Category Archives: Oceans

Polar concerns rise as ice now melts ever faster

An Antarctic glacier gathers pace. In the north, the Arctic ice thins faster. Racing climate heat is feeding polar concerns.

LONDON, 15 June, 2021 − An Antarctic glacier has begun to move more quickly towards the open ocean, as the shelf of sea ice that once held it back starts to collapse. The water in that one glacier is enough to raise global sea levels by half a metre. And that’s not all that’s raising polar concerns across the scientific world.

At the other end of the Earth global heating is accelerating the loss of Arctic ice. A new study reports that the thinning of sea ice in three separate coastal regions could now be happening twice as fast.

Both findings are linked to the inexorable rise in global average temperatures as the profligate use of fossil fuels heightens the ratio of greenhouse gases in the planet’s atmosphere.

Antarctic scientists have been worrying about warming in Antarctica for years. And they have been anxiously watching the Pine Island glacier in West Antarctica for decades.

Glaciers move at the proverbial glacial pace towards the sea, to be held in check, in the polar oceans, by vast shelves of sea ice. Between 2017 and 2020 the ice shelves have undergone a series of collapses and lost one fifth of their area, possibly because the glacier has been accelerating.

“The thickness of the sea ice is a sensitive indicator of the health of the Arctic”

“We may not have the luxury of waiting for slow changes on Pine Island; things could actually go much quicker than expected,” said Ian Joughin, of the University of Washington in the US.

“The processes we’d been studying in this region were leading to an irreversible collapse, but at a fairly measured pace. Things could be much more abrupt if we lose the rest of that ice shelf.”

He and his colleagues report in the journal Science Advances that the Pine Island glacier has already become Antarctica’s biggest contributor to sea level rise. The pace of flow remained fairly steady from 2009 to 2017, but they found that data from Europe’s Copernicus Sentinel satellite system showed an acceleration of 12% in the past three years.

The Pine Island glacier contains roughly 180 trillion tonnes of ice, enough to raise global sea levels by 0.5 metres. Researchers had calculated that it might take a century or more for slowly-warming polar waters to thin the ice shelves to the point where they could no longer stem the glacier flow. But it now seems that the big player in the shelf ice collapse is the glacier itself, as the flow rate increases.

“The loss of Pine Island’s ice shelf now looks possibly like it could occur in the next decade or two, as opposed to the melt-driven sub-surface change playing out over more than 100 or more years,” said Pierre Dutrieux of the British Antarctic Survey, a co-author. “So it’s a potentially much more rapid and abrupt change.”

Snow fall dwindles

Abrupt change, too, may be on the way in the Arctic Ocean. British researchers used a new computer simulation to explore measurements from Europe’s CryoSat-2 satellite. The scientists report in the journal The Cryosphere that the thinning of ice in the Laptev and Kara Seas north of Siberia, and the Chukchi Sea between Siberia and Alaska, has stepped up by 70%, 98% and 110% respectively.

Sea ice diminishes each summer and forms again each winter; each successive summer reveals an ever-greater loss, as the ice itself thins and the area covered by ice dwindles.

Calculations of ice thickness have always allowed for the falls of fresh winter snow. But since the formation of sea ice has been later every year, there has been less time for the snow to accumulate. Such things make a difference.

“The thickness of the sea ice is a sensitive indicator of the health of the Arctic,” said Robbie Mallett, of University College London.

“It is important as thicker ice acts as an insulating blanket, stopping the ocean from warming up the atmosphere in winter, and protecting the ocean from sunshine in summer. Thinner ice is also less likely to survive the summer melt.” − Climate News Network

An Antarctic glacier gathers pace. In the north, the Arctic ice thins faster. Racing climate heat is feeding polar concerns.

LONDON, 15 June, 2021 − An Antarctic glacier has begun to move more quickly towards the open ocean, as the shelf of sea ice that once held it back starts to collapse. The water in that one glacier is enough to raise global sea levels by half a metre. And that’s not all that’s raising polar concerns across the scientific world.

At the other end of the Earth global heating is accelerating the loss of Arctic ice. A new study reports that the thinning of sea ice in three separate coastal regions could now be happening twice as fast.

Both findings are linked to the inexorable rise in global average temperatures as the profligate use of fossil fuels heightens the ratio of greenhouse gases in the planet’s atmosphere.

Antarctic scientists have been worrying about warming in Antarctica for years. And they have been anxiously watching the Pine Island glacier in West Antarctica for decades.

Glaciers move at the proverbial glacial pace towards the sea, to be held in check, in the polar oceans, by vast shelves of sea ice. Between 2017 and 2020 the ice shelves have undergone a series of collapses and lost one fifth of their area, possibly because the glacier has been accelerating.

“The thickness of the sea ice is a sensitive indicator of the health of the Arctic”

“We may not have the luxury of waiting for slow changes on Pine Island; things could actually go much quicker than expected,” said Ian Joughin, of the University of Washington in the US.

“The processes we’d been studying in this region were leading to an irreversible collapse, but at a fairly measured pace. Things could be much more abrupt if we lose the rest of that ice shelf.”

He and his colleagues report in the journal Science Advances that the Pine Island glacier has already become Antarctica’s biggest contributor to sea level rise. The pace of flow remained fairly steady from 2009 to 2017, but they found that data from Europe’s Copernicus Sentinel satellite system showed an acceleration of 12% in the past three years.

The Pine Island glacier contains roughly 180 trillion tonnes of ice, enough to raise global sea levels by 0.5 metres. Researchers had calculated that it might take a century or more for slowly-warming polar waters to thin the ice shelves to the point where they could no longer stem the glacier flow. But it now seems that the big player in the shelf ice collapse is the glacier itself, as the flow rate increases.

“The loss of Pine Island’s ice shelf now looks possibly like it could occur in the next decade or two, as opposed to the melt-driven sub-surface change playing out over more than 100 or more years,” said Pierre Dutrieux of the British Antarctic Survey, a co-author. “So it’s a potentially much more rapid and abrupt change.”

Snow fall dwindles

Abrupt change, too, may be on the way in the Arctic Ocean. British researchers used a new computer simulation to explore measurements from Europe’s CryoSat-2 satellite. The scientists report in the journal The Cryosphere that the thinning of ice in the Laptev and Kara Seas north of Siberia, and the Chukchi Sea between Siberia and Alaska, has stepped up by 70%, 98% and 110% respectively.

Sea ice diminishes each summer and forms again each winter; each successive summer reveals an ever-greater loss, as the ice itself thins and the area covered by ice dwindles.

