Tag Archives: Sea levels

Polar link unites far extremes of north and south

They are different worlds, one an ocean, the other a continent. But a polar link keeps them in touch with each other.

LONDON, 30 November, 2020 − The Arctic and Antarctica are literally a world apart, but for an unlikely polar link. Change in the mass of ice in the north can and does precipitate change in the furthest reaches of the southern hemisphere.

According to 40,000 years of geological evidence, when the Arctic Ocean ice retreats, global sea levels rise to start washing away the sea ice around the shelf of the vast frozen continent at the other extreme of the planet.

This pattern of action at a distance is confirmed by computer simulations: the planet’s two hemispheres are in a kind of conversation, according to a new study in the journal Nature.

“Our results highlight how interconnected the Earth system is, with changes in one part of the planet driving changes in another,” said Natalya Gomez, of McGill University in Canada, who led the study.

“In the modern era, we haven’t seen the kind of large ice sheet retreat that we might see in our future warming world. Looking to records and models of change in Earth’s history can inform us about this.”

“Ice sheets can influence each other over great distances. It’s as though they were talking to one another about sea level changes”

The Arctic is one of the fastest-warming places on the planet: what happens in the far north has reverberations throughout the hemisphere. And Antarctica, too, is changing swiftly.

Although both extremes of cold are vulnerable to global heating driven by profligate fossil fuel use and global-scale loss of forests, climate scientists have tended to consider them as separate cases.

But a closer look at geological records − ice cores and samples from the ocean bottom that offer evidence of iceberg drift across the millennia − revealed a connection. The polar link is real.

At the height of the last ice age more than 20,000 years ago, the mass of ice in the north lowered global sea levels and the Antarctic ice shelf advanced. As the world began to warm again, ice in the north began to flow into the sea. Sea levels rose in the southern hemisphere and this began to force a retreat of the Antarctic ice.

“Ice sheets can influence each other over great distances due to the water that flows between them. It’s as though they were talking to one another about sea level changes,” Dr Gomez said.

Dynamic ice

“Polar ice sheets are not just large static mounds of ice. They evolve on various different time scales and are in constant flux, with ice growing and retreating, depending on the climate and the surrounding water levels.

“They gain ice as snow piles up on top of them, then spread outwards under their own weight, and stream out into the surrounding ocean where their edges break off into icebergs.”

The evidence showed that sea level change in Antarctica and ice mass loss in the Arctic were linked, over a sequence of at least 40,000 years.

“These ice sheets are really dynamic, exciting and intriguing parts of the Earth’s climate system. It’s staggering to think of ice that is several kilometres thick, that covers an entire continent, and that is evolving on all of these different timescales with global consequences,” Dr Gomez said.

“It’s just motivation for trying to better understand these really massive systems that are so far away from us.” − Climate News Network

They are different worlds, one an ocean, the other a continent. But a polar link keeps them in touch with each other.

LONDON, 30 November, 2020 − The Arctic and Antarctica are literally a world apart, but for an unlikely polar link. Change in the mass of ice in the north can and does precipitate change in the furthest reaches of the southern hemisphere.

According to 40,000 years of geological evidence, when the Arctic Ocean ice retreats, global sea levels rise to start washing away the sea ice around the shelf of the vast frozen continent at the other extreme of the planet.

This pattern of action at a distance is confirmed by computer simulations: the planet’s two hemispheres are in a kind of conversation, according to a new study in the journal Nature.

“Our results highlight how interconnected the Earth system is, with changes in one part of the planet driving changes in another,” said Natalya Gomez, of McGill University in Canada, who led the study.

“In the modern era, we haven’t seen the kind of large ice sheet retreat that we might see in our future warming world. Looking to records and models of change in Earth’s history can inform us about this.”

“Ice sheets can influence each other over great distances. It’s as though they were talking to one another about sea level changes”

The Arctic is one of the fastest-warming places on the planet: what happens in the far north has reverberations throughout the hemisphere. And Antarctica, too, is changing swiftly.

Although both extremes of cold are vulnerable to global heating driven by profligate fossil fuel use and global-scale loss of forests, climate scientists have tended to consider them as separate cases.

But a closer look at geological records − ice cores and samples from the ocean bottom that offer evidence of iceberg drift across the millennia − revealed a connection. The polar link is real.

At the height of the last ice age more than 20,000 years ago, the mass of ice in the north lowered global sea levels and the Antarctic ice shelf advanced. As the world began to warm again, ice in the north began to flow into the sea. Sea levels rose in the southern hemisphere and this began to force a retreat of the Antarctic ice.

“Ice sheets can influence each other over great distances due to the water that flows between them. It’s as though they were talking to one another about sea level changes,” Dr Gomez said.

Dynamic ice

“Polar ice sheets are not just large static mounds of ice. They evolve on various different time scales and are in constant flux, with ice growing and retreating, depending on the climate and the surrounding water levels.

“They gain ice as snow piles up on top of them, then spread outwards under their own weight, and stream out into the surrounding ocean where their edges break off into icebergs.”

The evidence showed that sea level change in Antarctica and ice mass loss in the Arctic were linked, over a sequence of at least 40,000 years.

“These ice sheets are really dynamic, exciting and intriguing parts of the Earth’s climate system. It’s staggering to think of ice that is several kilometres thick, that covers an entire continent, and that is evolving on all of these different timescales with global consequences,” Dr Gomez said.

“It’s just motivation for trying to better understand these really massive systems that are so far away from us.” − Climate News Network

Global heating may go on for five more centuries

Global heating now means more warming for 500 years ahead, even if all greenhouse emissions stop. Or is that too simple?

LONDON, 20 November, 2020 − Norwegian scientists have mapped the future of the Earth in a regime of climate change and have come to an uncomfortable conclusion: it’s likely that global heating will persist until around the year 2500.

Even if human beings immediately ceased all use of fossil fuels that spill greenhouse gases into the planetary atmosphere, the world would be committed to warming for the next five centuries, they suggest.

By then global temperatures would be at least 3°C higher, and sea levels three metres higher, than they would have been in 1850. Even with a dramatic halt to the emissions that fuel global heating, they warn in the journal Scientific Reports, the Arctic ice would go on melting, water vapour would continue to build up in the atmosphere, the permafrost would continue to thaw and vast reservoirs of ancient carbon that had been trapped in the once-frozen ground would escape into the atmosphere.

The message − one that comes hedged with caution − is that to keep continental temperatures and sea levels as they were for most of human history, nations should have started to reduce greenhouse gas emissions six decades ago.

And to slow the warming that might now be inexorable, nations must unite to somehow remove 33 billion tonnes of carbon dioxide (CO2) − an almost unimaginable volume − from the atmosphere every year from now on.

Challenged by colleagues

Caution is necessary because, as the researchers themselves point out, the finding presents an extremely simple model of cause and effect on a simulated planet not unlike Earth, but without the untidy mosaic of natural and human processes that directly influence the rate at which CO2 builds up in the atmosphere.

And the two scientists who wrote the study directly urge other climate researchers to check their findings with more sophisticated simulations. They have made a stab at predicting the future, and they know it could be wrong.

But if it isn’t wrong, then the message is that profligate human use of fossil fuels, combined with heedless destruction of many of the planet’s natural ecosystems, and then topped with the massive construction of human cities, industries and travel networks, may have already pushed the planet past a tipping point, beyond which the slide into potentially catastrophic climate change has become inexorable.

And they are not the first to make such a suggestion. Nor are they the first to warn that what had once been trailed as a notional “worst case” scenario has of late increasingly begun to look like modern reality.

The finding has been comprehensively challenged by British scientists, not because it could be wrong, but because the simulation is too simple, and doesn’t incorporate many of the processes that happen in the real world. One distinguished researcher called it “a toy model”.

“To keep global warming to just 1.5°C this century we already know we will have to have negative carbon emissions from 2050 to 2100”

But almost all who commented also conceded that to steer the planet away from permanent and devastating climate change, nations may have left concerted and sustained action a bit late.

Reduction of carbon emissions to zero in the next three decades would be just a start. And the world would go on warming for some time, just as a reaction to the extra carbon dioxide already spilled into the atmosphere in the last three decades.

“To keep global warming to just 1.5°C this century we already know we will have to have negative carbon emissions from 2050 to 2100,” said Mark Maslin, a climatologist at University College, London.

“If this study is confirmed, then we may have to continue drawing down carbon dioxide from the atmosphere way beyond the end of this century. And I would suggest that if we have been able to successfully deal with climate change in this century, we really will not have to worry about dealing with a much smaller warming over the next 400 years.”

But even as both the authors and their critics warn that the outcome should be treated with caution, other research has almost coincidentally begun to suggest that the world may be nearing a tipping point.

Positive feedback?

Last month German scientists contemplated the increasing loss of ice in the Arctic − all the sea ice could have vanished in summer before mid-century − and in the mountain regions worldwide, and reasoned that, instead of reflecting radiation back into space, the darker ocean or rock revealed beneath the ice would absorb it, to increase rates of warming.

