Tag Archives: Sea levels

Rising tides will leave no choice for US millions

Time and tide wait for no-one. As sea levels rise, the rising tides will become more impatient. Millions of Americans will have to migrate.

LONDON, 26 February, 2020 – The Texan city of Houston is about to grow in unexpected ways, thanks to the rising tides. So will Dallas. Real estate agents in Atlanta, Georgia; Denver, Colorado; and Las Vegas, Nevada could expect to do roaring business.

The inland counties around Los Angeles, and close to New Orleans in Louisiana, will suddenly get a little more crowded. And from Boston in the north-east to the tip of Florida, Americans will be on the move.

That is because an estimated 13 million US citizens could some time in this century become climate refugees, driven from their seaside homes by sea level rise of possibly 1.8 metres, according to new research.

And they will have to move home in a poorer economic climate: worldwide. If governments and city authorities do not take the right steps, sea level rise could erode 4% of the global annual economy, says a separate study. That is, coast-dwellers could witness not just their towns and even cities washed away: they could see their prosperity go under as well.

Californian scientists report in the Public Library of Science journal PLOS One that they used machine learning techniques – in effect, artificial intelligence systems – to calculate what is most likely to happen as US citizens desert Delaware Bay, slip away from the cities of North and South Carolina, and flee Florida in the face of rising sea levels, coastal flooding and increasingly catastrophic windstorms.

“Sea level rise will affect every county in the United States … everybody should care about sea level rise, whether they live on the coast or not”

In the year 2000, a third of all the planet’s urban land was in a zone vulnerable to flood. By 2040, this could rise to 40%. In 2010, in the US, more than 120m citizens – that is nearly 40% of the entire population – lived in coastal counties. By 2020, this proportion could already be higher.

And by 2100, at least 13.1m people could be living on land likely to be inundated if sea levels rise by 1.8 metres. Except that they won’t: they will have already seen the future and moved away from it, to some settlement well away from the rising tides.

Those who might otherwise have purchased their abandoned seaside houses will be looking for somewhere safer and adding to the pressure on the housing market.

“Sea level rise will affect every county in the United States,” said Bistra Dilkina of the University of Southern California at Irvine, a computer scientist who worked with engineers to model the human response to the future.

She and her colleagues started from patterns of movement that began with Hurricane Katrina, in 2004, and Hurricane Rita a year later, both in Louisiana. They then let the algorithms take over the challenge of guessing what American families and businesses are most likely to do as the tides begin to flood the high streets.

Action promised

“We hope this research will empower urban planners and local decision-makers to prepare to accept populations displaced by sea level rise. Our findings indicate that everybody should care about sea level rise, whether they live on the coast or not,” she said.

The California team’s worst-case forecasts are based on a premise that the world takes no real action to combat sea level rise, which is driven by global warming powered in turn by fossil fuel emissions into the atmosphere on an ever-increasing scale.

But in Paris in 2015, more than 190 nations did agree to act: to contain global warming to “well below” 2°C by the century’s end. So far, very few have committed to sufficient action, and the President of the US has pronounced climate change a “hoax” and announced a withdrawal from the Paris Agreement.

Researchers in Austria report in the journal Environmental Research Communications that they decided to consider the potential economic cost worldwide of sea level rise alone. Scientists have been trying for years to guess the cost of flood damage to come: the latest study is of the impact of sea level rise and coastal flooding upon national economies worldwide.

The scientists considered two scenarios, including one in which the world kept the promises made in Paris, and one in which it did not, and made no attempt to adapt to or mitigate climate change.

Significant impact

By 2050 losses in each scenario would be significant and much the same. But by 2100, the do-nothing option promised to hit the gross domestic product – an economist’s favourite measure of economic well-being – by 4%.

Europe and Japan would be significantly hit; China , India and Canada hardest of all. If the world’s richest nations actually worked to limit climate change and adapt to the challenges ahead, the impact on the economy could be limited to 1%.

“The findings of this paper demonstrate that we need to think long term while acting swiftly,” said Thomas Schinko of the International Institute for Applied Systems Analysis in Austria, who led the study.

“Macroeconomic impacts up to and beyond 2050 as a result of coastal flooding due to sea level rise – not taking into account any other climate-related impacts such as drought – are severe and increasing.

“We, as a global society, need to further co-ordinate mitigation, adaptation and climate-resilient development and consider where we build cities and situate important infrastructure.” – Climate News Network

Time and tide wait for no-one. As sea levels rise, the rising tides will become more impatient. Millions of Americans will have to migrate.

LONDON, 26 February, 2020 – The Texan city of Houston is about to grow in unexpected ways, thanks to the rising tides. So will Dallas. Real estate agents in Atlanta, Georgia; Denver, Colorado; and Las Vegas, Nevada could expect to do roaring business.

The inland counties around Los Angeles, and close to New Orleans in Louisiana, will suddenly get a little more crowded. And from Boston in the north-east to the tip of Florida, Americans will be on the move.

That is because an estimated 13 million US citizens could some time in this century become climate refugees, driven from their seaside homes by sea level rise of possibly 1.8 metres, according to new research.

And they will have to move home in a poorer economic climate: worldwide. If governments and city authorities do not take the right steps, sea level rise could erode 4% of the global annual economy, says a separate study. That is, coast-dwellers could witness not just their towns and even cities washed away: they could see their prosperity go under as well.

Californian scientists report in the Public Library of Science journal PLOS One that they used machine learning techniques – in effect, artificial intelligence systems – to calculate what is most likely to happen as US citizens desert Delaware Bay, slip away from the cities of North and South Carolina, and flee Florida in the face of rising sea levels, coastal flooding and increasingly catastrophic windstorms.

“Sea level rise will affect every county in the United States … everybody should care about sea level rise, whether they live on the coast or not”

In the year 2000, a third of all the planet’s urban land was in a zone vulnerable to flood. By 2040, this could rise to 40%. In 2010, in the US, more than 120m citizens – that is nearly 40% of the entire population – lived in coastal counties. By 2020, this proportion could already be higher.

And by 2100, at least 13.1m people could be living on land likely to be inundated if sea levels rise by 1.8 metres. Except that they won’t: they will have already seen the future and moved away from it, to some settlement well away from the rising tides.

Those who might otherwise have purchased their abandoned seaside houses will be looking for somewhere safer and adding to the pressure on the housing market.

“Sea level rise will affect every county in the United States,” said Bistra Dilkina of the University of Southern California at Irvine, a computer scientist who worked with engineers to model the human response to the future.

She and her colleagues started from patterns of movement that began with Hurricane Katrina, in 2004, and Hurricane Rita a year later, both in Louisiana. They then let the algorithms take over the challenge of guessing what American families and businesses are most likely to do as the tides begin to flood the high streets.

Action promised

“We hope this research will empower urban planners and local decision-makers to prepare to accept populations displaced by sea level rise. Our findings indicate that everybody should care about sea level rise, whether they live on the coast or not,” she said.

The California team’s worst-case forecasts are based on a premise that the world takes no real action to combat sea level rise, which is driven by global warming powered in turn by fossil fuel emissions into the atmosphere on an ever-increasing scale.

But in Paris in 2015, more than 190 nations did agree to act: to contain global warming to “well below” 2°C by the century’s end. So far, very few have committed to sufficient action, and the President of the US has pronounced climate change a “hoax” and announced a withdrawal from the Paris Agreement.

Researchers in Austria report in the journal Environmental Research Communications that they decided to consider the potential economic cost worldwide of sea level rise alone. Scientists have been trying for years to guess the cost of flood damage to come: the latest study is of the impact of sea level rise and coastal flooding upon national economies worldwide.

The scientists considered two scenarios, including one in which the world kept the promises made in Paris, and one in which it did not, and made no attempt to adapt to or mitigate climate change.

Significant impact

By 2050 losses in each scenario would be significant and much the same. But by 2100, the do-nothing option promised to hit the gross domestic product – an economist’s favourite measure of economic well-being – by 4%.

Europe and Japan would be significantly hit; China , India and Canada hardest of all. If the world’s richest nations actually worked to limit climate change and adapt to the challenges ahead, the impact on the economy could be limited to 1%.

“The findings of this paper demonstrate that we need to think long term while acting swiftly,” said Thomas Schinko of the International Institute for Applied Systems Analysis in Austria, who led the study.

“Macroeconomic impacts up to and beyond 2050 as a result of coastal flooding due to sea level rise – not taking into account any other climate-related impacts such as drought – are severe and increasing.

“We, as a global society, need to further co-ordinate mitigation, adaptation and climate-resilient development and consider where we build cities and situate important infrastructure.” – Climate News Network

Record Antarctic temperatures fuel sea level worry


Sea levels may threaten coastal cities sooner than expected, scientists say, as ice loss speeds up and Antarctic temperatures rise.

LONDON, 20 February, 2020 − Across the world, people now alive in coastal areas may face dangerously rising seas within their lifetimes, as record Antarctic temperatures and rapid melting of the continent’s ice drive global sea levels upwards.

Temperatures on the Antarctic Peninsula reached more than 20°C for the first time in history earlier this month, the Guardian reported: “The 20.75C logged by Brazilian scientists at Seymour Island on 9 February was almost a full degree higher than the previous record of 19.8C, taken on Signy Island in January 1982.”

The Antarctic Peninsula has warmed by almost 3°C since the start of the Industrial Revolution around 200 years ago − faster than almost anywhere else on Earth. But scientists are increasingly concerned not only about the Peninsula, but with the possibility that the entire southern continent may be heating up much faster than current estimates suggest.

Among evidence of increasing scientific effort to determine what is happening is a joint UK-US collaboration, due to report in 2023 on the chances of the collapse of the huge Thwaites glacier in West Antarctica, where from 1992 to 2017 the annual rate of ice loss rose threefold.

