Tag Archives: Sea levels

The very expensive human cost of climate change

Storms devastate. Climate change makes them more devastating. Now we know how much the human cost of climate change really is.

LONDON, 25 May, 2021 − We know already that the human cost of climate change is immense. Now we can put a figure on it. Nine years on, New Yorkers have a clearer idea of the direct cost of human-driven climate change to them during just one stormy weekend in October 2012.

They became poorer by $8.1 billion, say researchers from Princeton, New Brunswick and Hoboken in New Jersey, and Boston in Massachusetts, just because of sea level rise powered first by global heating fuelled by profligate combustion worldwide of coal, oil and gas, and then by a superstorm called Hurricane Sandy.

Researchers can also number the additional people who suffered damages inflicted precisely because of human-driven climate change on that one long, painful weekend: 71,000.

“This study is the first to isolate the human-contributed sea level effects during a coastal storm and put a dollar sign to the additional flooding damage,” said Philip Orton, of Stevens Institute of Technology in Hoboken, one of the authors.

“With coastal flooding increasingly impacting communities and causing widespread destruction, pinpointing the financial toll and lives affected by climate change will hopefully add urgency to our efforts to reduce it.”

“If we were to calculate the cost of climate change across all flooding events that figure would provide clarity on the severe damage we are inflicting on our planet”

There would have been damage anyway: Sandy was a powerful hurricane that slammed into the northeast US coast so hard it set the earthquake alarms ringing. The destruction attributed to Sandy is more than $62 billion, as one of the worst storms in history at the New York bight arrived with the evening high tide to cause devastation and disruption in New York City, New Jersey and Connecticut.

It also killed 43 people in New York City and destroyed thousands of homes and around a quarter of a million cars, vans, buses and trucks.

And now a study in the journal Nature Communications reasons that anthropogenic or human-powered sea level rise must have accounted for at least 13% of the total bill. That is because global heating from greenhouse gas emissions seems to have raised mean sea levels in the New York region by around 10 cms over the last century or so. In fact, Sandy arrived with the highest water level in at least 300 years in the New York metropolitan area.

The researchers set themselves the target of identifying precisely the impact of climate change on sea level rise in that region. To do that, they had to subtract the change that could be explained by coastal subsidence: as a consequence of heavy construction and groundwater abstraction, coastal settlements everywhere are likely to subside.

Knowing the threat

Then they combed maps of the damage, contour data and insurance data to arrive at a specific contribution by sea level rise linked to climate change: at the very least, they judged, $4.7bn, at the most $14bn, and so they compromised on $8bn.

They then numbered the humans who might not have been hit by flooding had there been no climate change: they calculated at least 40,000, and no more than 131,000, before settling on 70,000 additional victims.

Such exercises matter: city planners, coastal defence agencies, insurers and seaside property-holders need to know the scale of extra risk conferred by climate change. There will be more storm damage and flooding, and the new methodology could be adapted to other vulnerable cities.

US coasts already face more frequent floods, rising seas promise more such superstorms and − once again because of global heating − the north-eastern US seaboard can expect to be in the track of fiercer hurricanes.

“If we were to calculate the cost of climate change across all flooding events − both nuisance floods and those caused by extreme storm events − that figure would be enormous,” Dr Orton said. ”It would provide clarity on the severe damage we are inflicting on ourselves and on our planet.” − Climate News Network

Storms devastate. Climate change makes them more devastating. Now we know how much the human cost of climate change really is.

LONDON, 25 May, 2021 − We know already that the human cost of climate change is immense. Now we can put a figure on it. Nine years on, New Yorkers have a clearer idea of the direct cost of human-driven climate change to them during just one stormy weekend in October 2012.

They became poorer by $8.1 billion, say researchers from Princeton, New Brunswick and Hoboken in New Jersey, and Boston in Massachusetts, just because of sea level rise powered first by global heating fuelled by profligate combustion worldwide of coal, oil and gas, and then by a superstorm called Hurricane Sandy.

Researchers can also number the additional people who suffered damages inflicted precisely because of human-driven climate change on that one long, painful weekend: 71,000.

“This study is the first to isolate the human-contributed sea level effects during a coastal storm and put a dollar sign to the additional flooding damage,” said Philip Orton, of Stevens Institute of Technology in Hoboken, one of the authors.

“With coastal flooding increasingly impacting communities and causing widespread destruction, pinpointing the financial toll and lives affected by climate change will hopefully add urgency to our efforts to reduce it.”

“If we were to calculate the cost of climate change across all flooding events that figure would provide clarity on the severe damage we are inflicting on our planet”

There would have been damage anyway: Sandy was a powerful hurricane that slammed into the northeast US coast so hard it set the earthquake alarms ringing. The destruction attributed to Sandy is more than $62 billion, as one of the worst storms in history at the New York bight arrived with the evening high tide to cause devastation and disruption in New York City, New Jersey and Connecticut.

It also killed 43 people in New York City and destroyed thousands of homes and around a quarter of a million cars, vans, buses and trucks.

And now a study in the journal Nature Communications reasons that anthropogenic or human-powered sea level rise must have accounted for at least 13% of the total bill. That is because global heating from greenhouse gas emissions seems to have raised mean sea levels in the New York region by around 10 cms over the last century or so. In fact, Sandy arrived with the highest water level in at least 300 years in the New York metropolitan area.

The researchers set themselves the target of identifying precisely the impact of climate change on sea level rise in that region. To do that, they had to subtract the change that could be explained by coastal subsidence: as a consequence of heavy construction and groundwater abstraction, coastal settlements everywhere are likely to subside.

Knowing the threat

Then they combed maps of the damage, contour data and insurance data to arrive at a specific contribution by sea level rise linked to climate change: at the very least, they judged, $4.7bn, at the most $14bn, and so they compromised on $8bn.

They then numbered the humans who might not have been hit by flooding had there been no climate change: they calculated at least 40,000, and no more than 131,000, before settling on 70,000 additional victims.

Such exercises matter: city planners, coastal defence agencies, insurers and seaside property-holders need to know the scale of extra risk conferred by climate change. There will be more storm damage and flooding, and the new methodology could be adapted to other vulnerable cities.

US coasts already face more frequent floods, rising seas promise more such superstorms and − once again because of global heating − the north-eastern US seaboard can expect to be in the track of fiercer hurricanes.

“If we were to calculate the cost of climate change across all flooding events − both nuisance floods and those caused by extreme storm events − that figure would be enormous,” Dr Orton said. ”It would provide clarity on the severe damage we are inflicting on ourselves and on our planet.” − Climate News Network

Faster Greenland ice melt could be unstoppable

A rapid thaw could destroy a whole ice sheet if the faster Greenland ice melt scientists have found spreads across the island.

LONDON, 24 May, 2021 − Researchers say the faster Greenland ice melt affecting part of the island could mean a large area is on the verge of irreversible loss. Their new study shows that the central western region of the ice sheet is near what climate scientists call “a tipping point.”

That is, once the ice starts to slide away, most of it will tip into the sea, to raise global sea levels and potentially to trigger the collapse of the great Atlantic Ocean current that enhances the climate of north-west Europe.

“We have found evidence that the central western part of the Greenland ice sheet has been destabilising and is now close to a critical transition,” said Niklas Boers, of the Potsdam Institute for Climate Impact Research. “Our results suggest there will be substantially enhanced melting in the future − which is quite worrying.”

Dr Boers and his colleague Martin Rypdal of the Arctic University of Norway report in the Proceedings of the National Academy of Sciences that they looked at data since 1880 of melt rates and ice-sheet altitude shifts of a region called the Jakobshavn basin in the central western region of the northern hemisphere’s biggest single block of ice − a block big enough to raise global sea levels by seven metres, were it all to melt.

And what they saw was something alarming: evidence that surface melting is beginning to accelerate. The conclusion, for now, is tentative.

“It’s high time we dramatically and substantially reduce greenhouse gas emissions from burning fossil fuels”

“We might be seeing the beginning of a large scale destabilisation, but at the moment we cannot tell, unfortunately,” Dr Boers said. “So far the signals we see are only regional, but that might simply be due to the scarcity of accurate and long-term data for other parts of the ice sheet.”

The region is home to the Jakobshavn glacier, which began to accelerate its flow to the sea this century, but the alarm is consistent with other studies of the mass of ice piled up on Greenland.

