Tag Archives: Antarctic

Polar ice loss speeds up by leaps and bounds

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

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

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

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

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

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

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

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

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

Growing concern

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

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

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

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

Puzzling picture

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

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

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

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

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

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

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

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

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

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

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

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

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

Growing concern

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

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

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

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

Puzzling picture

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

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

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

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

Underwater walls might avert sea level rise

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

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

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

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

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

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

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

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

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

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

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

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

Huge impact

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

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

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

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

Left behind

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Huge impact

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

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

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

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

Left behind

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

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

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

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

Frozen Arctic moves seawards in hectic melt

Once trapped in a Russian ice cap north of Siberia, the frozen Arctic is moving fast, racing in decades from metres to kilometres a year.

LONDON, 5 October, 2018 – Satellite images have revealed a dramatic change in Russia’s frozen Arctic. An ice cap that once crept almost imperceptibly across the barren rocks of October Revolution island, in the Kara Sea, is on the move.

All ice, even when permanently frozen to the bedrock, moves. From 1952 to 1985, the western edge of the Vavilov ice cap, 1,820 square kilometres in area and between 300 metres and 600 metres in thickness, shifted at about 12 metres a year. Between 1998 and 2011, it stepped up the pace to 75 metres a year. Between 2014 and 2015, the ice front had broken into tongues that moved at more than 1,000 metres a year.

And between 2015 and 2016 the leading edge had started racing into the Kara Sea at 5,000 metres a year. It is also thinning at the rate of a third of a metre a day, according to a new study in the journal Earth and Planetary Science Letters.

The high Arctic is the fastest-warming place on Earth, and researchers have for more than 30 years been measuring changes in the rate at which sea ice shrinks and Greenland glaciers flow.

Role as metaphor

“In a warming climate, glacier acceleration is becoming more and more common, but the rate of ice loss at Vavilov is extreme and unexpected,” said Michael Willis, a geologist at the University of California Boulder, who led the study by scientists from the US, UK and Russia.

Glaciers and icecaps such as Vavilov cover about 450,000 square kilometres of the planet’s surface and hold enough frozen water to raise global sea levels by 30 cms. They form on land in polar “deserts” in which the temperatures are below freezing and snow falls at no more than 25 cms a year.

In the Arctic summer the snow cover melts, and water trickles down through the ice; over the years, snowfall patterns shift and the ice cap shifts under gravitational tug. All glaciers flow, but so slowly that their pace has been incorporated into metaphor.

For the study authors, who used decades of satellite studies of the high Arctic to measure the change, the puzzle is one of geophysics: how could a fast-frozen mass of ice get to the stage where it can slide, as if lubricated, across a rocky surface above sea level?

“Glacier acceleration is becoming more and more common, but the rate of ice loss at Vavilov is extreme and unexpected”

“We’ve never seen anything like this before, this study has raised as many questions as it has answered,” said Dr Willis. “And we’re now working on modelling the whole situation to get a better handle on the physics involved.”

But for climate scientists concerned with the bigger picture, the study is another instance of potentially catastrophic climate change in the making. Once an ice cap starts to flow, the process is unlikely to stop.

And a second study in the same week from the other end of the globe shows that it doesn’t take much to start the ice flowing into the sea. It has confirmed that average global warming of no more than 2°C above historic levels, given long enough,  could melt much of the world’s largest ice sheet.

Planetary average temperatures have already risen by 1°C since the first industrial exploitation of coal, gas and oil only 200 years ago, and right now, although 195 nations vowed in Paris in 2015 to keep the rise to “well below” 2°C by 2100, the world seems headed for at least a 3°C rise later this century.

Future loss inevitable

British, Australian, New Zealand, Spanish and Japanese scientists report in Nature that they reconstructed the impact of change on the East Antarctic ice sheet during interglacials, those warm pauses during the last Ice Age.

For about 2,500 years, Antarctic air temperatures rose by about 2°C, the huge fastness of ice began to melt, and sea levels rose. The West Antarctic ice sheet, which has repeatedly shown signs of thawing, holds enough water to raise sea levels by up to 5 metres. The apparently stable East Antarctic sheet holds enough to lift global sea levels by 53 metres. During the interglacials of 400,000 years ago and 125,000 years ago, sea levels rose between 6 metres and 13 metres higher than they are today.

“What we have learned is that even modest warming of just two degrees, if sustained for a couple of thousand years, is enough to cause the East Antarctic ice sheet to retreat in some of its low-lying areas,” said David Wilson, of the UK’s Imperial College, who led the research.

“With current global temperatures already one degree higher than during pre-industrial times, future ice loss seems inevitable if we fail to reduce carbon emissions.” – Climate News Network

Once trapped in a Russian ice cap north of Siberia, the frozen Arctic is moving fast, racing in decades from metres to kilometres a year.

LONDON, 5 October, 2018 – Satellite images have revealed a dramatic change in Russia’s frozen Arctic. An ice cap that once crept almost imperceptibly across the barren rocks of October Revolution island, in the Kara Sea, is on the move.

All ice, even when permanently frozen to the bedrock, moves. From 1952 to 1985, the western edge of the Vavilov ice cap, 1,820 square kilometres in area and between 300 metres and 600 metres in thickness, shifted at about 12 metres a year. Between 1998 and 2011, it stepped up the pace to 75 metres a year. Between 2014 and 2015, the ice front had broken into tongues that moved at more than 1,000 metres a year.

And between 2015 and 2016 the leading edge had started racing into the Kara Sea at 5,000 metres a year. It is also thinning at the rate of a third of a metre a day, according to a new study in the journal Earth and Planetary Science Letters.

The high Arctic is the fastest-warming place on Earth, and researchers have for more than 30 years been measuring changes in the rate at which sea ice shrinks and Greenland glaciers flow.

Role as metaphor

“In a warming climate, glacier acceleration is becoming more and more common, but the rate of ice loss at Vavilov is extreme and unexpected,” said Michael Willis, a geologist at the University of California Boulder, who led the study by scientists from the US, UK and Russia.

Glaciers and icecaps such as Vavilov cover about 450,000 square kilometres of the planet’s surface and hold enough frozen water to raise global sea levels by 30 cms. They form on land in polar “deserts” in which the temperatures are below freezing and snow falls at no more than 25 cms a year.

In the Arctic summer the snow cover melts, and water trickles down through the ice; over the years, snowfall patterns shift and the ice cap shifts under gravitational tug. All glaciers flow, but so slowly that their pace has been incorporated into metaphor.

For the study authors, who used decades of satellite studies of the high Arctic to measure the change, the puzzle is one of geophysics: how could a fast-frozen mass of ice get to the stage where it can slide, as if lubricated, across a rocky surface above sea level?

“Glacier acceleration is becoming more and more common, but the rate of ice loss at Vavilov is extreme and unexpected”

“We’ve never seen anything like this before, this study has raised as many questions as it has answered,” said Dr Willis. “And we’re now working on modelling the whole situation to get a better handle on the physics involved.”

But for climate scientists concerned with the bigger picture, the study is another instance of potentially catastrophic climate change in the making. Once an ice cap starts to flow, the process is unlikely to stop.

And a second study in the same week from the other end of the globe shows that it doesn’t take much to start the ice flowing into the sea. It has confirmed that average global warming of no more than 2°C above historic levels, given long enough,  could melt much of the world’s largest ice sheet.

Planetary average temperatures have already risen by 1°C since the first industrial exploitation of coal, gas and oil only 200 years ago, and right now, although 195 nations vowed in Paris in 2015 to keep the rise to “well below” 2°C by 2100, the world seems headed for at least a 3°C rise later this century.