Big speed-up

Now a study by scientists co-ordinated by Germany’s Potsdam Institute for Climate Impact Research (PIK) says sea level rise caused by Antarctica’s ice loss could become a major risk for coastal protection in the near future.

After what they call “an exceptionally comprehensive comparison of state-of-the-art computer models from around the world”, they conclude that Antarctica alone could cause global sea level to rise by 2100 by up to three times more than it did in the last century.

“The ‘Antarctica Factor’ turns out to be the greatest risk, and also the greatest uncertainty, for sea levels around the globe,” says the lead author, Anders Levermann of PIK and Columbia University’s Lamont-Doherty Earth Observatory (LDEO) in New York.

“While we saw about 19 centimetres of sea level rise in the past 100 years, Antarctic ice loss could lead to up to 58 centimetres within this century”, he said.

“We know for certain that not stopping the burning of coal, oil and gas will drive up the risks for coastal metropolises from New York to Mumbai, Hamburg and Shanghai”

“Coastal planning cannot merely rely on the best guess. It requires a risk analysis. Our study provides exactly that. The sea level contribution of Antarctica is very likely not going to be more than 58 centimetres.”

Thermal expansion of the oceans by global warming and the melting of glaciers, which so far have been the most important factors in sea level rise, will add to the contribution from Antarctic ice loss, making the overall sea level rise risk even bigger. But the ‘Antarctica Factor’ is about to become the most important element, according to the study, published in the journal Earth System Dynamics.

The range of sea-level rise estimates the scientists have come up with is fairly large. Assuming that humanity keeps on emitting greenhouse gases as before, they say, the range they call “very likely” to describe the future is between 6 and 58 cms for this century.

If greenhouse gas emissions were reduced rapidly, it would be between 4 and 37 cms. Importantly, the difference between a business-as-usual scenario and one of emissions reductions becomes substantially greater as time passes.

More robust insights

Sixteen ice sheet modelling groups consisting of 36 researchers from 27 institutes contributed to the new study. A similar study six years ago had to rely on the output of only five ice sheet models.

“The more computer simulation models we use, all of them with slightly different dynamic representations of the Antarctic ice sheet, the wider the range of results that we yield − but also the more robust the insights that we gain”, said co-author Sophie Nowicki of the NASA Goddard Space Flight Center.

“There are still large uncertainties, but we are constantly improving our understanding of the largest ice sheet on Earth. Comparing model outputs is a forceful tool to provide society with the necessary information for rational decisions.”

Over the long term, the Antarctic ice sheet has the potential ultimately to raise sea levels by many tens of metres. “What we know for certain”, said Professor Levermann, “is that not stopping the burning of coal, oil and gas will drive up the risks for coastal metropolises from New York to Mumbai, Hamburg and Shanghai.” − Climate News Network


Sea levels may threaten coastal cities sooner than expected, scientists say, as ice loss speeds up and Antarctic temperatures rise.

LONDON, 20 February, 2020 − Across the world, people now alive in coastal areas may face dangerously rising seas within their lifetimes, as record Antarctic temperatures and rapid melting of the continent’s ice drive global sea levels upwards.

Temperatures on the Antarctic Peninsula reached more than 20°C for the first time in history earlier this month, the Guardian reported: “The 20.75C logged by Brazilian scientists at Seymour Island on 9 February was almost a full degree higher than the previous record of 19.8C, taken on Signy Island in January 1982.”

The Antarctic Peninsula has warmed by almost 3°C since the start of the Industrial Revolution around 200 years ago − faster than almost anywhere else on Earth. But scientists are increasingly concerned not only about the Peninsula, but with the possibility that the entire southern continent may be heating up much faster than current estimates suggest.

Among evidence of increasing scientific effort to determine what is happening is a joint UK-US collaboration, due to report in 2023 on the chances of the collapse of the huge Thwaites glacier in West Antarctica, where from 1992 to 2017 the annual rate of ice loss rose threefold.

Big speed-up

Now a study by scientists co-ordinated by Germany’s Potsdam Institute for Climate Impact Research (PIK) says sea level rise caused by Antarctica’s ice loss could become a major risk for coastal protection in the near future.

After what they call “an exceptionally comprehensive comparison of state-of-the-art computer models from around the world”, they conclude that Antarctica alone could cause global sea level to rise by 2100 by up to three times more than it did in the last century.

“The ‘Antarctica Factor’ turns out to be the greatest risk, and also the greatest uncertainty, for sea levels around the globe,” says the lead author, Anders Levermann of PIK and Columbia University’s Lamont-Doherty Earth Observatory (LDEO) in New York.

“While we saw about 19 centimetres of sea level rise in the past 100 years, Antarctic ice loss could lead to up to 58 centimetres within this century”, he said.

“We know for certain that not stopping the burning of coal, oil and gas will drive up the risks for coastal metropolises from New York to Mumbai, Hamburg and Shanghai”

“Coastal planning cannot merely rely on the best guess. It requires a risk analysis. Our study provides exactly that. The sea level contribution of Antarctica is very likely not going to be more than 58 centimetres.”

Thermal expansion of the oceans by global warming and the melting of glaciers, which so far have been the most important factors in sea level rise, will add to the contribution from Antarctic ice loss, making the overall sea level rise risk even bigger. But the ‘Antarctica Factor’ is about to become the most important element, according to the study, published in the journal Earth System Dynamics.

The range of sea-level rise estimates the scientists have come up with is fairly large. Assuming that humanity keeps on emitting greenhouse gases as before, they say, the range they call “very likely” to describe the future is between 6 and 58 cms for this century.

If greenhouse gas emissions were reduced rapidly, it would be between 4 and 37 cms. Importantly, the difference between a business-as-usual scenario and one of emissions reductions becomes substantially greater as time passes.

More robust insights

Sixteen ice sheet modelling groups consisting of 36 researchers from 27 institutes contributed to the new study. A similar study six years ago had to rely on the output of only five ice sheet models.

“The more computer simulation models we use, all of them with slightly different dynamic representations of the Antarctic ice sheet, the wider the range of results that we yield − but also the more robust the insights that we gain”, said co-author Sophie Nowicki of the NASA Goddard Space Flight Center.

“There are still large uncertainties, but we are constantly improving our understanding of the largest ice sheet on Earth. Comparing model outputs is a forceful tool to provide society with the necessary information for rational decisions.”

Over the long term, the Antarctic ice sheet has the potential ultimately to raise sea levels by many tens of metres. “What we know for certain”, said Professor Levermann, “is that not stopping the burning of coal, oil and gas will drive up the risks for coastal metropolises from New York to Mumbai, Hamburg and Shanghai.” − Climate News Network

Speeding sea level rise threatens nuclear plants

With sea level rise accelerating faster than thought, the risk is growing for coastal cities − and for nuclear power stations.

LONDON, 14 February, 2020 − The latest science shows how the pace of sea level rise is speeding up, fuelling fears that not only millions of homes will be under threat, but that vulnerable installations like docks and power plants will be overwhelmed by the waves.

New research using satellite data over a 30-year period shows that around the year 2000 sea level rise was 2mm a year, by 2010 it was 3mm and now it is at 4mm, with the pace of change still increasing.

The calculations were made by a research student, Tadea Veng, at the Technical University of Denmark, which has a special interest in Greenland, where the icecap is melting fast. That, combined with accelerating melting in Antarctica and further warming of the oceans, is raising sea levels across the globe.

The report coincides with a European Environment Agency (EEA) study whose maps show large areas of the shorelines of countries with coastlines on the North Sea will go under water unless heavily defended against sea level rise.

Based on the maps, newspapers like The Guardian in London have predicted that more than half of one key UK east coast provincial port − Hull − will be swamped. Ironically, Hull is the base for making giant wind turbine blades for use in the North Sea.

“It’s not just the height of the rise in sea level that is important for the protection of nuclear facilities, it’s also the likely increase in storm surges”

The argument about how much the sea level will rise this century has been raging in scientific circles since the 1990s. At the start, predictions of sea level rise took into account only two possible causes: the expansion of seawater as it warmed, and the melting of mountain glaciers away from the poles.

In the early Intergovernmental Panel on Climate Change reports back then, the melting of the polar ice caps was not included, because scientists could not agree whether greater snowfall on the top of the ice caps in winter might balance out summer melting. Many of them also thought Antarctica would not melt at all, or not for centuries, because it was too cold.

Both the extra snow theory and the “too cold to melt” idea have now been discounted. In Antarctica this is partly because the sea has warmed up so much that it is melting the glaciers’ ice from beneath – something the scientists had not foreseen.

Alarm about sea level rise elsewhere has been increasing outside the scientific community, partly because many nuclear power plants are on coasts. Even those that are nearing the end of their working lives will be radio-active for another century, and many have highly dangerous spent fuel on site in storage ponds with no disposal route organised.

Perhaps most alarmed are British residents, whose government is currently planning a number of new seaside nuclear stations in low-lying coastal areas. Some will be under water this century according to the EEA, particularly one planned for Sizewell in eastern England.

Hard to tell

The Agency’s report says estimates of sea level rise by 2100 vary, with an upper limit of one metre generally accepted, but up to 2.5 metres predicted by some scientists. The latest research by Danish scientists suggests judiciously that with the speed of sea level rise continuing to accelerate, it is impossible to be sure.

A report by campaigners who oppose building nuclear power stations on Britain’s vulnerable coast expresses extreme alarm, saying both nuclear regulators and the giant French energy company EDF are too complacent about the problem.

The report says: “Polar ice caps appear to be melting faster than expected, and what is particularly worrying is that the rate of melting seems to be increasing. Some researchers say sea levels could rise by as much as six metres or more by 2100, even if the 2°C Paris targethttps://unfccc.int/process-and-meetings/the-paris-agreement/the-paris-agreement is met.