For most of the last 10,000 years or so, the summer loss of ice through melt and glacial flow has been replaced by winter snow. But in recent years, other research teams have warned, repeatedly, that the rate of  melting of Greenland’s surface ice has increased, in ways that really could threaten the stability of the entire sheet. Last year, ice loss reached a new record.

Greenland’s ice sheet is high: colder, therefore, at altitude. As the surface melts, the elevation becomes lower, and therefore increasingly warmer. So once the high ground surface begins to melt away, it could reach a level below which there is no obvious reason why the process should stop.

Climate computer simulations predict a threshold of global average temperature change that could, in effect, start a process in which the loss of the entire ice sheet would become inevitable. The loss would happen over hundreds of years, or perhaps thousands, but once begun it would continue inexorably.

Extreme Arctic warming

Global sea levels would rise at ever faster rates, and the arrival of so much fresh water in the north Atlantic would be enough to interfere with the ocean circulation.

For years oceanographers have been warning that the existing current, which takes warm tropical water as far north as the Arctic, could weaken, or fail, with unpredictable and uncomfortable consequences for north European nations.

The only way to stop Greenland’s accelerated melt, once it reaches a critical point, would be to lower the temperature of the whole planet back to that which was normal more than 200 years ago. That is unlikely to happen. Instead, for the moment, the evidence is that average temperatures worldwide could rise by 3°C or more by 2100. The Arctic, however, is likely to become much, much warmer.

“So practically, the current and near-future mass loss will be irreversible,” said Dr Boers, “That’s why it’s high time we dramatically and substantially reduce greenhouse gas emissions from burning fossil fuels and restabilise the ice sheet and our climate.” − Climate News Network

A rapid thaw could destroy a whole ice sheet if the faster Greenland ice melt scientists have found spreads across the island.

LONDON, 24 May, 2021 − Researchers say the faster Greenland ice melt affecting part of the island could mean a large area is on the verge of irreversible loss. Their new study shows that the central western region of the ice sheet is near what climate scientists call “a tipping point.”

That is, once the ice starts to slide away, most of it will tip into the sea, to raise global sea levels and potentially to trigger the collapse of the great Atlantic Ocean current that enhances the climate of north-west Europe.

“We have found evidence that the central western part of the Greenland ice sheet has been destabilising and is now close to a critical transition,” said Niklas Boers, of the Potsdam Institute for Climate Impact Research. “Our results suggest there will be substantially enhanced melting in the future − which is quite worrying.”

Dr Boers and his colleague Martin Rypdal of the Arctic University of Norway report in the Proceedings of the National Academy of Sciences that they looked at data since 1880 of melt rates and ice-sheet altitude shifts of a region called the Jakobshavn basin in the central western region of the northern hemisphere’s biggest single block of ice − a block big enough to raise global sea levels by seven metres, were it all to melt.

And what they saw was something alarming: evidence that surface melting is beginning to accelerate. The conclusion, for now, is tentative.

“It’s high time we dramatically and substantially reduce greenhouse gas emissions from burning fossil fuels”

“We might be seeing the beginning of a large scale destabilisation, but at the moment we cannot tell, unfortunately,” Dr Boers said. “So far the signals we see are only regional, but that might simply be due to the scarcity of accurate and long-term data for other parts of the ice sheet.”

The region is home to the Jakobshavn glacier, which began to accelerate its flow to the sea this century, but the alarm is consistent with other studies of the mass of ice piled up on Greenland.

For most of the last 10,000 years or so, the summer loss of ice through melt and glacial flow has been replaced by winter snow. But in recent years, other research teams have warned, repeatedly, that the rate of  melting of Greenland’s surface ice has increased, in ways that really could threaten the stability of the entire sheet. Last year, ice loss reached a new record.

Greenland’s ice sheet is high: colder, therefore, at altitude. As the surface melts, the elevation becomes lower, and therefore increasingly warmer. So once the high ground surface begins to melt away, it could reach a level below which there is no obvious reason why the process should stop.

Climate computer simulations predict a threshold of global average temperature change that could, in effect, start a process in which the loss of the entire ice sheet would become inevitable. The loss would happen over hundreds of years, or perhaps thousands, but once begun it would continue inexorably.

Extreme Arctic warming

Global sea levels would rise at ever faster rates, and the arrival of so much fresh water in the north Atlantic would be enough to interfere with the ocean circulation.

For years oceanographers have been warning that the existing current, which takes warm tropical water as far north as the Arctic, could weaken, or fail, with unpredictable and uncomfortable consequences for north European nations.

The only way to stop Greenland’s accelerated melt, once it reaches a critical point, would be to lower the temperature of the whole planet back to that which was normal more than 200 years ago. That is unlikely to happen. Instead, for the moment, the evidence is that average temperatures worldwide could rise by 3°C or more by 2100. The Arctic, however, is likely to become much, much warmer.

“So practically, the current and near-future mass loss will be irreversible,” said Dr Boers, “That’s why it’s high time we dramatically and substantially reduce greenhouse gas emissions from burning fossil fuels and restabilise the ice sheet and our climate.” − Climate News Network

Tide of climate refugees swells as Earth heats up

Prepare for the arrival of more displaced persons, climate refugees driven from their homes by global heating.

LONDON, 11 May, 2021 − Natural hazards − most of them driven by climate change − have forced an estimated 288 million people from their homes since 2008. That is three times the numbers displaced by war and conflict. These people have become, however briefly, climate refugees.

And the number will grow. A new study has found that for every 1°C rise in global average temperatures, the chance of displacement from river flooding alone will rise by 50%. And that calculation is based on population numbers right now. As human numbers rise, so will the risk − by 110%.

Another study makes an even more precise prediction: thanks to rising sea levels and more intense cyclonic storms, an estimated 1.3 million people in Bangladesh will be forced into migration by 2050. Many will move further inland − but many are likely to be forced across national borders, to trigger more displacement.

Drought and famine are climate-related natural disasters. So are forest fires, extreme heat waves, catastrophic windstorms and devastating floods, driven either by torrential rainfall or rising sea levels, or both.

Climate scientists, environmentalists and geographers have been warning for years that the numbers of people driven from their homes by climate change is on the increase: even in the US, as many as 13 million people could be forced from their coastal settlements by sea level rise.

“It is imperative that we have a better understanding of how the risks are changing”

Swiss scientists report in the journal Environmental Research Letters that even if the world keeps to an agreement to limit global warming to no more than 2°C, because the global population is rising, the average risk of displacement by river flooding is likely to rise by 110% by the end of the century.

If however nations take no drastic action, and go on burning ever more fossil fuels, the global average risk of being forced from home by swirling waters could rise by up to 350%.

“Because floods are a major driver of displacement, and due to the fact that they are influenced by climate change, it is imperative that we have a better understanding of how the risks are changing,” said Pui Man Kam of the Swiss Federal Institute of Technology, known as ETH Zurich, who led the study.

An estimated 680 million people worldwide live in low-lying coastal zones. Spanish, Italian and US scientists report in the journal Earth’s Future that they had developed a data model to predict the numbers likely to be displaced by any natural hazard to become climate refugees.

They tested it in the context of sea level rise, storms and floods in one low-lying country laced with rivers: Bangladesh. It is home to 163 million people, of whom 41% live at elevations lower than 10 metres above sea level.

Countrywide unrest likely

Their research found that although people in the coastal districts along the Bay of Bengal would be flooded, a surge of migration would ripple across the landscape and impact all 64 districts, including the capital, Dhaka.

Thanks to climate migration, numbers in the city should grow and eventually decline, as people moved to get away from the new arrivals. That is, flood events at the coast could ultimately trigger human unrest in the entire country.
“Droughts, desertification, floods, earthquakes, and wildfire threaten livelihoods worldwide; from wealthy to developing economies, every country is vulnerable to environmental change,” said Maurizio Porfiri of New York University’s Tandon School of Engineering.

“Mathematical models can assist in providing reliable predictions of environmental migration, which are critical for devising effective policy initiatives and improving our preparedness for future migration patterns.” − Climate News Network

Prepare for the arrival of more displaced persons, climate refugees driven from their homes by global heating.

LONDON, 11 May, 2021 − Natural hazards − most of them driven by climate change − have forced an estimated 288 million people from their homes since 2008. That is three times the numbers displaced by war and conflict. These people have become, however briefly, climate refugees.