Calculations of ice thickness have always allowed for the falls of fresh winter snow. But since the formation of sea ice has been later every year, there has been less time for the snow to accumulate. Such things make a difference.

“The thickness of the sea ice is a sensitive indicator of the health of the Arctic,” said Robbie Mallett, of University College London.

“It is important as thicker ice acts as an insulating blanket, stopping the ocean from warming up the atmosphere in winter, and protecting the ocean from sunshine in summer. Thinner ice is also less likely to survive the summer melt.” − Climate News Network

Fish supplies face rising threat from algal blooms

Fish farms, and the protein supply of over three billion people, are at increasing risk from algal blooms.

LONDON, 10 June, 2021 – Toxic algal blooms that can kill fish and sometimes humans cause severe economic losses and are an increasing danger to food supplies.

The threat has increased dramatically, not because the quantity of algae is necessarily increasing, but because humankind is relying more and more on aquaculture to provide fish. There has been a 16-fold increase in fish farming since 1985.

Around 3.3 billion people rely on seafood for a fifth of their animal protein, and it is an increasingly important source as land-based agriculture faces great strains because of climate change.

An international team of scientists who carried out a statistical analysis of three sources, notably HAEDAT, the Harmful Algal Event Database, covering the years from 1985 to 2018, report their findings in the journal Nature Communications: Earth & Environment.

Their analysis, the first of its kind, was undertaken because of a widespread belief that the problem is worsening. They say it may only appear to be more acute because wild fish, unlike those in fish farms, can swim safely away from algal blooms. So it is possible the blooms have simply not been reported as often because fish have managed to avoid them.

Climate heating implicated

They write: “Global trends in the occurrence, toxicity and risk posed by harmful algal blooms to natural systems, human health and coastal economies are poorly constrained, but are widely thought to be increasing due to climate change and nutrient pollution. . .

“We find no uniform global trend in the number of harmful algal events and their distribution over time, once data were adjusted for regional variations in monitoring effort.”

However, a new factor that may be increasing the danger of algae to aquaculture is climate change. This is because harmful blooms have occurred in temperature increase hotspots in the Asia Pacific region and off the coasts of Chile and south-east Australia. Other climatic factors such as ocean acidification, nutrient alterations and lower oxygen levels are also playing a role.

The researchers did though discover wide variations across the world in the incidence of harmful blooms, with some areas having reduced human poisoning and fish kills and others increasing occurrences. The reason is not known.

The use of coastal waters for aquaculture has been the key driver for the reporting of blooms, because the mass fish mortality has led occasionally to disastrous long-lasting economic impacts. This in turn has driven awareness of new harmful algal species and new toxin types.

“Global trends in the risk posed by harmful algal blooms are widely thought to be increasing”

There are about 5,000 species of marine phytoplankton, of which 200 can harm humans through the production of toxins that either make them ill or kill the fish or shellfish they would otherwise eat. Some toxins also kill marine mammals, particularly their calves.

By December 2019 a total of 9,503 events of harmful algae had been recorded from across the world. Nearly half were of toxins in seafood; 43% of blooms caused water discolouration or surface scum, producing other impacts, for example on tourism. Around 70 incidents caused mass animal or plant mortality.

The researchers say shellfish toxin outbreaks are now well-managed in developed countries and economies can recover swiftly, although  aquaculture industries can take many years to rebuild after mass mortality. The problem is becoming more acute because of the increasing reliance of an ever-larger human population on fish protein for survival.

Examples of severe economic losses from fish farms are a US$71 million loss in Japan in 1972, with $70m in Korea in 1995, $290m in China in 2012 and $100m in Norway in 2019. The worst was the 2016 Chilean salmon farm mortality that created a record $800m loss and caused major social unrest.

The scientists conclude that algal blooms are an increasing threat to the world’s food supply because of humans’ ever-growing reliance on aquaculture for protein. They recommend a worldwide sharing of knowledge and data in order to keep a check on the problem and how to control it. – Climate News Network

Fish farms, and the protein supply of over three billion people, are at increasing risk from algal blooms.

LONDON, 10 June, 2021 – Toxic algal blooms that can kill fish and sometimes humans cause severe economic losses and are an increasing danger to food supplies.

The threat has increased dramatically, not because the quantity of algae is necessarily increasing, but because humankind is relying more and more on aquaculture to provide fish. There has been a 16-fold increase in fish farming since 1985.

Around 3.3 billion people rely on seafood for a fifth of their animal protein, and it is an increasingly important source as land-based agriculture faces great strains because of climate change.

An international team of scientists who carried out a statistical analysis of three sources, notably HAEDAT, the Harmful Algal Event Database, covering the years from 1985 to 2018, report their findings in the journal Nature Communications: Earth & Environment.

Their analysis, the first of its kind, was undertaken because of a widespread belief that the problem is worsening. They say it may only appear to be more acute because wild fish, unlike those in fish farms, can swim safely away from algal blooms. So it is possible the blooms have simply not been reported as often because fish have managed to avoid them.

Climate heating implicated

They write: “Global trends in the occurrence, toxicity and risk posed by harmful algal blooms to natural systems, human health and coastal economies are poorly constrained, but are widely thought to be increasing due to climate change and nutrient pollution. . .

“We find no uniform global trend in the number of harmful algal events and their distribution over time, once data were adjusted for regional variations in monitoring effort.”

However, a new factor that may be increasing the danger of algae to aquaculture is climate change. This is because harmful blooms have occurred in temperature increase hotspots in the Asia Pacific region and off the coasts of Chile and south-east Australia. Other climatic factors such as ocean acidification, nutrient alterations and lower oxygen levels are also playing a role.

The researchers did though discover wide variations across the world in the incidence of harmful blooms, with some areas having reduced human poisoning and fish kills and others increasing occurrences. The reason is not known.

The use of coastal waters for aquaculture has been the key driver for the reporting of blooms, because the mass fish mortality has led occasionally to disastrous long-lasting economic impacts. This in turn has driven awareness of new harmful algal species and new toxin types.

“Global trends in the risk posed by harmful algal blooms are widely thought to be increasing”

There are about 5,000 species of marine phytoplankton, of which 200 can harm humans through the production of toxins that either make them ill or kill the fish or shellfish they would otherwise eat. Some toxins also kill marine mammals, particularly their calves.

By December 2019 a total of 9,503 events of harmful algae had been recorded from across the world. Nearly half were of toxins in seafood; 43% of blooms caused water discolouration or surface scum, producing other impacts, for example on tourism. Around 70 incidents caused mass animal or plant mortality.