“But it’s not just the height of the rise in sea level that is important for the protection of nuclear facilities, it’s also the likely increase in storm surges. An increase in sea level of 50cm would mean the storm that used to come every thousand years will now come every 100 years. If you increase that to a metre, then that millennial storm is likely to come once a decade.

“Bearing in mind that there will probably be nuclear waste on the Hinkley Point C site [home to the new twin reactors being built by EDF in the West of England] until at least 2150, the question neither the Office of Nuclear Regulation nor EDF seem to be asking is whether further flood protection measures can be put in place fast enough to deal with unexpected and unpredicted storm surges.” − Climate News Network

With sea level rise accelerating faster than thought, the risk is growing for coastal cities − and for nuclear power stations.

LONDON, 14 February, 2020 − The latest science shows how the pace of sea level rise is speeding up, fuelling fears that not only millions of homes will be under threat, but that vulnerable installations like docks and power plants will be overwhelmed by the waves.

New research using satellite data over a 30-year period shows that around the year 2000 sea level rise was 2mm a year, by 2010 it was 3mm and now it is at 4mm, with the pace of change still increasing.

The calculations were made by a research student, Tadea Veng, at the Technical University of Denmark, which has a special interest in Greenland, where the icecap is melting fast. That, combined with accelerating melting in Antarctica and further warming of the oceans, is raising sea levels across the globe.

The report coincides with a European Environment Agency (EEA) study whose maps show large areas of the shorelines of countries with coastlines on the North Sea will go under water unless heavily defended against sea level rise.

Based on the maps, newspapers like The Guardian in London have predicted that more than half of one key UK east coast provincial port − Hull − will be swamped. Ironically, Hull is the base for making giant wind turbine blades for use in the North Sea.

“It’s not just the height of the rise in sea level that is important for the protection of nuclear facilities, it’s also the likely increase in storm surges”

The argument about how much the sea level will rise this century has been raging in scientific circles since the 1990s. At the start, predictions of sea level rise took into account only two possible causes: the expansion of seawater as it warmed, and the melting of mountain glaciers away from the poles.

In the early Intergovernmental Panel on Climate Change reports back then, the melting of the polar ice caps was not included, because scientists could not agree whether greater snowfall on the top of the ice caps in winter might balance out summer melting. Many of them also thought Antarctica would not melt at all, or not for centuries, because it was too cold.

Both the extra snow theory and the “too cold to melt” idea have now been discounted. In Antarctica this is partly because the sea has warmed up so much that it is melting the glaciers’ ice from beneath – something the scientists had not foreseen.

Alarm about sea level rise elsewhere has been increasing outside the scientific community, partly because many nuclear power plants are on coasts. Even those that are nearing the end of their working lives will be radio-active for another century, and many have highly dangerous spent fuel on site in storage ponds with no disposal route organised.

Perhaps most alarmed are British residents, whose government is currently planning a number of new seaside nuclear stations in low-lying coastal areas. Some will be under water this century according to the EEA, particularly one planned for Sizewell in eastern England.

Hard to tell

The Agency’s report says estimates of sea level rise by 2100 vary, with an upper limit of one metre generally accepted, but up to 2.5 metres predicted by some scientists. The latest research by Danish scientists suggests judiciously that with the speed of sea level rise continuing to accelerate, it is impossible to be sure.

A report by campaigners who oppose building nuclear power stations on Britain’s vulnerable coast expresses extreme alarm, saying both nuclear regulators and the giant French energy company EDF are too complacent about the problem.

The report says: “Polar ice caps appear to be melting faster than expected, and what is particularly worrying is that the rate of melting seems to be increasing. Some researchers say sea levels could rise by as much as six metres or more by 2100, even if the 2°C Paris targethttps://unfccc.int/process-and-meetings/the-paris-agreement/the-paris-agreement is met.

“But it’s not just the height of the rise in sea level that is important for the protection of nuclear facilities, it’s also the likely increase in storm surges. An increase in sea level of 50cm would mean the storm that used to come every thousand years will now come every 100 years. If you increase that to a metre, then that millennial storm is likely to come once a decade.

“Bearing in mind that there will probably be nuclear waste on the Hinkley Point C site [home to the new twin reactors being built by EDF in the West of England] until at least 2150, the question neither the Office of Nuclear Regulation nor EDF seem to be asking is whether further flood protection measures can be put in place fast enough to deal with unexpected and unpredicted storm surges.” − Climate News Network

Little time left to arrest Greenland’s melting

Humans may still have time to stop Greenland’s melting, preventing Arctic ice sheet collapse and devastating sea level rise. But the time left may be short.

LONDON, 30 December, 2019 – It’s still possible, but it’s far from certain: stopping Greenland’s melting can be done, but it must be done soon.

Norwegian and US scientists have taken a close look at the ice age history of Greenland and come to a grim conclusion. All it takes to set the island’s ice cap melting away is a mean sea surface temperature higher than seven degrees Celsius. And the present mean sea surface temperature is already 7.7°C.

Greenland is the northern hemisphere’s single richest store of frozen water: the island’s bedrock holds enough to raise global sea levels by seven metres and drown or wash away the world’s coastal communities, including the great cities of New York and Miami, Shanghai and Kolkata, Amsterdam and London.

And the pattern of geological evidence – outlined in the Proceedings of the National Academy of Sciences – combined with climate models suggests that any sustained temperature rise could trigger an irreversible melt of the entire southern Greenland ice sheet.

The scientists suggest that the threshold for this calamity could be between 0.8°C above the post-Ice Age norm, and 3.2°C.

“The critical temperature threshold for past Greenland ice sheet decay will likely be surpassed this century”

In fact, because of profligate use of fossil fuels and the release of greenhouse gases into the atmosphere, the planet has already warmed by around 1°C above the level for most of human history, and warming of at least 3.2°C by the end of this century now seems almost certain.

Researchers publish their conclusions with the intention that they should be examined, tested, challenged and perhaps overturned. But widespread alarm at the rate of melt and mass loss in Greenland has been consistent and increasing with the years.

Researchers have repeatedly established that melting each summer is increasing the rate at which glaciers flow and deliver ice to increasingly warmer northern seas, and that this rate of melting has itself begun to accelerate.

So Nil Irvali of the University of Bergen and colleagues took a closer look at the story told by microfossils within cores from the ice and the ocean floor during four interglacial periods over the last 450,000 years.

During those warm spells ocean levels rose dramatically, and in two episodes Greenland’s vanishing ice could have contributed more than five metres in one case, and up to seven metres of sea level rise in the other.

Triggers identified

And in all four of those interglacials, conditions reached temperatures higher than they are right now.

Concern about the stability of the Greenland icecap is no surprise: the Arctic is already warming faster than anywhere else on the planet, thanks to profligate use of fossil fuels and the destruction of the rainforests, and researchers worldwide have begun to identify triggers that feed back into further warming: rain, for instance, in winter; the loss of cloud cover in summer; and the deposits of soot from polar wildfires that darken the snows and enhance the absorption of the sun’s rays.

Years ago, the phrase “at a glacial pace” ceased to be a valid cliché: US scientists clocked one river of ice moving at a rate of 46 metres a day.

So the new study simply confirms fears that already are widespread. What remains to be settled is the point at which the decline of the ice sheet becomes irreversible, the Bergen scientists say. As the ocean warms, this feeds back into the process of melting and triggers longer-term feedbacks.

“The exact point at which these feedbacks are triggered remains equivocal,” say Dr Irvali and her co-authors. “Notably, the critical temperature threshold for past Greenland ice sheet decay will likely be surpassed this century. The duration for which this threshold is exceeded will determine Greenland’s fate.” – Climate News Network

Humans may still have time to stop Greenland’s melting, preventing Arctic ice sheet collapse and devastating sea level rise. But the time left may be short.

LONDON, 30 December, 2019 – It’s still possible, but it’s far from certain: stopping Greenland’s melting can be done, but it must be done soon.

Norwegian and US scientists have taken a close look at the ice age history of Greenland and come to a grim conclusion. All it takes to set the island’s ice cap melting away is a mean sea surface temperature higher than seven degrees Celsius. And the present mean sea surface temperature is already 7.7°C.

Greenland is the northern hemisphere’s single richest store of frozen water: the island’s bedrock holds enough to raise global sea levels by seven metres and drown or wash away the world’s coastal communities, including the great cities of New York and Miami, Shanghai and Kolkata, Amsterdam and London.

And the pattern of geological evidence – outlined in the Proceedings of the National Academy of Sciences – combined with climate models suggests that any sustained temperature rise could trigger an irreversible melt of the entire southern Greenland ice sheet.

The scientists suggest that the threshold for this calamity could be between 0.8°C above the post-Ice Age norm, and 3.2°C.

“The critical temperature threshold for past Greenland ice sheet decay will likely be surpassed this century”

In fact, because of profligate use of fossil fuels and the release of greenhouse gases into the atmosphere, the planet has already warmed by around 1°C above the level for most of human history, and warming of at least 3.2°C by the end of this century now seems almost certain.

Researchers publish their conclusions with the intention that they should be examined, tested, challenged and perhaps overturned. But widespread alarm at the rate of melt and mass loss in Greenland has been consistent and increasing with the years.

Researchers have repeatedly established that melting each summer is increasing the rate at which glaciers flow and deliver ice to increasingly warmer northern seas, and that this rate of melting has itself begun to accelerate.

So Nil Irvali of the University of Bergen and colleagues took a closer look at the story told by microfossils within cores from the ice and the ocean floor during four interglacial periods over the last 450,000 years.

During those warm spells ocean levels rose dramatically, and in two episodes Greenland’s vanishing ice could have contributed more than five metres in one case, and up to seven metres of sea level rise in the other.

Triggers identified

And in all four of those interglacials, conditions reached temperatures higher than they are right now.