They warn in Nature Communications that this process alone could increase long-term global warming by 0.43°C, to accelerate yet more thawing of the permafrost: an example of the vicious circle that could go on delivering climate change by exactly the kind of positive feedback the Norwegian scientists fear.

And in one respect, their fellow scientists agree with them: further warming is already “baked in” to the future climate. Even if the world turns off greenhouse gas emissions right now, global heating will continue for decades. For how long, and how swiftly, is difficult to calculate.

“Even if the paper is right in every respect and we are already committed to at least 3°C warming if we stop emissions tomorrow, this warming will take 500 years,” said Andrew Watson, of the University of Exeter.

“This is preferable to 3°C warming over 100 years, which would be far more disruptive and might happen if we don’t cut emissions.” − Climate News Network

Global heating now means more warming for 500 years ahead, even if all greenhouse emissions stop. Or is that too simple?

LONDON, 20 November, 2020 − Norwegian scientists have mapped the future of the Earth in a regime of climate change and have come to an uncomfortable conclusion: it’s likely that global heating will persist until around the year 2500.

Even if human beings immediately ceased all use of fossil fuels that spill greenhouse gases into the planetary atmosphere, the world would be committed to warming for the next five centuries, they suggest.

By then global temperatures would be at least 3°C higher, and sea levels three metres higher, than they would have been in 1850. Even with a dramatic halt to the emissions that fuel global heating, they warn in the journal Scientific Reports, the Arctic ice would go on melting, water vapour would continue to build up in the atmosphere, the permafrost would continue to thaw and vast reservoirs of ancient carbon that had been trapped in the once-frozen ground would escape into the atmosphere.

The message − one that comes hedged with caution − is that to keep continental temperatures and sea levels as they were for most of human history, nations should have started to reduce greenhouse gas emissions six decades ago.

And to slow the warming that might now be inexorable, nations must unite to somehow remove 33 billion tonnes of carbon dioxide (CO2) − an almost unimaginable volume − from the atmosphere every year from now on.

Challenged by colleagues

Caution is necessary because, as the researchers themselves point out, the finding presents an extremely simple model of cause and effect on a simulated planet not unlike Earth, but without the untidy mosaic of natural and human processes that directly influence the rate at which CO2 builds up in the atmosphere.

And the two scientists who wrote the study directly urge other climate researchers to check their findings with more sophisticated simulations. They have made a stab at predicting the future, and they know it could be wrong.

But if it isn’t wrong, then the message is that profligate human use of fossil fuels, combined with heedless destruction of many of the planet’s natural ecosystems, and then topped with the massive construction of human cities, industries and travel networks, may have already pushed the planet past a tipping point, beyond which the slide into potentially catastrophic climate change has become inexorable.

And they are not the first to make such a suggestion. Nor are they the first to warn that what had once been trailed as a notional “worst case” scenario has of late increasingly begun to look like modern reality.

The finding has been comprehensively challenged by British scientists, not because it could be wrong, but because the simulation is too simple, and doesn’t incorporate many of the processes that happen in the real world. One distinguished researcher called it “a toy model”.

“To keep global warming to just 1.5°C this century we already know we will have to have negative carbon emissions from 2050 to 2100”

But almost all who commented also conceded that to steer the planet away from permanent and devastating climate change, nations may have left concerted and sustained action a bit late.

Reduction of carbon emissions to zero in the next three decades would be just a start. And the world would go on warming for some time, just as a reaction to the extra carbon dioxide already spilled into the atmosphere in the last three decades.

“To keep global warming to just 1.5°C this century we already know we will have to have negative carbon emissions from 2050 to 2100,” said Mark Maslin, a climatologist at University College, London.

“If this study is confirmed, then we may have to continue drawing down carbon dioxide from the atmosphere way beyond the end of this century. And I would suggest that if we have been able to successfully deal with climate change in this century, we really will not have to worry about dealing with a much smaller warming over the next 400 years.”

But even as both the authors and their critics warn that the outcome should be treated with caution, other research has almost coincidentally begun to suggest that the world may be nearing a tipping point.

Positive feedback?

Last month German scientists contemplated the increasing loss of ice in the Arctic − all the sea ice could have vanished in summer before mid-century − and in the mountain regions worldwide, and reasoned that, instead of reflecting radiation back into space, the darker ocean or rock revealed beneath the ice would absorb it, to increase rates of warming.

They warn in Nature Communications that this process alone could increase long-term global warming by 0.43°C, to accelerate yet more thawing of the permafrost: an example of the vicious circle that could go on delivering climate change by exactly the kind of positive feedback the Norwegian scientists fear.

And in one respect, their fellow scientists agree with them: further warming is already “baked in” to the future climate. Even if the world turns off greenhouse gas emissions right now, global heating will continue for decades. For how long, and how swiftly, is difficult to calculate.

“Even if the paper is right in every respect and we are already committed to at least 3°C warming if we stop emissions tomorrow, this warming will take 500 years,” said Andrew Watson, of the University of Exeter.

“This is preferable to 3°C warming over 100 years, which would be far more disruptive and might happen if we don’t cut emissions.” − Climate News Network

River deltas become even riskier as climate warms

River deltas are among the world’s richest habitats. They are also, increasingly, home to the most vulnerable people.

LONDON, 8 October, 2020 − Already, more than 30 million people worldwide are in danger of catastrophic floods − and now they face further danger from the river deltas which are their homes.

Ocean storm surges which are one threat could wash away their homes, their livelihoods, and even their lives. Another, rising tide levels, could turn their gardens to salt and sap the foundations of their lives. With many more, tropical cyclones could sweep in and literally rain their houses into the sea

What all these vulnerable people − in New Orleans, in Bangkok, in Shanghai, in the mouths of the Ganges-Brahmaputra, in any of more than 2,000 settlements − have in common is that they live on a river delta: that vital, ever-shifting zone where a great river spills its silt into the ocean.

And climate change driven by ever-rising ratios of greenhouse gases in the atmosphere − a consequence of ever-greater reliance on fossil fuels − can only make such hazards ever more dangerous. But the first challenge is: who, exactly, is most at risk? And where?

“To date, no-one has successfully quantified the global population in river deltas and assessed the cumulative impacts from climate change,” said Douglas Edmonds, of the University of Indiana in the US.

Costly endowment

“Since river deltas have long been recognised as hotspots of population growth, and with increasing impacts from climate change, we realised we needed to properly quantify what the cumulative risks are in river deltas.”

Dr Edmonds and his colleagues report in Nature Communications that they assembled a global database of 2,174 delta locations, to identity the populations settled on and around them in 2017, and the topography most at risk.

River deltas add up to perhaps 0.5% of the planet’s land surface, but they are home to 4.5% of the world’s population. Humans have settled on river deltas for at least 7,000 years: the rivers deliver nutrient-rich silts for new farmland, and the river estuaries have provided a focus for regional and international transport, to become some of the world’s greatest cities.

But such riches come at a cost: as the rivers have been contained and engineered, the land cover has changed and the land surface subsided. So as sea levels rise with climate change, deltaic areas could become 50% more vulnerable to coastal flood.

“No-one has successfully quantified the global population in river deltas and assessed the cumulative impacts from climate change”

Precisely because river deltas form at or even below sea level, they are highly prone to storm surges driven by tropical cyclones. And by 2100, these could become from 2% to 11% more intense.

The researchers found that in 2017, around 339m people had made their homes on 710,000 square kilometres of habitable land around river deltas: in this century alone, the population on deltas had grown by 34%.

Of these, 31m lived on floodplains vulnerable to the kind of storm surges that happen once a century. And of this 31m, 92% lived in developing or least-developed economies, often breathing polluted air, with poor housing and limited access to public services such as drainage. So, as usual, the poorest were also the most at risk from climate change.

In fact, as scientists have been warning for a decade or more, coastal flooding is a hazard inevitably on the increase, and an increasingly costly one, worldwide.

Even in the US, floods will become a serial nuisance in many cities and an estimated 13m Americans could eventually become climate refugees.

Very cautious estimates

Climate change is likely to deliver a hotter, wetter world with more soil erosion that could trigger catastrophic delta flooding. Hurricanes and typhoons driven by rising sea temperatures are likely to exact an ever-greater toll on human life and wealth.

The Indiana scientists warn that their estimates of those most at risk and the costs they face are likely to be highly conservative. They did not, for instance, consider the special case of what they call “compound interaction.”

This is sociological shorthand for what could happen when climate-related disaster overtakes those who are poorest, crowded into the least protected and unhealthiest zones of the cities. Altogether, 105m people have settled on the Ganges-Brahmaputra delta, half of them on low-lying farmland. The second most crowded is the Nile delta, with 45m people.

“To effectively prepare for more intense future coastal flooding,” Dr Edmonds said, “we need to reframe it as a problem that disproportionately impacts people on river deltas in developing and least developed economies.” − Climate News Network

River deltas are among the world’s richest habitats. They are also, increasingly, home to the most vulnerable people.

LONDON, 8 October, 2020 − Already, more than 30 million people worldwide are in danger of catastrophic floods − and now they face further danger from the river deltas which are their homes.