And the number will grow. A new study has found that for every 1°C rise in global average temperatures, the chance of displacement from river flooding alone will rise by 50%. And that calculation is based on population numbers right now. As human numbers rise, so will the risk − by 110%.

Another study makes an even more precise prediction: thanks to rising sea levels and more intense cyclonic storms, an estimated 1.3 million people in Bangladesh will be forced into migration by 2050. Many will move further inland − but many are likely to be forced across national borders, to trigger more displacement.

Drought and famine are climate-related natural disasters. So are forest fires, extreme heat waves, catastrophic windstorms and devastating floods, driven either by torrential rainfall or rising sea levels, or both.

Climate scientists, environmentalists and geographers have been warning for years that the numbers of people driven from their homes by climate change is on the increase: even in the US, as many as 13 million people could be forced from their coastal settlements by sea level rise.

“It is imperative that we have a better understanding of how the risks are changing”

Swiss scientists report in the journal Environmental Research Letters that even if the world keeps to an agreement to limit global warming to no more than 2°C, because the global population is rising, the average risk of displacement by river flooding is likely to rise by 110% by the end of the century.

If however nations take no drastic action, and go on burning ever more fossil fuels, the global average risk of being forced from home by swirling waters could rise by up to 350%.

“Because floods are a major driver of displacement, and due to the fact that they are influenced by climate change, it is imperative that we have a better understanding of how the risks are changing,” said Pui Man Kam of the Swiss Federal Institute of Technology, known as ETH Zurich, who led the study.

An estimated 680 million people worldwide live in low-lying coastal zones. Spanish, Italian and US scientists report in the journal Earth’s Future that they had developed a data model to predict the numbers likely to be displaced by any natural hazard to become climate refugees.

They tested it in the context of sea level rise, storms and floods in one low-lying country laced with rivers: Bangladesh. It is home to 163 million people, of whom 41% live at elevations lower than 10 metres above sea level.

Countrywide unrest likely

Their research found that although people in the coastal districts along the Bay of Bengal would be flooded, a surge of migration would ripple across the landscape and impact all 64 districts, including the capital, Dhaka.

Thanks to climate migration, numbers in the city should grow and eventually decline, as people moved to get away from the new arrivals. That is, flood events at the coast could ultimately trigger human unrest in the entire country.
“Droughts, desertification, floods, earthquakes, and wildfire threaten livelihoods worldwide; from wealthy to developing economies, every country is vulnerable to environmental change,” said Maurizio Porfiri of New York University’s Tandon School of Engineering.

“Mathematical models can assist in providing reliable predictions of environmental migration, which are critical for devising effective policy initiatives and improving our preparedness for future migration patterns.” − Climate News Network

2°C more heat may mean catastrophic sea level rise

The Paris Agreement to limit global heat could prevent catastrophic sea level rise, if states keep their promises to cut carbon.

LONDON, 7 May, 2021 − Climate scientists warn that − unless the world acts to limit global heating − the Antarctic ice sheet could begin irreversible collapse. The ice on the Antarctic continent could raise global sea levels by more than 47 metres, higher than a ten-storey building, and enough to unleash catastrophic sea level rise.

Global warming of just 3°C above the long-term average for most of human history would bring on a sea level rise from south polar melting of at least 0.5cms a year from about 2060 onwards.

Right now, greenhouse gas emissions continue to increase as nations burn ever more coal, oil and gas to power economic growth, and the world is on course for temperatures significantly above 3°C.

Researchers calculate in the journal Nature that any global warming that exceeds the target of no more than 2°C by 2100, agreed by almost all of the world’s nations in Paris in 2015, will put the ice shelves that ring the southern continent at risk of melting.

“Unstoppable, catastrophic sea level rise from Antarctica [may] be triggered if the Paris Agreement temperature targets are exceeded”

The mass and extent of sea ice acts as a buttress to flow from higher ground. If the sea ice melts, then the flow of glacial ice to the sea will accelerate.

“Ice-sheet collapse is irreversible over thousands of years, and if the Antarctic ice sheet collapse becomes unstable it could continue to retreat for centuries,” said Daniel Gilford of Rutgers University in the US, one of the research team. “That’s regardless of whether emissions mitigation strategies such as removing carbon dioxide from the atmosphere are employed.”

The finding is based on computer simulation backed up by detailed knowledge of at least some of the more prominent glaciers in West Antarctica, and of the response of the sea ice offshore to warmer winds and ocean currents.

Nor can it be a surprise to climate scientists: they have been warning for years of the potential loss of shelf-ice, they have already warned that ice loss could become irreversible, and they have measured the rates of loss often enough to be confident that this is accelerating.

On course for 3°C

The ice in Antarctica sits on a landmass bigger than the entire US and European Union combined: the burden of ice adds up to 30 million cubic kilometres, and some of it flows as vast glaciers 50kms wide and 2000 metres deep. And there has been concern for years that some flows are accelerating.

The Paris Agreement actually settled on the phrase “well below 2°C” as the global ambition for 2100. The national plans declared so far to reduce emissions commit the planet to a warming of 3°C or more.

The fear is that at 3°C nothing could prevent eventual ice sheet attrition over the following centuries. The latest research confirms that fear with a more than usually forthright scientific conclusion.

“These results demonstrate the possibility that unstoppable, catastrophic sea level rise from Antarctica will be triggered if the Paris Agreement temperature targets are exceeded,” the scientists write. − Climate News Network

The Paris Agreement to limit global heat could prevent catastrophic sea level rise, if states keep their promises to cut carbon.

LONDON, 7 May, 2021 − Climate scientists warn that − unless the world acts to limit global heating − the Antarctic ice sheet could begin irreversible collapse. The ice on the Antarctic continent could raise global sea levels by more than 47 metres, higher than a ten-storey building, and enough to unleash catastrophic sea level rise.

Global warming of just 3°C above the long-term average for most of human history would bring on a sea level rise from south polar melting of at least 0.5cms a year from about 2060 onwards.

Right now, greenhouse gas emissions continue to increase as nations burn ever more coal, oil and gas to power economic growth, and the world is on course for temperatures significantly above 3°C.

Researchers calculate in the journal Nature that any global warming that exceeds the target of no more than 2°C by 2100, agreed by almost all of the world’s nations in Paris in 2015, will put the ice shelves that ring the southern continent at risk of melting.

“Unstoppable, catastrophic sea level rise from Antarctica [may] be triggered if the Paris Agreement temperature targets are exceeded”

The mass and extent of sea ice acts as a buttress to flow from higher ground. If the sea ice melts, then the flow of glacial ice to the sea will accelerate.

“Ice-sheet collapse is irreversible over thousands of years, and if the Antarctic ice sheet collapse becomes unstable it could continue to retreat for centuries,” said Daniel Gilford of Rutgers University in the US, one of the research team. “That’s regardless of whether emissions mitigation strategies such as removing carbon dioxide from the atmosphere are employed.”

The finding is based on computer simulation backed up by detailed knowledge of at least some of the more prominent glaciers in West Antarctica, and of the response of the sea ice offshore to warmer winds and ocean currents.

Nor can it be a surprise to climate scientists: they have been warning for years of the potential loss of shelf-ice, they have already warned that ice loss could become irreversible, and they have measured the rates of loss often enough to be confident that this is accelerating.

On course for 3°C

The ice in Antarctica sits on a landmass bigger than the entire US and European Union combined: the burden of ice adds up to 30 million cubic kilometres, and some of it flows as vast glaciers 50kms wide and 2000 metres deep. And there has been concern for years that some flows are accelerating.

The Paris Agreement actually settled on the phrase “well below 2°C” as the global ambition for 2100. The national plans declared so far to reduce emissions commit the planet to a warming of 3°C or more.

The fear is that at 3°C nothing could prevent eventual ice sheet attrition over the following centuries. The latest research confirms that fear with a more than usually forthright scientific conclusion.

“These results demonstrate the possibility that unstoppable, catastrophic sea level rise from Antarctica will be triggered if the Paris Agreement temperature targets are exceeded,” the scientists write. − Climate News Network

Faster glacier melting raises hunger threat

The world’s upland icecaps are in retreat. Faster glacier melting could slow to a trickle streams that once fed foaming rivers.

LONDON, 5 May, 2021 − Glacial retreat − the rate at which mountain ice is turning to running water − has accelerated. In the last two decades, the world’s 220,000 glaciers have lost ice at the rate of 267 billion tonnes a year on average, and this faster glacier melting could soon imperil downstream food and water supplies.