Concern about the stability of the Greenland icecap is no surprise: the Arctic is already warming faster than anywhere else on the planet, thanks to profligate use of fossil fuels and the destruction of the rainforests, and researchers worldwide have begun to identify triggers that feed back into further warming: rain, for instance, in winter; the loss of cloud cover in summer; and the deposits of soot from polar wildfires that darken the snows and enhance the absorption of the sun’s rays.

Years ago, the phrase “at a glacial pace” ceased to be a valid cliché: US scientists clocked one river of ice moving at a rate of 46 metres a day.

So the new study simply confirms fears that already are widespread. What remains to be settled is the point at which the decline of the ice sheet becomes irreversible, the Bergen scientists say. As the ocean warms, this feeds back into the process of melting and triggers longer-term feedbacks.

“The exact point at which these feedbacks are triggered remains equivocal,” say Dr Irvali and her co-authors. “Notably, the critical temperature threshold for past Greenland ice sheet decay will likely be surpassed this century. The duration for which this threshold is exceeded will determine Greenland’s fate.” – Climate News Network

Heat the Arctic to cool the Earth, scientists say

If we seriously want to tackle the climate crisis, here’s a drastic idea: we could heat the Arctic to cool the planet.

LONDON, 19 December, 2019 − With politicians failing to cut greenhouse gas emissions far and fast enough, the only hope may be to find a different way to cool the planet. One group of researchers has put forward an idea so different that critics may regard it as outlandish: heat the Arctic.

To heat the Arctic so much that the sea ice disappears even in the winter sounds like a weird idea. But the researchers believe it would have the beneficial effect of cooling the planet down.

They argue that with the Arctic ice already expected to disappear during the summer months within the next 30 years, and large increases in temperature and changes in the polar climate already certain, we should turn this radical shift to our advantage.

Their point is that since, at the current rate of progress, politicians seem unlikely to cut greenhouse gas emissions enough to prevent drastic temperature rise, humankind must find other ways to cool the Earth if it is to survive.

“Climate change is a major issue and all options should be considered when dealing with it”

Heating the planet in order to cool it is certainly counter-intuitive. But, whether or not the scheme could ever work, it shows the ingenuity and enterprise now being poured into stabilising global temperatures close to their historic level.

It also, of course, shows how horribly late we have left it to rein in the climate crisis, when wise and determined action 30 years ago could have achieved so much.

The idea proposed is, in principle, simple enough: to ensure that the warm currents of the Gulf Stream, known by science as the North Atlantic Oscillation (NAO) continue northwards across the Arctic Circle the whole year round. This would release massive amounts of heat from the ocean into the atmosphere and beyond that into space, so cooling the sea and ultimately the Earth.

“The Arctic Ocean ice cover works as a strong insulator, impeding the heat from the ocean below to warm up the atmosphere above. If this ice layer were however removed, the atmosphere would increase in temperature by around 20°C during the winter.

More heat escapes

“This increase in temperature would in turn increase the heat irradiated into space, thus cooling down the oceans,” explains the lead author of the study which details the proposal, published in the journal SN Applied Sciences. He is Julian Hunt, a postdoctoral research scholar at IIASA, the International Institute for Applied Systems Analysis.

The problem that needs to be overcome is that very cold and only mildly salty water currently floats on the surface of the Arctic Ocean, freezing in the winter and capturing the warmth of the water in the ocean depths.

The authors say the main factor helping to maintain the Arctic sea ice cover is the fact that the top 100 metres of the ocean is less saline than the Atlantic, preventing the Atlantic from flowing above the cold Arctic waters. Increasing the salinity of the Arctic Ocean’s surface, they say, would let the warmer and less salty North Atlantic current flow over it, warming the atmosphere considerably and releasing the ocean heat trapped under the ice.

They suggest three ways to keep fresh water out of the Arctic. The first would divert the big rivers of North America and Siberia southwards to prevent them draining into the polar ocean. The second would place submerged obstructions in front of the rapidly melting Greenland glaciers, to slow the speed of the ice sheets’ melting, while the third would use a solar- and wind-powered icebreaker to pump cold, near-fresh water deeper into the ocean to mix with the saltier water below, allowing the warmer currents to sweep in from the south.

Unknown consequences

Dr Hunt and his colleagues say there could be terrific benefits. Shipping could navigate the ice-free Arctic Ocean all year round, cutting journey times between Asia, Europe and North America. The need for heating homes in the northern hemisphere during the winter would be drastically reduced, because their plan would raise air temperatures by as much as 20°C.

But the massive interference with natural systems in the Arctic would also have its downside. The rapid year-round rise in temperature would dramatically increase the melting of Greenland and therefore of sea level rise the world over. The effect on the northern hemisphere climate, particularly much increased rainfall with a warmer sea and atmosphere, is impossible to predict.

But Dr Hunt says that while there are clearly huge risks, the world is already heading for uncharted waters, so humans must do something drastic. “Although it is important to mitigate the impacts from climate change with the reduction in CO2 emissions, we should also think of ways to adapt the world to the new climate conditions to avoid uncontrollable, unpredictable and destructive climate change resulting in socio-economic and environmental collapse.

“Climate change is a major issue and all options should be considered when dealing with it.” − Climate News Network

If we seriously want to tackle the climate crisis, here’s a drastic idea: we could heat the Arctic to cool the planet.

LONDON, 19 December, 2019 − With politicians failing to cut greenhouse gas emissions far and fast enough, the only hope may be to find a different way to cool the planet. One group of researchers has put forward an idea so different that critics may regard it as outlandish: heat the Arctic.

To heat the Arctic so much that the sea ice disappears even in the winter sounds like a weird idea. But the researchers believe it would have the beneficial effect of cooling the planet down.

They argue that with the Arctic ice already expected to disappear during the summer months within the next 30 years, and large increases in temperature and changes in the polar climate already certain, we should turn this radical shift to our advantage.

Their point is that since, at the current rate of progress, politicians seem unlikely to cut greenhouse gas emissions enough to prevent drastic temperature rise, humankind must find other ways to cool the Earth if it is to survive.

“Climate change is a major issue and all options should be considered when dealing with it”

Heating the planet in order to cool it is certainly counter-intuitive. But, whether or not the scheme could ever work, it shows the ingenuity and enterprise now being poured into stabilising global temperatures close to their historic level.

It also, of course, shows how horribly late we have left it to rein in the climate crisis, when wise and determined action 30 years ago could have achieved so much.

The idea proposed is, in principle, simple enough: to ensure that the warm currents of the Gulf Stream, known by science as the North Atlantic Oscillation (NAO) continue northwards across the Arctic Circle the whole year round. This would release massive amounts of heat from the ocean into the atmosphere and beyond that into space, so cooling the sea and ultimately the Earth.

“The Arctic Ocean ice cover works as a strong insulator, impeding the heat from the ocean below to warm up the atmosphere above. If this ice layer were however removed, the atmosphere would increase in temperature by around 20°C during the winter.

More heat escapes

“This increase in temperature would in turn increase the heat irradiated into space, thus cooling down the oceans,” explains the lead author of the study which details the proposal, published in the journal SN Applied Sciences. He is Julian Hunt, a postdoctoral research scholar at IIASA, the International Institute for Applied Systems Analysis.

The problem that needs to be overcome is that very cold and only mildly salty water currently floats on the surface of the Arctic Ocean, freezing in the winter and capturing the warmth of the water in the ocean depths.

The authors say the main factor helping to maintain the Arctic sea ice cover is the fact that the top 100 metres of the ocean is less saline than the Atlantic, preventing the Atlantic from flowing above the cold Arctic waters. Increasing the salinity of the Arctic Ocean’s surface, they say, would let the warmer and less salty North Atlantic current flow over it, warming the atmosphere considerably and releasing the ocean heat trapped under the ice.

They suggest three ways to keep fresh water out of the Arctic. The first would divert the big rivers of North America and Siberia southwards to prevent them draining into the polar ocean. The second would place submerged obstructions in front of the rapidly melting Greenland glaciers, to slow the speed of the ice sheets’ melting, while the third would use a solar- and wind-powered icebreaker to pump cold, near-fresh water deeper into the ocean to mix with the saltier water below, allowing the warmer currents to sweep in from the south.

Unknown consequences

Dr Hunt and his colleagues say there could be terrific benefits. Shipping could navigate the ice-free Arctic Ocean all year round, cutting journey times between Asia, Europe and North America. The need for heating homes in the northern hemisphere during the winter would be drastically reduced, because their plan would raise air temperatures by as much as 20°C.

But the massive interference with natural systems in the Arctic would also have its downside. The rapid year-round rise in temperature would dramatically increase the melting of Greenland and therefore of sea level rise the world over. The effect on the northern hemisphere climate, particularly much increased rainfall with a warmer sea and atmosphere, is impossible to predict.

But Dr Hunt says that while there are clearly huge risks, the world is already heading for uncharted waters, so humans must do something drastic. “Although it is important to mitigate the impacts from climate change with the reduction in CO2 emissions, we should also think of ways to adapt the world to the new climate conditions to avoid uncontrollable, unpredictable and destructive climate change resulting in socio-economic and environmental collapse.

“Climate change is a major issue and all options should be considered when dealing with it.” − Climate News Network

Greenland ice melt feeds glacier instability

In a runaway effect, the Greenland ice melt lets surface water gurgle down to the bedrock – and at unexpected speeds.

LONDON, 6 December, 2019 – British scientists have caught a huge ice sheet in the act of draining away, with significant effects on its surroundings: they have seen what happens to the water created by the Greenland ice melt.

For the first time – and with help from drones – researchers have witnessed water flowing at a million cubic metres an hour from the surface of ice sheets through caverns in the ice and down to the glacial bedrock.

The study does not change the big picture of increasingly rapid melt as greenhouse gases build up in the atmosphere, and ever more of the northern hemisphere’s biggest ice cap flows downhill to raise global sea levels.