Ocean storm surges which are one threat could wash away their homes, their livelihoods, and even their lives. Another, rising tide levels, could turn their gardens to salt and sap the foundations of their lives. With many more, tropical cyclones could sweep in and literally rain their houses into the sea

What all these vulnerable people − in New Orleans, in Bangkok, in Shanghai, in the mouths of the Ganges-Brahmaputra, in any of more than 2,000 settlements − have in common is that they live on a river delta: that vital, ever-shifting zone where a great river spills its silt into the ocean.

And climate change driven by ever-rising ratios of greenhouse gases in the atmosphere − a consequence of ever-greater reliance on fossil fuels − can only make such hazards ever more dangerous. But the first challenge is: who, exactly, is most at risk? And where?

“To date, no-one has successfully quantified the global population in river deltas and assessed the cumulative impacts from climate change,” said Douglas Edmonds, of the University of Indiana in the US.

Costly endowment

“Since river deltas have long been recognised as hotspots of population growth, and with increasing impacts from climate change, we realised we needed to properly quantify what the cumulative risks are in river deltas.”

Dr Edmonds and his colleagues report in Nature Communications that they assembled a global database of 2,174 delta locations, to identity the populations settled on and around them in 2017, and the topography most at risk.

River deltas add up to perhaps 0.5% of the planet’s land surface, but they are home to 4.5% of the world’s population. Humans have settled on river deltas for at least 7,000 years: the rivers deliver nutrient-rich silts for new farmland, and the river estuaries have provided a focus for regional and international transport, to become some of the world’s greatest cities.

But such riches come at a cost: as the rivers have been contained and engineered, the land cover has changed and the land surface subsided. So as sea levels rise with climate change, deltaic areas could become 50% more vulnerable to coastal flood.

“No-one has successfully quantified the global population in river deltas and assessed the cumulative impacts from climate change”

Precisely because river deltas form at or even below sea level, they are highly prone to storm surges driven by tropical cyclones. And by 2100, these could become from 2% to 11% more intense.

The researchers found that in 2017, around 339m people had made their homes on 710,000 square kilometres of habitable land around river deltas: in this century alone, the population on deltas had grown by 34%.

Of these, 31m lived on floodplains vulnerable to the kind of storm surges that happen once a century. And of this 31m, 92% lived in developing or least-developed economies, often breathing polluted air, with poor housing and limited access to public services such as drainage. So, as usual, the poorest were also the most at risk from climate change.

In fact, as scientists have been warning for a decade or more, coastal flooding is a hazard inevitably on the increase, and an increasingly costly one, worldwide.

Even in the US, floods will become a serial nuisance in many cities and an estimated 13m Americans could eventually become climate refugees.

Very cautious estimates

Climate change is likely to deliver a hotter, wetter world with more soil erosion that could trigger catastrophic delta flooding. Hurricanes and typhoons driven by rising sea temperatures are likely to exact an ever-greater toll on human life and wealth.

The Indiana scientists warn that their estimates of those most at risk and the costs they face are likely to be highly conservative. They did not, for instance, consider the special case of what they call “compound interaction.”

This is sociological shorthand for what could happen when climate-related disaster overtakes those who are poorest, crowded into the least protected and unhealthiest zones of the cities. Altogether, 105m people have settled on the Ganges-Brahmaputra delta, half of them on low-lying farmland. The second most crowded is the Nile delta, with 45m people.

“To effectively prepare for more intense future coastal flooding,” Dr Edmonds said, “we need to reframe it as a problem that disproportionately impacts people on river deltas in developing and least developed economies.” − Climate News Network

Rivers flood, seas rise – and land faces erosion

Polar melting cannot be separated from farmland soil erosion and estuarine flooding. All are part of climate change.

LONDON, 7 September, 2020 – Climate heating often ensures that calamities don’t come singly: so don’t forget what erosion can do.

In a warmer world the glaciers will melt ever faster to raise global sea levels ever higher. In a wetter world, more and more topsoil will be swept off the farmlands and downriver into the ever-rising seas.

And the pay-off of silt-laden rivers and rising sea levels could be catastrophic floods, as swollen rivers suddenly change course. Since many of the world’s greatest cities are built on river estuaries, lives and economies will be at risk.

Three new studies in two journals deliver a sharp reminder that the consequences of global heating are not straightforward: the world responds to change in unpredictable ways.

First: the melting of the ice sheets and the mountain glaciers. Researchers warn in the journal Nature Climate Change that if the loss of ice from Antarctica, Greenland and the frozen rivers continues, then climate forecasters and government agencies will have to think again: sea levels could rise to at least 17cms higher than the worst predictions so far.

“Avulsions are the earthquakes of rivers. They are sudden and sometimes catastrophic. We are trying to understand where and when the next avulsions will occur”

That means an additional 16 million people at hazard from estuarine floods and storm surges.

In the last 30 years, the flow from the Antarctic ice cap has raised sea levels by 7.2mm, and from Greenland by 10.6mm. Every year, the world’s oceans are 4mm higher than they were the year before.

“Although we anticipated the ice sheets would lose increasing amounts of ice in response to the warming of the oceans and the atmosphere, the rate at which they are melting has accelerated faster than we could have imagined,” said Tom Slater of the University of Leeds, in the UK, who led the research.

“The melting is overtaking the climate models we use to guide us, and we are in danger of being unprepared for the risks posed by sea level rise.”

Dr Slater and his colleagues are the third team to warn in the last month that observations of climate already match the worst-case scenarios dreamed up by forecasters preparing for a range of possible climate outcomes.

Erosion risk rises

The latest reading of glacial melt rates suggests that the risk of storm surges for many of the world’s greatest cities will double by the close of the century. But coastal cities – and the farmers who already work 38% of the terrestrial surface to feed almost 8bn people – have another more immediate problem.

In a warmer world, more water evaporates. In a warmer atmosphere, the capacity of the air to hold moisture also increases, so along with more intense droughts, heavier rainfall is on the way for much of the world. And the heavier the rain, or the more prolonged the drought, the higher the risk of soil erosion.

In 2015 the world’s farmers and foresters watched 43 billion tonnes of topsoil wash away from hillsides or blow away from tilled land and into the sea. By 2070, this burden of silt swept away by water or blown by wind will have risen by between 30% and 66%: probably more than 28 bn tons of additional loss.

This could only impoverish the farmland, according to a study by Swiss scientists in the Proceedings of the National Academy of Sciences. It could also impoverish people, communities and countries. The worst hit could be in the less developed nations of the tropics and subtropics.

But the flow of ever-higher silt levels into ever-rising seas also raises a new hazard: hydrologists call it river avulsion. It’s a simple and natural process. As conditions change, so rivers will naturally change their flow to spill over new floodplains and extend coastal lands.

Survival in question

But river avulsions can also be helped along by rising sea levels. Since 10% of humanity is crowded into rich, fertile delta lands, and since some of the deadliest floods in human history – two in China in 1887 and 1931 claimed six million lives – have been caused by river avulsions, the question becomes a matter of life and death.

US scientists report, also in the Proceedings of the National Academy of Sciences, that rising sea levels alone could make abrupt river avulsion more probable, especially as delta lands could be subsiding, because of groundwater and other extraction.

The dangers of avulsion are affected by the rate of sediment deposit in the river channels, and this is likely to rise with sea levels. This in turn raises the level of the river and eventually a breach of a levee or other flood defence will force the river to find a swifter, steeper path to the sea.

Cities such as New Orleans and the coastal communities of the Mississippi delta are already vulnerable. “Avulsions are the earthquakes of rivers,” said Michael Lamb, of California Institute of Technology, one of the authors.

“They are sudden and sometimes catastrophic natural events that occur with statistical regularity, shifting the direction of major rivers. We are trying to understand where and when the next avulsions will occur.” – Climate News Network

Polar melting cannot be separated from farmland soil erosion and estuarine flooding. All are part of climate change.

LONDON, 7 September, 2020 – Climate heating often ensures that calamities don’t come singly: so don’t forget what erosion can do.

In a warmer world the glaciers will melt ever faster to raise global sea levels ever higher. In a wetter world, more and more topsoil will be swept off the farmlands and downriver into the ever-rising seas.

And the pay-off of silt-laden rivers and rising sea levels could be catastrophic floods, as swollen rivers suddenly change course. Since many of the world’s greatest cities are built on river estuaries, lives and economies will be at risk.

Three new studies in two journals deliver a sharp reminder that the consequences of global heating are not straightforward: the world responds to change in unpredictable ways.

First: the melting of the ice sheets and the mountain glaciers. Researchers warn in the journal Nature Climate Change that if the loss of ice from Antarctica, Greenland and the frozen rivers continues, then climate forecasters and government agencies will have to think again: sea levels could rise to at least 17cms higher than the worst predictions so far.

“Avulsions are the earthquakes of rivers. They are sudden and sometimes catastrophic. We are trying to understand where and when the next avulsions will occur”

That means an additional 16 million people at hazard from estuarine floods and storm surges.

