.”

Snow falls on the great icecaps of the two hemispheres, freezes, melts a little in the summer and freezes again, so that – like the rings of a tree – the accumulated precipitation tells a story of successive years of climate change. The two researchers and their colleagues report in Nature that ice cores taken from the icecap between 2003 and 2015 contained enough information for them to assess annual melting rates over several centuries.

They found a clear pattern of more intense melting nearer the present, and over the last 20 years the intensity increased by between 250% and 575%, compared to the 18th century. In the last century the entire planet has warmed by around 1°C as greenhouse gas levels in the atmosphere have risen, in response to ever greater use of fossil fuels.

The message for the future is ominous. “Rather than increasing steadily as climate warms, Greenland will melt increasingly more and more for every degree of warming,” said Dr Trusel. “The melting and sea level rise we’ve observed will already be dwarfed by what may be expected in the future as climate continues to warm.”

Greenland has served for decades as a climate laboratory: change almost imperceptible in lower latitudes can be measured almost on a yearly basis in the high fastnesses of the island, and the Nature study is only the latest twist in a story that is already alarming.

Dangers identified

Scientists long ago took the measure of change on the ice cap, in the glaciers and at the boundary with the Atlantic, and identified the dangers of accelerated warming in the Arctic.

They monitored unexpected increases in the flow of the island’s biggest glaciers, monitored the way the island’s bedrock rose in response to an increased loss of ice, and even identified those reaches of ice that had passed the point of no return.

The Nature scientists backed up their on-the-ground observations with measurements made by satellites. And in an entirely separate study, European researchers report in the journal Earth and Planetary Science Letters that, according to their readings too, the elevation of the icecap had begun to change in ways that enabled them to measure ice loss with the decades, and a recent speed-up.

“A pattern of thinning appears to dominate a large fraction of the ice sheet margins at the beginning of the millennium, with individual outlet glaciers exhibiting large thinning rates,” said Louise Sandberg Sørenson, of the Danish National Space Institute, who led the research.

“Over the full 25-year period, the general picture shows much larger volume losses are experienced in west, northwest and southeast basins of Greenland, compared to the more steady-state situations in the colder north.” – Climate News Network

Recent melting of Greenland’s icecap has been more intense than ever. And all the signs are that it could get worse.

LONDON, 13 December, 2018 – Greenland’s icecap – the largest single store of frozen freshwater in the northern hemisphere – is melting faster than ever, according to two separate studies using two different approaches.

Surface meltwater started flowing over the surface and percolating through the ice at a greater rate in the mid-19th century and accelerated dramatically during the 20th and the first decades of the 21st century, according to a new study of ice cores taken more than 2,000 metres above sea level.

And a 25-year record of European Space Agency satellite data confirms the alarming picture: the elevation of the Greenland ice sheet was changing in the mid-1990s, and the pace of thinning stepped up after 2003. Greenland’s bedrock carries enough ice to raise global sea levels by around seven metres.

“Melting of the Greenland Ice Sheet has gone into overdrive. As a result, Greenland melt is adding to sea level more than at any time in the last three and a half centuries, if not thousands of years,” said Luke Trusel, a glaciologist at Rowan University in the US.

“And increasing melt began around the same time as we started altering the atmosphere in the mid 1800s.”

“The melting and sea level rise we’ve observed will already be dwarfed by what may be expected in the future”

His co-author Sarah Das of the Woods Hole Oceanographic Institution said: “From a historical perspective, today’s melt rates are off the charts, and this study provides the evidence.”

Snow falls on the great icecaps of the two hemispheres, freezes, melts a little in the summer and freezes again, so that – like the rings of a tree – the accumulated precipitation tells a story of successive years of climate change. The two researchers and their colleagues report in Nature that ice cores taken from the icecap between 2003 and 2015 contained enough information for them to assess annual melting rates over several centuries.

They found a clear pattern of more intense melting nearer the present, and over the last 20 years the intensity increased by between 250% and 575%, compared to the 18th century. In the last century the entire planet has warmed by around 1°C as greenhouse gas levels in the atmosphere have risen, in response to ever greater use of fossil fuels.

The message for the future is ominous. “Rather than increasing steadily as climate warms, Greenland will melt increasingly more and more for every degree of warming,” said Dr Trusel. “The melting and sea level rise we’ve observed will already be dwarfed by what may be expected in the future as climate continues to warm.”

Greenland has served for decades as a climate laboratory: change almost imperceptible in lower latitudes can be measured almost on a yearly basis in the high fastnesses of the island, and the Nature study is only the latest twist in a story that is already alarming.