But it does throw light on the mechanisms by which glaciers turn to sea water, and it does suggest that many estimates of melt rate so far might prove to be under-estimates.

Greenland is the planet’s second largest ice sheet and the biggest single contributor to global sea level rise. Researchers have been alarmed for years about the increasing rate of summer melt and the accelerating speed of what had once been imperceptible glacial flows.

“These glaciers are already moving quite fast, so the effect of the lakes may not appear as dramatic as on slower-moving glaciers elsewhere, but the overall effect is in fact very significant”

And researchers from the universities of Cambridge, Aberystwyth and Lancaster have now been able to put a measure on water surface loss.

They report in the Proceedings of the National Academy of Sciences that they used custom-built aerial drones and complex computer modelling to work out how fractures form below vast lakes of meltwater that collect on the surface of the Store Glacier on the island’s northwestern sheet.

They watched splits form in the glacial ice, to suddenly open up an escape route for the supraglacial pool. As they watched, such fractures became caverns called moulins, down which in one case five million cubic metres of water – think of 2,000 Olympic swimming pools – flowed in just five hours.

The ice of the glacier is typically a kilometre thick, so the scientists may have observed the planet’s longest waterfall. And as the ice drained away to the bottom of the ice sheet, it may have served as a lubricant to speed up glacier flow over the bedrock.

The ice sheet lifted by half a metre, presumably in response to the sub-surface flood, and four kilometres downstream glacial speed picked up from a speed of two metres to more than five metres a day.

Daily billion-tonne loss

“It’s possible we’ve under-estimated the effects of these glaciers on the overall instability of the Greenland ice sheet. It’s a rare thing to observe these fast-draining lakes – we were lucky to be in the right place at the right time,” said Tom Chudley, of the Scott Polar Research Institute in Cambridge, one of the authors.

Until now, scientists have been able to estimate glacial flow and surface melt only by satellite studies – which reveal little of the detail – or direct on-the-ground measurement under conditions that are difficult even in good weather.

But even with these constraints researchers have been able to calculate the shrinkage of the Greenland ice sheet at the rate of a billion tonnes a day, as temperatures rise in response to ever-increasing use of fossil fuels around the globe.

The next step is to deploy drilling equipment for a closer look at how the water gets below the glacier to reach the bedrock, and calculate how the ice sheet may change not just over hours but over the coming decades as well.

“These glaciers are already moving quite fast, so the effect of the lakes may not appear as dramatic as on slower-moving glaciers elsewhere,” said Poul Christofferson, who led the project, “but the overall effect is in fact very significant.” – Climate News Network

In a runaway effect, the Greenland ice melt lets surface water gurgle down to the bedrock – and at unexpected speeds.

LONDON, 6 December, 2019 – British scientists have caught a huge ice sheet in the act of draining away, with significant effects on its surroundings: they have seen what happens to the water created by the Greenland ice melt.

For the first time – and with help from drones – researchers have witnessed water flowing at a million cubic metres an hour from the surface of ice sheets through caverns in the ice and down to the glacial bedrock.

The study does not change the big picture of increasingly rapid melt as greenhouse gases build up in the atmosphere, and ever more of the northern hemisphere’s biggest ice cap flows downhill to raise global sea levels.

But it does throw light on the mechanisms by which glaciers turn to sea water, and it does suggest that many estimates of melt rate so far might prove to be under-estimates.

Greenland is the planet’s second largest ice sheet and the biggest single contributor to global sea level rise. Researchers have been alarmed for years about the increasing rate of summer melt and the accelerating speed of what had once been imperceptible glacial flows.

“These glaciers are already moving quite fast, so the effect of the lakes may not appear as dramatic as on slower-moving glaciers elsewhere, but the overall effect is in fact very significant”

And researchers from the universities of Cambridge, Aberystwyth and Lancaster have now been able to put a measure on water surface loss.

They report in the Proceedings of the National Academy of Sciences that they used custom-built aerial drones and complex computer modelling to work out how fractures form below vast lakes of meltwater that collect on the surface of the Store Glacier on the island’s northwestern sheet.

They watched splits form in the glacial ice, to suddenly open up an escape route for the supraglacial pool. As they watched, such fractures became caverns called moulins, down which in one case five million cubic metres of water – think of 2,000 Olympic swimming pools – flowed in just five hours.

The ice of the glacier is typically a kilometre thick, so the scientists may have observed the planet’s longest waterfall. And as the ice drained away to the bottom of the ice sheet, it may have served as a lubricant to speed up glacier flow over the bedrock.

The ice sheet lifted by half a metre, presumably in response to the sub-surface flood, and four kilometres downstream glacial speed picked up from a speed of two metres to more than five metres a day.

Daily billion-tonne loss

“It’s possible we’ve under-estimated the effects of these glaciers on the overall instability of the Greenland ice sheet. It’s a rare thing to observe these fast-draining lakes – we were lucky to be in the right place at the right time,” said Tom Chudley, of the Scott Polar Research Institute in Cambridge, one of the authors.

Until now, scientists have been able to estimate glacial flow and surface melt only by satellite studies – which reveal little of the detail – or direct on-the-ground measurement under conditions that are difficult even in good weather.

But even with these constraints researchers have been able to calculate the shrinkage of the Greenland ice sheet at the rate of a billion tonnes a day, as temperatures rise in response to ever-increasing use of fossil fuels around the globe.

The next step is to deploy drilling equipment for a closer look at how the water gets below the glacier to reach the bedrock, and calculate how the ice sheet may change not just over hours but over the coming decades as well.

“These glaciers are already moving quite fast, so the effect of the lakes may not appear as dramatic as on slower-moving glaciers elsewhere,” said Poul Christofferson, who led the project, “but the overall effect is in fact very significant.” – Climate News Network

Earth nears irreversible tipping points

Changes afoot now in at least nine areas could drastically alter the Earth’s climate. There’s no time left to act on these tipping points.

LONDON, 28 November, 2019 – On the eve of a global climate summit in Madrid, seven distinguished climate scientists have issued an urgent warning of approaching planetary tipping points: within a few years, they say, humankind could enter a state of potentially catastrophic climate change on a new “hothouse” Earth.

They warn that dramatic changes to planetary stability may already be happening in nine vulnerable ecosystems. As these changes happen, they could reinforce each other and at the same time amplify planetary temperature rise, commit the oceans to inexorable sea level rise of around 10 metres, and threaten the existence of human civilisations.

Their warning is issued in a commentary in the journal Nature. Their conclusions are not – and perhaps cannot be – confirmed by direct evidence or the consensus of other scientists. They present an opinion, not a set of facts that can be scrutinised and challenged or endorsed by their peers.

And the seven researchers recognise that although such changes are happening at speed, some of the consequences of those changes will follow more slowly. Their point is that the risks of irreversible change are too great not to act – and to act now.

Happening now

But the fact that they have chosen to issue such an alarm at all is a measure of the concern raised by the rapid retreat of the Arctic ice, the steady loss of the Greenland ice cap, the damage to the boreal forests, the thaw of the polar permafrost, the slowing of a great ocean current, the loss of tropical corals and the collapse of ice sheets in East and West Antarctica.

Each of these happenings – and many more – was identified more than a decade ago as a potential “tipping point”: an irreversible change that would amplify global heating and trigger a cascade of other climate changes.

“Now we see evidence that over half of them have been activated,” said Tim Lenton of the University of Exeter, UK. “The growing threat of rapid, irreversible changes means it is no longer responsible to wait and see.”

“The stability and resilience of our planet is in peril. International action – not just words – must reflect this”

The idea of a climate tipping point – a threshold beyond which dramatic climate change would be irreversible – is an old one. Two decades ago the Intergovernmental Panel on Climate Change examined the idea and proposed that, were the planet to warm by 5°C above the long-term average for most of human history, then it could tip into a new climate regime.

But in the last few decades, carbon dioxide concentrations in the atmosphere have gone from around 280 parts per million to more than 400 ppm, and global average temperatures have risen by more than 1°C. And the rate of change, driven by profligate use of fossil fuels that deposit greenhouse gases into the atmosphere, has been alarming.

“It is not only human pressures on Earth that continue rising to unprecedented levels. It is also that, as science advances, we must admit that we have underestimated the risks of unleashing irreversible changes, where the planet self-amplifies global warming. This is what we are seeing already at 1°C global warming,” said Johan Rockström, who directs the Potsdam Institute for Climate Impact Research in Germany, and who is another signatory.

“Scientifically, this provides strong evidence for declaring a state of planetary emergency, to unleash world action that accelerates the path towards a world that can continue evolving on a stable planet.”

Inadequate pledges

In 2015, at a climate summit in Paris, 195 nations promised to contain planetary heating to “well below” 2°C, and ideally to 1.5°C, by 2100. But the Nature signatories point at that even if the pledges those nations made are implemented – a “big if”, they warn – then they will ensure only that the world is committed to at least 3°C warming.

The scientists believe there is still time to act – but their dangerous tipping points are now dangerously close.

The arguments go like this. In West Antarctica, ice may already be retreating beyond the “grounding line” where ice, ocean and bedrock meet. If so, then the rest of the West Antarctic ice sheet could collapse, and sea levels could rise by three metres.

New evidence suggests the East Antarctic ice sheet could be similarly unstable, and precipitate further sea level rise of up to four metres. Hundreds of millions are already at risk from coastal flooding.

Timescale controlled

The Greenland ice sheet is melting at an accelerating rate, and once past a critical threshold could lose enough water to raise sea levels by seven metres. Even a 1.5°C warming might condemn Greenland to irreversible melting – and on present form the world could warm by 1.5°C by 2030.

“Thus we might have already committed future generations to living with sea level rises of around 10m over thousands of years. But the timescale is still under our control,” the authors warn.