To make sense of this almost unimaginable volume, think of a country the size of Switzerland. And then submerge it six metres deep in water. And then go on doing that every year for 20 years.

European scientists report in the journal Nature that, on the basis of satellite data, they assembled a global snapshot of the entire world’s stock of land-borne ice, excluding Antarctica and Greenland. And then they began to measure the impact of global heating driven by profligate fossil fuel use on the lofty, frozen beauty of the Alps, the Hindu Kush, the Andes, the Himalayas and the mountains of Alaska.

They found not just loss, but a loss that was accelerating sharply. Between 2000 and 2004, the glaciers together surrendered 227 billion tons of ice a year on average. By 2015 to 2019, the annual loss had risen to 298 billion tonnes. The run-off from the retreating glaciers alone caused more than one-fifth of observed sea level rise this century.

“The world really needs to act now to prevent the worst case climate change scenario”

Right now an estimated 200 million people live on land that is likely to be flooded by high tides at the close of this century. Altogether, one billion people could face water shortages and failed harvests within the next three decades, in many instances because of glacier loss.

Glacial ice in the high mountains represents so much water stored, to be released in the summer melt to nourish crops downstream. The fastest melt is in Alaska, Iceland and the Alps, but global warming is also affecting the Pamirs, the Hindu Kush and other peaks in Central Asia.

“The situation in the Himalayas is particularly worrying,” said Romain Hugonnet, of the Swiss Federal Institute of Technology, known as ETH Zurich, and the University of Toulouse.

“During the dry season, glacial meltwater is an important source that feeds major waterways such as the Ganges, Brahmaputra and Indus rivers. Right now, this increased melting acts as a buffer for people living in the region, but if Himalayan glacier shrinkage keeps accelerating, populous countries like India and Bangladesh could face food and water shortages in a few decades.”

Climate change link

Such news could hardly be a shock to geographers and climate scientists: researchers have been warning for years that as many as half of the planet’s mountain glaciers could be gone by the century’s end. Europe’s Alps could by 2100 have lost nine-tenths of all the continent’s flowing ice.

Researchers have also identified the consequent risk to water supplies for millions, and confirmed an “irrefutable” link between human-induced climate change and glacier loss. So the latest research is an update, and a check on subtle changes in rates of loss, based on imagery from Nasa’s Terra satellite, which has been orbiting the planet every 100 minutes since 1999.

The scientists found that melt rates in Greenland, Iceland and Scandinavia all slowed in the first two decades of the century, perhaps because of a change in temperatures and precipitation in the North Atlantic. Conversely, glaciers in the Karakoram range that had once seemed anomalously stable had now started to melt.

“Our findings are important on a political level,” said Daniel Farinotti, also of ETH Zurich. “The world really needs to act now to prevent the worst case climate change scenario.” − Climate News Network

The world’s upland icecaps are in retreat. Faster glacier melting could slow to a trickle streams that once fed foaming rivers.

LONDON, 5 May, 2021 − Glacial retreat − the rate at which mountain ice is turning to running water − has accelerated. In the last two decades, the world’s 220,000 glaciers have lost ice at the rate of 267 billion tonnes a year on average, and this faster glacier melting could soon imperil downstream food and water supplies.

To make sense of this almost unimaginable volume, think of a country the size of Switzerland. And then submerge it six metres deep in water. And then go on doing that every year for 20 years.

European scientists report in the journal Nature that, on the basis of satellite data, they assembled a global snapshot of the entire world’s stock of land-borne ice, excluding Antarctica and Greenland. And then they began to measure the impact of global heating driven by profligate fossil fuel use on the lofty, frozen beauty of the Alps, the Hindu Kush, the Andes, the Himalayas and the mountains of Alaska.

They found not just loss, but a loss that was accelerating sharply. Between 2000 and 2004, the glaciers together surrendered 227 billion tons of ice a year on average. By 2015 to 2019, the annual loss had risen to 298 billion tonnes. The run-off from the retreating glaciers alone caused more than one-fifth of observed sea level rise this century.

“The world really needs to act now to prevent the worst case climate change scenario”

Right now an estimated 200 million people live on land that is likely to be flooded by high tides at the close of this century. Altogether, one billion people could face water shortages and failed harvests within the next three decades, in many instances because of glacier loss.

Glacial ice in the high mountains represents so much water stored, to be released in the summer melt to nourish crops downstream. The fastest melt is in Alaska, Iceland and the Alps, but global warming is also affecting the Pamirs, the Hindu Kush and other peaks in Central Asia.

“The situation in the Himalayas is particularly worrying,” said Romain Hugonnet, of the Swiss Federal Institute of Technology, known as ETH Zurich, and the University of Toulouse.

“During the dry season, glacial meltwater is an important source that feeds major waterways such as the Ganges, Brahmaputra and Indus rivers. Right now, this increased melting acts as a buffer for people living in the region, but if Himalayan glacier shrinkage keeps accelerating, populous countries like India and Bangladesh could face food and water shortages in a few decades.”

Climate change link

Such news could hardly be a shock to geographers and climate scientists: researchers have been warning for years that as many as half of the planet’s mountain glaciers could be gone by the century’s end. Europe’s Alps could by 2100 have lost nine-tenths of all the continent’s flowing ice.

Researchers have also identified the consequent risk to water supplies for millions, and confirmed an “irrefutable” link between human-induced climate change and glacier loss. So the latest research is an update, and a check on subtle changes in rates of loss, based on imagery from Nasa’s Terra satellite, which has been orbiting the planet every 100 minutes since 1999.

The scientists found that melt rates in Greenland, Iceland and Scandinavia all slowed in the first two decades of the century, perhaps because of a change in temperatures and precipitation in the North Atlantic. Conversely, glaciers in the Karakoram range that had once seemed anomalously stable had now started to melt.

“Our findings are important on a political level,” said Daniel Farinotti, also of ETH Zurich. “The world really needs to act now to prevent the worst case climate change scenario.” − Climate News Network

Climate heating may speed up to unexpected levels

When the ice thaws, ocean levels rise. And four new studies show climate heating can happen fast.

LONDON, 15 April, 2021 − If climate heating continues apace and the planet goes on warming, then up to a third of Antarctica’s ice shelf could tip into the sea.

And tip is the operative word, according to a separate study: at least one Antarctic glacier could be about to tip into rapid and irreversible retreat if temperatures go on rising.

And rise they could: evidence from the past in a third research programme confirms that at the end of the last Ice Age, Greenland’s temperature rose by somewhere between 5°C and 16°C in just decades, in line with a cascade of climate change events.

And ominously a fourth study of climate change 14,600 years ago confirmed that as the ice retreated, sea levels rose at 10 times the current rate, to 3.6 metres in just a century, and up to 18 metres in a 500-year sequence.

Each study is, on its own, an examination of the complexities of the planetary climate machine and the role of the polar ice sheets in climate change. But the message of the four together is a stark one: climate change is happening, could accelerate and could happen at unexpected speeds.

Unstable at 4°C

The Antarctic ice sheet floats on the sea: were it all to melt, sea levels globally would remain much the same. But the ice sheet plays an important role in stabilising the massive reserves of ice on the continental surface.

“Ice shelves are important buffers preventing glaciers on land from flowing freely into the ocean and contributing to sea level rise,” warned Ella Gilbert, a meteorologist at the University of Reading in the UK. “When they collapse, it’s like a giant cork being removed from a bottle, allowing unimaginable amounts of water from glaciers to pour into the sea.”

She and colleagues report in the journal Geophysical Research Letters that their detailed study of the vulnerable platforms of floating ice around the continent revealed that half a million square kilometres of shelf − 34% in total, including two-thirds of all the ice off the Antarctic Peninsula − would become unstable if global temperatures rose by 4°C, under the business-as-usual scenario in which nations went on burning ever-greater quantities of fossil fuel.

If however the world kept to the limit it agreed in Paris in 2015, that would halve the area at risk and perhaps avoid significant sea level rise. But already, just two Antarctic glaciers are responsible for around 10% of sea level rise at the current rate, and researchers have been warning for years that the Pine Island and Thwaites glaciers in West Antarctica could be at risk.

Now researchers in the UK report in the journal The Cryosphere that their computer simulation had identified a series of tipping points for the Pine Island flow.