Dangers identified

Scientists long ago took the measure of change on the ice cap, in the glaciers and at the boundary with the Atlantic, and identified the dangers of accelerated warming in the Arctic.

They monitored unexpected increases in the flow of the island’s biggest glaciers, monitored the way the island’s bedrock rose in response to an increased loss of ice, and even identified those reaches of ice that had passed the point of no return.

The Nature scientists backed up their on-the-ground observations with measurements made by satellites. And in an entirely separate study, European researchers report in the journal Earth and Planetary Science Letters that, according to their readings too, the elevation of the icecap had begun to change in ways that enabled them to measure ice loss with the decades, and a recent speed-up.

“A pattern of thinning appears to dominate a large fraction of the ice sheet margins at the beginning of the millennium, with individual outlet glaciers exhibiting large thinning rates,” said Louise Sandberg Sørenson, of the Danish National Space Institute, who led the research.

“Over the full 25-year period, the general picture shows much larger volume losses are experienced in west, northwest and southeast basins of Greenland, compared to the more steady-state situations in the colder north.” – Climate News Network

Better land use could slash US emissions

New research confirms again that nature knows best. The US could cut a fifth of its greenhouse gas emissions through better land use.

LONDON, 7 December, 2018 – US scientists have found a new way to cut or offset 22% of the greenhouse gas emissions from American factory chimneys, car exhausts and power stations: better land use.

Their answer is to leave it to nature. What they identify as 21 natural climate solutions – better use of croplands, the restoration of forests and tidal wetlands, slowing the felling of timber and the containment of urban sprawl – could help limit global warming, slow climate change and reduce sea level rise for the nation that has over the last century emitted more greenhouse gas than any other country.

The most effective single action in a study launched by the US Nature Conservancy and 21 other institutions, and published in the journal Science Advances, would be to step up reforestation: this alone could absorb the emissions of 65 million passenger cars.

“One of America’s greatest assets is its land. Through changes in management, along with protecting and restoring natural lands, we demonstrated we could reduce carbon pollution and filter water, enhance fish and wildlife habitat, and have better soil health to grow our food — all at the same time,” said Joseph Fargione, director of science for the Nature Conservancy, who led the study.

New thinking – and old

“Nature offers us a simple, cost-effective way to help fight global warming. In combination with transitioning to zero carbon energy production, natural climate solutions can help protect our climate for future generations.”

Paradoxically, some of the solutions rely not on new thinking, but on old. If areas of the US that were forested before the European settlers arrived were returned to woodland, the land could absorb 381 million tonnes of carbon dioxide equivalent. If commercial foresters extended the cycles of logging and improved forest management practices, they could effectively save 267 million tonnes a year of CO2.

Around 4,000 square kilometres of grassland is converted to cropland in a year: the act of ploughing releases 28% of the soil carbon to the atmosphere. The scientists reckon that at least 52,000 square kilometres of marginal or unprofitable cropland could be restored to natural grassland or prairie.

Right now, 27% of US tidal wetlands are cut off from the ocean and being flooded by river water: accordingly, these release huge quantities of the potent greenhouse gas methane. All it would take to stop this would be to restore the twice-daily marine inundation: reconnection with the ocean, sometimes just by a culvert under a road, would save 12 million tonnes of CO2 equivalent a year.

“Nature offers us a simple, cost-effective way to help fight global warming”

The researchers identified just 10 of their 21 possible solutions that together could reduce emissions by more than a billion tonnes of carbon dioxide equivalent a year.

That more efficient use of land is a net benefit is not news: researchers have repeatedly argued that world food security is consistent with forest restoration, and that forests left untouched are of greater overall economic value than cleared land, and that considered changes to farming practices could both deliver more food and leave farmers better off.

But, ironically, efforts to promote natural climate solutions in the US get only 0.8% of public and private climate finance, even though these could provide 37% of the climate mitigation needed by 2030. The scientists argue that if the US is to commit to the Paris Accord of 2015, to contain global average warming to 2°C or less above the levels for most of human history, then natural climate solutions make a promising start.

Lynn Scarlett, a former acting secretary of the US Department of the Interior and now at the Nature Conservancy, said: “This study provides good news that making investments in nature will make a big difference, while offering the potential for new revenue to farmers, ranchers, foresters and coastal communities at the same time.” – Climate News Network

New research confirms again that nature knows best. The US could cut a fifth of its greenhouse gas emissions through better land use.