They also warn that a “staggering 99% of tropical corals” could be lost if the planet heats by even 2°C – at a profound cost to both marine sea life and human economies.

They say 17% of the Amazon rainforest has been lost since 1970: a loss of somewhere between 20% and 40% could tip the entire rainforest into a destabilised state, increasingly at risk from drought and fire.

Risks multiply

In the boreal forests of northern Asia, Europe and Canada, insect outbreaks, fire and dieback could turn some regions into sources of more carbon, rather than sinks that soak up the extra carbon dioxide.

Permafrost thaw could release ever-greater volumes of stored methane, a greenhouse gas 30 times more potent, over a century, than carbon dioxide, and so on. The dangers multiply, and each one amplifies planetary heating.

“If damaging tipping cascades can occur and a global tipping point cannot be ruled out, then this is an existential threat to civilisation,” the authors warn.

“The stability and resilience of our planet is in peril. International action – not just words – must reflect this.” – Climate News Network

Changes afoot now in at least nine areas could drastically alter the Earth’s climate. There’s no time left to act on these tipping points.

LONDON, 28 November, 2019 – On the eve of a global climate summit in Madrid, seven distinguished climate scientists have issued an urgent warning of approaching planetary tipping points: within a few years, they say, humankind could enter a state of potentially catastrophic climate change on a new “hothouse” Earth.

They warn that dramatic changes to planetary stability may already be happening in nine vulnerable ecosystems. As these changes happen, they could reinforce each other and at the same time amplify planetary temperature rise, commit the oceans to inexorable sea level rise of around 10 metres, and threaten the existence of human civilisations.

Their warning is issued in a commentary in the journal Nature. Their conclusions are not – and perhaps cannot be – confirmed by direct evidence or the consensus of other scientists. They present an opinion, not a set of facts that can be scrutinised and challenged or endorsed by their peers.

And the seven researchers recognise that although such changes are happening at speed, some of the consequences of those changes will follow more slowly. Their point is that the risks of irreversible change are too great not to act – and to act now.

Happening now

But the fact that they have chosen to issue such an alarm at all is a measure of the concern raised by the rapid retreat of the Arctic ice, the steady loss of the Greenland ice cap, the damage to the boreal forests, the thaw of the polar permafrost, the slowing of a great ocean current, the loss of tropical corals and the collapse of ice sheets in East and West Antarctica.

Each of these happenings – and many more – was identified more than a decade ago as a potential “tipping point”: an irreversible change that would amplify global heating and trigger a cascade of other climate changes.

“Now we see evidence that over half of them have been activated,” said Tim Lenton of the University of Exeter, UK. “The growing threat of rapid, irreversible changes means it is no longer responsible to wait and see.”

“The stability and resilience of our planet is in peril. International action – not just words – must reflect this”

The idea of a climate tipping point – a threshold beyond which dramatic climate change would be irreversible – is an old one. Two decades ago the Intergovernmental Panel on Climate Change examined the idea and proposed that, were the planet to warm by 5°C above the long-term average for most of human history, then it could tip into a new climate regime.

But in the last few decades, carbon dioxide concentrations in the atmosphere have gone from around 280 parts per million to more than 400 ppm, and global average temperatures have risen by more than 1°C. And the rate of change, driven by profligate use of fossil fuels that deposit greenhouse gases into the atmosphere, has been alarming.

“It is not only human pressures on Earth that continue rising to unprecedented levels. It is also that, as science advances, we must admit that we have underestimated the risks of unleashing irreversible changes, where the planet self-amplifies global warming. This is what we are seeing already at 1°C global warming,” said Johan Rockström, who directs the Potsdam Institute for Climate Impact Research in Germany, and who is another signatory.

“Scientifically, this provides strong evidence for declaring a state of planetary emergency, to unleash world action that accelerates the path towards a world that can continue evolving on a stable planet.”

Inadequate pledges

In 2015, at a climate summit in Paris, 195 nations promised to contain planetary heating to “well below” 2°C, and ideally to 1.5°C, by 2100. But the Nature signatories point at that even if the pledges those nations made are implemented – a “big if”, they warn – then they will ensure only that the world is committed to at least 3°C warming.

The scientists believe there is still time to act – but their dangerous tipping points are now dangerously close.

The arguments go like this. In West Antarctica, ice may already be retreating beyond the “grounding line” where ice, ocean and bedrock meet. If so, then the rest of the West Antarctic ice sheet could collapse, and sea levels could rise by three metres.

New evidence suggests the East Antarctic ice sheet could be similarly unstable, and precipitate further sea level rise of up to four metres. Hundreds of millions are already at risk from coastal flooding.

Timescale controlled

The Greenland ice sheet is melting at an accelerating rate, and once past a critical threshold could lose enough water to raise sea levels by seven metres. Even a 1.5°C warming might condemn Greenland to irreversible melting – and on present form the world could warm by 1.5°C by 2030.

“Thus we might have already committed future generations to living with sea level rises of around 10m over thousands of years. But the timescale is still under our control,” the authors warn.

They also warn that a “staggering 99% of tropical corals” could be lost if the planet heats by even 2°C – at a profound cost to both marine sea life and human economies.

They say 17% of the Amazon rainforest has been lost since 1970: a loss of somewhere between 20% and 40% could tip the entire rainforest into a destabilised state, increasingly at risk from drought and fire.

Risks multiply

In the boreal forests of northern Asia, Europe and Canada, insect outbreaks, fire and dieback could turn some regions into sources of more carbon, rather than sinks that soak up the extra carbon dioxide.

Permafrost thaw could release ever-greater volumes of stored methane, a greenhouse gas 30 times more potent, over a century, than carbon dioxide, and so on. The dangers multiply, and each one amplifies planetary heating.

“If damaging tipping cascades can occur and a global tipping point cannot be ruled out, then this is an existential threat to civilisation,” the authors warn.

“The stability and resilience of our planet is in peril. International action – not just words – must reflect this.” – Climate News Network

Global climate treaty is not working

Three out of four nations have yet to start to honour the global climate treaty. The world waits, the seas go on rising – and greenhouse gases too.

LONDON, 13 November, 2019 – Three nations in every four that vowed in the global climate treaty, the Paris Agreement, to contain global heating to “well below” 2°C by the century’s end have failed to deliver pledges that will reduce emissions by even 40% by 2030.

In Paris in 2015, a total of 195 nations agreed that action was vital. Since then only 36 countries have taken steps to meet the targets they agreed, according to a new study by the Universal Ecological Fund. And one nation has announced that it will withdraw altogether from the agreement.

“The comprehensive examination found that with few exceptions, the pledges of the rich, middle income and poor countries are insufficient to address climate change,” said Sir Robert Watson, once chair of the Intergovernmental Panel on Climate Change, which was present at the Paris meeting, and co-author of the study. “Simply, the pledges are far too little, too late.

“Even if all climate pledges, which are voluntary, are fully implemented, they will cover less than half of what is needed to limit the acceleration of climate change in the next decade.”

“The more carbon we release now the more sea level rise we are locking in for the future”

What happens now will affect the planetary climate and its ocean systems for much longer than that for at least the next two centuries. Researchers report in the Proceedings of the National Academy of Sciences that they looked at the impact to come even if all nations were to honour all the pledges made in Paris.

They agree that the global emissions of greenhouse gases since Paris and by 2030 would alone be enough to raise global sea levels by 20 cms: half of that from China, the US, the EU, India and Russia, the top five emitters. But they add a much more ominous long-term warning

“Our results show that what we do today will have a huge effect in 2300. 20 cms is very significant; it is basically as much sea-level rise as we’ve observed over the entire 20th century. To cause that with only 15 years of emissions is quite staggering”, said Alexander Nauels, of Climate Analytics, who led the study.

“The true consequences of our emissions on sea level rise unfold over centuries, due to the slow pace at which the ocean, polar ice sheets and glaciers respond to global warming. The more carbon we release now the more sea level rise we are locking in for the future.”

And as if to add force to the need for drastic action, a new US and German study has warned that even if nations honour their pledges by 2030, sea levels around the world will go on rising, and stay at higher levels for thousands of years.

Leaking permafrost

As the polar ice retreats, and rising tides batter the shores of the Arctic Ocean, vast volumes of carbon dioxide so far imprisoned  in the permafrost of the polar coasts – 34% of all the world’s coastlines  – could escape to accelerate further warming and of course yet greater sea level rise.

Climate scientists have been wrestling for decades with what they call the carbon budget – the accounting of all the ways in which carbon dioxide gets into the atmosphere and out of it again – and missed another potentially dangerous source of the greenhouse gas.

As glaciers retreat and the frozen coasts and soils thaw, this could begin to seep into the atmosphere. Laboratory experiments suggest it will seep even faster as sea levels rise and waves grow more powerful. For every gram, dry weight, of eroded permafrost, more than 4 grams of carbon dioxide would escape into the atmosphere.

“Carbon budgets and climate simulations have so far missed coastal erosion in their equations even though it might be a substantial source of carbon dioxide,” says George Tanski of Vrije Universiteit Amsterdam, the lead author.

“Our research found that the erosion of permafrost coastlines can lead to the rapid release of significant quantities of CO2, which can be expected to increase as coastal erosion accelerates, temperatures increase, sea ice diminishes and stronger storms batter Arctic coasts.”

Early warning

That the Paris Agreement was backed up by pledges that might fail to contain global warning to an ideal target of 1.5°C was clear from the start, and scientists who looked at the promises made at the time warned that unless they were increased, they committed the world to a warming of at least 3°C above the long term average for most of human history.

The latest study from the Universal Ecological Fund now finds that not only are the pledges not enough; some are not being honoured. China and India pledged to reduce the intensity of their emissions relative to gross domestic product, but since their economies continue to grow, so will their emissions.