Future loss inevitable

British, Australian, New Zealand, Spanish and Japanese scientists report in Nature that they reconstructed the impact of change on the East Antarctic ice sheet during interglacials, those warm pauses during the last Ice Age.

For about 2,500 years, Antarctic air temperatures rose by about 2°C, the huge fastness of ice began to melt, and sea levels rose. The West Antarctic ice sheet, which has repeatedly shown signs of thawing, holds enough water to raise sea levels by up to 5 metres. The apparently stable East Antarctic sheet holds enough to lift global sea levels by 53 metres. During the interglacials of 400,000 years ago and 125,000 years ago, sea levels rose between 6 metres and 13 metres higher than they are today.

“What we have learned is that even modest warming of just two degrees, if sustained for a couple of thousand years, is enough to cause the East Antarctic ice sheet to retreat in some of its low-lying areas,” said David Wilson, of the UK’s Imperial College, who led the research.

“With current global temperatures already one degree higher than during pre-industrial times, future ice loss seems inevitable if we fail to reduce carbon emissions.” – Climate News Network

Warming climate leaves its varied marks

The warming climate is changing the globe: mountain species climb higher, valley floors sink and animal numbers fall, while their living space shrinks.

LONDON, 28 September, 2018 – The Earth’s warming climate is already reshaping the planet. A new study confirms that plants and animals unique to the mountains are climbing ever higher to survive.

A second research team has taken a closer look at the valley floors of Central California to find that one of them is now, thanks to drought conditions, sinking by up to half a metre a year.

In central and eastern Europe, German scientists have found that the Danube – on which people used to skate every winter – has frozen only a handful of times in the last 70 years.

And far to the south, French scientists report that one of the world’s largest colonies of king penguins has dwindled by 88% since 1982.

In all cases, researchers identify a possible environmental cause: and in all cases the changes could be linked to global warming. In three instances out of four, climate change has already been implicated by other studies.

“The scientists calculate that for every 1°C rise in temperature, species are moving an average of 100 metres uphill”

Years ago, Swiss scientists observed a steady uphill migration of alpine butterflies and birds; while US scientists have charted change in mountain flora in the Rockies and Danish scientists revisited an Andean mountain first explored by the great Alexander von Humboldt to find that the plants he recorded had climbed 500 metres in 210 years.

Now Canadian scientists report in the journal Global Ecology and Biogeography that they set themselves the challenge of the global picture: they reviewed studies of elevation shifts in 975 species of plant, insect and animal.

In the French Pyrenees, the mountain burnet butterfly has shifted uphill by 430 metres and surrendered 79% of its range. In the Himalayas, where temperatures have risen by 2.2°C in 150 years, one meadow flower has migrated more than 600 metres and lost 28% of its preferred habitat. In Nevada’s Ruby Mountains, the northern pocket gopher has responded to a warming of 1.1°C in 80 years by climbing higher and surrendering 70% of its living room.

Altogether, the scientists calculate that for every 1°C rise in temperature, species are moving an average of 100 metres uphill.

In the mountains of California, the peaks are getting ever higher because the reduced mass of snowfall no longer depresses the rock.

Sinking feeling

Paradoxically, thanks to the combination of sustained drought and relentless abstraction of groundwater for agriculture, things are going downhill in the San Joaquin valley of California,, according to scientists from Cornell University who report in the journal Science Advances. The valley is home to 75% of California’s irrigated farmland. It supplies 8% of US agricultural output and it has a long record of slow subsidence.

The Cornell scientists report that between 1962 and 2011, the valley lost groundwater at the rate of 1.85 cubic kilometres a year. Between 2012 and 2016, during the state’s worst-ever drought, the same basin lost 40 cubic kilometres of groundwater, and the ground fell at 50 cms a year, except for a slowdown in subsidence during the heavy rains of 2017. The previous rate of subsidence has resumed.

The Danube Commission has kept records since 1836 of the behaviour of Europe’s second largest river as it flows from the Alps to the Black Sea. Researchers from Germany’s Alfred Wegener Institute write in the journal Scientific Reports that archivists reported ice cover almost every year, ice thick enough to bear skaters.

But between 1951 and 2016, the river froze only 10 times. Although more people live in Europe than ever before, and discharge more outflow into the Danube basin, the researchers identify global warming as a substantial cause: winter temperatures have risen and are now more than 1.0°C warmer than in the first half of the 20th century.

Problems for penguins

And rising temperatures might be at the heart of the crisis for king penguins on the Iles Crozet archipelago in Antarctica: French scientists report in the journal Antarctic Science that in 1982 the colony was home to 500,000 breeding pairs and two million specimens of Aptenodytes patagonicus.

Now the colony has shrunk, and vegetation cover has expanded. The loss might be linked to lack of food, or a major natural warming event such as El Nino, or to disease such as avian cholera.

But global warming and climate change have already been linked to alarms over the king penguin elsewhere, and to the possible fate of the emperor penguin.

The research is based on aerial imagery and satellite studies, and on-the-ground research is still needed to explain quite why a colony which once supported 500,000 breeding pairs should now number only 60,000 penguin couples.

“The cause of the massive decline of the colony remains a mystery, and needs to be resolved,” the French scientists say. – Climate News Network

The warming climate is changing the globe: mountain species climb higher, valley floors sink and animal numbers fall, while their living space shrinks.

LONDON, 28 September, 2018 – The Earth’s warming climate is already reshaping the planet. A new study confirms that plants and animals unique to the mountains are climbing ever higher to survive.

A second research team has taken a closer look at the valley floors of Central California to find that one of them is now, thanks to drought conditions, sinking by up to half a metre a year.

In central and eastern Europe, German scientists have found that the Danube – on which people used to skate every winter – has frozen only a handful of times in the last 70 years.

And far to the south, French scientists report that one of the world’s largest colonies of king penguins has dwindled by 88% since 1982.

In all cases, researchers identify a possible environmental cause: and in all cases the changes could be linked to global warming. In three instances out of four, climate change has already been implicated by other studies.

“The scientists calculate that for every 1°C rise in temperature, species are moving an average of 100 metres uphill”

Years ago, Swiss scientists observed a steady uphill migration of alpine butterflies and birds; while US scientists have charted change in mountain flora in the Rockies and Danish scientists revisited an Andean mountain first explored by the great Alexander von Humboldt to find that the plants he recorded had climbed 500 metres in 210 years.

Now Canadian scientists report in the journal Global Ecology and Biogeography that they set themselves the challenge of the global picture: they reviewed studies of elevation shifts in 975 species of plant, insect and animal.

In the French Pyrenees, the mountain burnet butterfly has shifted uphill by 430 metres and surrendered 79% of its range. In the Himalayas, where temperatures have risen by 2.2°C in 150 years, one meadow flower has migrated more than 600 metres and lost 28% of its preferred habitat. In Nevada’s Ruby Mountains, the northern pocket gopher has responded to a warming of 1.1°C in 80 years by climbing higher and surrendering 70% of its living room.

Altogether, the scientists calculate that for every 1°C rise in temperature, species are moving an average of 100 metres uphill.

In the mountains of California, the peaks are getting ever higher because the reduced mass of snowfall no longer depresses the rock.

Sinking feeling

Paradoxically, thanks to the combination of sustained drought and relentless abstraction of groundwater for agriculture, things are going downhill in the San Joaquin valley of California,, according to scientists from Cornell University who report in the journal Science Advances. The valley is home to 75% of California’s irrigated farmland. It supplies 8% of US agricultural output and it has a long record of slow subsidence.