LONDON, 7 December, 2018 – US scientists have found a new way to cut or offset 22% of the greenhouse gas emissions from American factory chimneys, car exhausts and power stations: better land use.

Their answer is to leave it to nature. What they identify as 21 natural climate solutions – better use of croplands, the restoration of forests and tidal wetlands, slowing the felling of timber and the containment of urban sprawl – could help limit global warming, slow climate change and reduce sea level rise for the nation that has over the last century emitted more greenhouse gas than any other country.

The most effective single action in a study launched by the US Nature Conservancy and 21 other institutions, and published in the journal Science Advances, would be to step up reforestation: this alone could absorb the emissions of 65 million passenger cars.

“One of America’s greatest assets is its land. Through changes in management, along with protecting and restoring natural lands, we demonstrated we could reduce carbon pollution and filter water, enhance fish and wildlife habitat, and have better soil health to grow our food — all at the same time,” said Joseph Fargione, director of science for the Nature Conservancy, who led the study.

New thinking – and old

“Nature offers us a simple, cost-effective way to help fight global warming. In combination with transitioning to zero carbon energy production, natural climate solutions can help protect our climate for future generations.”

Paradoxically, some of the solutions rely not on new thinking, but on old. If areas of the US that were forested before the European settlers arrived were returned to woodland, the land could absorb 381 million tonnes of carbon dioxide equivalent. If commercial foresters extended the cycles of logging and improved forest management practices, they could effectively save 267 million tonnes a year of CO2.

Around 4,000 square kilometres of grassland is converted to cropland in a year: the act of ploughing releases 28% of the soil carbon to the atmosphere. The scientists reckon that at least 52,000 square kilometres of marginal or unprofitable cropland could be restored to natural grassland or prairie.

Right now, 27% of US tidal wetlands are cut off from the ocean and being flooded by river water: accordingly, these release huge quantities of the potent greenhouse gas methane. All it would take to stop this would be to restore the twice-daily marine inundation: reconnection with the ocean, sometimes just by a culvert under a road, would save 12 million tonnes of CO2 equivalent a year.

“Nature offers us a simple, cost-effective way to help fight global warming”

The researchers identified just 10 of their 21 possible solutions that together could reduce emissions by more than a billion tonnes of carbon dioxide equivalent a year.

That more efficient use of land is a net benefit is not news: researchers have repeatedly argued that world food security is consistent with forest restoration, and that forests left untouched are of greater overall economic value than cleared land, and that considered changes to farming practices could both deliver more food and leave farmers better off.

But, ironically, efforts to promote natural climate solutions in the US get only 0.8% of public and private climate finance, even though these could provide 37% of the climate mitigation needed by 2030. The scientists argue that if the US is to commit to the Paris Accord of 2015, to contain global average warming to 2°C or less above the levels for most of human history, then natural climate solutions make a promising start.

Lynn Scarlett, a former acting secretary of the US Department of the Interior and now at the Nature Conservancy, said: “This study provides good news that making investments in nature will make a big difference, while offering the potential for new revenue to farmers, ranchers, foresters and coastal communities at the same time.” – Climate News Network

Climate change is drying out parched world

Researchers say most of the water vanishing from the Aral Sea and the Great Salt Lake is now in the oceans of this increasingly parched world.

LONDON, 5 December, 2018 – Climate change has begun to dry out the heart of almost every continent. This parched world’s landlocked basins – they make up a fifth of the Earth’s surface – have lost at least 100 billion tonnes of water every year since the century began. And US researchers now know where that water has gone.

Groundwater, lake and inland sea evaporation from inland Australia, the US West, the Chilean deserts, Saharan Africa, the Middle East and central Asia is now in the oceans, to account for 4mm, or at least 8%, of global sea level rise so far.

In effect, many of the world’s arid zones are becoming progressively more arid, according to a new study in the journal Nature Geoscience.

“Human activities such as groundwater depletion are significantly accelerating this drying”

Researchers used 14 years of observation by a set of orbiting satellites – known as GRACE, for Gravity Recovery and Climate Experiment – to observe the steady desiccation of regions that geographers know as endorheic basins. These are inland regions into which mountain streams, subterranean flows and sluggish rivers drain: among them the Caspian and the Aral Seas in Eurasia, and the Great Salt Lake in the US.

They are very different from the world’s great exorheic basins, better known as the Nile, the Amazon, the Mississippi and the Yangtze, all of which flow into the sea.