China already contributes more than 26% of all global emissions, India 7%. The US, which contributes 13% of all greenhouse emissions, is to quit the Paris Agreement in 2020, and has in any case reversed much of its climate legislation. Russia, which contributes 4.6% of all atmospheric carbon dioxide, has submitted no pledges.

Europe’s 28 nations, and seven others, have promised to reduce emissions by 40% by 2040. Of the remaining 152 nations, responsible for more than 36% of all emissions, 127 have submitted conditional plans, but rely upon technical assistance and funding from the wealthy nations to execute these. But the US and Australia have stopped making contributions to such funding.

Almost 70% of emissions are from fossil fuels: successful action would require the closure of 2,400 coal-fired power stations. In fact, 250 new coal-fired power stations are now under construction. The message is that governments are doing too little, too slowly, leaving horrendous future consequences. – Climate News Network

Three out of four nations have yet to start to honour the global climate treaty. The world waits, the seas go on rising – and greenhouse gases too.

LONDON, 13 November, 2019 – Three nations in every four that vowed in the global climate treaty, the Paris Agreement, to contain global heating to “well below” 2°C by the century’s end have failed to deliver pledges that will reduce emissions by even 40% by 2030.

In Paris in 2015, a total of 195 nations agreed that action was vital. Since then only 36 countries have taken steps to meet the targets they agreed, according to a new study by the Universal Ecological Fund. And one nation has announced that it will withdraw altogether from the agreement.

“The comprehensive examination found that with few exceptions, the pledges of the rich, middle income and poor countries are insufficient to address climate change,” said Sir Robert Watson, once chair of the Intergovernmental Panel on Climate Change, which was present at the Paris meeting, and co-author of the study. “Simply, the pledges are far too little, too late.

“Even if all climate pledges, which are voluntary, are fully implemented, they will cover less than half of what is needed to limit the acceleration of climate change in the next decade.”

“The more carbon we release now the more sea level rise we are locking in for the future”

What happens now will affect the planetary climate and its ocean systems for much longer than that for at least the next two centuries. Researchers report in the Proceedings of the National Academy of Sciences that they looked at the impact to come even if all nations were to honour all the pledges made in Paris.

They agree that the global emissions of greenhouse gases since Paris and by 2030 would alone be enough to raise global sea levels by 20 cms: half of that from China, the US, the EU, India and Russia, the top five emitters. But they add a much more ominous long-term warning

“Our results show that what we do today will have a huge effect in 2300. 20 cms is very significant; it is basically as much sea-level rise as we’ve observed over the entire 20th century. To cause that with only 15 years of emissions is quite staggering”, said Alexander Nauels, of Climate Analytics, who led the study.

“The true consequences of our emissions on sea level rise unfold over centuries, due to the slow pace at which the ocean, polar ice sheets and glaciers respond to global warming. The more carbon we release now the more sea level rise we are locking in for the future.”

And as if to add force to the need for drastic action, a new US and German study has warned that even if nations honour their pledges by 2030, sea levels around the world will go on rising, and stay at higher levels for thousands of years.

Leaking permafrost

As the polar ice retreats, and rising tides batter the shores of the Arctic Ocean, vast volumes of carbon dioxide so far imprisoned  in the permafrost of the polar coasts – 34% of all the world’s coastlines  – could escape to accelerate further warming and of course yet greater sea level rise.

Climate scientists have been wrestling for decades with what they call the carbon budget – the accounting of all the ways in which carbon dioxide gets into the atmosphere and out of it again – and missed another potentially dangerous source of the greenhouse gas.

As glaciers retreat and the frozen coasts and soils thaw, this could begin to seep into the atmosphere. Laboratory experiments suggest it will seep even faster as sea levels rise and waves grow more powerful. For every gram, dry weight, of eroded permafrost, more than 4 grams of carbon dioxide would escape into the atmosphere.

“Carbon budgets and climate simulations have so far missed coastal erosion in their equations even though it might be a substantial source of carbon dioxide,” says George Tanski of Vrije Universiteit Amsterdam, the lead author.

“Our research found that the erosion of permafrost coastlines can lead to the rapid release of significant quantities of CO2, which can be expected to increase as coastal erosion accelerates, temperatures increase, sea ice diminishes and stronger storms batter Arctic coasts.”

Early warning

That the Paris Agreement was backed up by pledges that might fail to contain global warning to an ideal target of 1.5°C was clear from the start, and scientists who looked at the promises made at the time warned that unless they were increased, they committed the world to a warming of at least 3°C above the long term average for most of human history.

The latest study from the Universal Ecological Fund now finds that not only are the pledges not enough; some are not being honoured. China and India pledged to reduce the intensity of their emissions relative to gross domestic product, but since their economies continue to grow, so will their emissions.

China already contributes more than 26% of all global emissions, India 7%. The US, which contributes 13% of all greenhouse emissions, is to quit the Paris Agreement in 2020, and has in any case reversed much of its climate legislation. Russia, which contributes 4.6% of all atmospheric carbon dioxide, has submitted no pledges.

Europe’s 28 nations, and seven others, have promised to reduce emissions by 40% by 2040. Of the remaining 152 nations, responsible for more than 36% of all emissions, 127 have submitted conditional plans, but rely upon technical assistance and funding from the wealthy nations to execute these. But the US and Australia have stopped making contributions to such funding.

Almost 70% of emissions are from fossil fuels: successful action would require the closure of 2,400 coal-fired power stations. In fact, 250 new coal-fired power stations are now under construction. The message is that governments are doing too little, too slowly, leaving horrendous future consequences. – Climate News Network

Climate ‘is the election priority’ for the UK

Britain’s general election campaign is squarely focused on the UK leaving the EU. But persuasive voices say the climate “is the election priority”.

LONDON, 7 November, 2019 − The real issue facing the United Kingdom in next month’s general election is not whether to choose Brexit, to stay in the European Union or leave it, a prominent lawyer says, because the climate “is the election priority” for the UK.

With Britain due to host the November 2020 United Nations climate talks, she told a London conference, it is vital that the new government elected on 12 December takes the lead by enacting policies to tackle the climate emergency.

Farhana Yamin, an international climate change lawyer, said that currently the world was failing to tackle the climate and ecological disaster facing the planet. The UK posed as a climate leader but was “way, way behind” what was needed and did not have the policies in place to reach its own target of net zero emissions by 2050.

“Nothing less than a green industrial revolution is required to turn the situation around. A war-like mobilisation of society to stop nature being destroyed needs to be in place by next year when the climate talks are being held in Glasgow”, she said. British voters had an opportunity to choose a government that could lead the world by example.

“The fact is we already know that normal life is going to be disrupted. Change is coming, whether you like it or not. The electorate has a chance to shape that change.

Inadequate Paris Agreement

“This is going to be a climate and ecological election. The future will be very different depending on the decisions taken in the next five years – and it depends on which direction the new government wants to take,” she said.

This was because it was already clear that the commitments made in Paris in 2015 to cut greenhouse gas emissions were nowhere near enough to hold global temperature rise to safe levels. The whole pack of nations was failing, and needed to make new commitments at the Glasgow talks a year from now.

Yamin, from Pakistan, lives in Britain and is an advocate and adviser to the Marshall Islands. She has represented many members of the Alliance of Small Island States (AOSIS) which are most threatened by climate change, particularly sea level rise.

Talking to an audience of senior business executives and heads of environmental groups at the conference of the Fit for the Future network, she said the horrors of climate change were already apparent.

The 20 million people in Delhi suffering from toxic air pollution, and those in the Marshall Islands which she champions who are facing inundation by the sea, were just two examples of the problem, and 2020 was a crucial year to try to turn the problem round.

“We already know that normal life is going to be disrupted. Change is coming, whether you like it or not. The electorate has a chance to shape that change”

Yamin told the Climate News Network she feared that in the UK election Brexit would crowd out the much more important issue of climate change. This was not to suggest how people should vote, but she asked people to cast aside other considerations and look at the parties’ climate policies.

“Whatever government is elected now will take decisions that will have a fundamental effect on the future of the planet. Take the right decisions in this four-year term of office, and there is still a chance of turning things around,” she said.

The co-leader of the UK Green Party, Sian Berry, said at the launch of the Greens’ campaign yesterday: “Some things are even bigger than Brexit. This must be the climate election.”

Yamin took part in London’s Extinction Rebellion protests and is one of the 1,300 people arrested there: she superglued herself to the entrance of the Shell oil giant’s London HQ. That had been necessary to raise public awareness of the problem, she said.

“For me it is the most historic and meaningful election I can remember. The environmental movement is all about social justice, so people now have the opportunity to vote to live and work in an equal society,” she said. − Climate News Network

Britain’s general election campaign is squarely focused on the UK leaving the EU. But persuasive voices say the climate “is the election priority”.

LONDON, 7 November, 2019 − The real issue facing the United Kingdom in next month’s general election is not whether to choose Brexit, to stay in the European Union or leave it, a prominent lawyer says, because the climate “is the election priority” for the UK.

With Britain due to host the November 2020 United Nations climate talks, she told a London conference, it is vital that the new government elected on 12 December takes the lead by enacting policies to tackle the climate emergency.

Farhana Yamin, an international climate change lawyer, said that currently the world was failing to tackle the climate and ecological disaster facing the planet. The UK posed as a climate leader but was “way, way behind” what was needed and did not have the policies in place to reach its own target of net zero emissions by 2050.

“Nothing less than a green industrial revolution is required to turn the situation around. A war-like mobilisation of society to stop nature being destroyed needs to be in place by next year when the climate talks are being held in Glasgow”, she said. British voters had an opportunity to choose a government that could lead the world by example.

“The fact is we already know that normal life is going to be disrupted. Change is coming, whether you like it or not. The electorate has a chance to shape that change.