The Cornell scientists report that between 1962 and 2011, the valley lost groundwater at the rate of 1.85 cubic kilometres a year. Between 2012 and 2016, during the state’s worst-ever drought, the same basin lost 40 cubic kilometres of groundwater, and the ground fell at 50 cms a year, except for a slowdown in subsidence during the heavy rains of 2017. The previous rate of subsidence has resumed.

The Danube Commission has kept records since 1836 of the behaviour of Europe’s second largest river as it flows from the Alps to the Black Sea. Researchers from Germany’s Alfred Wegener Institute write in the journal Scientific Reports that archivists reported ice cover almost every year, ice thick enough to bear skaters.

But between 1951 and 2016, the river froze only 10 times. Although more people live in Europe than ever before, and discharge more outflow into the Danube basin, the researchers identify global warming as a substantial cause: winter temperatures have risen and are now more than 1.0°C warmer than in the first half of the 20th century.

Problems for penguins

And rising temperatures might be at the heart of the crisis for king penguins on the Iles Crozet archipelago in Antarctica: French scientists report in the journal Antarctic Science that in 1982 the colony was home to 500,000 breeding pairs and two million specimens of Aptenodytes patagonicus.

Now the colony has shrunk, and vegetation cover has expanded. The loss might be linked to lack of food, or a major natural warming event such as El Nino, or to disease such as avian cholera.

But global warming and climate change have already been linked to alarms over the king penguin elsewhere, and to the possible fate of the emperor penguin.

The research is based on aerial imagery and satellite studies, and on-the-ground research is still needed to explain quite why a colony which once supported 500,000 breeding pairs should now number only 60,000 penguin couples.

“The cause of the massive decline of the colony remains a mystery, and needs to be resolved,” the French scientists say. – Climate News Network

Hothouse Earth could soon be unavoidable

Researchers say the world may be approaching a tipping point, followed by a dangerous slide towards Hothouse Earth, an overheated planet.

LONDON, 7 August, 2018 – Human actions threaten to push the planet into a new state, called Hothouse Earth. In such a world global average temperatures could stabilise at 4°C or even 5°C higher than they have been for most of human history.

Global sea levels, too, would rise, by 10 metres, or even as much as 60 metres, to drown all the world’s great coastal cities. Such a transition might happen “in only a century or two”, but once started, there might be no stopping it.

It would be uncontrollable and dangerous to many and “it poses severe risks for health, economies, political stability … and ultimately the habitability of the planet for humans.”

And, say scientists who have completed a survey of the research landscape, there is no knowing how close the threshold of dramatic change might be. The planet has already warmed by 1°C in the last century, and the thermometer is climbing at a rate of 0.17°C per decade.

Even at the ambitious target temperature rise of no more than 2°C by the end of the century – a target endorsed by 195 nations in Paris in 2015 – humans might already have triggered a cascade of feedbacks that would set the planet sliding to a point hotter than at any time in the last 10 million years.

“These tipping elements can potentially act like a row of dominoes. Once one is pushed over, it pushes Earth towards another. It may be very difficult or impossible to stop the whole row of dominoes from tumbling over”

Researchers, led by Will Steffen of the Australian National University and backed by some of the big names of European climate science, report in the Proceedings of the National Academy of Sciences that they considered 10 natural processes, among them a number of tipping points that could lead to change once a certain temperature threshold had been crossed.

These feedbacks could turn what are, right now, carbon sinks – stores of atmospheric carbon locked away in the soils and the forests – into sources of greenhouse gases that could accelerate global warming.

These future hazards include thawing of the permafrost, the loss of methane hydrates stored in the ocean floor, the weakening of carbon stores both on land and in the oceans, increasing bacterial activity in the seas, dieback in the tropical Amazon forest and in the cool forests of the north, the loss of sea ice in the Arctic summer, and the loss of Antarctic sea ice and the polar ice sheets.

“These tipping elements can potentially act like a row of dominoes. Once one is pushed over, it pushes Earth towards another. It may be very difficult or impossible to stop the whole row of dominoes from tumbling over. Places on Earth will become uninhabitable if ‘Hothouse Earth’ becomes a reality,” said Johan Rockström, of the Stockholm Resilience Centre.

Losing balance

And a co-author, Hans Joachim Schellnhuber, who directs the Potsdam Institute for Climate Impact Research, said: “We show how industrial age greenhouse gas emissions force our climate, and ultimately the Earth system, out of balance.

“In particular, we address tipping elements in the planetary machinery that might, once a certain level has been passed, one by one change fundamentally rapidly, and perhaps irreversibly. The cascade of events may tip the entire Earth system into a new mode of operation.”

The message, although alarming, is a restatement of previous findings and a reconsideration of existing evidence, enhanced by lessons from the more recent geological past, in which rocks and the fossils buried with them tell a story of dramatic changes in temperature and sea level.

Other researchers have raised the hazard of “tipping points” that could send the climate into a state of irreversible change. Professor Steffen three years ago warned that of the nine safe “planetary boundaries” that kept Earth in a stable climate state, four had already been crossed.

Potsdam scientists have already proposed that human release of greenhouse gases – the consequence of profligate use of fossil fuels – has now lifted the Earth from its million year cycle of Ice Ages and interglacials into a new stabilised state, known variously as the  Anthropocene and “the Deglacial.” And Stockholm scientists have joined them in warning that there are more uncertainties and climate stresses to come.

Planetary threshold

The new study however re-examines the possibilities and once again spells out the dangers in language of uncompromising clarity. “The Earth system may be approaching a planetary threshold that could lock in a continuing rapid pathway toward much hotter conditions – Hothouse Earth.

“This pathway would be propelled by strong, intrinsic, biogeophysical feedbacks difficult to influence by human actions, a pathway that could not be reversed, steered or substantially slowed.”

And, the authors warn, the impact on human society would be “massive, sometimes abrupt and undoubtedly disruptive.”

But, of course, nobody knows at what point such a dangerous slide into a new temperature zone could become inexorable, and the researchers make this clear.

“What we do not know is whether the climate system can be safely ‘parked’ near 2°C above preindustrial levels, as the Paris Agreement envisages,” said Professor Schellnhuber, “or if it will, once pushed so far, slip down the slope towards a hothouse planet. Research must assess this risk as soon as possible.” – Climate News Network

Researchers say the world may be approaching a tipping point, followed by a dangerous slide towards Hothouse Earth, an overheated planet.

LONDON, 7 August, 2018 – Human actions threaten to push the planet into a new state, called Hothouse Earth. In such a world global average temperatures could stabilise at 4°C or even 5°C higher than they have been for most of human history.

Global sea levels, too, would rise, by 10 metres, or even as much as 60 metres, to drown all the world’s great coastal cities. Such a transition might happen “in only a century or two”, but once started, there might be no stopping it.

It would be uncontrollable and dangerous to many and “it poses severe risks for health, economies, political stability … and ultimately the habitability of the planet for humans.”

And, say scientists who have completed a survey of the research landscape, there is no knowing how close the threshold of dramatic change might be. The planet has already warmed by 1°C in the last century, and the thermometer is climbing at a rate of 0.17°C per decade.

Even at the ambitious target temperature rise of no more than 2°C by the end of the century – a target endorsed by 195 nations in Paris in 2015 – humans might already have triggered a cascade of feedbacks that would set the planet sliding to a point hotter than at any time in the last 10 million years.

“These tipping elements can potentially act like a row of dominoes. Once one is pushed over, it pushes Earth towards another. It may be very difficult or impossible to stop the whole row of dominoes from tumbling over”

Researchers, led by Will Steffen of the Australian National University and backed by some of the big names of European climate science, report in the Proceedings of the National Academy of Sciences that they considered 10 natural processes, among them a number of tipping points that could lead to change once a certain temperature threshold had been crossed.