The researchers say shellfish toxin outbreaks are now well-managed in developed countries and economies can recover swiftly, although  aquaculture industries can take many years to rebuild after mass mortality. The problem is becoming more acute because of the increasing reliance of an ever-larger human population on fish protein for survival.

Examples of severe economic losses from fish farms are a US$71 million loss in Japan in 1972, with $70m in Korea in 1995, $290m in China in 2012 and $100m in Norway in 2019. The worst was the 2016 Chilean salmon farm mortality that created a record $800m loss and caused major social unrest.

The scientists conclude that algal blooms are an increasing threat to the world’s food supply because of humans’ ever-growing reliance on aquaculture for protein. They recommend a worldwide sharing of knowledge and data in order to keep a check on the problem and how to control it. – Climate News Network

Pathway to global climate catastrophe is clear

Global climate catastrophe could be nearer than we think. New research suggests how it could happen.

LONDON, 8 June, 2021 − Here is a set of circumstances that could trigger global climate catastrophe. The Greenland ice sheet could begin a process of irreversible melting.

As it does, greater quantities of fresh water would flood into the Arctic Ocean, to further slow the already slowing Atlantic meridional overturning circulation, that great flow of water sometimes called the Gulf Stream that  distributes warmth from the tropics.

But as the Atlantic flow weakens, so rises the probability of increased and sustained drought and dieback in the Amazon rainforest: the entire region could begin to tip inexorably into savannah.

And the Southern Ocean would begin to warm: it could warm enough to hasten the disintegration of the West Antarctic ice sheet, to accelerate the rise of global sea levels and intensify the whole machinery of global heating.

Alarmingly, this process could begin to happen while global temperatures are still not much higher than they are now: 1.5°C has been repeatedly described as the limit beyond which global average temperatures should not rise, but the official global agreed target is a limit of 2°C.

In fact, the chance of a cascade of domino effects − of tipping points that trigger other climate tipping points − could begin somewhere between those two figures, and the probability rises thereafter.

No way back

And, researchers warn, when they say irreversible, they mean it. Once the Greenland ice sheet starts to slide into the sea, there will be no stopping it. The only question is how swiftly all these things could happen.

“Once triggered, the actual tipping process might take several years up to millennia, depending on the respective response times of the system,” the scientists write in the journal Earth System Dynamics.

It’s a scenario, not a prediction. It’s a calculation of possibilities and probabilities inherent in the process of global warming and climate change. It’s an identification of the way atmospheric warming driven by greenhouse gas emissions from human economies can and might change the climate system that drives planetary weather.

“We provide risk analysis, not a prediction, yet our findings still raise concern,” said Ricarda Winkelmann, of the Potsdam Institute for Climate Impact Research, one of the authors.

She and her colleagues base their study on computer simulations of planetary response to temperature rise. And one third of those simulations suggest that if the world reaches 2°C, then one of those elements could begin to tip towards irreversible change, and at the same time trigger other tipping points.

“We’re shifting the odds, and not to our favour − the risk is clearly increasing the more we heat our planet,” said her colleague and co-author Jonathan Donges. “It rises substantially between 1°C and 3°C.

“Rapidly reducing greenhouse gas emissions is indispensable to limit the risks of crossing tipping points in the climate system”

“If greenhouse gas emissions and the resulting climate change cannot be halted, the upper level of this warming range could most likely be crossed by the end of this century. With even higher temperatures, more tipping cascades are to be expected, with long-term devastating effects.”

Climate science has been concerned with the idea of tipping points − temperatures beyond which climate change might be irreversible − for decades. There have been repeated findings that some of these might be nearer than anybody had suspected.

Greenland is in effect the reservoir of most of the Northern hemisphere’s ice − enough to raise sea levels by seven metres − and it is melting at an ever-accelerating rate.

Researchers have again and again identified a possible faltering of the Atlantic current, to warn of a paradoxical consequence: if the Gulf Stream slows, then average temperatures in western Europe could actually fall in a globally-heating world.

The Amazon rainforest − a vital part of the planet’s climate machinery since the end of the last Ice Age − has been hit not just by human degradation but by drought and forest fire, and could be about to slide into permanent savannah.

Overshoot nears

And scientists in Antarctica have been warning for a decade of thinning ice sheets, and accelerating glaciers.

The planet has already warmed by more than a degree Celsius in the last century or so. There is a high chance that some time this decade the annual average planetary temperature could pass the 1.5°C threshold, if only temporarily.

Right now, although 195 nations in Paris in 2015 committed themselves to a target of “well below” 2°C by 2100, the world is heading for a temperature rise by the end of the century of more than 3°C.

The authors concede that their results contain a lot of uncertainties: there is more research to be done. But that doesn’t mean there is no urgency.

“Our analysis is conservative in the sense that several interactions and tipping elements are not yet considered”, said Professor Winkelmann. It would hence be a daring bet to hope that the uncertainties play out in a good way, given what is at stake.

“From a precautionary perspective, rapidly reducing greenhouse gas emissions is indispensable to limit the risks of crossing tipping points in the climate system, and potentially causing domino effects.” − Climate News Network

Global climate catastrophe could be nearer than we think. New research suggests how it could happen.

LONDON, 8 June, 2021 − Here is a set of circumstances that could trigger global climate catastrophe. The Greenland ice sheet could begin a process of irreversible melting.

As it does, greater quantities of fresh water would flood into the Arctic Ocean, to further slow the already slowing Atlantic meridional overturning circulation, that great flow of water sometimes called the Gulf Stream that  distributes warmth from the tropics.

But as the Atlantic flow weakens, so rises the probability of increased and sustained drought and dieback in the Amazon rainforest: the entire region could begin to tip inexorably into savannah.

And the Southern Ocean would begin to warm: it could warm enough to hasten the disintegration of the West Antarctic ice sheet, to accelerate the rise of global sea levels and intensify the whole machinery of global heating.

Alarmingly, this process could begin to happen while global temperatures are still not much higher than they are now: 1.5°C has been repeatedly described as the limit beyond which global average temperatures should not rise, but the official global agreed target is a limit of 2°C.

In fact, the chance of a cascade of domino effects − of tipping points that trigger other climate tipping points − could begin somewhere between those two figures, and the probability rises thereafter.

No way back

And, researchers warn, when they say irreversible, they mean it. Once the Greenland ice sheet starts to slide into the sea, there will be no stopping it. The only question is how swiftly all these things could happen.

“Once triggered, the actual tipping process might take several years up to millennia, depending on the respective response times of the system,” the scientists write in the journal Earth System Dynamics.