In the last 30 years, the flow from the Antarctic ice cap has raised sea levels by 7.2mm, and from Greenland by 10.6mm. Every year, the world’s oceans are 4mm higher than they were the year before.

“Although we anticipated the ice sheets would lose increasing amounts of ice in response to the warming of the oceans and the atmosphere, the rate at which they are melting has accelerated faster than we could have imagined,” said Tom Slater of the University of Leeds, in the UK, who led the research.

“The melting is overtaking the climate models we use to guide us, and we are in danger of being unprepared for the risks posed by sea level rise.”

Dr Slater and his colleagues are the third team to warn in the last month that observations of climate already match the worst-case scenarios dreamed up by forecasters preparing for a range of possible climate outcomes.

Erosion risk rises

The latest reading of glacial melt rates suggests that the risk of storm surges for many of the world’s greatest cities will double by the close of the century. But coastal cities – and the farmers who already work 38% of the terrestrial surface to feed almost 8bn people – have another more immediate problem.

In a warmer world, more water evaporates. In a warmer atmosphere, the capacity of the air to hold moisture also increases, so along with more intense droughts, heavier rainfall is on the way for much of the world. And the heavier the rain, or the more prolonged the drought, the higher the risk of soil erosion.

In 2015 the world’s farmers and foresters watched 43 billion tonnes of topsoil wash away from hillsides or blow away from tilled land and into the sea. By 2070, this burden of silt swept away by water or blown by wind will have risen by between 30% and 66%: probably more than 28 bn tons of additional loss.

This could only impoverish the farmland, according to a study by Swiss scientists in the Proceedings of the National Academy of Sciences. It could also impoverish people, communities and countries. The worst hit could be in the less developed nations of the tropics and subtropics.

But the flow of ever-higher silt levels into ever-rising seas also raises a new hazard: hydrologists call it river avulsion. It’s a simple and natural process. As conditions change, so rivers will naturally change their flow to spill over new floodplains and extend coastal lands.

Survival in question

But river avulsions can also be helped along by rising sea levels. Since 10% of humanity is crowded into rich, fertile delta lands, and since some of the deadliest floods in human history – two in China in 1887 and 1931 claimed six million lives – have been caused by river avulsions, the question becomes a matter of life and death.

US scientists report, also in the Proceedings of the National Academy of Sciences, that rising sea levels alone could make abrupt river avulsion more probable, especially as delta lands could be subsiding, because of groundwater and other extraction.

The dangers of avulsion are affected by the rate of sediment deposit in the river channels, and this is likely to rise with sea levels. This in turn raises the level of the river and eventually a breach of a levee or other flood defence will force the river to find a swifter, steeper path to the sea.

Cities such as New Orleans and the coastal communities of the Mississippi delta are already vulnerable. “Avulsions are the earthquakes of rivers,” said Michael Lamb, of California Institute of Technology, one of the authors.

“They are sudden and sometimes catastrophic natural events that occur with statistical regularity, shifting the direction of major rivers. We are trying to understand where and when the next avulsions will occur.” – Climate News Network

Arctic heating races ahead of worst case estimates

Arctic heating is happening far faster than anybody had anticipated. And the ice record suggests this has happened before.

LONDON, 2 September, 2020 – An international team of scientists brings bad news about Arctic heating: the polar ocean is warming not only faster than anybody predicted, it is getting hotter at a rate faster than even the worst case climate scenario predictions have so far foreseen.

Such dramatic rises in Arctic temperatures have been recorded before, but only during the last Ice Age. Evidence from the Greenland ice cores suggests that temperatures rose by 10°C or even 12°C, over a period of between 40 years and a century, between 120,000 years and 11,000 years ago.

“We have been clearly underestimating the rate of temperature increases in the atmosphere nearest to the sea level, which has ultimately caused sea ice to disappear faster than we had anticipated,” said Jens Hesselbjerg Christensen, a physicist at the University of Copenhagen in Denmark, one of 16 scientists who report in the journal Nature Climate Change on a new analysis of 40 years of data from the Arctic region.

They found that, on average, the Arctic has been warming at the rate of 1°C per decade for the last four decades. Around Norway’s Svalbard archipelago, temperatures rose even faster, at 1.5°C every 10 years.

“We have been clearly underestimating the rate of temperature increases in the atmosphere nearest to the sea level, which has ultimately caused sea ice to disappear faster than we had anticipated”

During the last two centuries, as atmospheric levels of carbon dioxide climbed from an average of around 285 parts per million to more than 400ppm, so the global average temperature of the planet rose: by a fraction more than 1°C.

The latest study is a reminder that temperatures in the Arctic are rising far faster than that. And the news is hardly a shock: within the past few weeks, separate teams of researchers, reporting to other journals, have warned that Greenland – the biggest single reservoir of ice in the northern hemisphere – is melting faster than ever; more alarmingly, its icecap is losing mass at a rate that suggests the loss could become irreversible.

Researchers have also confirmed that the average planetary temperature  continues to rise inexorably, that the Arctic Ocean could be free of ice in  summer as early as 2035, and that the climate scientists’ “worst case” scenarios are no longer to be regarded as a warning of what could happen: the evidence is that what is happening now already matches the climate forecaster’s worst case. The latest finding implicitly and explicitly supports this flurry of ominous observation.

“We have looked at the climate models analysed and assessed by the UN Climate Panel,” said Professor Christensen. “Only those models based on the worst case scenario, with the highest carbon dioxide emissions, come close to what our temperature measurements show over the past 40 years, from 1979 to today.” – Climate News Network

Arctic heating is happening far faster than anybody had anticipated. And the ice record suggests this has happened before.

LONDON, 2 September, 2020 – An international team of scientists brings bad news about Arctic heating: the polar ocean is warming not only faster than anybody predicted, it is getting hotter at a rate faster than even the worst case climate scenario predictions have so far foreseen.

Such dramatic rises in Arctic temperatures have been recorded before, but only during the last Ice Age. Evidence from the Greenland ice cores suggests that temperatures rose by 10°C or even 12°C, over a period of between 40 years and a century, between 120,000 years and 11,000 years ago.

“We have been clearly underestimating the rate of temperature increases in the atmosphere nearest to the sea level, which has ultimately caused sea ice to disappear faster than we had anticipated,” said Jens Hesselbjerg Christensen, a physicist at the University of Copenhagen in Denmark, one of 16 scientists who report in the journal Nature Climate Change on a new analysis of 40 years of data from the Arctic region.

They found that, on average, the Arctic has been warming at the rate of 1°C per decade for the last four decades. Around Norway’s Svalbard archipelago, temperatures rose even faster, at 1.5°C every 10 years.

“We have been clearly underestimating the rate of temperature increases in the atmosphere nearest to the sea level, which has ultimately caused sea ice to disappear faster than we had anticipated”

During the last two centuries, as atmospheric levels of carbon dioxide climbed from an average of around 285 parts per million to more than 400ppm, so the global average temperature of the planet rose: by a fraction more than 1°C.

The latest study is a reminder that temperatures in the Arctic are rising far faster than that. And the news is hardly a shock: within the past few weeks, separate teams of researchers, reporting to other journals, have warned that Greenland – the biggest single reservoir of ice in the northern hemisphere – is melting faster than ever; more alarmingly, its icecap is losing mass at a rate that suggests the loss could become irreversible.

Researchers have also confirmed that the average planetary temperature  continues to rise inexorably, that the Arctic Ocean could be free of ice in  summer as early as 2035, and that the climate scientists’ “worst case” scenarios are no longer to be regarded as a warning of what could happen: the evidence is that what is happening now already matches the climate forecaster’s worst case. The latest finding implicitly and explicitly supports this flurry of ominous observation.

“We have looked at the climate models analysed and assessed by the UN Climate Panel,” said Professor Christensen. “Only those models based on the worst case scenario, with the highest carbon dioxide emissions, come close to what our temperature measurements show over the past 40 years, from 1979 to today.” – Climate News Network

In Arctic heat Greenland’s ice loss grows faster still

Greenland’s ice loss tipped a new record last year. This ominous milestone is just the latest in a run of alarming news.

LONDON, 24 August, 2020 – Its icecap is now smaller than at any time since measurements began: Greenland’s ice loss means it lost mass in 2019 at a record rate.

By the close of the year, thanks to high summer melt and low snowfall, the northern hemisphere’s biggest reservoir of ice had shed 532 billion tonnes into the sea – raising global sea levels by around 1.5mm in a year.

The previous record loss for Greenland was in 2012. In that year, the island lost 464 billion tonnes, according to studies of satellite data published by European scientists in the journal Communications Earth and Environment.

Greenland’s ice cap has been shrinking, if unsteadily, for many years. In 2017 and 2018, the losses continued, but only at around 100bn tonnes a year.

“After a two-year breather, the mass loss increased steeply and exceeded all annual losses since 1948, and probably for more than 100 years,” said Ingo Sasgen of the Alfred Wegener Institute in Bremerhaven, Germany, who led the study.