These feedbacks could turn what are, right now, carbon sinks – stores of atmospheric carbon locked away in the soils and the forests – into sources of greenhouse gases that could accelerate global warming.

These future hazards include thawing of the permafrost, the loss of methane hydrates stored in the ocean floor, the weakening of carbon stores both on land and in the oceans, increasing bacterial activity in the seas, dieback in the tropical Amazon forest and in the cool forests of the north, the loss of sea ice in the Arctic summer, and the loss of Antarctic sea ice and the polar ice sheets.

“These tipping elements can potentially act like a row of dominoes. Once one is pushed over, it pushes Earth towards another. It may be very difficult or impossible to stop the whole row of dominoes from tumbling over. Places on Earth will become uninhabitable if ‘Hothouse Earth’ becomes a reality,” said Johan Rockström, of the Stockholm Resilience Centre.

Losing balance

And a co-author, Hans Joachim Schellnhuber, who directs the Potsdam Institute for Climate Impact Research, said: “We show how industrial age greenhouse gas emissions force our climate, and ultimately the Earth system, out of balance.

“In particular, we address tipping elements in the planetary machinery that might, once a certain level has been passed, one by one change fundamentally rapidly, and perhaps irreversibly. The cascade of events may tip the entire Earth system into a new mode of operation.”

The message, although alarming, is a restatement of previous findings and a reconsideration of existing evidence, enhanced by lessons from the more recent geological past, in which rocks and the fossils buried with them tell a story of dramatic changes in temperature and sea level.

Other researchers have raised the hazard of “tipping points” that could send the climate into a state of irreversible change. Professor Steffen three years ago warned that of the nine safe “planetary boundaries” that kept Earth in a stable climate state, four had already been crossed.

Potsdam scientists have already proposed that human release of greenhouse gases – the consequence of profligate use of fossil fuels – has now lifted the Earth from its million year cycle of Ice Ages and interglacials into a new stabilised state, known variously as the  Anthropocene and “the Deglacial.” And Stockholm scientists have joined them in warning that there are more uncertainties and climate stresses to come.

Planetary threshold

The new study however re-examines the possibilities and once again spells out the dangers in language of uncompromising clarity. “The Earth system may be approaching a planetary threshold that could lock in a continuing rapid pathway toward much hotter conditions – Hothouse Earth.

“This pathway would be propelled by strong, intrinsic, biogeophysical feedbacks difficult to influence by human actions, a pathway that could not be reversed, steered or substantially slowed.”

And, the authors warn, the impact on human society would be “massive, sometimes abrupt and undoubtedly disruptive.”

But, of course, nobody knows at what point such a dangerous slide into a new temperature zone could become inexorable, and the researchers make this clear.

“What we do not know is whether the climate system can be safely ‘parked’ near 2°C above preindustrial levels, as the Paris Agreement envisages,” said Professor Schellnhuber, “or if it will, once pushed so far, slip down the slope towards a hothouse planet. Research must assess this risk as soon as possible.” – Climate News Network

Alien seaweed arrives in Antarctica

For more than a century, scientists believed that only humans could cross the hostile oceans to reach Antarctica. Some strands of alien seaweed tell another story.

LONDON, 19 July, 2018 – A foreign invader, a species of alien seaweed, has managed to cross the oceans to reach the frozen Antarctic shores. So scientists may have to give up a cherished belief: that Antarctica is inviolate.

For a century, researchers have assumed that the mix of ocean currents, distance and temperature have kept the Great White Continent shielded from invasion by Pacific or Atlantic flotsam.

But the discovery of strands of kelp on an Antarctic beach – seaweed that may have drifted for considerable periods and a distance of 20,000 kms before becoming stranded far from home – brings an end to that belief. And the discovery suggests that global warming could bring serious changes to Antarctic ecosystems.

“Our findings also indicate that plants and animals living on Antarctica could be more vulnerable to climate change than we suspected”

“This finding shows us that living plants and animals can reach Antarctica across the ocean, with temperate and sub-Antarctic marine species probably bombarding Antarctic coastlines all the time,” said Ceridwen Fraser, of the Australian National University.

“We always thought Antarctic plants and animals were distinct because they were isolated, but this research now suggests these differences are almost entirely due to environmental extremes, not isolation.”

Dr Fraser and her colleagues report in the journal Nature Climate Change that strands of southern bull kelp, Durvillaea antarctica, found by a Chilean scientist, must have floated 20,000 km from the Kerguelen Islands and South Georgia. The kelp was encrusted with barnacles, evidence of a long time adrift.

In fact, researchers believe, it may be evidence of the longest episode of “biological rafting” ever confirmed. The word raft is significant: such floating platforms could provide shelter and transport for other biological invaders.

Plastic next?

Until now, the assumption has been that the pattern of surface currents and westerly winds tends to drive drifting material northwards from Antarctica. The discovery suggests that if kelp can get there, so can floating driftwood, or plastic debris, or any other unwelcome visitor.

The researchers think large waves driven by Southern Ocean storms may have steered the kelp rafts over what had been considered a natural ocean barrier. Global warming has begun to change conditions in Antarctica, and the continent – considered the last great tract of terrain unmarked by human colonisation – could become increasingly vulnerable to change.

“This is an unequivocal demonstration that marine species from the north can reach Antarctica. To get there the kelp had to pass through barriers created by polar winds and currents that were, until now, thought to be impenetrable,” Dr Fraser said.

“Our findings also indicate that plants and animals living on Antarctica could be more vulnerable to climate change than we suspected.” – Climate News Network

For more than a century, scientists believed that only humans could cross the hostile oceans to reach Antarctica. Some strands of alien seaweed tell another story.

LONDON, 19 July, 2018 – A foreign invader, a species of alien seaweed, has managed to cross the oceans to reach the frozen Antarctic shores. So scientists may have to give up a cherished belief: that Antarctica is inviolate.

For a century, researchers have assumed that the mix of ocean currents, distance and temperature have kept the Great White Continent shielded from invasion by Pacific or Atlantic flotsam.

But the discovery of strands of kelp on an Antarctic beach – seaweed that may have drifted for considerable periods and a distance of 20,000 kms before becoming stranded far from home – brings an end to that belief. And the discovery suggests that global warming could bring serious changes to Antarctic ecosystems.

“Our findings also indicate that plants and animals living on Antarctica could be more vulnerable to climate change than we suspected”

“This finding shows us that living plants and animals can reach Antarctica across the ocean, with temperate and sub-Antarctic marine species probably bombarding Antarctic coastlines all the time,” said Ceridwen Fraser, of the Australian National University.

“We always thought Antarctic plants and animals were distinct because they were isolated, but this research now suggests these differences are almost entirely due to environmental extremes, not isolation.”

Dr Fraser and her colleagues report in the journal Nature Climate Change that strands of southern bull kelp, Durvillaea antarctica, found by a Chilean scientist, must have floated 20,000 km from the Kerguelen Islands and South Georgia. The kelp was encrusted with barnacles, evidence of a long time adrift.

In fact, researchers believe, it may be evidence of the longest episode of “biological rafting” ever confirmed. The word raft is significant: such floating platforms could provide shelter and transport for other biological invaders.

Plastic next?

Until now, the assumption has been that the pattern of surface currents and westerly winds tends to drive drifting material northwards from Antarctica. The discovery suggests that if kelp can get there, so can floating driftwood, or plastic debris, or any other unwelcome visitor.

The researchers think large waves driven by Southern Ocean storms may have steered the kelp rafts over what had been considered a natural ocean barrier. Global warming has begun to change conditions in Antarctica, and the continent – considered the last great tract of terrain unmarked by human colonisation – could become increasingly vulnerable to change.