“Ice shelves are important buffers preventing glaciers on land from contributing to sea level rise. When they collapse, it’s like a giant cork being removed from a bottle, allowing unimaginable amounts of water to pour into the sea”

The third of these, triggered by ocean temperatures that had warmed just 1.2°C, would lead to irretrievable retreat of the entire glacier. Hilmar Gudmundsson, a glaciologist at the UK’s Northumbria University and one of the authors, called the research a “major step forward” in the understanding of the dynamics of the region.

“But the findings of this study also concern me”, he said. “Should the glacier enter unstable irreversible retreat, the impact on sea level could be measured in metres, and as this study shows, once the retreat starts it might be impossible to halt it.”

Rapid polar melt is part of the pattern of climate history. Danish researchers report in Nature Communications that, on the evidence preserved in Greenland ice cores, they identified a series of 30 abrupt climate changes at the close of the Last Ice Age, affecting North Atlantic ocean currents, wind and rainfall patterns and the spread of sea ice: a set of physical processes that changed together, like a row of cascading dominoes.

The precise order of events was difficult to ascertain, but during that sequence the temperature of Greenland soared by 5°C to 16°C in decades to centuries. The question remains open: could such things happen today?

“The results emphasise the importance of trying to limit climate change by, for example, cutting anthropogenic emissions of CO2 and other greenhouse gases, both to reduce the predictable, gradual climate change and to reduce the risk of future abrupt climate change,” said Sune Olander Rasmussen, at the Niels Bohr Institute in Copenhagen, one of the authors.

Greenland’s future role

“If you do not want the dominoes to topple over, you are better off not to push the table they stand on too much.”

And another study in the same journal by British scientists reports on a close study of geological evidence to decipher the pattern of events during the largest and most rapid pulse of sea level rise at the close of the last Ice Age.

Their study suggested that although the sea levels rose 18 metres in about 500 years − a rate of about 3.6 metres a century − it all happened with relatively little help from a melting Antarctica. As the great glaciers retreated from North America, Europe and Asia, so the oceans rose.

“The next big question is to work out what triggered the ice melt, and what impact the massive influx of meltwater had on ocean currents in the North Atlantic,” said Pippa Whitehouse of the University of Durham, one of the researchers.

“This is very much on our minds today − any disruption to the Gulf Stream, for example due to melting of the Greenland Ice Sheet, will have significant consequences for the UK climate.” − Climate News Network

When the ice thaws, ocean levels rise. And four new studies show climate heating can happen fast.

LONDON, 15 April, 2021 − If climate heating continues apace and the planet goes on warming, then up to a third of Antarctica’s ice shelf could tip into the sea.

And tip is the operative word, according to a separate study: at least one Antarctic glacier could be about to tip into rapid and irreversible retreat if temperatures go on rising.

And rise they could: evidence from the past in a third research programme confirms that at the end of the last Ice Age, Greenland’s temperature rose by somewhere between 5°C and 16°C in just decades, in line with a cascade of climate change events.

And ominously a fourth study of climate change 14,600 years ago confirmed that as the ice retreated, sea levels rose at 10 times the current rate, to 3.6 metres in just a century, and up to 18 metres in a 500-year sequence.

Each study is, on its own, an examination of the complexities of the planetary climate machine and the role of the polar ice sheets in climate change. But the message of the four together is a stark one: climate change is happening, could accelerate and could happen at unexpected speeds.

Unstable at 4°C

The Antarctic ice sheet floats on the sea: were it all to melt, sea levels globally would remain much the same. But the ice sheet plays an important role in stabilising the massive reserves of ice on the continental surface.

“Ice shelves are important buffers preventing glaciers on land from flowing freely into the ocean and contributing to sea level rise,” warned Ella Gilbert, a meteorologist at the University of Reading in the UK. “When they collapse, it’s like a giant cork being removed from a bottle, allowing unimaginable amounts of water from glaciers to pour into the sea.”

She and colleagues report in the journal Geophysical Research Letters that their detailed study of the vulnerable platforms of floating ice around the continent revealed that half a million square kilometres of shelf − 34% in total, including two-thirds of all the ice off the Antarctic Peninsula − would become unstable if global temperatures rose by 4°C, under the business-as-usual scenario in which nations went on burning ever-greater quantities of fossil fuel.

If however the world kept to the limit it agreed in Paris in 2015, that would halve the area at risk and perhaps avoid significant sea level rise. But already, just two Antarctic glaciers are responsible for around 10% of sea level rise at the current rate, and researchers have been warning for years that the Pine Island and Thwaites glaciers in West Antarctica could be at risk.

Now researchers in the UK report in the journal The Cryosphere that their computer simulation had identified a series of tipping points for the Pine Island flow.

“Ice shelves are important buffers preventing glaciers on land from contributing to sea level rise. When they collapse, it’s like a giant cork being removed from a bottle, allowing unimaginable amounts of water to pour into the sea”

The third of these, triggered by ocean temperatures that had warmed just 1.2°C, would lead to irretrievable retreat of the entire glacier. Hilmar Gudmundsson, a glaciologist at the UK’s Northumbria University and one of the authors, called the research a “major step forward” in the understanding of the dynamics of the region.

“But the findings of this study also concern me”, he said. “Should the glacier enter unstable irreversible retreat, the impact on sea level could be measured in metres, and as this study shows, once the retreat starts it might be impossible to halt it.”

Rapid polar melt is part of the pattern of climate history. Danish researchers report in Nature Communications that, on the evidence preserved in Greenland ice cores, they identified a series of 30 abrupt climate changes at the close of the Last Ice Age, affecting North Atlantic ocean currents, wind and rainfall patterns and the spread of sea ice: a set of physical processes that changed together, like a row of cascading dominoes.

The precise order of events was difficult to ascertain, but during that sequence the temperature of Greenland soared by 5°C to 16°C in decades to centuries. The question remains open: could such things happen today?

“The results emphasise the importance of trying to limit climate change by, for example, cutting anthropogenic emissions of CO2 and other greenhouse gases, both to reduce the predictable, gradual climate change and to reduce the risk of future abrupt climate change,” said Sune Olander Rasmussen, at the Niels Bohr Institute in Copenhagen, one of the authors.

Greenland’s future role

“If you do not want the dominoes to topple over, you are better off not to push the table they stand on too much.”

And another study in the same journal by British scientists reports on a close study of geological evidence to decipher the pattern of events during the largest and most rapid pulse of sea level rise at the close of the last Ice Age.

Their study suggested that although the sea levels rose 18 metres in about 500 years − a rate of about 3.6 metres a century − it all happened with relatively little help from a melting Antarctica. As the great glaciers retreated from North America, Europe and Asia, so the oceans rose.

“The next big question is to work out what triggered the ice melt, and what impact the massive influx of meltwater had on ocean currents in the North Atlantic,” said Pippa Whitehouse of the University of Durham, one of the researchers.

“This is very much on our minds today − any disruption to the Gulf Stream, for example due to melting of the Greenland Ice Sheet, will have significant consequences for the UK climate.” − Climate News Network

Declining English wetland ‘is poor advert for UK’

A declining English wetland will embarrass the UK government at November’s UN climate conference, campaigners say.

LONDON, 23 March, 2021− The area around Chichester Harbour on Britain’s south coast overlooks the English Channel. Famed as a beauty spot, it is a draw for holiday-makers from the crowded towns and cities of southern Britain. It is also one of the UK’s key habitats for many bird species and for endangered mammals such as water voles. But the condition of this declining English wetland is stirring concern.

Coastal wetlands are not only important for wildlife and tourism, conservationists argue. They are one of nature’s most efficient ecosystems for absorbing carbon dioxide, and among the best forms of coastal protection, increasingly recognised for making low-lying areas more resilient and adaptable to sea level rise.

A report by researchers at the University of Cambridge, UK, published in the journal Nature Sustainability, spells out how the value of natural wetlands far exceeds that of managed or farmed land.

The low-lying coastal plain surrounding the ancient Roman city of Chichester is one of the UK areas most vulnerable to sea level rise, increased storminess and intense rainfall.

“The sad plight of Chichester’s wetlands is an embarrassment for the government as it prepares to host COP-26, the UN’s annual climate conference”

It has done pioneering work in climate change mitigation and adaptation, including protecting the Medmerry Reserve wetlands, Europe’s largest coastal realignment scheme  when it opened in 2013. The Harbour contains the largest salt marsh on the south coast, but nearly half of it has been lost since 1970.