It’s a scenario, not a prediction. It’s a calculation of possibilities and probabilities inherent in the process of global warming and climate change. It’s an identification of the way atmospheric warming driven by greenhouse gas emissions from human economies can and might change the climate system that drives planetary weather.

“We provide risk analysis, not a prediction, yet our findings still raise concern,” said Ricarda Winkelmann, of the Potsdam Institute for Climate Impact Research, one of the authors.

She and her colleagues base their study on computer simulations of planetary response to temperature rise. And one third of those simulations suggest that if the world reaches 2°C, then one of those elements could begin to tip towards irreversible change, and at the same time trigger other tipping points.

“We’re shifting the odds, and not to our favour − the risk is clearly increasing the more we heat our planet,” said her colleague and co-author Jonathan Donges. “It rises substantially between 1°C and 3°C.

“Rapidly reducing greenhouse gas emissions is indispensable to limit the risks of crossing tipping points in the climate system”

“If greenhouse gas emissions and the resulting climate change cannot be halted, the upper level of this warming range could most likely be crossed by the end of this century. With even higher temperatures, more tipping cascades are to be expected, with long-term devastating effects.”

Climate science has been concerned with the idea of tipping points − temperatures beyond which climate change might be irreversible − for decades. There have been repeated findings that some of these might be nearer than anybody had suspected.

Greenland is in effect the reservoir of most of the Northern hemisphere’s ice − enough to raise sea levels by seven metres − and it is melting at an ever-accelerating rate.

Researchers have again and again identified a possible faltering of the Atlantic current, to warn of a paradoxical consequence: if the Gulf Stream slows, then average temperatures in western Europe could actually fall in a globally-heating world.

The Amazon rainforest − a vital part of the planet’s climate machinery since the end of the last Ice Age − has been hit not just by human degradation but by drought and forest fire, and could be about to slide into permanent savannah.

Overshoot nears

And scientists in Antarctica have been warning for a decade of thinning ice sheets, and accelerating glaciers.

The planet has already warmed by more than a degree Celsius in the last century or so. There is a high chance that some time this decade the annual average planetary temperature could pass the 1.5°C threshold, if only temporarily.

Right now, although 195 nations in Paris in 2015 committed themselves to a target of “well below” 2°C by 2100, the world is heading for a temperature rise by the end of the century of more than 3°C.

The authors concede that their results contain a lot of uncertainties: there is more research to be done. But that doesn’t mean there is no urgency.

“Our analysis is conservative in the sense that several interactions and tipping elements are not yet considered”, said Professor Winkelmann. It would hence be a daring bet to hope that the uncertainties play out in a good way, given what is at stake.

“From a precautionary perspective, rapidly reducing greenhouse gas emissions is indispensable to limit the risks of crossing tipping points in the climate system, and potentially causing domino effects.” − Climate News Network

Ecosystem sentinels sound alarm for the oceans

Sea birds are known as ecosystem sentinels, warning of marine loss. As their numbers fall, so could the riches of the ocean.

LONDON, 7 June, 2021 − For a tern in the northern hemisphere, life may be about to take a turn for the worse. For murres or guillemots, as the temperature rises, the chance of survival takes a dive. Many of the world’s seabirds could be in trouble.

And for a mix of reasons, the birds of the southern hemisphere could also be heading into difficulties, but at a slower pace. A worldwide team of 40 
ornithologists has looked at 50 years of breeding records for 67 seabird species to find that as global temperatures notch up, breeding rates are down.

That may be just an indicator of deteriorating conditions on and below the surface of the oceans: the researchers call their seabird subjects “ecosystem sentinels”.

The scientists report in the journal Science that they used their data to test a proposition: that seabird productivity − the numbers that survive each breeding season − would track “hemispheric asymmetry” in ocean climate change and human use.

Put simply, because there is less land and fewer people south of the Equator, because the southern waters are less overfished and subjected to lower pollution levels, and because a bigger ocean space ought to absorb extremes of heat more effectively, seabird survival rates would be worse north of the line than to the south.

“When seabirds aren’t doing well, this is a red flag that something bigger is happening below the ocean’s surface”

And that is because the fish and plankton that seabirds eat can move with the climate, but the seabirds cannot: during the breeding season, they return to the same colonies. And hunt they must: the species Uria aalge, known as the murre or the guillemot, must eat half its bodyweight in fish each day to survive. When a long-term marine heatwave hit the north-east Pacific in 2015-2016, almost a million of them starved to death.

Breeding colonies also suffered. The pattern of change is not uniform: surface-feeding birds were more likely to be in decline; birds like puffins that plunged below the surface tended to fare a little better at rearing offspring to survival.

“Seabirds travel long distances − some going from one hemisphere to the other − chasing their food in the ocean. This makes them sensitive to changes in things like ocean productivity, often over a large area,” said P Dee Boersma, a conservation biologist at the University of Washington in the US.

“They have to compete with us for food. They get caught in our fishing nets. They eat our plastic, which they think is food. All of these factors can kill off large numbers of long-lived seabirds.”

She and colleagues have monitored the breeding success of a colony of Magellanic penguins in southern Argentina for 35 years. These birds go back to the water each season to feed their chicks: the further they have to swim, the greater the chance of a starved penguin chick.

Competition for food

Stormier weather on land, too, can destroy nests. Female penguins find survival tougher, and are more likely to die at sea. So the proportion of male Magellanic penguins is rising. Today the breeding population at the research site is about half of its numbers 40 years ago.

William Sydeman of the Farallon Institute in Northern California, who led the study, warned that falling seabird numbers could be an indicator of worse things happening at sea.

“What’s also at stake is the health of fish populations such as salmon and cod, as well as marine mammals and large invertebrates, such as squid, that are eating the same small forage fish and plankton that seabirds eat,” he said.

“When seabirds aren’t doing well, this is a red flag that something bigger is happening below the ocean’s surface which is concerning, because we depend on healthy oceans for quality of life.” − Climate News Network

Sea birds are known as ecosystem sentinels, warning of marine loss. As their numbers fall, so could the riches of the ocean.

LONDON, 7 June, 2021 − For a tern in the northern hemisphere, life may be about to take a turn for the worse. For murres or guillemots, as the temperature rises, the chance of survival takes a dive. Many of the world’s seabirds could be in trouble.

And for a mix of reasons, the birds of the southern hemisphere could also be heading into difficulties, but at a slower pace. A worldwide team of 40 
ornithologists has looked at 50 years of breeding records for 67 seabird species to find that as global temperatures notch up, breeding rates are down.