“There are increasingly frequent, stable high-pressure areas over the ice sheet, which promote the influx of warm air from the middle latitudes. We saw a similar pattern in the previous record year, 2012.”

“The ice sheet has lost ice every year for the past 20. If everyone’s alarm bells were not already ringing, they must be now”

He and colleagues made their calculations from data delivered by two Nasa satellites, GRACE and GRACE-FO, that measure changes in the surface gravity of the planet: a way of calculating the mass of water stored as ice, or in aquifers, and observing sea level change.

The finding is the latest in a succession of polar climate alarms. It follows closely on a warning from US scientists that ice loss from Greenland may  have reached the point of no return.

And it also follows a sober calculation of the alarming rate of planetary temperature rise in response to ever-higher use of fossil fuels that trigger ever-higher measures of greenhouse gases in the atmosphere.

And that in turn followed a warning that the entire Arctic was now warming so swiftly that the Arctic sea ice might be all but gone in the summer of 2035.

And that was only days after another research team, looking at the big picture of climate change, warned that the scenario climate forecasters liked to use as an example of their “worst case” was now a simple description of what was already happening.

“It is devastating that 2019 was another record year of ice loss. In 2012, it had been about 150 years since the ice sheet had experienced similar melt extent, and then a further 600-plus years back to find another similar event,” said Twila Moon, of the University of Colorado at Boulder, who was not involved in the research.

Damage off the scale

“We have now had record-breaking ice loss twice in less than 10 years, and the ice sheet has lost ice every year for the past 20. If everyone’s alarm bells were not already ringing, they must be now.”

The implications of continued loss of Greenland ice have been explored repeatedly: the run-off of fresh water from the ice cap to the sea is now so great that the North Atlantic is now “fresher” than at any time in the last 100 years.

And this change in water temperature and chemistry could – on the evidence of the distant past – possibly slow or switch off the circulation of the North Atlantic current, which for most of the history of human civilisation has kept the United Kingdom and north-western Europe from five to 10°C warmer than similar latitudes elsewhere.

“This tipping point in the climate system is one of the potential climate disasters facing us,” said Stuart Cunningham of the Scottish Association for Marine Science, commenting on the study.

“To transform the way we power, finance and run the world in the way we know we should is proving entirely beyond us,” said Chris Rapley, now a climate scientist at University College London, but once director of the British Antarctic Survey.

“Torpor, incompetence and indifference at the top may kill people in a health crisis, and torpedo the careers of young students in an education crisis; but the damage they are generating in the pipeline from climate change is on another scale.” – Climate News Network

Greenland’s ice loss tipped a new record last year. This ominous milestone is just the latest in a run of alarming news.

LONDON, 24 August, 2020 – Its icecap is now smaller than at any time since measurements began: Greenland’s ice loss means it lost mass in 2019 at a record rate.

By the close of the year, thanks to high summer melt and low snowfall, the northern hemisphere’s biggest reservoir of ice had shed 532 billion tonnes into the sea – raising global sea levels by around 1.5mm in a year.

The previous record loss for Greenland was in 2012. In that year, the island lost 464 billion tonnes, according to studies of satellite data published by European scientists in the journal Communications Earth and Environment.

Greenland’s ice cap has been shrinking, if unsteadily, for many years. In 2017 and 2018, the losses continued, but only at around 100bn tonnes a year.

“After a two-year breather, the mass loss increased steeply and exceeded all annual losses since 1948, and probably for more than 100 years,” said Ingo Sasgen of the Alfred Wegener Institute in Bremerhaven, Germany, who led the study.

“There are increasingly frequent, stable high-pressure areas over the ice sheet, which promote the influx of warm air from the middle latitudes. We saw a similar pattern in the previous record year, 2012.”

“The ice sheet has lost ice every year for the past 20. If everyone’s alarm bells were not already ringing, they must be now”

He and colleagues made their calculations from data delivered by two Nasa satellites, GRACE and GRACE-FO, that measure changes in the surface gravity of the planet: a way of calculating the mass of water stored as ice, or in aquifers, and observing sea level change.

The finding is the latest in a succession of polar climate alarms. It follows closely on a warning from US scientists that ice loss from Greenland may  have reached the point of no return.

And it also follows a sober calculation of the alarming rate of planetary temperature rise in response to ever-higher use of fossil fuels that trigger ever-higher measures of greenhouse gases in the atmosphere.

And that in turn followed a warning that the entire Arctic was now warming so swiftly that the Arctic sea ice might be all but gone in the summer of 2035.

And that was only days after another research team, looking at the big picture of climate change, warned that the scenario climate forecasters liked to use as an example of their “worst case” was now a simple description of what was already happening.

“It is devastating that 2019 was another record year of ice loss. In 2012, it had been about 150 years since the ice sheet had experienced similar melt extent, and then a further 600-plus years back to find another similar event,” said Twila Moon, of the University of Colorado at Boulder, who was not involved in the research.

Damage off the scale

“We have now had record-breaking ice loss twice in less than 10 years, and the ice sheet has lost ice every year for the past 20. If everyone’s alarm bells were not already ringing, they must be now.”

The implications of continued loss of Greenland ice have been explored repeatedly: the run-off of fresh water from the ice cap to the sea is now so great that the North Atlantic is now “fresher” than at any time in the last 100 years.

And this change in water temperature and chemistry could – on the evidence of the distant past – possibly slow or switch off the circulation of the North Atlantic current, which for most of the history of human civilisation has kept the United Kingdom and north-western Europe from five to 10°C warmer than similar latitudes elsewhere.

“This tipping point in the climate system is one of the potential climate disasters facing us,” said Stuart Cunningham of the Scottish Association for Marine Science, commenting on the study.

“To transform the way we power, finance and run the world in the way we know we should is proving entirely beyond us,” said Chris Rapley, now a climate scientist at University College London, but once director of the British Antarctic Survey.

“Torpor, incompetence and indifference at the top may kill people in a health crisis, and torpedo the careers of young students in an education crisis; but the damage they are generating in the pipeline from climate change is on another scale.” – Climate News Network

250 million coastal dwellers will face rising floods

Once again, researchers confirm that coastal dwellers can expect worse floods, more often and more expensively.

LONDON, 6 August, 2020 – In the next 80 years flooding around the planet’s land masses is likely to rise by almost 50%, endangering many millions of coastal dwellers.

If humans go on burning ever greater volumes of fossil fuels, while destroying ever more natural forest, then another 77 million people could be at risk of flooding, a rise of 52%.

And these floods – increasingly frequent and extending over greater areas – will put at risk cities, homes, resorts and industries valued at more than $14 trillion (£10.7tn).

This sum alone is worth 20% of global gross domestic product, the economist’s preferred indicator of economic health and wealth, according to a new study in the journal Scientific Reports.

The researchers built their argument on historic data from 681 tide-gauge stations around the world to model the growing hazard at 10,000 coastal locations.

“Compared with now, what we see as a one-in-100-year extreme flood event will be ten times more frequent because of climate change”

They conclude that the land area exposed to extreme flood will increase by more than 250,000 sq kms – an increase of 48% – to 800,000 sq kms, a threat to 252 million people.

“A warming climate is driving sea level rise because water expands as it warms, and glaciers are melting. Climate change is also increasing the frequency of extreme seas, which will further increase the risk of flooding,” said Ebru Kirezci of the University of Melbourne, Australia, who led the study.

“What the data and our model are saying is that compared with now, what we see as a one-in-100-year extreme flood event will be ten times more frequent because of climate change.”

None of this should come as a surprise to civic authorities, governments, hydraulic engineers and oceanographers: researchers have been warning for years that coastal floods driven by global heating will end up costing colossal and seemingly ever increasing sums.

On a global scale, and on regional examination, the story remains the same, and wealthy and developed societies in Europe and the US face the same rising tide of hazard as the world’s poorest in the crowded coastal cities of Africa and Asia.

Estimate too low?

A mix of more extreme storms and storm surges, combined with ever higher sea levels, will sweep away the world’s beaches and turn millions of comfortable US citizens into climate refugees.

It is even possible that researchers have under-estimated the hazard, simply because satellite-based measurements may have misread precise land elevation: in some cases, too, coasts are sinking independently of sea level rise.

The latest study identifies a series of flood “hotspots” around the world. These include south-eastern China, Australia’s Northern Territory, Bangladesh, West Bengal and Gujarat in India, the US states of North Carolina, Virginia and Maryland, and north-west Europe including the UK, northern France and northern Germany. The new map of risks takes no account of existing flood defences, but highlights the levels of threat to come.

“This is critical research from a policy point of view, because it provides politicians with a credible estimate of the risks and costs we are facing, and a basis for taking action,” said Ian Young, an engineer at the University of Melbourne, and a co-author.

“This data should act as a wake-up call to inform policy at global and local government levels so that more flood defences can be built to safeguard coastal life and infrastructure.” – Climate News Network

Once again, researchers confirm that coastal dwellers can expect worse floods, more often and more expensively.

LONDON, 6 August, 2020 – In the next 80 years flooding around the planet’s land masses is likely to rise by almost 50%, endangering many millions of coastal dwellers.