“This is an unequivocal demonstration that marine species from the north can reach Antarctica. To get there the kelp had to pass through barriers created by polar winds and currents that were, until now, thought to be impenetrable,” Dr Fraser said.

“Our findings also indicate that plants and animals living on Antarctica could be more vulnerable to climate change than we suspected.” – Climate News Network

Past warming shows 2°C brink may be close

Once again, past warming warns of the power of climate change. The surprise is that it doesn’t take much warming to raise sea levels six metres.

LONDON, 10 July, 2018 – Even if the world’s nations keep their promise to contain global warming to within 2°C, past warming shows that the Earth will still change visibly – and perhaps sooner than science currently expects.

Sea levels could rise by six metres.  Large tracts of the polar ice caps could collapse. The Sahara could become green. The edges of what are now tropical forests could turn into savannah, to be seared and maintained by regular outbreaks of fire. The northern forests could move 200 km nearer the north pole and, ahead of them, the tundra.

That is what will happen, if the past is a sure guide to the present. A 2°C rise in temperature is the maximum agreed by 195 nations when they met in Paris in 2015, a promise that can be maintained only by reducing carbon dioxide emissions, chiefly by switching rapidly from fossil fuels to renewable sources such as solar and wind power.

Three times in the last 3.5 million years, the planetary thermometer has risen, to up to 2°C higher than those temperatures humans enjoyed for most of the last 2,000 years. And three times the global climate has changed in response.

What is less certain is the rate of change: a six metre rise in sea levels fuelled by the thermal expansion of the oceans and the loss of the world’s glaciers, and the retreat of the Greenland and Antarctic ice caps, could take thousands of years. But once such changes began it would be very difficult to halt or reverse them.

“The carbon budget to avoid 2°C warming may be far smaller than estimated, leaving very little margin of error”

All geology is based on an axiom that the present is the key to the past: landscape around us tells a story of the conditions under which the rocks were formed. It follows that the past should also foretell the possibilities of the future, and researchers from 17 nations report in the journal Nature Geoscience that they looked again at three recent intervals when the world was warmer.

One of these began at the close of the Ice Age, 9000 to 5000 years ago; one between the last two ice ages 129,000 to 116,000 years ago; and one from a warm period known as the mid-Pliocene 3.3 to 3 million years ago. The first two were responses to very subtle but predictable shifts in the planet’s orbit.

But the oldest of these warmings was driven by an increase of carbon dioxide in the atmosphere to between 350 and 450 parts per million. These are levels that match those of today, as a consequence of 200 years of fossil fuel exploitation.

The research raises questions about the completeness of the climate models now used by scientists to predict future change.

Slow to act

As ice retreats and vegetation cover changes, so does the traffic in carbon between living things and the rocks, ocean and atmosphere. And the catch – for climate modellers – is that although the world’s nations promised to act, action so far has been slow. Fossil fuel is still “business as usual”. And this inevitably will play into the calculations in unpredictable ways.

“While climate model predictions seem to be trustworthy when considering relatively small changes over the next decades, it is worrisome that these models likely underestimate climate change under higher emission scenarios, such as a ‘business as usual’ scenario, and especially over longer time scales,” said one of the scientists, Katrin Meissner, of the University of New South Wales, in Australia.

And Hubertus Fischer, of the University of Bern, in Switzerland, who led the study, said: “Observations of past warming periods suggest that a number of amplifying mechanisms, which are poorly represented in climate models, increase long-term warming beyond climate model projections.

“This suggests the carbon budget to avoid 2°C warming may be far smaller than estimated, leaving very little margin of error to meet the Paris targets.” – Climate News Network

Once again, past warming warns of the power of climate change. The surprise is that it doesn’t take much warming to raise sea levels six metres.

LONDON, 10 July, 2018 – Even if the world’s nations keep their promise to contain global warming to within 2°C, past warming shows that the Earth will still change visibly – and perhaps sooner than science currently expects.

Sea levels could rise by six metres.  Large tracts of the polar ice caps could collapse. The Sahara could become green. The edges of what are now tropical forests could turn into savannah, to be seared and maintained by regular outbreaks of fire. The northern forests could move 200 km nearer the north pole and, ahead of them, the tundra.

That is what will happen, if the past is a sure guide to the present. A 2°C rise in temperature is the maximum agreed by 195 nations when they met in Paris in 2015, a promise that can be maintained only by reducing carbon dioxide emissions, chiefly by switching rapidly from fossil fuels to renewable sources such as solar and wind power.

Three times in the last 3.5 million years, the planetary thermometer has risen, to up to 2°C higher than those temperatures humans enjoyed for most of the last 2,000 years. And three times the global climate has changed in response.

What is less certain is the rate of change: a six metre rise in sea levels fuelled by the thermal expansion of the oceans and the loss of the world’s glaciers, and the retreat of the Greenland and Antarctic ice caps, could take thousands of years. But once such changes began it would be very difficult to halt or reverse them.

“The carbon budget to avoid 2°C warming may be far smaller than estimated, leaving very little margin of error”

All geology is based on an axiom that the present is the key to the past: landscape around us tells a story of the conditions under which the rocks were formed. It follows that the past should also foretell the possibilities of the future, and researchers from 17 nations report in the journal Nature Geoscience that they looked again at three recent intervals when the world was warmer.

One of these began at the close of the Ice Age, 9000 to 5000 years ago; one between the last two ice ages 129,000 to 116,000 years ago; and one from a warm period known as the mid-Pliocene 3.3 to 3 million years ago. The first two were responses to very subtle but predictable shifts in the planet’s orbit.

But the oldest of these warmings was driven by an increase of carbon dioxide in the atmosphere to between 350 and 450 parts per million. These are levels that match those of today, as a consequence of 200 years of fossil fuel exploitation.

The research raises questions about the completeness of the climate models now used by scientists to predict future change.

Slow to act

As ice retreats and vegetation cover changes, so does the traffic in carbon between living things and the rocks, ocean and atmosphere. And the catch – for climate modellers – is that although the world’s nations promised to act, action so far has been slow. Fossil fuel is still “business as usual”. And this inevitably will play into the calculations in unpredictable ways.

“While climate model predictions seem to be trustworthy when considering relatively small changes over the next decades, it is worrisome that these models likely underestimate climate change under higher emission scenarios, such as a ‘business as usual’ scenario, and especially over longer time scales,” said one of the scientists, Katrin Meissner, of the University of New South Wales, in Australia.

And Hubertus Fischer, of the University of Bern, in Switzerland, who led the study, said: “Observations of past warming periods suggest that a number of amplifying mechanisms, which are poorly represented in climate models, increase long-term warming beyond climate model projections.

“This suggests the carbon budget to avoid 2°C warming may be far smaller than estimated, leaving very little margin of error to meet the Paris targets.” – Climate News Network

Rising seas’ cost may be $27tn a year by 2100

In 80 years the rising seas’ cost may be $27tn a year globally, with the oceans possibly nearing two metres above their present levels.

LONDON, 4 July, 2018 – The rising seas’ cost may be US$27tn a year for the world by 2100 if it fails to meet the UN’s 2ºC global warming limit by then, with sea level rise of, at its worst, almost six feet (nearly two metres), new research says.

A study led by the UK’s National Oceanography Centre (NOC) says the worldwide cost of flooding caused by rising sea levels, at their median level, could by 2100 be $14 trillion, if governments miss the United Nations target of keeping the rise in global temperatures, caused by unremitting fossil fuel use, to less than 2ºC above pre-industrial levels. But the extent and cost could be much higher.