That may be just an indicator of deteriorating conditions on and below the surface of the oceans: the researchers call their seabird subjects “ecosystem sentinels”.

The scientists report in the journal Science that they used their data to test a proposition: that seabird productivity − the numbers that survive each breeding season − would track “hemispheric asymmetry” in ocean climate change and human use.

Put simply, because there is less land and fewer people south of the Equator, because the southern waters are less overfished and subjected to lower pollution levels, and because a bigger ocean space ought to absorb extremes of heat more effectively, seabird survival rates would be worse north of the line than to the south.

“When seabirds aren’t doing well, this is a red flag that something bigger is happening below the ocean’s surface”

And that is because the fish and plankton that seabirds eat can move with the climate, but the seabirds cannot: during the breeding season, they return to the same colonies. And hunt they must: the species Uria aalge, known as the murre or the guillemot, must eat half its bodyweight in fish each day to survive. When a long-term marine heatwave hit the north-east Pacific in 2015-2016, almost a million of them starved to death.

Breeding colonies also suffered. The pattern of change is not uniform: surface-feeding birds were more likely to be in decline; birds like puffins that plunged below the surface tended to fare a little better at rearing offspring to survival.

“Seabirds travel long distances − some going from one hemisphere to the other − chasing their food in the ocean. This makes them sensitive to changes in things like ocean productivity, often over a large area,” said P Dee Boersma, a conservation biologist at the University of Washington in the US.

“They have to compete with us for food. They get caught in our fishing nets. They eat our plastic, which they think is food. All of these factors can kill off large numbers of long-lived seabirds.”

She and colleagues have monitored the breeding success of a colony of Magellanic penguins in southern Argentina for 35 years. These birds go back to the water each season to feed their chicks: the further they have to swim, the greater the chance of a starved penguin chick.

Competition for food

Stormier weather on land, too, can destroy nests. Female penguins find survival tougher, and are more likely to die at sea. So the proportion of male Magellanic penguins is rising. Today the breeding population at the research site is about half of its numbers 40 years ago.

William Sydeman of the Farallon Institute in Northern California, who led the study, warned that falling seabird numbers could be an indicator of worse things happening at sea.

“What’s also at stake is the health of fish populations such as salmon and cod, as well as marine mammals and large invertebrates, such as squid, that are eating the same small forage fish and plankton that seabirds eat,” he said.

“When seabirds aren’t doing well, this is a red flag that something bigger is happening below the ocean’s surface which is concerning, because we depend on healthy oceans for quality of life.” − 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

Many creatures of the deep face a stifling future

The oceans will go on warming and rising for five centuries. Some creatures of the deep will have less room to breathe.

LONDON, 22 April, 2021 − Even if humans stopped all use of fossil fuels immediately, and drastically reduced greenhouse gas emissions, the oceans would go on warming. And as the waters warmed, their burden of dissolved oxygen would continue to dwindle, stifling many creatures of the deep.

This could continue for another 500 years, at the end of which oxygen loss in the seas would have multiplied fourfold. Since oxygen is vital to almost all complex life on Earth, and since the ocean − covering 70% of the globe and reaching in places to depths of almost 11 kilometres − provides by far the oldest and biggest breathing space for living things, that could commit many creatures to a slow, stifling end, according to a new study in the journal Nature Communications.

Both oxygen and carbon dioxide are soluble in seawater. The colder the water, the greater the capacity for dissolved gases, which ultimately is why polar seas are vastly and massively richer in life than tropical waters. But the latest study of the long-term consequences of carbon dioxide emissions offers a bleak picture for the future.

As the planet has warmed, so have the seas. As the greenhouse gas burden of the atmosphere has increased, so has the acidity of the ocean. And as the ocean waters have warmed, the levels of dissolved oxygen have fallen.

In the last 50 years, the ocean has on average lost 2% of its dissolved oxygen. That’s an average figure. In some parts of the water column, the loss has been much higher, directly as a consequence of global warming. And this loss will continue until around 2650.

“The deep ocean appears committed to turning into an as-yet-unrecognised area where the slogan ‘If you can’t breathe, nothing else matters’ will become reality for many centuries to come”

Andreas Oschlies of the Geomar Helmholtz Centre for Ocean Research in Kiel in Germany used a climate model of the Earth system to work out what would happen to the ocean in the long term if all carbon dioxide emissions stopped right now.

He says: “The results show that even in this extreme scenario, the oxygen depletion will continue for centuries, more than quadrupling the oxygen loss we have seen to date in the ocean.”

Most of this loss will be at depths of 2000 metres or more, partly because ocean circulation is becoming more sluggish in response to climate change. So the deepest parts of the ocean could lose more than a tenth of all the oxygen it once held before the launch of the Industrial Revolution and the accelerated use of coal, oil and gas to drive national economies. And that would be bad news for the creatures that swim and replicate at depth: some of them could face a decline of up to 25%.

And if nations could achieve the impossible and halt all emissions now, surface air temperatures would stabilise rapidly. But the oceans would go on absorbing the extra carbon dioxide already in the atmosphere. Between now and 2650, according to the calculations of Professor Oschlies, the ocean would go on absorbing another 720 billion tonnes of the gas. This is larger than all the CO2 the oceans have taken up till now: an estimated 634 billion tonnes.

Too little air

But the atmospheric heat the oceans will absorb in the next five centuries is likely to be three times the heat already absorbed up till now. This warmth alone − because warm water is less dense than cold water − will mean another 16cms of unavoidable sea level rise. And as the waters warm, the oxygen levels in that water will continue to diminish: by 2650 it will have fallen by 7.4% compared with oxygen levels a century or more ago. And this is more than three times the loss that has already happened.

Those sea creatures that had adapted over a million years to one set of oxygen levels are going to face a problem: there won’t be enough oxygen dissolved in the deep seas to support all of them. Some regions of the ocean will slowly become “dead zones”.

Oceanography is a costly science, and most of the ocean is unexplored: humans have mapped the surface and plundered the coastal waters but have yet to explore the depths in much detail over vast tracts of the planet’s largest living room.

There’s a lot more research to be done, before researchers can be sure of the ways in which human action is about to irrevocably change the submarine world. But the outlook so far is ominous.

Professor Oschlies warns: “The deep ocean appears committed to turning into an as-yet-unrecognised area where the slogan of the American Lung Association − ‘If you can’t breathe, nothing else matters’ − will become reality for many centuries to come.” − Climate News Network

The oceans will go on warming and rising for five centuries. Some creatures of the deep will have less room to breathe.