If humans go on burning ever greater volumes of fossil fuels, while destroying ever more natural forest, then another 77 million people could be at risk of flooding, a rise of 52%.

And these floods – increasingly frequent and extending over greater areas – will put at risk cities, homes, resorts and industries valued at more than $14 trillion (£10.7tn).

This sum alone is worth 20% of global gross domestic product, the economist’s preferred indicator of economic health and wealth, according to a new study in the journal Scientific Reports.

The researchers built their argument on historic data from 681 tide-gauge stations around the world to model the growing hazard at 10,000 coastal locations.

“Compared with now, what we see as a one-in-100-year extreme flood event will be ten times more frequent because of climate change”

They conclude that the land area exposed to extreme flood will increase by more than 250,000 sq kms – an increase of 48% – to 800,000 sq kms, a threat to 252 million people.

“A warming climate is driving sea level rise because water expands as it warms, and glaciers are melting. Climate change is also increasing the frequency of extreme seas, which will further increase the risk of flooding,” said Ebru Kirezci of the University of Melbourne, Australia, who led the study.

“What the data and our model are saying is that compared with now, what we see as a one-in-100-year extreme flood event will be ten times more frequent because of climate change.”

None of this should come as a surprise to civic authorities, governments, hydraulic engineers and oceanographers: researchers have been warning for years that coastal floods driven by global heating will end up costing colossal and seemingly ever increasing sums.

On a global scale, and on regional examination, the story remains the same, and wealthy and developed societies in Europe and the US face the same rising tide of hazard as the world’s poorest in the crowded coastal cities of Africa and Asia.

Estimate too low?

A mix of more extreme storms and storm surges, combined with ever higher sea levels, will sweep away the world’s beaches and turn millions of comfortable US citizens into climate refugees.

It is even possible that researchers have under-estimated the hazard, simply because satellite-based measurements may have misread precise land elevation: in some cases, too, coasts are sinking independently of sea level rise.

The latest study identifies a series of flood “hotspots” around the world. These include south-eastern China, Australia’s Northern Territory, Bangladesh, West Bengal and Gujarat in India, the US states of North Carolina, Virginia and Maryland, and north-west Europe including the UK, northern France and northern Germany. The new map of risks takes no account of existing flood defences, but highlights the levels of threat to come.

“This is critical research from a policy point of view, because it provides politicians with a credible estimate of the risks and costs we are facing, and a basis for taking action,” said Ian Young, an engineer at the University of Melbourne, and a co-author.

“This data should act as a wake-up call to inform policy at global and local government levels so that more flood defences can be built to safeguard coastal life and infrastructure.” – Climate News Network

Antarctic melting could bring a much hotter future

Antarctic melting can force sea ice retreat of 50 metres daily. CO2 levels are at their highest for 23 million years. Learn from the past.

LONDON, 23 June, 2020 – Antarctic melting starts with dramatic speed. Ice shelves during the sudden warm spell at the close of the last Ice Age retreated at up to 50 metres a day.

This finding is not based on climate simulations generated by computer algorithms. It is based on direct evidence left 12,000 years ago on the Antarctic sea floor by retreating ice.

The finding is an indirect indicator of how warm things could get – and how high sea levels could rise – as humans burn ever more fossil fuels and raise atmospheric greenhouse gas levels to ever higher ratios.

And as if to highlight the approaching climate catastrophe, a second and separate study finds that the measure of carbon dioxide in the atmosphere now is not just higher than at any time in human history or at any interval in the Ice Ages. It is the highest for at least 23 million years.

“Should climate change continue to weaken the ice shelves in the coming decades, we could see similar rates of retreat, with profound implications for global sea level rise”

British scientists report in the journal Science that they used an autonomous underwater vehicle (AUV), cruising at depth in the Weddell Sea, to read the pattern of the past preserved in ridges of the Antarctic seabed.

The original push for the expedition had been to search for the ship Endurance, commanded by the polar explorer Ernest Shackleton on his doomed voyage in 1914. The loss of the ship, crushed in the polar ice, and the rescue of his crew became one of the epic stories of maritime history.

The researchers did not find Endurance. But they did find an enduring record of past ice retreat.

Sea ice skirts about 75% of the continent’s coastline: when it melts it makes no difference to sea levels, but while it remains frozen it does serve the purpose of buttressing glacial flow from the high Antarctic interior. Brushed by increasingly warm air each summer, and swept by slowly warming ocean currents all year round, the ice shelves are thinning and retreating.

Tell-tale line

Underneath the ice, the research team’s robot submarine spotted wave-like ridges, each about a metre high and 20 to 25 metres apart: ridges formed at what had once been the grounding line – the point at which a grounded ice sheet starts to float, and evidence of ice rising and falling with the tides.

There are twelve hours between high tide and low, so by measuring the distance between the ridges, scientists could measure the pace of retreat at the end of the last Ice Age. It is estimated at 40 to 50 metres a day.

Right now, the fastest retreat measured from grounding lines in Antarctica is only about 1.6 kms a year. The implication is that it could get a lot faster.

“Should climate change continue to weaken the ice shelves in the coming decades, we could see similar rates of retreat, with profound implications for global sea level rise,” said Julian Dowdeswell, director of the Scott Polar Research Institute in Cambridge, who led the research.

Faster change ahead

Past warm periods are associated only with relatively modest rises in atmospheric carbon dioxide. Right now, researchers have repeatedly confirmed that the present increasingly rapid rise is the highest in the last 800,000 years.

Now a team from the US and Norway report in the journal Geology that they have measured past atmospheric carbon levels in fossil plants to establish that present day carbon levels are higher currently than at any time in the last 23 million years.

This means that – unless there are drastic steps to contain global warming – the retreat will become increasingly more rapid, and the rate of glacial flow towards the sea ever faster.

Were all the ice in Antarctica to melt, sea levels would rise by about 60 metres, completely submerging many of the world’s great cities. – Climate News Network

Antarctic melting can force sea ice retreat of 50 metres daily. CO2 levels are at their highest for 23 million years. Learn from the past.

LONDON, 23 June, 2020 – Antarctic melting starts with dramatic speed. Ice shelves during the sudden warm spell at the close of the last Ice Age retreated at up to 50 metres a day.

This finding is not based on climate simulations generated by computer algorithms. It is based on direct evidence left 12,000 years ago on the Antarctic sea floor by retreating ice.

The finding is an indirect indicator of how warm things could get – and how high sea levels could rise – as humans burn ever more fossil fuels and raise atmospheric greenhouse gas levels to ever higher ratios.

And as if to highlight the approaching climate catastrophe, a second and separate study finds that the measure of carbon dioxide in the atmosphere now is not just higher than at any time in human history or at any interval in the Ice Ages. It is the highest for at least 23 million years.

“Should climate change continue to weaken the ice shelves in the coming decades, we could see similar rates of retreat, with profound implications for global sea level rise”

British scientists report in the journal Science that they used an autonomous underwater vehicle (AUV), cruising at depth in the Weddell Sea, to read the pattern of the past preserved in ridges of the Antarctic seabed.

The original push for the expedition had been to search for the ship Endurance, commanded by the polar explorer Ernest Shackleton on his doomed voyage in 1914. The loss of the ship, crushed in the polar ice, and the rescue of his crew became one of the epic stories of maritime history.

The researchers did not find Endurance. But they did find an enduring record of past ice retreat.

Sea ice skirts about 75% of the continent’s coastline: when it melts it makes no difference to sea levels, but while it remains frozen it does serve the purpose of buttressing glacial flow from the high Antarctic interior. Brushed by increasingly warm air each summer, and swept by slowly warming ocean currents all year round, the ice shelves are thinning and retreating.

Tell-tale line

Underneath the ice, the research team’s robot submarine spotted wave-like ridges, each about a metre high and 20 to 25 metres apart: ridges formed at what had once been the grounding line – the point at which a grounded ice sheet starts to float, and evidence of ice rising and falling with the tides.

There are twelve hours between high tide and low, so by measuring the distance between the ridges, scientists could measure the pace of retreat at the end of the last Ice Age. It is estimated at 40 to 50 metres a day.

Right now, the fastest retreat measured from grounding lines in Antarctica is only about 1.6 kms a year. The implication is that it could get a lot faster.

“Should climate change continue to weaken the ice shelves in the coming decades, we could see similar rates of retreat, with profound implications for global sea level rise,” said Julian Dowdeswell, director of the Scott Polar Research Institute in Cambridge, who led the research.

Faster change ahead

Past warm periods are associated only with relatively modest rises in atmospheric carbon dioxide. Right now, researchers have repeatedly confirmed that the present increasingly rapid rise is the highest in the last 800,000 years.

Now a team from the US and Norway report in the journal Geology that they have measured past atmospheric carbon levels in fossil plants to establish that present day carbon levels are higher currently than at any time in the last 23 million years.

This means that – unless there are drastic steps to contain global warming – the retreat will become increasingly more rapid, and the rate of glacial flow towards the sea ever faster.