The target was agreed by 195 nations in Paris in 2015, with many politicians and most scientists urging them to treat 2ºC as a more modest and feasible limit while aiming if possible for 1.5°C. The cuts in greenhouse gas emissions already promised through the UN Framework Convention on Climate Change are not yet enough to achieve the 2ºC limit, let alone the more stringent figure, and much deeper cuts will be needed.

“These results place further emphasis on putting even greater efforts into mitigating rising global temperatures”

The researchers also found that it was upper-middle income countries such as China that would see the largest increase in flood costs, while the richest ones would suffer the least, because of the high levels of protection infrastructure they already enjoyed. The research is published in the journal Environmental Research Letters.

Svetlana Jevrejeva of the NOC is the study’s lead author. She said: “More than 600 million people live in low-elevation coastal areas, less than 10 metres above sea level. In a warming climate, global sea level will rise due to the melting of land-based glaciers and ice sheets, and from the thermal expansion of ocean waters. So sea level rise is one of the most damaging aspects of our warming climate.”

The researchers explored the pace and consequences of global and regional sea level rise under warming limited to both 1.5 ºC and 2 ºC, and compared their findings with projections for unmitigated warming.

Using World Bank income groups (high, upper-middle, lower-middle and low income countries), they then assessed the impact of sea level rise in coastal areas from a global perspective.

Steep increase

Dr Jevrejeva said: “We found that with a temperature rise trajectory of 1.5°C, by 2100 the median sea level will have risen by 0.52m (1.7ft). But, if the 2°C target is missed, we will see a median sea level rise of 0.86m (2.8ft), and a worst-case rise of 1.8m (5.9ft).”

If warming was not mitigated the global annual flood costs without adaptation would increase to $14tn annually for the median sea level rise of 0.86m, and up to $27tn per year for 1.8m. This would account for 2.8% of global GDP in 2100.

The conclusions she and her colleagues reached sound hair-raising and possibly far-fetched. But an earlier study put the possible global cost by 2100 of coastal flooding at nearly four times more than the NOC team – $100tn.

Another group of researchers suggested that if global warming continued at its present rate it could start a process in Antarctica which would lead ultimately to sea level rise of almost three metres.

Impact on tropics

The projected difference in coastal sea levels is also likely to mean that tropical areas will see very high sea levels more often, the study says.

“These extreme sea levels will have a negative effect on the economies of developing coastal nations, and the habitability of low-lying coastlines,” said Dr Jevrejeva.

“Small, low-lying island nations such as the Maldives will be very easily affected, and the pressures on their natural resources and environment will become even greater.

“These results place further emphasis on putting even greater efforts into mitigating rising global temperatures.” – Climate News Network

In 80 years the rising seas’ cost may be $27tn a year globally, with the oceans possibly nearing two metres above their present levels.

LONDON, 4 July, 2018 – The rising seas’ cost may be US$27tn a year for the world by 2100 if it fails to meet the UN’s 2ºC global warming limit by then, with sea level rise of, at its worst, almost six feet (nearly two metres), new research says.

A study led by the UK’s National Oceanography Centre (NOC) says the worldwide cost of flooding caused by rising sea levels, at their median level, could by 2100 be $14 trillion, if governments miss the United Nations target of keeping the rise in global temperatures, caused by unremitting fossil fuel use, to less than 2ºC above pre-industrial levels. But the extent and cost could be much higher.

The target was agreed by 195 nations in Paris in 2015, with many politicians and most scientists urging them to treat 2ºC as a more modest and feasible limit while aiming if possible for 1.5°C. The cuts in greenhouse gas emissions already promised through the UN Framework Convention on Climate Change are not yet enough to achieve the 2ºC limit, let alone the more stringent figure, and much deeper cuts will be needed.

“These results place further emphasis on putting even greater efforts into mitigating rising global temperatures”

The researchers also found that it was upper-middle income countries such as China that would see the largest increase in flood costs, while the richest ones would suffer the least, because of the high levels of protection infrastructure they already enjoyed. The research is published in the journal Environmental Research Letters.

Svetlana Jevrejeva of the NOC is the study’s lead author. She said: “More than 600 million people live in low-elevation coastal areas, less than 10 metres above sea level. In a warming climate, global sea level will rise due to the melting of land-based glaciers and ice sheets, and from the thermal expansion of ocean waters. So sea level rise is one of the most damaging aspects of our warming climate.”

The researchers explored the pace and consequences of global and regional sea level rise under warming limited to both 1.5 ºC and 2 ºC, and compared their findings with projections for unmitigated warming.

Using World Bank income groups (high, upper-middle, lower-middle and low income countries), they then assessed the impact of sea level rise in coastal areas from a global perspective.

Steep increase

Dr Jevrejeva said: “We found that with a temperature rise trajectory of 1.5°C, by 2100 the median sea level will have risen by 0.52m (1.7ft). But, if the 2°C target is missed, we will see a median sea level rise of 0.86m (2.8ft), and a worst-case rise of 1.8m (5.9ft).”

If warming was not mitigated the global annual flood costs without adaptation would increase to $14tn annually for the median sea level rise of 0.86m, and up to $27tn per year for 1.8m. This would account for 2.8% of global GDP in 2100.

The conclusions she and her colleagues reached sound hair-raising and possibly far-fetched. But an earlier study put the possible global cost by 2100 of coastal flooding at nearly four times more than the NOC team – $100tn.

Another group of researchers suggested that if global warming continued at its present rate it could start a process in Antarctica which would lead ultimately to sea level rise of almost three metres.

Impact on tropics

The projected difference in coastal sea levels is also likely to mean that tropical areas will see very high sea levels more often, the study says.

“These extreme sea levels will have a negative effect on the economies of developing coastal nations, and the habitability of low-lying coastlines,” said Dr Jevrejeva.

“Small, low-lying island nations such as the Maldives will be very easily affected, and the pressures on their natural resources and environment will become even greater.

“These results place further emphasis on putting even greater efforts into mitigating rising global temperatures.” – Climate News Network

West Antarctica’s rocks’ rise may slow ice melt

The southern continent is changing fast. West Antarctica’s rocks are on the rise, something which could slow the rate of ice melt.

LONDON, 26 June, 2018 – Its ice sheet may be melting, but West Antarctica’s rocks are on the way up. In a dramatic demonstration of geology’s in-depth response to surface change, the submerged bedrock of that part of the southern continent is springing upwards at 41mm a year.

And as it does so, it may slow the rate of inexorable ice melt, as the western part of the continent sheds ice in response to global warming driven by profligate human combustion of fossil fuels.

But for the moment the finding is yet another surprising demonstration of what geophysicists call isostatic response: as mass is shifted from the surface of the continent – and that region of Antarctica has lost three trillion metric tons of ice in the last 25 years – the semi-liquid rocks of the Earth’s mantle, deep below the continental crust, flow below the lightening burden to liftthe crustal rocks higher.

This rate of rise is unexpectedly rapid. As more ice melts, the process is likely to accelerate. A century from now, that stretch of Antarctic peninsula could have risen by 8 metres.

“To keep global sea levels from rising more than a few feet this century and beyond, we must still limit greenhouse gas concentrations in the atmosphere”

“When the ice melts and gets thinner, the Earth readjusts, and rises immediately by a few millimetres, which depends on the ice lost,” said Valentina Barletta, of the Technical University of Denmark, who led the research.

“But the earth also acts a bit like a very hard memory-foam mattress. And it slowly keeps readjusting for several thousand years after the melting. In Scandinavia the bedrock is still rising about 10 millimetres per year because of the last ice age.”