LONDON, 22 April, 2021 − Even if humans stopped all use of fossil fuels immediately, and drastically reduced greenhouse gas emissions, the oceans would go on warming. And as the waters warmed, their burden of dissolved oxygen would continue to dwindle, stifling many creatures of the deep.

This could continue for another 500 years, at the end of which oxygen loss in the seas would have multiplied fourfold. Since oxygen is vital to almost all complex life on Earth, and since the ocean − covering 70% of the globe and reaching in places to depths of almost 11 kilometres − provides by far the oldest and biggest breathing space for living things, that could commit many creatures to a slow, stifling end, according to a new study in the journal Nature Communications.

Both oxygen and carbon dioxide are soluble in seawater. The colder the water, the greater the capacity for dissolved gases, which ultimately is why polar seas are vastly and massively richer in life than tropical waters. But the latest study of the long-term consequences of carbon dioxide emissions offers a bleak picture for the future.

As the planet has warmed, so have the seas. As the greenhouse gas burden of the atmosphere has increased, so has the acidity of the ocean. And as the ocean waters have warmed, the levels of dissolved oxygen have fallen.

In the last 50 years, the ocean has on average lost 2% of its dissolved oxygen. That’s an average figure. In some parts of the water column, the loss has been much higher, directly as a consequence of global warming. And this loss will continue until around 2650.

“The deep ocean appears committed to turning into an as-yet-unrecognised area where the slogan ‘If you can’t breathe, nothing else matters’ will become reality for many centuries to come”

Andreas Oschlies of the Geomar Helmholtz Centre for Ocean Research in Kiel in Germany used a climate model of the Earth system to work out what would happen to the ocean in the long term if all carbon dioxide emissions stopped right now.

He says: “The results show that even in this extreme scenario, the oxygen depletion will continue for centuries, more than quadrupling the oxygen loss we have seen to date in the ocean.”

Most of this loss will be at depths of 2000 metres or more, partly because ocean circulation is becoming more sluggish in response to climate change. So the deepest parts of the ocean could lose more than a tenth of all the oxygen it once held before the launch of the Industrial Revolution and the accelerated use of coal, oil and gas to drive national economies. And that would be bad news for the creatures that swim and replicate at depth: some of them could face a decline of up to 25%.

And if nations could achieve the impossible and halt all emissions now, surface air temperatures would stabilise rapidly. But the oceans would go on absorbing the extra carbon dioxide already in the atmosphere. Between now and 2650, according to the calculations of Professor Oschlies, the ocean would go on absorbing another 720 billion tonnes of the gas. This is larger than all the CO2 the oceans have taken up till now: an estimated 634 billion tonnes.

Too little air

But the atmospheric heat the oceans will absorb in the next five centuries is likely to be three times the heat already absorbed up till now. This warmth alone − because warm water is less dense than cold water − will mean another 16cms of unavoidable sea level rise. And as the waters warm, the oxygen levels in that water will continue to diminish: by 2650 it will have fallen by 7.4% compared with oxygen levels a century or more ago. And this is more than three times the loss that has already happened.

Those sea creatures that had adapted over a million years to one set of oxygen levels are going to face a problem: there won’t be enough oxygen dissolved in the deep seas to support all of them. Some regions of the ocean will slowly become “dead zones”.

Oceanography is a costly science, and most of the ocean is unexplored: humans have mapped the surface and plundered the coastal waters but have yet to explore the depths in much detail over vast tracts of the planet’s largest living room.

There’s a lot more research to be done, before researchers can be sure of the ways in which human action is about to irrevocably change the submarine world. But the outlook so far is ominous.

Professor Oschlies warns: “The deep ocean appears committed to turning into an as-yet-unrecognised area where the slogan of the American Lung Association − ‘If you can’t breathe, nothing else matters’ − will become reality for many centuries to come.” − Climate News Network

Protect fish to increase catches − and cut carbon

There is a clear way to get more value from the seas: protect fish. New research confirms an old argument.

LONDON, 25 March, 2021 − Scientists have identified a sure way towards more profitable fishing: don’t do it. Protect fish and leave as much of the seas as possible untouched.

To convert the right stretches of the blue planet into marine sanctuaries would actually deliver bigger hauls than any uncontrolled harvests could promise. It could also protect marine wildlife and reduce greenhouse gas emissions to the atmosphere.

“Ocean life has been declining worldwide because of overfishing, habitat destruction and climate change. Yet only 7% of the ocean is currently under some kind of protection,” said Enric Sala, of the Pristine Seas project at the National Geographic Society.

“In this study, we’ve pioneered a new way to identify the places that − if protected − will boost food production and safeguard marine life, all while reducing carbon emissions,” Dr Sala said.

“It’s clear that humanity and the economy will benefit from a healthier ocean. And we can realise those benefits quickly if countries work together to protect at least 30% of the ocean by 2030.”

No to exploitation

He and 25 other scientists from the US, Canada, France, Germany and Australia report in the journal Nature that they have devised a planning framework and identified regions of ocean that would benefit most from status as Marine Protected Areas, or MPAs.

Right now only around 2.7% of the high seas are fully or highly protected, and in all 7% have been designated or proposed as suitable for such status.

The scientists argue that to safeguard their proposed areas could offer safety for 80% of marine species, ultimately add eight million tonnes more to the global catch than any uncontrolled trawling could offer, and prevent the release of more than a billion tonnes of carbon dioxide a year − simply by preventing disturbance of the sea floor.

They see an enormous gain if even 21% of the ocean is protected, and they want to see 30% of the global ocean undisturbed and valued as a conservation resource by the year 2030.

The argument that humans can profit more from conserving the wilderness than by ruthlessly exploiting it sounds radical. But it has been made again and again.

“We’ve pioneered a new way to identify the places that − if protected − will boost food production and safeguard marine life, all while reducing carbon emissions”

On land, separate research teams have found repeatedly that forests and wetlands deliver a higher net return in the long term, and to the greatest number of people, than mining, felling or farming can offer.

And it has been the same story afloat: world fish catches would benefit from protected areas; fishing itself would become more dangerous and
with lower returns in a regime of uncontrolled global climate change; and a reduction in the rate of global heating would pay off in richer marine harvests.

Diplomats and scientists from 190 nations will meet in Kunming in China this year for a conference of the UN Convention on Biological Diversity. The US, Canada, the European Commission and other nations have committed to the goal of protecting 30% of the planet by 2030.

But the implication of the latest study is that such declarations are only as good as the effort to realise them that sponsor nations are prepared to make. Most of the proposed protected stretches of sea are within the 200-mile exclusive economic zones of coastal nations; others − the Mid-Atlantic Ridge, for instance, and the Southwest Indian Ridge between South Africa and Antarctica, are governed by international law.