Were all the ice in Antarctica to melt, sea levels would rise by about 60 metres, completely submerging many of the world’s great cities. – Climate News Network

Threatened mangrove forests won’t protect coasts

Rising tides driven by global heating could swamp the mangrove forests – bad news for the natural world, and for humans.

LONDON, 17 June, 2020 – If sea levels go on rising at ever higher rates, then by 2050 the world’s mangrove forests could be obliterated, drowned by rising tides.

Mangrove forests cover between 140,000 and 200,000 square kilometres of the intertidal zones that fringe more than 100 tropical and subtropical countries, and have become among the richest ecosystems of the planet.

They are estimated to store at least 30 million tonnes of atmospheric carbon each year, and a couple of sq kms of this saltwater forest can harbour nursery space for what could become 100 tonnes of commercial fish catch every year.

They also provide shelter for a huge range of creatures, including an estimated 500 Bengal tigers in the vast Sundarbans mangrove forests along the Ganges-Brahmaputra delta.

And while most of the 80 or so species of mangrove tree can keep up with an annual sea level rise of around 5mm a year, they seem unlikely, on evidence from the past, to be able to survive a 10mm rise. Right now, the world is heading for the higher end of the scale.

Sheltering people

A second and separate study finds that, importantly for humans, along with coral reefs, the mangrove forests provide vital natural protection from tropical storms for 31 million very vulnerable people in North and Central America and the crowded archipelagos of Indonesia and the Philippines.

Researchers from Australia, China, Singapore and the US report in the journal Science that they looked at the evidence locked in the sediments in 78 locations from the last 10,000 years, to work out how mangrove forests have – through the millennia – responded to changes in sea level.

At the close of the last ice age, sea levels rose at 10mm a year and slowed to nearly stable conditions 4000 years ago.

In a high emissions scenario, by 2050 sea level rise would exceed 6mm: the scientists found a 90% probability that mangroves would not be able to grow fast enough to keep up. Nor – because of the development of coastal settlements worldwide – would the forests be able to shift inland.

“Simply put, it’s much cheaper to conserve a mangrove than build a sea wall”

“This research therefore highlights yet another compelling reason why countries must take urgent action to reduce carbon emissions,” said Benjamin Horton of Nanyang Technical University in Singapore., one of the researchers.

“Mangroves are among the most valuable of natural ecosystems, supporting coastal fisheries and biodiversity, while protecting shorelines from wave and storm attack across the tropics.”

As so often happens in research, confirmatory evidence of the importance of mangroves had been published only days earlier, in the Public Library of Science journal PLOS One.

US researchers found that – in the Gulf of Mexico and the Caribbean, off the coasts of east Africa and in the Indo-Pacific – a total of 30.9 million people lived in regions vulnerable to powerful tropical storms such as Typhoon Haiyan and Hurricane Harvey.

Of these, more than 8 million people were offered severe weather protection by shoreline mangrove forests and coral reefs, both of which absorb wave energy, reduce wave heights and keep coastal settlements safer.

Not enough protection

But only 38% of mangroves and 11% of coral reefs along the vulnerable coastlines are protected, they found.

A 100-metre screen of shoreline mangrove forest can reduce wave heights by as much as two-thirds. By 2100, coastal floods could be costing the world’s nations US$1 trillion a year in economic damage.

Geographers have argued for decades that natural protection is the most efficient way of saving lives and settlements from the storm surges and flooding associated with tropical cyclone extremes.

“Simply put”, said Holly Jones of Northern Illinois University, who led the research, “it’s much cheaper to conserve a mangrove than build a sea wall.” – Climate News Network

Rising tides driven by global heating could swamp the mangrove forests – bad news for the natural world, and for humans.

LONDON, 17 June, 2020 – If sea levels go on rising at ever higher rates, then by 2050 the world’s mangrove forests could be obliterated, drowned by rising tides.

Mangrove forests cover between 140,000 and 200,000 square kilometres of the intertidal zones that fringe more than 100 tropical and subtropical countries, and have become among the richest ecosystems of the planet.

They are estimated to store at least 30 million tonnes of atmospheric carbon each year, and a couple of sq kms of this saltwater forest can harbour nursery space for what could become 100 tonnes of commercial fish catch every year.

They also provide shelter for a huge range of creatures, including an estimated 500 Bengal tigers in the vast Sundarbans mangrove forests along the Ganges-Brahmaputra delta.

And while most of the 80 or so species of mangrove tree can keep up with an annual sea level rise of around 5mm a year, they seem unlikely, on evidence from the past, to be able to survive a 10mm rise. Right now, the world is heading for the higher end of the scale.

Sheltering people

A second and separate study finds that, importantly for humans, along with coral reefs, the mangrove forests provide vital natural protection from tropical storms for 31 million very vulnerable people in North and Central America and the crowded archipelagos of Indonesia and the Philippines.

Researchers from Australia, China, Singapore and the US report in the journal Science that they looked at the evidence locked in the sediments in 78 locations from the last 10,000 years, to work out how mangrove forests have – through the millennia – responded to changes in sea level.

At the close of the last ice age, sea levels rose at 10mm a year and slowed to nearly stable conditions 4000 years ago.

In a high emissions scenario, by 2050 sea level rise would exceed 6mm: the scientists found a 90% probability that mangroves would not be able to grow fast enough to keep up. Nor – because of the development of coastal settlements worldwide – would the forests be able to shift inland.

“Simply put, it’s much cheaper to conserve a mangrove than build a sea wall”

“This research therefore highlights yet another compelling reason why countries must take urgent action to reduce carbon emissions,” said Benjamin Horton of Nanyang Technical University in Singapore., one of the researchers.

“Mangroves are among the most valuable of natural ecosystems, supporting coastal fisheries and biodiversity, while protecting shorelines from wave and storm attack across the tropics.”

As so often happens in research, confirmatory evidence of the importance of mangroves had been published only days earlier, in the Public Library of Science journal PLOS One.

US researchers found that – in the Gulf of Mexico and the Caribbean, off the coasts of east Africa and in the Indo-Pacific – a total of 30.9 million people lived in regions vulnerable to powerful tropical storms such as Typhoon Haiyan and Hurricane Harvey.

Of these, more than 8 million people were offered severe weather protection by shoreline mangrove forests and coral reefs, both of which absorb wave energy, reduce wave heights and keep coastal settlements safer.

Not enough protection

But only 38% of mangroves and 11% of coral reefs along the vulnerable coastlines are protected, they found.

A 100-metre screen of shoreline mangrove forest can reduce wave heights by as much as two-thirds. By 2100, coastal floods could be costing the world’s nations US$1 trillion a year in economic damage.

Geographers have argued for decades that natural protection is the most efficient way of saving lives and settlements from the storm surges and flooding associated with tropical cyclone extremes.

“Simply put”, said Holly Jones of Northern Illinois University, who led the research, “it’s much cheaper to conserve a mangrove than build a sea wall.” – Climate News Network

Unanswered questions dog UK’s new nuclear plans

A French company has designs on the United Kingdom: new nuclear plans for more reactors, with British consumers footing the bill.

LONDON, 11 June, 2020 – The French company EDF, a company in a hurry, wants permission to start building two more reactors in the United Kingdom, and it hopes to save money – by arranging for British taxpayers to pay the capital costs of its new nuclear plans.

EDF is already building two reactors at Hinkley Point in the West of England, and it is hoping to transfer workers from that site to Suffolk, on the east coast, believing that will help it to save up to 20% of the construction cost of the two planned reactors, because everyone employed there will know already what to do.

The catch is that EDF has no money itself to finance the construction and wants the UK government to impose a new tax on British electricity consumers so that they will pay the cost through their electricity bills.

The UK has yet to decide whether to go ahead with this tax, euphemistically called a Regulated Asset Base. If adopted, what the scheme means is that the UK consumer will pay EDF’s bills rather than the company having to borrow the money from banks, which are increasingly unlikely to lend money to such expensive schemes because they take so long to build and promise little return.

Anxieties abound

Meanwhile EDF, which has a Chinese nuclear company as its junior partner, promises to create 25,000 jobs, including 1,000 apprenticeships during construction, and says 900 full-time jobs will be available when Sizewell C, as the station will be called, is complete.

If all goes to plan the company hopes to start work in 18 months and says the two reactors will take 10 years to build. It expects them to provide 7% of the UK’s electricity, enough for six million homes.

There are many objectors. Some say much of the coastline will be badly affected, including internationally important nature reserves. Others fear the site is highly vulnerable to sea level rise and therefore a danger to the public.

Local people also fear that the construction site, with its attendant lorry and commuter traffic, will disrupt their lives for a decade, destroying the important tourist trade.

Cheaper options

Other more strategic objections, which might weigh heavier with the government, are that nuclear power is very expensive and much cheaper and less controversial alternatives exist, particularly on-shore and off-shore wind and solar power, and biogas.

More importantly, a drive for energy efficiency, badly neglected in the UK at present, would render the whole project unnecessary.