Inadequate Paris Agreement

“This is going to be a climate and ecological election. The future will be very different depending on the decisions taken in the next five years – and it depends on which direction the new government wants to take,” she said.

This was because it was already clear that the commitments made in Paris in 2015 to cut greenhouse gas emissions were nowhere near enough to hold global temperature rise to safe levels. The whole pack of nations was failing, and needed to make new commitments at the Glasgow talks a year from now.

Yamin, from Pakistan, lives in Britain and is an advocate and adviser to the Marshall Islands. She has represented many members of the Alliance of Small Island States (AOSIS) which are most threatened by climate change, particularly sea level rise.

Talking to an audience of senior business executives and heads of environmental groups at the conference of the Fit for the Future network, she said the horrors of climate change were already apparent.

The 20 million people in Delhi suffering from toxic air pollution, and those in the Marshall Islands which she champions who are facing inundation by the sea, were just two examples of the problem, and 2020 was a crucial year to try to turn the problem round.

“We already know that normal life is going to be disrupted. Change is coming, whether you like it or not. The electorate has a chance to shape that change”

Yamin told the Climate News Network she feared that in the UK election Brexit would crowd out the much more important issue of climate change. This was not to suggest how people should vote, but she asked people to cast aside other considerations and look at the parties’ climate policies.

“Whatever government is elected now will take decisions that will have a fundamental effect on the future of the planet. Take the right decisions in this four-year term of office, and there is still a chance of turning things around,” she said.

The co-leader of the UK Green Party, Sian Berry, said at the launch of the Greens’ campaign yesterday: “Some things are even bigger than Brexit. This must be the climate election.”

Yamin took part in London’s Extinction Rebellion protests and is one of the 1,300 people arrested there: she superglued herself to the entrance of the Shell oil giant’s London HQ. That had been necessary to raise public awareness of the problem, she said.

“For me it is the most historic and meaningful election I can remember. The environmental movement is all about social justice, so people now have the opportunity to vote to live and work in an equal society,” she said. − Climate News Network

New land height metric raises sea level rise risk

Millions of us now live in danger: we could be at risk from future high tides and winds, says a new approach to measuring land height.

 

LONDON, 4 November, 2019 – Researchers have taken a closer look at estimates of coastal land height – and found that the numbers of people already at risk from sea level rise driven by global heating have multiplied threefold.

More than 100 million people already live below the high tide line, and 250 million live on plains that are lower than the current annual flood heights. Previous estimates have put these numbers at 28 million, and 65 million.

And even if the world takes immediate drastic action and reduces greenhouse gas emissions by the end of the century, at least 190 million people will find themselves below sea level.

If the world’s nations continue on the notorious business-as-usual track and go on burning ever greater volumes of fossil fuels, then around 630 million will, by the year 2100, find themselves on land that will be below the expected annual flood levels.

Protection in question

“These assessments show the potential of climate change to reshape cities, economies, coastlines and entire global regions within our lifetime,” said Scott Kulp of Climate Central, who led a study published in the journal Nature Communications.

“As the tideline rises higher than the ground people call home, nations will increasingly confront questions about whether, how much, and how long coastal defences can protect them.”

At the heart of the new research is a revised estimate of what constitutes sea level, and how it should be measured. Individuals and communities find out the hard way how the highest tides can rise to poison their farmlands with salt and wash away the foundations of their homes.

But the big picture – across nations and regions worldwide – is harder to estimate: for decades researchers have relied on satellite readings, confirmed by flights over limited spaces with radar equipment.

“There is still a great need for . . . more accurate elevation data. Lives and livelihoods depend on it”

But space-based readings by Nasa’s radar topography programme tend to be over-estimates, the researchers argue. That is because the technology measures the height of the first reflecting surface the radar signal touches. In open country, this may not matter. But forests and high buildings in densely-peopled cities distort the picture.

In parts of coastal Australia, and using a new approach, the researchers found that satellite readings delivered over-estimates of 2.5 metres. So global averages in the past have over-estimated, by around 2 metres, the elevation of lands that are home to billions.

Research of this kind helps clarify the challenge that faces governments, civic authorities and private citizens: communities grow up along low-lying coasts and estuaries because these provide good land, reliable water supplies and easy transport. But the catch with flood plains is that, sooner or later, they flood.

The repeated evidence of a decade of climate science is that floods will become more devastating, more frequent and more prolonged for a mix of reasons.

Multiple risks

Soils will subside because of the growing demand for groundwater and for clays and stone for bricks and mortar; because global average temperatures will rise and oceans expand as they warm; glaciers will melt and tip more water into the sea to raise ocean levels; and tropical cyclones will become more intense to drive more destructive storm surges.

Researchers have already warned that sea level rise could be accelerating, to bring more flooding to, for instance, the great cities of the US coasts, while some cities can expect ever more battering from Atlantic storms.

Coastal flooding is likely to create millions of climate refugees even within the US, and the worldwide costs of coastal flooding could reach $1 trillion a year by the end of the century.

The latest study confirms that the hazards are real, and may have so far been under-estimated. The researchers calculated that, in parts of China, Bangladesh, India, Vietnam and Thailand, places now home to 237 million people could face coastal flooding every year by 2050 – a figure 183 million higher than previous estimates.

US coasts threatened

The same study highlights faulty estimates of ground elevation even in the richest and most advanced nations. In some parts of the crowded coastal cities of New York, Boston and Miami, for instance, the researchers believe satellite readings have over-estimated ground height by almost five metres. They say their new approach reduces the margin of error to 2.5 cms.

Right now, around a billion people live on lands less than 10 metres above high tide levels. Around 250 million live within one metre above high tide.

“For all of the critical research that’s been done on climate change and sea level projections, it turns out that for most of the global coast we didn’t know the height of the ground beneath our feet,” said Benjamin Strauss, president and chief scientist of Climate Central, and co-author.

“Our data improves the picture, but there is still a great need for governments and insurance companies to produce and release more accurate elevation data. Lives and livelihoods depend on it.” – Climate News Network

Millions of us now live in danger: we could be at risk from future high tides and winds, says a new approach to measuring land height.

 

LONDON, 4 November, 2019 – Researchers have taken a closer look at estimates of coastal land height – and found that the numbers of people already at risk from sea level rise driven by global heating have multiplied threefold.

More than 100 million people already live below the high tide line, and 250 million live on plains that are lower than the current annual flood heights. Previous estimates have put these numbers at 28 million, and 65 million.

And even if the world takes immediate drastic action and reduces greenhouse gas emissions by the end of the century, at least 190 million people will find themselves below sea level.

If the world’s nations continue on the notorious business-as-usual track and go on burning ever greater volumes of fossil fuels, then around 630 million will, by the year 2100, find themselves on land that will be below the expected annual flood levels.

Protection in question

“These assessments show the potential of climate change to reshape cities, economies, coastlines and entire global regions within our lifetime,” said Scott Kulp of Climate Central, who led a study published in the journal Nature Communications.

“As the tideline rises higher than the ground people call home, nations will increasingly confront questions about whether, how much, and how long coastal defences can protect them.”

At the heart of the new research is a revised estimate of what constitutes sea level, and how it should be measured. Individuals and communities find out the hard way how the highest tides can rise to poison their farmlands with salt and wash away the foundations of their homes.

But the big picture – across nations and regions worldwide – is harder to estimate: for decades researchers have relied on satellite readings, confirmed by flights over limited spaces with radar equipment.

“There is still a great need for . . . more accurate elevation data. Lives and livelihoods depend on it”

But space-based readings by Nasa’s radar topography programme tend to be over-estimates, the researchers argue. That is because the technology measures the height of the first reflecting surface the radar signal touches. In open country, this may not matter. But forests and high buildings in densely-peopled cities distort the picture.

In parts of coastal Australia, and using a new approach, the researchers found that satellite readings delivered over-estimates of 2.5 metres. So global averages in the past have over-estimated, by around 2 metres, the elevation of lands that are home to billions.

Research of this kind helps clarify the challenge that faces governments, civic authorities and private citizens: communities grow up along low-lying coasts and estuaries because these provide good land, reliable water supplies and easy transport. But the catch with flood plains is that, sooner or later, they flood.

The repeated evidence of a decade of climate science is that floods will become more devastating, more frequent and more prolonged for a mix of reasons.

Multiple risks

Soils will subside because of the growing demand for groundwater and for clays and stone for bricks and mortar; because global average temperatures will rise and oceans expand as they warm; glaciers will melt and tip more water into the sea to raise ocean levels; and tropical cyclones will become more intense to drive more destructive storm surges.

Researchers have already warned that sea level rise could be accelerating, to bring more flooding to, for instance, the great cities of the US coasts, while some cities can expect ever more battering from Atlantic storms.

Coastal flooding is likely to create millions of climate refugees even within the US, and the worldwide costs of coastal flooding could reach $1 trillion a year by the end of the century.

The latest study confirms that the hazards are real, and may have so far been under-estimated. The researchers calculated that, in parts of China, Bangladesh, India, Vietnam and Thailand, places now home to 237 million people could face coastal flooding every year by 2050 – a figure 183 million higher than previous estimates.

US coasts threatened

The same study highlights faulty estimates of ground elevation even in the richest and most advanced nations. In some parts of the crowded coastal cities of New York, Boston and Miami, for instance, the researchers believe satellite readings have over-estimated ground height by almost five metres. They say their new approach reduces the margin of error to 2.5 cms.

Right now, around a billion people live on lands less than 10 metres above high tide levels. Around 250 million live within one metre above high tide.

“For all of the critical research that’s been done on climate change and sea level projections, it turns out that for most of the global coast we didn’t know the height of the ground beneath our feet,” said Benjamin Strauss, president and chief scientist of Climate Central, and co-author.

“Our data improves the picture, but there is still a great need for governments and insurance companies to produce and release more accurate elevation data. Lives and livelihoods depend on it.” – Climate News Network