The researchers’ proposals would require a ban on bottom trawling, in which heavy nets scour the submarine ooze. The carbon dioxide released into the ocean from this practice alone is higher than emissions from global aviation; higher even than most countries’ annual carbon emissions.

More is worse

“The ocean floor is the world’s largest carbon storehouse. If we’re to succeed in stopping global warming, we must leave the carbon-rich seabed undisturbed,” said Trisha Atwood of Utah State University, one of the authors.

“Yet every day, we are trawling the seafloor, depleting its biodiversity and mobilising millennia-old carbon and thus exacerbating climate change. Our findings about the climate impacts of bottom trawling will make the activities on the ocean’s seabed hard to ignore in climate plans going forward.”

The overall argument the researchers put to the world’s great fishing nations is a simple one: the worst enemy of successful fishing is overfishing.

“It’s simple: When overfishing and other damaging activities cease, marine life bounces back,” said Reniel Cabral of the University of California Santa Barbara, another of the signatories.

“After protections are put in place, the diversity and abundance of marine life increase over time, with measurable recovery within reserves occurring in as little as three years. Target species and large predators come back, and entire ecosystems are restored within MPAs. With time, the ocean can heal itself and again provide services to humankind.” − Climate News Network

There is a clear way to get more value from the seas: protect fish. New research confirms an old argument.

LONDON, 25 March, 2021 − Scientists have identified a sure way towards more profitable fishing: don’t do it. Protect fish and leave as much of the seas as possible untouched.

To convert the right stretches of the blue planet into marine sanctuaries would actually deliver bigger hauls than any uncontrolled harvests could promise. It could also protect marine wildlife and reduce greenhouse gas emissions to the atmosphere.

“Ocean life has been declining worldwide because of overfishing, habitat destruction and climate change. Yet only 7% of the ocean is currently under some kind of protection,” said Enric Sala, of the Pristine Seas project at the National Geographic Society.

“In this study, we’ve pioneered a new way to identify the places that − if protected − will boost food production and safeguard marine life, all while reducing carbon emissions,” Dr Sala said.

“It’s clear that humanity and the economy will benefit from a healthier ocean. And we can realise those benefits quickly if countries work together to protect at least 30% of the ocean by 2030.”

No to exploitation

He and 25 other scientists from the US, Canada, France, Germany and Australia report in the journal Nature that they have devised a planning framework and identified regions of ocean that would benefit most from status as Marine Protected Areas, or MPAs.

Right now only around 2.7% of the high seas are fully or highly protected, and in all 7% have been designated or proposed as suitable for such status.

The scientists argue that to safeguard their proposed areas could offer safety for 80% of marine species, ultimately add eight million tonnes more to the global catch than any uncontrolled trawling could offer, and prevent the release of more than a billion tonnes of carbon dioxide a year − simply by preventing disturbance of the sea floor.

They see an enormous gain if even 21% of the ocean is protected, and they want to see 30% of the global ocean undisturbed and valued as a conservation resource by the year 2030.

The argument that humans can profit more from conserving the wilderness than by ruthlessly exploiting it sounds radical. But it has been made again and again.

“We’ve pioneered a new way to identify the places that − if protected − will boost food production and safeguard marine life, all while reducing carbon emissions”

On land, separate research teams have found repeatedly that forests and wetlands deliver a higher net return in the long term, and to the greatest number of people, than mining, felling or farming can offer.

And it has been the same story afloat: world fish catches would benefit from protected areas; fishing itself would become more dangerous and
with lower returns in a regime of uncontrolled global climate change; and a reduction in the rate of global heating would pay off in richer marine harvests.

Diplomats and scientists from 190 nations will meet in Kunming in China this year for a conference of the UN Convention on Biological Diversity. The US, Canada, the European Commission and other nations have committed to the goal of protecting 30% of the planet by 2030.

But the implication of the latest study is that such declarations are only as good as the effort to realise them that sponsor nations are prepared to make. Most of the proposed protected stretches of sea are within the 200-mile exclusive economic zones of coastal nations; others − the Mid-Atlantic Ridge, for instance, and the Southwest Indian Ridge between South Africa and Antarctica, are governed by international law.

The researchers’ proposals would require a ban on bottom trawling, in which heavy nets scour the submarine ooze. The carbon dioxide released into the ocean from this practice alone is higher than emissions from global aviation; higher even than most countries’ annual carbon emissions.

More is worse

“The ocean floor is the world’s largest carbon storehouse. If we’re to succeed in stopping global warming, we must leave the carbon-rich seabed undisturbed,” said Trisha Atwood of Utah State University, one of the authors.

“Yet every day, we are trawling the seafloor, depleting its biodiversity and mobilising millennia-old carbon and thus exacerbating climate change. Our findings about the climate impacts of bottom trawling will make the activities on the ocean’s seabed hard to ignore in climate plans going forward.”

The overall argument the researchers put to the world’s great fishing nations is a simple one: the worst enemy of successful fishing is overfishing.

“It’s simple: When overfishing and other damaging activities cease, marine life bounces back,” said Reniel Cabral of the University of California Santa Barbara, another of the signatories.

“After protections are put in place, the diversity and abundance of marine life increase over time, with measurable recovery within reserves occurring in as little as three years. Target species and large predators come back, and entire ecosystems are restored within MPAs. With time, the ocean can heal itself and again provide services to humankind.” − Climate News Network

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

Weakening Gulf Stream may disrupt world weather

The Gulf Stream is growing feebler, the Arctic seas are gaining fresh water. Together they could affect the world’s weather.

LONDON, 2 March, 2021 − The Atlantic Conveyer, otherwise the Gulf Stream − that great flow of surface water pouring northwards that overturns in the Arctic and heads south again at great depth − is now weaker than at any point in the last 1,000 years, European scientists report.

And in a second, separate but related study, researchers have found that the Beaufort Sea, in the Arctic, has gained two-fifths more fresh water in the last 20 years: water that could flow into the Atlantic to affect the Conveyor, and with it, climatic conditions.

Scientists call it the Atlantic Meridional Overturning Circulation or just AMOC. Europeans know it as the Gulf Stream: the current that conveys tropic warmth to their coasts and keeps Britain and Western Europe at a temperature several degrees higher than latitude alone might dictate.

And for years, oceanographers and climate scientists have been observing a slowing of the flow, by as much as 15%. But direct measurement of the great current began only relatively recently in 2004: researchers needed to know whether the slowdown was part of a natural cycle, or a consequence of climate change driven by global heating.