But now local people charge the government with neglecting their efforts to increase the area’s resilience. Libby Alexander founded the Save our South Coast Alliance (SOSCA). She says: “The sad plight of Chichester’s wetlands is an embarrassment for the government as it prepares to host COP-26, the UN’s annual climate conference, due to be held this year in Glasgow in November.” Nor is the physical condition of the Harbour her only concern.

“The government continues to preach to us and the rest of the world about climate change and the environment”, she says, “but practices an entirely different agenda. It is driving forward a building programme which is endangering the future of some of the country’s most important wetlands.”

Unfavourable condition

A report in the Guardian newspaper described the fear of many local people at “the threat of ‘rural sprawl’ creating new landscapes … the ‘suburbanisation’ of the countryside”, resulting from the government’s plans for changes to England’s planning system.

SOSCA says the threats it faces from the government’s drive for more housebuilding in south-east England include 12,650 unnecessary new homes across the coastal plain with the strong possibility of many more − “the wrong houses in the wrong places” − which will inevitably lead to extensive and irreversible damage through pollution and flooding. It says Chichester is being forced by the government to build far more new houses than it can safely accommodate.

Residents say a real threat is the untreated sewage that is pumped into the harbour, for which the local water company, Southern Water, has been penalised. It was fined £126 million in 2019 for spills of waste water into the environment from its sewage plants and for deliberately misreporting its performance. A great number of these discharges went into Chichester Harbour. The Environment Agency is reported to have launched a criminal investigation into the case.

Chichester Harbour Trust says not enough is being done to improve water quality in the Harbour. Its chairman, John Nelson, said: “We all need to force the regulators to take immediate action before we have an environmental and public health catastrophe.”

In January this year the Chichester Observer reported that over the 2020 Christmas period there were uninterrupted sewage discharges into Chichester Harbour for six days. Mr Nelson said: “Given Southern Water’s record over the Christmas period the time has come to implement radical change. The Trust is calling on the regulatory body Ofwat to use its legislative powers to put Southern Water into special administration in order to avoid an environmental catastrophe.”

Natural England is the government’s official environment adviser. It has published a new and authoritative report which describes Chichester Harbour, globally important for migratory birds, as now being in an “unfavourable and declining” condition, because of increasing development and rising sea levels.

Serious climate change adaptation and mitigation needs to be factored into the planning process immediately, says SOSCA. “Ironically, the UK government is promoting global coastal wetland conservation through its Blue Forests Initiative but failing to support the efforts of its own citizens”, said Libby Alexander. − Climate News Network

* * * * * * *

Dr Carolyn Cobbold is a Research Fellow at the University of Cambridge. A former journalist, she has been writing about climate change issues since the mid-1980s. Twitter: @DrCobbold

A declining English wetland will embarrass the UK government at November’s UN climate conference, campaigners say.

LONDON, 23 March, 2021− The area around Chichester Harbour on Britain’s south coast overlooks the English Channel. Famed as a beauty spot, it is a draw for holiday-makers from the crowded towns and cities of southern Britain. It is also one of the UK’s key habitats for many bird species and for endangered mammals such as water voles. But the condition of this declining English wetland is stirring concern.

Coastal wetlands are not only important for wildlife and tourism, conservationists argue. They are one of nature’s most efficient ecosystems for absorbing carbon dioxide, and among the best forms of coastal protection, increasingly recognised for making low-lying areas more resilient and adaptable to sea level rise.

A report by researchers at the University of Cambridge, UK, published in the journal Nature Sustainability, spells out how the value of natural wetlands far exceeds that of managed or farmed land.

The low-lying coastal plain surrounding the ancient Roman city of Chichester is one of the UK areas most vulnerable to sea level rise, increased storminess and intense rainfall.

“The sad plight of Chichester’s wetlands is an embarrassment for the government as it prepares to host COP-26, the UN’s annual climate conference”

It has done pioneering work in climate change mitigation and adaptation, including protecting the Medmerry Reserve wetlands, Europe’s largest coastal realignment scheme  when it opened in 2013. The Harbour contains the largest salt marsh on the south coast, but nearly half of it has been lost since 1970.

But now local people charge the government with neglecting their efforts to increase the area’s resilience. Libby Alexander founded the Save our South Coast Alliance (SOSCA). She says: “The sad plight of Chichester’s wetlands is an embarrassment for the government as it prepares to host COP-26, the UN’s annual climate conference, due to be held this year in Glasgow in November.” Nor is the physical condition of the Harbour her only concern.

“The government continues to preach to us and the rest of the world about climate change and the environment”, she says, “but practices an entirely different agenda. It is driving forward a building programme which is endangering the future of some of the country’s most important wetlands.”

Unfavourable condition

A report in the Guardian newspaper described the fear of many local people at “the threat of ‘rural sprawl’ creating new landscapes … the ‘suburbanisation’ of the countryside”, resulting from the government’s plans for changes to England’s planning system.

SOSCA says the threats it faces from the government’s drive for more housebuilding in south-east England include 12,650 unnecessary new homes across the coastal plain with the strong possibility of many more − “the wrong houses in the wrong places” − which will inevitably lead to extensive and irreversible damage through pollution and flooding. It says Chichester is being forced by the government to build far more new houses than it can safely accommodate.

Residents say a real threat is the untreated sewage that is pumped into the harbour, for which the local water company, Southern Water, has been penalised. It was fined £126 million in 2019 for spills of waste water into the environment from its sewage plants and for deliberately misreporting its performance. A great number of these discharges went into Chichester Harbour. The Environment Agency is reported to have launched a criminal investigation into the case.

Chichester Harbour Trust says not enough is being done to improve water quality in the Harbour. Its chairman, John Nelson, said: “We all need to force the regulators to take immediate action before we have an environmental and public health catastrophe.”

In January this year the Chichester Observer reported that over the 2020 Christmas period there were uninterrupted sewage discharges into Chichester Harbour for six days. Mr Nelson said: “Given Southern Water’s record over the Christmas period the time has come to implement radical change. The Trust is calling on the regulatory body Ofwat to use its legislative powers to put Southern Water into special administration in order to avoid an environmental catastrophe.”

Natural England is the government’s official environment adviser. It has published a new and authoritative report which describes Chichester Harbour, globally important for migratory birds, as now being in an “unfavourable and declining” condition, because of increasing development and rising sea levels.

Serious climate change adaptation and mitigation needs to be factored into the planning process immediately, says SOSCA. “Ironically, the UK government is promoting global coastal wetland conservation through its Blue Forests Initiative but failing to support the efforts of its own citizens”, said Libby Alexander. − Climate News Network

* * * * * * *

Dr Carolyn Cobbold is a Research Fellow at the University of Cambridge. A former journalist, she has been writing about climate change issues since the mid-1980s. Twitter: @DrCobbold

World’s coastal cities face risk from land and sea

As the tides rise ever higher, the world’s coastal cities carry on sinking. It’s a recipe for civic catastrophe.

LONDON, 15 March, 2021 − Citizens of many of the world’s coastal cities have even more to fear from rising tides. As ocean levels swell, in response to rising temperatures and melting glaciers, the land on which those cities are built is sinking.

This means that although, worldwide, oceans are now 2.6mm higher every year in response to climate change, many citizens of some of the world’s great delta cities face the risk of an average sea level rise of up to almost 10mm a year. Both the rising waters and the sinking city streets are ultimately a consequence of human actions.

Humans have not only burned fossil fuels to alter the planet’s atmosphere and raise global temperatures, they have also pumped water from the ground below the cities. They have raised massive structures on riverine sediments; they have pumped oil and gas from offshore, and they have dammed rivers to slow the flow of new sediments.

And because of such steps, some of the world’s great cities have been steadily going downhill. Tokyo in Japan has subsided by four metres in the course of the 20th century. Shanghai in China, Bangkok in Thailand, New Orleans in the US and Djakarta on the island of Java in Indonesia have all sunk by between two and three metres in the last 100 years.

Now a new study in the journal Nature Climate Change has found that 58% of the world’s coastal citizens live on soil and bedrock that is collapsing beneath their feet. Fewer than 1% are settled on terrain that is uplifting. Most are exposed to possible relative sea level rises of between 7.8mm and 9.9mm a year.

“The message to governments and local authorities is: start thinking about subsidence now”

“We wanted to look at the big picture globally, to better understand the impact of global sea level rise combined with measurements of sinking land,” said Robert Nicholls, of the University of East Anglia in the UK.