Dr Barletta and US colleagues report in the journal Science that they gathered data from six global positioning satellite stations fixed to the exposed rock around a stretch of West Antarctica called the Amundsen Sea embayment.

They coupled that with seismic studies of the crustal bedrock and then ran an immense number of computer simulations to settle on the most likely explanation – that deep beneath that point of the southern continent, the Earth’s mantle was relatively hotter and more fluid, and could respond to changes in mass more swiftly.

Polar perplexities

At the heart of such research is the puzzle of southern polar dynamics: the complex interplay of ocean, atmosphere, precipitation and topography that keeps Antarctica the coldest, driest, iciest place on the planet: it may be technically a desert, but its continental crust carries almost two thirds of the world’s freshwater in frozen form. If it all melted, global sea levels would rise by 70 metres.

But such is the weight of ice that some parts of the continent are depressed below sea level. In West Antarctica the surrounding sea ice is so thick it is anchored to submerged bedrock, to provide a buffer that slows the rate of glacial flow from inland.

Right now, the West Antarctic Ice Sheet is spilling into the oceans the equivalent of a quarter of all the planet’s melting ice. If all of West Antarctica were to melt, global sea levels would rise by three metres.

And the fear is that, as the oceans and atmosphere warm in response to ever-rising levels of greenhouse gases in the atmosphere, winds and currents could loosen the great shelves of sea ice and send them floating north, at which point the glacial flow from the high ground of the continent to the sea would accelerate.

Stability explained

So the latest discovery helps explain the wider puzzle of why Antarctica’s ice has been relatively stable over long geological periods: as the ice melts, the bedrock rises, and the ice shelves are more likely to stay anchored to the mainland, at least at that particular “pinning point” above a hotter, more fluid mantle.

There is another factor at work: the gravitational pull of the ice itself, which raises sea level near the great mass of ancient polar ice. As the ice melts, the gravitational tug diminishes, and the sea levels subside.

“The lowering of the sea level, the rising of the pinning points and the decrease of the inland slope due to the uplift of the bedrock are all feedbacks that can stabilise the ice sheet,” said Terry Wilson, of Ohio State University, and one of the authors. “Under many realistic climate models, this should be enough to stabilise the ice sheet.”

But as planetary average temperatures rise, so does the hazard. Rick Aster, of Colorado State University, and another of the authors, warned: “To keep global sea levels from rising more than a few feet this century and beyond, we must still limit greenhouse gas concentrations in the atmosphere, which can only occur through international cooperation and innovation.” – Climate News Network

The southern continent is changing fast. West Antarctica’s rocks are on the rise, something which could slow the rate of ice melt.

LONDON, 26 June, 2018 – Its ice sheet may be melting, but West Antarctica’s rocks are on the way up. In a dramatic demonstration of geology’s in-depth response to surface change, the submerged bedrock of that part of the southern continent is springing upwards at 41mm a year.

And as it does so, it may slow the rate of inexorable ice melt, as the western part of the continent sheds ice in response to global warming driven by profligate human combustion of fossil fuels.

But for the moment the finding is yet another surprising demonstration of what geophysicists call isostatic response: as mass is shifted from the surface of the continent – and that region of Antarctica has lost three trillion metric tons of ice in the last 25 years – the semi-liquid rocks of the Earth’s mantle, deep below the continental crust, flow below the lightening burden to liftthe crustal rocks higher.

This rate of rise is unexpectedly rapid. As more ice melts, the process is likely to accelerate. A century from now, that stretch of Antarctic peninsula could have risen by 8 metres.

“To keep global sea levels from rising more than a few feet this century and beyond, we must still limit greenhouse gas concentrations in the atmosphere”

“When the ice melts and gets thinner, the Earth readjusts, and rises immediately by a few millimetres, which depends on the ice lost,” said Valentina Barletta, of the Technical University of Denmark, who led the research.

“But the earth also acts a bit like a very hard memory-foam mattress. And it slowly keeps readjusting for several thousand years after the melting. In Scandinavia the bedrock is still rising about 10 millimetres per year because of the last ice age.”

Dr Barletta and US colleagues report in the journal Science that they gathered data from six global positioning satellite stations fixed to the exposed rock around a stretch of West Antarctica called the Amundsen Sea embayment.

They coupled that with seismic studies of the crustal bedrock and then ran an immense number of computer simulations to settle on the most likely explanation – that deep beneath that point of the southern continent, the Earth’s mantle was relatively hotter and more fluid, and could respond to changes in mass more swiftly.

Polar perplexities

At the heart of such research is the puzzle of southern polar dynamics: the complex interplay of ocean, atmosphere, precipitation and topography that keeps Antarctica the coldest, driest, iciest place on the planet: it may be technically a desert, but its continental crust carries almost two thirds of the world’s freshwater in frozen form. If it all melted, global sea levels would rise by 70 metres.

But such is the weight of ice that some parts of the continent are depressed below sea level. In West Antarctica the surrounding sea ice is so thick it is anchored to submerged bedrock, to provide a buffer that slows the rate of glacial flow from inland.

Right now, the West Antarctic Ice Sheet is spilling into the oceans the equivalent of a quarter of all the planet’s melting ice. If all of West Antarctica were to melt, global sea levels would rise by three metres.

And the fear is that, as the oceans and atmosphere warm in response to ever-rising levels of greenhouse gases in the atmosphere, winds and currents could loosen the great shelves of sea ice and send them floating north, at which point the glacial flow from the high ground of the continent to the sea would accelerate.

Stability explained

So the latest discovery helps explain the wider puzzle of why Antarctica’s ice has been relatively stable over long geological periods: as the ice melts, the bedrock rises, and the ice shelves are more likely to stay anchored to the mainland, at least at that particular “pinning point” above a hotter, more fluid mantle.

There is another factor at work: the gravitational pull of the ice itself, which raises sea level near the great mass of ancient polar ice. As the ice melts, the gravitational tug diminishes, and the sea levels subside.

“The lowering of the sea level, the rising of the pinning points and the decrease of the inland slope due to the uplift of the bedrock are all feedbacks that can stabilise the ice sheet,” said Terry Wilson, of Ohio State University, and one of the authors. “Under many realistic climate models, this should be enough to stabilise the ice sheet.”

But as planetary average temperatures rise, so does the hazard. Rick Aster, of Colorado State University, and another of the authors, warned: “To keep global sea levels from rising more than a few feet this century and beyond, we must still limit greenhouse gas concentrations in the atmosphere, which can only occur through international cooperation and innovation.” – Climate News Network

Antarctic buffer damage spurs ice break-up

The Antarctic buffer which has for millennia sheltered the continent’s huge inland ice sheet is being battered by seaborne wave action.

LONDON, 21 June, 2018 – The vast southern ice sheet, despite the Antarctic buffer which has protected it for so long, is now being threatened by ocean swells chipping away at the continent’s coastal edge, says a new study by US scientists published in the journal Nature.

For millennia the southern ice sheet has had this protective buffer of sea ice ringing its coastal shelves. But now the swells from the north are flexing them and can weaken their stabilising seaward edge. Regular inundation by summer meltwater as the edge breaks away can also contribute to rapid ice shelf disintegration.

Ice shelves, with their ring of sea ice, are thick plates of ice fed by tributary glaciers, floating seaward extensions of the massive grounded inland ice sheet. They slow the flow of ice from the sheet, so rapidly disintegrating shelves have implications for sea level rise.

“Sea ice here acts like the bumpers on a car – with the bumpers in place, the car can take a shock and not be damaged. Take them off, and every hit adds up,” said Ted Scambos, study co-author and senior research scientist at the National Snow and Ice Data Center at the University of Colorado Boulder.