Now they know a little more. European researchers report in Nature Geoscience that they looked for evidence of ocean circulation shifts in what they call “proxy evidence”: the story of climate change told by tree growth rings, ice cores, ocean sediments, corals and historical records, including naval logbooks.

The combined evidence of temperature patterns, the sizes of particles of ocean floor sediment and the salinity and density of sub-surface water helps build up a picture of the Atlantic current for the last 1,600 years.

“The Gulf Stream System moves nearly 20 million cubic meters of water per second, almost a hundred times the Amazon flow”

The verdict? Up to the 19th century, ocean currents were stable. The flow is now more sluggish than at any time in the last millennium.

This is roughly what climate models have predicted: the warm salty water moves north, cools, becomes more dense, sinks to the deep and flows back south. But the Arctic has begun to warm, Greenland to melt, and the flow of fresh water into the northern seas to intensify.

Since the flow is driven by the difference in temperatures, any change in the regional thermometer will play back into the rate of flow. And any extra arrival of fresh water could further slow the overturning circulation.

“The Gulf Stream system works like a giant conveyor belt, carrying warm surface water from the equator up north, and sending cold, low-salinity deep water back down south. It moves nearly 20 million cubic meters of water per second, almost a hundred times the Amazon flow,” said Stefan Rahmstorf, of the Potsdam Institute for Climate Impact Research, in Germany, one of the authors.

“For the first time, we have combined a range of previous studies and found they provide a consistent picture of the AMOC evolution over the past 1600 years. The study results suggest that it has been relatively stable until the late 19th century.

“With the end of the Little Ice Age in about 1850, the ocean currents began to decline, with a second, more drastic decline following since the mid-20th century.”

Outcome awaited

The change could have ominous consequences for European weather systems: it could also deliver more intense coastal flooding to the US eastern seaboard. If the current continues to weaken, the consequences could be catastrophic.

Which is why a new study in Nature Communications matters so much. US researchers tracked the flow of fresh water from the Beaufort Sea − melt water from glaciers, rivers and disappearing Arctic sea ice − through the Canadian Archipelago and into the Labrador Sea.

Arctic water is fresher than Atlantic water, and richer in nutrients. But this extra volume, measured at a total of 23,300 cubic kilometres, could also affect the rate of flow of the overturning circulation. That is because relatively fresh water is less dense than saline water, and tends to float on top.

Quite what role it could play is uncertain: the message is that, sooner or later, it will escape into the North Atlantic. Then the world will find out.

“People have already spent a lot of time studying why the Beaufort Sea fresh water has gotten so high in the past few decades,” said Jiaxu Zhang,  of the Los Alamos National Laboratory, first author. “But they rarely care where the freshwater goes, and we think that’s a much more important problem.” − Climate News Network

The Gulf Stream is growing feebler, the Arctic seas are gaining fresh water. Together they could affect the world’s weather.

LONDON, 2 March, 2021 − The Atlantic Conveyer, otherwise the Gulf Stream − that great flow of surface water pouring northwards that overturns in the Arctic and heads south again at great depth − is now weaker than at any point in the last 1,000 years, European scientists report.

And in a second, separate but related study, researchers have found that the Beaufort Sea, in the Arctic, has gained two-fifths more fresh water in the last 20 years: water that could flow into the Atlantic to affect the Conveyor, and with it, climatic conditions.

Scientists call it the Atlantic Meridional Overturning Circulation or just AMOC. Europeans know it as the Gulf Stream: the current that conveys tropic warmth to their coasts and keeps Britain and Western Europe at a temperature several degrees higher than latitude alone might dictate.

And for years, oceanographers and climate scientists have been observing a slowing of the flow, by as much as 15%. But direct measurement of the great current began only relatively recently in 2004: researchers needed to know whether the slowdown was part of a natural cycle, or a consequence of climate change driven by global heating.

Now they know a little more. European researchers report in Nature Geoscience that they looked for evidence of ocean circulation shifts in what they call “proxy evidence”: the story of climate change told by tree growth rings, ice cores, ocean sediments, corals and historical records, including naval logbooks.

The combined evidence of temperature patterns, the sizes of particles of ocean floor sediment and the salinity and density of sub-surface water helps build up a picture of the Atlantic current for the last 1,600 years.

“The Gulf Stream System moves nearly 20 million cubic meters of water per second, almost a hundred times the Amazon flow”

The verdict? Up to the 19th century, ocean currents were stable. The flow is now more sluggish than at any time in the last millennium.

This is roughly what climate models have predicted: the warm salty water moves north, cools, becomes more dense, sinks to the deep and flows back south. But the Arctic has begun to warm, Greenland to melt, and the flow of fresh water into the northern seas to intensify.

Since the flow is driven by the difference in temperatures, any change in the regional thermometer will play back into the rate of flow. And any extra arrival of fresh water could further slow the overturning circulation.

“The Gulf Stream system works like a giant conveyor belt, carrying warm surface water from the equator up north, and sending cold, low-salinity deep water back down south. It moves nearly 20 million cubic meters of water per second, almost a hundred times the Amazon flow,” said Stefan Rahmstorf, of the Potsdam Institute for Climate Impact Research, in Germany, one of the authors.

“For the first time, we have combined a range of previous studies and found they provide a consistent picture of the AMOC evolution over the past 1600 years. The study results suggest that it has been relatively stable until the late 19th century.

“With the end of the Little Ice Age in about 1850, the ocean currents began to decline, with a second, more drastic decline following since the mid-20th century.”

Outcome awaited

The change could have ominous consequences for European weather systems: it could also deliver more intense coastal flooding to the US eastern seaboard. If the current continues to weaken, the consequences could be catastrophic.

Which is why a new study in Nature Communications matters so much. US researchers tracked the flow of fresh water from the Beaufort Sea − melt water from glaciers, rivers and disappearing Arctic sea ice − through the Canadian Archipelago and into the Labrador Sea.

Arctic water is fresher than Atlantic water, and richer in nutrients. But this extra volume, measured at a total of 23,300 cubic kilometres, could also affect the rate of flow of the overturning circulation. That is because relatively fresh water is less dense than saline water, and tends to float on top.

Quite what role it could play is uncertain: the message is that, sooner or later, it will escape into the North Atlantic. Then the world will find out.

“People have already spent a lot of time studying why the Beaufort Sea fresh water has gotten so high in the past few decades,” said Jiaxu Zhang,  of the Los Alamos National Laboratory, first author. “But they rarely care where the freshwater goes, and we think that’s a much more important problem.” − 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