“We found that coastal populations live with sea level rise at three and four times the global average and that the impacts of sea level rise being experienced today are much larger than the global numbers being reported by the Intergovernmental Panel on Climate Change.”

So the message to governments and local authorities is: start thinking about subsidence now.

Coastal flooding has been a source of increasing alarm for a decade. Eight years ago, researchers warned that by 2050 coastal floods could be costing the world US$1 trillion a year.

Since then individual research teams have been looking at the risks from extremes of rainfall, storm surges, shifts in ocean temperatures and currents, to find that by the century’s end what had once been once-a-century events could become 10 times more frequent.

Faulty readings

And yet another group has questioned the assumptions on which sea and coastal land heights are based. Many of the estimates have been confirmed by satellite radar topography measurements, but these in turn are based on reflections from the first surface the radar signal touches. If it falls on bare farmland, it will be accurate. If the signal hits buildings or tree tops, then the measurements might be misleading: the land surface could be much lower.

Other research teams have looked at rates of melting in Greenland and the Antarctic to warn that previous forecasts could prove to have been underestimates: by the end of the century, oceans could have risen by as much as two metres in a worst case scenario. Once again, how bad things turn out will depend on what steps humans take now.

So, like all the research that has preceded it, this last study confirms that, however bad things looked before, they now look even more alarming. The point of such research, of course, is to help governments prepare for the worst. Tokyo, Shanghai and Bangkok have already slowed the extraction of groundwater. Other nations must consider other solutions.

“One of the main reasons that Jakarta, the capital city of Indonesia, is being moved to Borneo is because the city is sinking due to groundwater extraction from shallow wells,” said Professor Nicholls.

“We hope that our analysis improves the understanding of how sea level rise and subsidence are hand-in-hand for science and coastal management policy worldwide. Jakarta might be just the beginning.” − Climate News Network

As the tides rise ever higher, the world’s coastal cities carry on sinking. It’s a recipe for civic catastrophe.

LONDON, 15 March, 2021 − Citizens of many of the world’s coastal cities have even more to fear from rising tides. As ocean levels swell, in response to rising temperatures and melting glaciers, the land on which those cities are built is sinking.

This means that although, worldwide, oceans are now 2.6mm higher every year in response to climate change, many citizens of some of the world’s great delta cities face the risk of an average sea level rise of up to almost 10mm a year. Both the rising waters and the sinking city streets are ultimately a consequence of human actions.

Humans have not only burned fossil fuels to alter the planet’s atmosphere and raise global temperatures, they have also pumped water from the ground below the cities. They have raised massive structures on riverine sediments; they have pumped oil and gas from offshore, and they have dammed rivers to slow the flow of new sediments.

And because of such steps, some of the world’s great cities have been steadily going downhill. Tokyo in Japan has subsided by four metres in the course of the 20th century. Shanghai in China, Bangkok in Thailand, New Orleans in the US and Djakarta on the island of Java in Indonesia have all sunk by between two and three metres in the last 100 years.

Now a new study in the journal Nature Climate Change has found that 58% of the world’s coastal citizens live on soil and bedrock that is collapsing beneath their feet. Fewer than 1% are settled on terrain that is uplifting. Most are exposed to possible relative sea level rises of between 7.8mm and 9.9mm a year.

“The message to governments and local authorities is: start thinking about subsidence now”

“We wanted to look at the big picture globally, to better understand the impact of global sea level rise combined with measurements of sinking land,” said Robert Nicholls, of the University of East Anglia in the UK.

“We found that coastal populations live with sea level rise at three and four times the global average and that the impacts of sea level rise being experienced today are much larger than the global numbers being reported by the Intergovernmental Panel on Climate Change.”

So the message to governments and local authorities is: start thinking about subsidence now.

Coastal flooding has been a source of increasing alarm for a decade. Eight years ago, researchers warned that by 2050 coastal floods could be costing the world US$1 trillion a year.

Since then individual research teams have been looking at the risks from extremes of rainfall, storm surges, shifts in ocean temperatures and currents, to find that by the century’s end what had once been once-a-century events could become 10 times more frequent.

Faulty readings

And yet another group has questioned the assumptions on which sea and coastal land heights are based. Many of the estimates have been confirmed by satellite radar topography measurements, but these in turn are based on reflections from the first surface the radar signal touches. If it falls on bare farmland, it will be accurate. If the signal hits buildings or tree tops, then the measurements might be misleading: the land surface could be much lower.

Other research teams have looked at rates of melting in Greenland and the Antarctic to warn that previous forecasts could prove to have been underestimates: by the end of the century, oceans could have risen by as much as two metres in a worst case scenario. Once again, how bad things turn out will depend on what steps humans take now.

So, like all the research that has preceded it, this last study confirms that, however bad things looked before, they now look even more alarming. The point of such research, of course, is to help governments prepare for the worst. Tokyo, Shanghai and Bangkok have already slowed the extraction of groundwater. Other nations must consider other solutions.

“One of the main reasons that Jakarta, the capital city of Indonesia, is being moved to Borneo is because the city is sinking due to groundwater extraction from shallow wells,” said Professor Nicholls.

“We hope that our analysis improves the understanding of how sea level rise and subsidence are hand-in-hand for science and coastal management policy worldwide. Jakarta might be just the beginning.” − Climate News Network

Antarctic warming speed-up alarms researchers

The world’s largest reservoir of snow and ice could be melting faster than ever. Two new studies highlight Antarctic warming.

LONDON, 4 March, 2021 − Antarctic warming is accelerating: at least one of the southern continent’s ice shelves has been melting faster than ever. The polar summer of 2019-20 set a new record for temperatures above freezing point over the George VI ice shelf off the Antarctic Peninsula.

The finding is ominous: the ice shelves form a natural buttress that slows the rate of glacier flow from the continental bedrock. The faster the glaciers flow into the sea, the higher the hazard of sea level rise.

And a second study confirms that this is already happening in West Antarctica: researchers looked at 25 years of satellite observation of 14 glaciers in the Getz sector to find that meltwater is flowing into the Amundsen Sea ever faster. Between 1994 and 2018, these glaciers lost 315 billion tonnes of ice, enough to raise global sea levels by almost 1mm.

Melting rates in Antarctica have been a source of alarm for years. The latest studies confirm the picture of continuing melt.

“The high rates of increased glacier speed − coupled with ice thinning − confirm the Getz basin is losing more ice than it gains through snowfall”

US scientists report in the journal The Cryosphere that they too used satellite observation − 41 years of it − to measure summer meltwater on the ice and in the near-surface snow of the northern part of the George VI ice shelf. They identified the most widespread melt and the greatest total of melt days of any season during the 2019-2020 summer.

Air temperatures were above freezing for up to 90 hours, allowing pools of meltwater to collect on the shelf. At its peak 23% of the region was covered with water: the equivalent, in glaciology’s favourite popular measure, of 250,000 Olympic swimming pools.

“When the temperature is above zero degrees Celsius, that limits refreezing and also leads to further melting,” said Alison Banwell, of the University of Colorado at Boulder, who led the study. “Water absorbs more radiation than snow and ice, and that leads to even more melting.”

Remote and untrodden

The Getz shelf is one of the biggest of a sector of the West Antarctic known as Marie Byrd Land. A new report in Nature Communications confirms that all 14 measured glaciers there have picked up speed and reach the ocean ever more swiftly.

Three of them have accelerated by more than 44%. And over the years the loss of ice has been the equivalent of 126 million Olympic swimming pools − all of it now adding to global sea level rise.

“The Getz region of Antarctica is so remote that humans have never set foot on most of this part of the continent,” said Heather Selley, of the University of Leeds, UK, first author. “Satellite radar altimetry records have shown substantial thinning of the ice sheet.

“However, the high rates of increased glacier speed − coupled with ice thinning − now confirm the Getz basin is in dynamic imbalance, meaning that it is losing more ice than it gains through snowfall.” − Climate News Network

The world’s largest reservoir of snow and ice could be melting faster than ever. Two new studies highlight Antarctic warming.

LONDON, 4 March, 2021 − Antarctic warming is accelerating: at least one of the southern continent’s ice shelves has been melting faster than ever. The polar summer of 2019-20 set a new record for temperatures above freezing point over the George VI ice shelf off the Antarctic Peninsula.