The problem EDF has is its track record on construction and repairs. The type of reactor it plans to build, the European Pressurised Water Reactor, said by the company to be the most powerful in the world, is proving extremely difficult to build, and till now none has yet been completed outside China.

Construction is running more than 10 years late in both Finland and France, and costs continue to escalate.

“It is hard to understand why, when the scale of the problems became clear, EDF did not cut its losses and close the reactors”

EDF’s debts are now huge, so big that the French state is working out how to restructure the company by splitting it into a renewables arm (which is profitable) and a nuclear branch.

There are serious doubts about the reliability of EDF’s claims and timetables for fixing existing power stations and opening new ones. The company currently owns all of the UK’s operating nuclear reactors, most of which are near the end of their lives, and there are serious doubts about whether they are economic and in some cases even safe.

Two reactors at Hunterston in Scotland have serious cracking in the graphite blocks that are part of the control mechanism. The company has spent two years trying to justify continuing to operate the reactors to the Office for Nuclear Regulation (ONR).

Similarly, at the other end of the UK, at Dungeness in south-east England, the station is also closed for extensive repairs, an outage that was going to take weeks has now stretched to two years – and the start-up date has just been put back again.

Looking on the bright side

One of the features of all of EDF’s activities is the extraordinary optimism the company seems to have, particularly about when reactors will be finished or ready to restart after repairs. With the Hunterston reactors restart dates have been announced nine times, only to be postponed each time.

This track record led the Climate News Network to ask EDF some searching questions, including why they continued to offer optimistic start-up dates that were repeatedly postponed. We also asked why the company kept the Hunterston and Dungeness stations open at all, since repairing them was costly and they were already near the end of their operating lives.

We asked EDF: “At what point do you cut your losses and close the stations permanently?” After five days of pleading for more time to answer, it sent us already published press releases extolling the virtues of the plan to build Sizewell, and several comments.

On Dungeness B it said: “For the past two years we have undertaken a major investment programme at Dungeness to secure the station’s longer-term future. Since the start of the year we have made great progress in  tackling some of the complex problems our works identified.

Extensive repairs

“However we still have further engineering works to complete, and a detailed safety case to finalise, before we ask for restart approval from our regulator. Our present position for estimated return to service is 11 September for Reactor 22 and 21 September for Reactor 21.”

On Hunterston B, EDF said: “We are continuing to work constructively with the regulator to ensure the work at Hunterston B is done thoroughly and helps inform future decisions. The safety case for Hunterston B, Reactor 3, has been submitted to the ONR for its independent assessment.

“Since the first reactor was taken offline we have carried out the most extensive graphite inspection programme ever undertaken, the results of which have been fed into this case”, referring us to the information the company provides on graphite blocks.

The ONR could not answer for EDF on its estimated reactor re-opening dates, but on Hunterston it said it was looking at the safety case, would not be hurried and would not give permission to restart until it was satisfied it was safe to do so.

Unexpected snags

Stephen Thomas, professor of energy policy at the University of Greenwich, commented on the constantly postponed start-up dates for the ageing reactors:

“It is clear, given that shutdowns expected to take two months are now expected to take two years or more, that EDF has found huge unanticipated problems”, he said.

“It is hard to understand why, when the scale of the problems became clear, EDF did not cut its losses and close the reactors, but continues to pour money into plants to get a couple more years of operation out of plants highly likely to be loss-makers.

“It is depressing that ONR, which has a duty to keep the public informed on such important issues, chooses to hide behind bland statements such as that it will take as long as it takes, and that it will not comment on EDF’s decisions.” – Climate News Network

A French company has designs on the United Kingdom: new nuclear plans for more reactors, with British consumers footing the bill.

LONDON, 11 June, 2020 – The French company EDF, a company in a hurry, wants permission to start building two more reactors in the United Kingdom, and it hopes to save money – by arranging for British taxpayers to pay the capital costs of its new nuclear plans.

EDF is already building two reactors at Hinkley Point in the West of England, and it is hoping to transfer workers from that site to Suffolk, on the east coast, believing that will help it to save up to 20% of the construction cost of the two planned reactors, because everyone employed there will know already what to do.

The catch is that EDF has no money itself to finance the construction and wants the UK government to impose a new tax on British electricity consumers so that they will pay the cost through their electricity bills.

The UK has yet to decide whether to go ahead with this tax, euphemistically called a Regulated Asset Base. If adopted, what the scheme means is that the UK consumer will pay EDF’s bills rather than the company having to borrow the money from banks, which are increasingly unlikely to lend money to such expensive schemes because they take so long to build and promise little return.

Anxieties abound

Meanwhile EDF, which has a Chinese nuclear company as its junior partner, promises to create 25,000 jobs, including 1,000 apprenticeships during construction, and says 900 full-time jobs will be available when Sizewell C, as the station will be called, is complete.

If all goes to plan the company hopes to start work in 18 months and says the two reactors will take 10 years to build. It expects them to provide 7% of the UK’s electricity, enough for six million homes.

There are many objectors. Some say much of the coastline will be badly affected, including internationally important nature reserves. Others fear the site is highly vulnerable to sea level rise and therefore a danger to the public.

Local people also fear that the construction site, with its attendant lorry and commuter traffic, will disrupt their lives for a decade, destroying the important tourist trade.

Cheaper options

Other more strategic objections, which might weigh heavier with the government, are that nuclear power is very expensive and much cheaper and less controversial alternatives exist, particularly on-shore and off-shore wind and solar power, and biogas.

More importantly, a drive for energy efficiency, badly neglected in the UK at present, would render the whole project unnecessary.

The problem EDF has is its track record on construction and repairs. The type of reactor it plans to build, the European Pressurised Water Reactor, said by the company to be the most powerful in the world, is proving extremely difficult to build, and till now none has yet been completed outside China.

Construction is running more than 10 years late in both Finland and France, and costs continue to escalate.

“It is hard to understand why, when the scale of the problems became clear, EDF did not cut its losses and close the reactors”

EDF’s debts are now huge, so big that the French state is working out how to restructure the company by splitting it into a renewables arm (which is profitable) and a nuclear branch.

There are serious doubts about the reliability of EDF’s claims and timetables for fixing existing power stations and opening new ones. The company currently owns all of the UK’s operating nuclear reactors, most of which are near the end of their lives, and there are serious doubts about whether they are economic and in some cases even safe.

Two reactors at Hunterston in Scotland have serious cracking in the graphite blocks that are part of the control mechanism. The company has spent two years trying to justify continuing to operate the reactors to the Office for Nuclear Regulation (ONR).

Similarly, at the other end of the UK, at Dungeness in south-east England, the station is also closed for extensive repairs, an outage that was going to take weeks has now stretched to two years – and the start-up date has just been put back again.

Looking on the bright side

One of the features of all of EDF’s activities is the extraordinary optimism the company seems to have, particularly about when reactors will be finished or ready to restart after repairs. With the Hunterston reactors restart dates have been announced nine times, only to be postponed each time.

This track record led the Climate News Network to ask EDF some searching questions, including why they continued to offer optimistic start-up dates that were repeatedly postponed. We also asked why the company kept the Hunterston and Dungeness stations open at all, since repairing them was costly and they were already near the end of their operating lives.

We asked EDF: “At what point do you cut your losses and close the stations permanently?” After five days of pleading for more time to answer, it sent us already published press releases extolling the virtues of the plan to build Sizewell, and several comments.

On Dungeness B it said: “For the past two years we have undertaken a major investment programme at Dungeness to secure the station’s longer-term future. Since the start of the year we have made great progress in  tackling some of the complex problems our works identified.

Extensive repairs

“However we still have further engineering works to complete, and a detailed safety case to finalise, before we ask for restart approval from our regulator. Our present position for estimated return to service is 11 September for Reactor 22 and 21 September for Reactor 21.”

On Hunterston B, EDF said: “We are continuing to work constructively with the regulator to ensure the work at Hunterston B is done thoroughly and helps inform future decisions. The safety case for Hunterston B, Reactor 3, has been submitted to the ONR for its independent assessment.

“Since the first reactor was taken offline we have carried out the most extensive graphite inspection programme ever undertaken, the results of which have been fed into this case”, referring us to the information the company provides on graphite blocks.

The ONR could not answer for EDF on its estimated reactor re-opening dates, but on Hunterston it said it was looking at the safety case, would not be hurried and would not give permission to restart until it was satisfied it was safe to do so.

Unexpected snags

Stephen Thomas, professor of energy policy at the University of Greenwich, commented on the constantly postponed start-up dates for the ageing reactors:

“It is clear, given that shutdowns expected to take two months are now expected to take two years or more, that EDF has found huge unanticipated problems”, he said.

“It is hard to understand why, when the scale of the problems became clear, EDF did not cut its losses and close the reactors, but continues to pour money into plants to get a couple more years of operation out of plants highly likely to be loss-makers.

“It is depressing that ONR, which has a duty to keep the public informed on such important issues, chooses to hide behind bland statements such as that it will take as long as it takes, and that it will not comment on EDF’s decisions.” – Climate News Network