Since 1995, three large ice shelves on the Antarctic Peninsula – Larsen A, Larsen B and Wilkins – have suddenly and dramatically disintegrated.
Occurring over a few weeks, or sometimes even only a few days, these break-ups mark an unprecedented departure from the more typical and natural recurring calving of larger icebergs every decade or so.

Trigger found

Until recently researchers had thought intense surface melting caused by a warming climate and ice fracturing were the sole culprits. But the new findings suggest that loss of sea ice and the calving of the seaward edge into narrow sliver-like icebergs are the trigger that sets off a rapid ice shelf disintegration.

“Our study breaks new ground in how it implicates sea ice change in sea level rise,” said Rob Massom, the study’s lead author and a senior research scientist at the Australian Antarctic Division and Antarctic Climate and Ecosystems Cooperative Research Centre.

“It introduces ocean wave-induced breakage of the outer margins of ice shelves following loss of a protective sea ice buffer as the straw that breaks the camel’s back.”

He and his colleagues analysed disintegrations on three ice shelves that had been stable for centuries or even millennia: Larsen A in 1995, Larsen B in 2002, and Wilkins in 2008 and 2009.

They confirmed that atmospheric warming led to increased meltwater on the surfaces of the shelves. Pooled meltwater then percolated downward through crevasses, setting off a hydrofracturing process that weakened the ice.

“Ocean wave-induced breakage of the outer margins of ice shelves following loss of a protective sea ice buffer [is] the straw that breaks the camel’s back”

Earlier studies have identified the central role that ice shelves play in making sea level rise more likely and the accelerating pace of Antarctic melting.

But, crucially, what the NSIDC analysis reveals is a previously little-recognised link to sea ice: all three disintegrations happened when there was little or no sea ice cover along the shelf edge. Without that protective buffer, the shelves became exposed to waves which flexed the already fractured ice.

“What we’ve found is that increased flexing of the outer parts of ice shelves by waves sets the ice up for destruction. Even though the movement is tiny, over time the shelf is weakened,” Scambos said.

In each case, ocean swells began affecting the ice shelf edge. As the shelves flexed, existing fractures along the seaward edge chipped off as long, thin, sliver-shaped icebergs, not the larger tabular icebergs more typical of Antarctic ice shelf calvings. The remaining ice shelf was then ripe for runaway collapse.

“Other ice shelves can survive for centuries if they don’t have surface meltwater – or if the water can run off easily,” Scambos said. “But with meltwater ponding and a legacy of weakening from sea ice loss, you can destroy a shelf in just a few weeks.”

Pressure off

Because ice shelves are already floating in the ocean and displacing their volume, like ice cubes in a glass of water, their disintegration does not contribute directly to sea level rise.

But they do provide a backpressure that moderates glacier flow speed. Once they’re gone, so is the backpressure, allowing the glaciers to flow more rapidly into the ocean and ultimately contribute to sea level rise.

“This represents an important pathway towards reducing current large uncertainty in predictions of the response of the Antarctic cryosphere to climate change and its contribution to sea level rise,” Dr Massom said.

The Antarctic ice sheet contains enough ice to raise sea level by approximately 57 metres (187 feet), about half the length of a soccer pitch. Worldwide, more than 100 million people currently live within 1m of mean sea level. – Climate News Network

The Antarctic buffer which has for millennia sheltered the continent’s huge inland ice sheet is being battered by seaborne wave action.

LONDON, 21 June, 2018 – The vast southern ice sheet, despite the Antarctic buffer which has protected it for so long, is now being threatened by ocean swells chipping away at the continent’s coastal edge, says a new study by US scientists published in the journal Nature.

For millennia the southern ice sheet has had this protective buffer of sea ice ringing its coastal shelves. But now the swells from the north are flexing them and can weaken their stabilising seaward edge. Regular inundation by summer meltwater as the edge breaks away can also contribute to rapid ice shelf disintegration.

Ice shelves, with their ring of sea ice, are thick plates of ice fed by tributary glaciers, floating seaward extensions of the massive grounded inland ice sheet. They slow the flow of ice from the sheet, so rapidly disintegrating shelves have implications for sea level rise.

“Sea ice here acts like the bumpers on a car – with the bumpers in place, the car can take a shock and not be damaged. Take them off, and every hit adds up,” said Ted Scambos, study co-author and senior research scientist at the National Snow and Ice Data Center at the University of Colorado Boulder.

Since 1995, three large ice shelves on the Antarctic Peninsula – Larsen A, Larsen B and Wilkins – have suddenly and dramatically disintegrated.
Occurring over a few weeks, or sometimes even only a few days, these break-ups mark an unprecedented departure from the more typical and natural recurring calving of larger icebergs every decade or so.

Trigger found

Until recently researchers had thought intense surface melting caused by a warming climate and ice fracturing were the sole culprits. But the new findings suggest that loss of sea ice and the calving of the seaward edge into narrow sliver-like icebergs are the trigger that sets off a rapid ice shelf disintegration.

“Our study breaks new ground in how it implicates sea ice change in sea level rise,” said Rob Massom, the study’s lead author and a senior research scientist at the Australian Antarctic Division and Antarctic Climate and Ecosystems Cooperative Research Centre.

“It introduces ocean wave-induced breakage of the outer margins of ice shelves following loss of a protective sea ice buffer as the straw that breaks the camel’s back.”

He and his colleagues analysed disintegrations on three ice shelves that had been stable for centuries or even millennia: Larsen A in 1995, Larsen B in 2002, and Wilkins in 2008 and 2009.

They confirmed that atmospheric warming led to increased meltwater on the surfaces of the shelves. Pooled meltwater then percolated downward through crevasses, setting off a hydrofracturing process that weakened the ice.

“Ocean wave-induced breakage of the outer margins of ice shelves following loss of a protective sea ice buffer [is] the straw that breaks the camel’s back”

Earlier studies have identified the central role that ice shelves play in making sea level rise more likely and the accelerating pace of Antarctic melting.

But, crucially, what the NSIDC analysis reveals is a previously little-recognised link to sea ice: all three disintegrations happened when there was little or no sea ice cover along the shelf edge. Without that protective buffer, the shelves became exposed to waves which flexed the already fractured ice.

“What we’ve found is that increased flexing of the outer parts of ice shelves by waves sets the ice up for destruction. Even though the movement is tiny, over time the shelf is weakened,” Scambos said.

In each case, ocean swells began affecting the ice shelf edge. As the shelves flexed, existing fractures along the seaward edge chipped off as long, thin, sliver-shaped icebergs, not the larger tabular icebergs more typical of Antarctic ice shelf calvings. The remaining ice shelf was then ripe for runaway collapse.

“Other ice shelves can survive for centuries if they don’t have surface meltwater – or if the water can run off easily,” Scambos said. “But with meltwater ponding and a legacy of weakening from sea ice loss, you can destroy a shelf in just a few weeks.”

Pressure off

Because ice shelves are already floating in the ocean and displacing their volume, like ice cubes in a glass of water, their disintegration does not contribute directly to sea level rise.

But they do provide a backpressure that moderates glacier flow speed. Once they’re gone, so is the backpressure, allowing the glaciers to flow more rapidly into the ocean and ultimately contribute to sea level rise.

“This represents an important pathway towards reducing current large uncertainty in predictions of the response of the Antarctic cryosphere to climate change and its contribution to sea level rise,” Dr Massom said.

The Antarctic ice sheet contains enough ice to raise sea level by approximately 57 metres (187 feet), about half the length of a soccer pitch. Worldwide, more than 100 million people currently live within 1m of mean sea level. – Climate News Network