People in exorheic basins know their water supply will always be replenished. People farming or grazing cattle in the endorheic basins can now see their most vital resource slowly vanishing.

Evidence mounts

“Over the past few decades, we have seen increasing evidence of perturbations to the endorheic water balance,” said Jida Wang, a geographer at Kansas State University, who led the study.

“This includes, for example, the desiccating Aral Sea, the depleting Arabian aquifer and the retreating Eurasian glaciers. This evidence motivated us to ask: Is the total water storage across the global endorheic system, about one-fifth of the continental surface, undergoing a net decline?”

The GRACE satellites have already answered a series of huge questions about the world’s traffic in ice and water: they have “weighed” the loss of ice in the Antarctic, and put a total to the impact of devastating floods in Australia in 2011.

Speed of disappearance

And the remote sensing instruments now deliver a measure of the rate at which endorheic water is disappearing. Not only does it account for nearly one tenth of sea level rise so far, it adds up to nearly half the loss of water from retreating mountain glaciers in the densely occupied countries – that is, excluding Greenland and Antarctica – and it matches the entire extraction of groundwater, everywhere in the world, for irrigation and to nourish towns and cities in the drier regions.

The parching of the inland basins is uneven – some report more rainfall – but around 75% have been steadily getting drier. “The water losses from the world’s endorheic basins are yet another example of how climate change is further drying the already dry arid and semi-arid regions of the globe,” said Jay Famiglietti, one of the co-authors, who directs the Global Institute of Water Security, at the University of Saskatchewan in Canada.

“Meanwhile, human activities such as groundwater depletion are significantly accelerating this drying.” – Climate News Network

Researchers say most of the water vanishing from the Aral Sea and the Great Salt Lake is now in the oceans of this increasingly parched world.

LONDON, 5 December, 2018 – Climate change has begun to dry out the heart of almost every continent. This parched world’s landlocked basins – they make up a fifth of the Earth’s surface – have lost at least 100 billion tonnes of water every year since the century began. And US researchers now know where that water has gone.

Groundwater, lake and inland sea evaporation from inland Australia, the US West, the Chilean deserts, Saharan Africa, the Middle East and central Asia is now in the oceans, to account for 4mm, or at least 8%, of global sea level rise so far.

In effect, many of the world’s arid zones are becoming progressively more arid, according to a new study in the journal Nature Geoscience.

“Human activities such as groundwater depletion are significantly accelerating this drying”

Researchers used 14 years of observation by a set of orbiting satellites – known as GRACE, for Gravity Recovery and Climate Experiment – to observe the steady desiccation of regions that geographers know as endorheic basins. These are inland regions into which mountain streams, subterranean flows and sluggish rivers drain: among them the Caspian and the Aral Seas in Eurasia, and the Great Salt Lake in the US.

They are very different from the world’s great exorheic basins, better known as the Nile, the Amazon, the Mississippi and the Yangtze, all of which flow into the sea.

People in exorheic basins know their water supply will always be replenished. People farming or grazing cattle in the endorheic basins can now see their most vital resource slowly vanishing.

Evidence mounts

“Over the past few decades, we have seen increasing evidence of perturbations to the endorheic water balance,” said Jida Wang, a geographer at Kansas State University, who led the study.

“This includes, for example, the desiccating Aral Sea, the depleting Arabian aquifer and the retreating Eurasian glaciers. This evidence motivated us to ask: Is the total water storage across the global endorheic system, about one-fifth of the continental surface, undergoing a net decline?”

The GRACE satellites have already answered a series of huge questions about the world’s traffic in ice and water: they have “weighed” the loss of ice in the Antarctic, and put a total to the impact of devastating floods in Australia in 2011.

Speed of disappearance

And the remote sensing instruments now deliver a measure of the rate at which endorheic water is disappearing. Not only does it account for nearly one tenth of sea level rise so far, it adds up to nearly half the loss of water from retreating mountain glaciers in the densely occupied countries – that is, excluding Greenland and Antarctica – and it matches the entire extraction of groundwater, everywhere in the world, for irrigation and to nourish towns and cities in the drier regions.

The parching of the inland basins is uneven – some report more rainfall – but around 75% have been steadily getting drier. “The water losses from the world’s endorheic basins are yet another example of how climate change is further drying the already dry arid and semi-arid regions of the globe,” said Jay Famiglietti, one of the co-authors, who directs the Global Institute of Water Security, at the University of Saskatchewan in Canada.

“Meanwhile, human activities such as groundwater depletion are significantly accelerating this drying.” – Climate News Network