The finding is ominous: the ice shelves form a natural buttress that slows the rate of glacier flow from the continental bedrock. The faster the glaciers flow into the sea, the higher the hazard of sea level rise.

And a second study confirms that this is already happening in West Antarctica: researchers looked at 25 years of satellite observation of 14 glaciers in the Getz sector to find that meltwater is flowing into the Amundsen Sea ever faster. Between 1994 and 2018, these glaciers lost 315 billion tonnes of ice, enough to raise global sea levels by almost 1mm.

Melting rates in Antarctica have been a source of alarm for years. The latest studies confirm the picture of continuing melt.

“The high rates of increased glacier speed − coupled with ice thinning − confirm the Getz basin is losing more ice than it gains through snowfall”

US scientists report in the journal The Cryosphere that they too used satellite observation − 41 years of it − to measure summer meltwater on the ice and in the near-surface snow of the northern part of the George VI ice shelf. They identified the most widespread melt and the greatest total of melt days of any season during the 2019-2020 summer.

Air temperatures were above freezing for up to 90 hours, allowing pools of meltwater to collect on the shelf. At its peak 23% of the region was covered with water: the equivalent, in glaciology’s favourite popular measure, of 250,000 Olympic swimming pools.

“When the temperature is above zero degrees Celsius, that limits refreezing and also leads to further melting,” said Alison Banwell, of the University of Colorado at Boulder, who led the study. “Water absorbs more radiation than snow and ice, and that leads to even more melting.”

Remote and untrodden

The Getz shelf is one of the biggest of a sector of the West Antarctic known as Marie Byrd Land. A new report in Nature Communications confirms that all 14 measured glaciers there have picked up speed and reach the ocean ever more swiftly.

Three of them have accelerated by more than 44%. And over the years the loss of ice has been the equivalent of 126 million Olympic swimming pools − all of it now adding to global sea level rise.

“The Getz region of Antarctica is so remote that humans have never set foot on most of this part of the continent,” said Heather Selley, of the University of Leeds, UK, first author. “Satellite radar altimetry records have shown substantial thinning of the ice sheet.

“However, the high rates of increased glacier speed − coupled with ice thinning − now confirm the Getz basin is in dynamic imbalance, meaning that it is losing more ice than it gains through snowfall.” − Climate News Network

Rising sea levels may make some airports unusable

High flyers could soon have a problem with high water. Rising sea levels could one day shut down airports.

LONDON, 3 February, 2021 − Passengers, prepare for splashdown. Take-off may have to wait for low tide. By 2100, thanks to rising sea levels, around 100 of the world’s airports could be below mean sea level and at least 364 will be vulnerable to flooding.

And that’s assuming the world’s nations keep a promise made in 2015 and confine global heating to no more than 2°C above the average maintained for most of human history. If humans go on burning fossil fuels and clearing forests at the present rate, then at least 572 of the world’s airports could be at risk of flooding from extreme tides, according to a new study in the journal Climate Risk Management.

These things have already happened: in 2018 a typhoon storm surge inundated Kansai International Airport in Osaka Bay, Japan. Superstorm Sandy in 2012 closed New York City’s La Guardia Airport for three days. One-tenth of the planet’s population lives on coastlines less than 10 metres above sea level.

Airports grow up around the great cities: they require flat land and a clear flight path. Coastal flood plains, wetlands and reclaimed land provide exactly that.

Serious risk

“These coastal airports are disproportionately important to the global airline network, and by 2100 between 10% and 20% of all routes will be at risk of disruption,” said Richard Dawson, an engineer at Newcastle University in the United Kingdom. “Sea level rise therefore poses a serious risk to global passenger and freight movements, with considerable cost of damage and disruption.”

He and a colleague looked at the world’s 14,000 airports and helicopter pads to identify 1,238 airports in what geographers call low elevation coastal zones: that is, down by the seaside. Of these, 199, serving 3,436 routes, were in the US; China had 30 airports serving 2,333 routes.

They found that just 20 airports at risk handled more than 800 million passengers in 2018 − approaching a fifth of the world’s passenger traffic that year − and nearly 16 million tonnes of cargo: one-fourth of all the world’s air freight that year. They then started looking at what climate change could do to all that business.

Even before the shutdown of traffic because of the global pandemic, the world’s airlines had been feeling the heat. Research teams have confirmed that ever higher global temperatures mean more atmospheric turbulence at altitude; that wind speed changes will slow flights and raise costs; that extremes of heat could even close airport runways and delay flights for extended periods.

“These coastal airports are disproportionately important to the global airline network, and by 2100 between 10% and 20% of all routes will be at risk of disruption”

Now Professor Dawson and his colleague have compiled a table of hazard rankings for flooded airstrips under a range of climate change scenarios.

Right now, 269 of the world’s airports are at some risk of coastal flooding. This number must rise: by how much, and at what cost, depends on what actions the world takes. But the researchers calculate that by 2100 the risk of disruption could increase 17-fold, or even 69-fold. And because so many important airports are already at or near sea level, up to a fifth of all the world’s routes will be at risk.

And that means higher costs for flood protection, or action to raise airport sites, or relocation. The choice is to adapt or, quite literally, to go under.

“The cost of adaptation will be modest in the context of global infrastructure expenditure,” Professor Dawson said. “However, in some locations the rate of sea level rise, limited economic resources or space for alternative locations will make some airports unviable.” − Climate News Network

High flyers could soon have a problem with high water. Rising sea levels could one day shut down airports.

LONDON, 3 February, 2021 − Passengers, prepare for splashdown. Take-off may have to wait for low tide. By 2100, thanks to rising sea levels, around 100 of the world’s airports could be below mean sea level and at least 364 will be vulnerable to flooding.

And that’s assuming the world’s nations keep a promise made in 2015 and confine global heating to no more than 2°C above the average maintained for most of human history. If humans go on burning fossil fuels and clearing forests at the present rate, then at least 572 of the world’s airports could be at risk of flooding from extreme tides, according to a new study in the journal Climate Risk Management.

These things have already happened: in 2018 a typhoon storm surge inundated Kansai International Airport in Osaka Bay, Japan. Superstorm Sandy in 2012 closed New York City’s La Guardia Airport for three days. One-tenth of the planet’s population lives on coastlines less than 10 metres above sea level.

Airports grow up around the great cities: they require flat land and a clear flight path. Coastal flood plains, wetlands and reclaimed land provide exactly that.

Serious risk

“These coastal airports are disproportionately important to the global airline network, and by 2100 between 10% and 20% of all routes will be at risk of disruption,” said Richard Dawson, an engineer at Newcastle University in the United Kingdom. “Sea level rise therefore poses a serious risk to global passenger and freight movements, with considerable cost of damage and disruption.”

He and a colleague looked at the world’s 14,000 airports and helicopter pads to identify 1,238 airports in what geographers call low elevation coastal zones: that is, down by the seaside. Of these, 199, serving 3,436 routes, were in the US; China had 30 airports serving 2,333 routes.

They found that just 20 airports at risk handled more than 800 million passengers in 2018 − approaching a fifth of the world’s passenger traffic that year − and nearly 16 million tonnes of cargo: one-fourth of all the world’s air freight that year. They then started looking at what climate change could do to all that business.

Even before the shutdown of traffic because of the global pandemic, the world’s airlines had been feeling the heat. Research teams have confirmed that ever higher global temperatures mean more atmospheric turbulence at altitude; that wind speed changes will slow flights and raise costs; that extremes of heat could even close airport runways and delay flights for extended periods.

“These coastal airports are disproportionately important to the global airline network, and by 2100 between 10% and 20% of all routes will be at risk of disruption”

Now Professor Dawson and his colleague have compiled a table of hazard rankings for flooded airstrips under a range of climate change scenarios.

Right now, 269 of the world’s airports are at some risk of coastal flooding. This number must rise: by how much, and at what cost, depends on what actions the world takes. But the researchers calculate that by 2100 the risk of disruption could increase 17-fold, or even 69-fold. And because so many important airports are already at or near sea level, up to a fifth of all the world’s routes will be at risk.

And that means higher costs for flood protection, or action to raise airport sites, or relocation. The choice is to adapt or, quite literally, to go under.

“The cost of adaptation will be modest in the context of global infrastructure expenditure,” Professor Dawson said. “However, in some locations the rate of sea level rise, limited economic resources or space for alternative locations will make some airports unviable.” − Climate News Network