Category Archives: Oceans

Ocean heat waves damage reefs and kill coral

Heat extremes on land can kill. Ocean heat waves can devastate coral reefs and other ecosystems – and these too are on the increase.

LONDON, 12 August, 2019 − Heat extremes on the high seas are on the increase, with ocean heat waves disturbing ecosystems in two hemispheres and two great oceans, US scientists report.

And these same sudden rises in sea temperatures don’t just damage coral reefs, they kill the corals and start the process of reef decay, according to a separate study by Australian researchers.

Andrew Pershing of the Gulf of Maine Research Institute and colleagues report in the Proceedings of the National Academy of Sciences that they examined data from 65 marine ecosystems over the years 1854 to 2018 to work out how frequently ocean temperatures suddenly rose to unexpected levels.

They found such deviations from the average in the Arctic, North Atlantic, eastern Pacific and off the Australian coasts. They expected to find evidence of occasional hot flushes. But they did not expect to find quite so many.

“Severe marine heatwave events can have a far more severe impact than coral bleaching – the animal dies and its underlying skeleton is all that remains”

“Across the 65 ecosystems we examined, we expected about six or seven of them would experience these ‘surprises’ each year,” Dr Pershing said. “Instead, we’ve seen an average of 12 ecosystems experiencing these warming events each year over the past seven years, including a high of 23 ‘surprises’ in 2016.”

Intense and sudden changes in sea temperatures affect crustaceans, algae, corals, molluscs and many millions of humans who depend on the oceans for income. And a new study by researchers from Australian universities reports that even a rise of 0.5°C is reflected in deaths during an outbreak of coral bleaching.

Corals live in symbiosis with algae: ocean warming periodically disturbs this normally beneficial relationship. The coral animals evert (turn out) the algae and once-lurid reefs will bleach, and become more vulnerable to disease.

Corals support the world’s richest ocean ecosystems so such changes are a challenge, both to the survival of biodiversity and to local incomes from the tourism linked to the beauty of the reefs.

Very warm water

“What we are seeing is that severe marine heatwave events can have a far more severe impact than coral bleaching: the water temperatures are so warm that that the coral animal doesn’t bleach – in terms of a loss of its symbiosis – the animal dies and its underlying skeleton is all that remains,” said Tracy Ainsworth of the University of New South Wales.

The researchers report in the journal Current Biology that they used computer tomography scanning techniques to explore the marine destruction. In 2016, more than 30% of the northern part of Australia’s Great Barrier Reef experienced temperatures higher than those in which corals can survive.

“We find that the skeleton is immediately overgrown by rapid growth of algae and bacteria,” said Bill Leggat of the University of Newcastle, a co-author.

“We show that this process is devastating not just for the animal tissue but also for the skeleton that is left behind, which is rapidly eroded and weakened.” − Climate News Network

Heat extremes on land can kill. Ocean heat waves can devastate coral reefs and other ecosystems – and these too are on the increase.

LONDON, 12 August, 2019 − Heat extremes on the high seas are on the increase, with ocean heat waves disturbing ecosystems in two hemispheres and two great oceans, US scientists report.

And these same sudden rises in sea temperatures don’t just damage coral reefs, they kill the corals and start the process of reef decay, according to a separate study by Australian researchers.

Andrew Pershing of the Gulf of Maine Research Institute and colleagues report in the Proceedings of the National Academy of Sciences that they examined data from 65 marine ecosystems over the years 1854 to 2018 to work out how frequently ocean temperatures suddenly rose to unexpected levels.

They found such deviations from the average in the Arctic, North Atlantic, eastern Pacific and off the Australian coasts. They expected to find evidence of occasional hot flushes. But they did not expect to find quite so many.

“Severe marine heatwave events can have a far more severe impact than coral bleaching – the animal dies and its underlying skeleton is all that remains”

“Across the 65 ecosystems we examined, we expected about six or seven of them would experience these ‘surprises’ each year,” Dr Pershing said. “Instead, we’ve seen an average of 12 ecosystems experiencing these warming events each year over the past seven years, including a high of 23 ‘surprises’ in 2016.”

Intense and sudden changes in sea temperatures affect crustaceans, algae, corals, molluscs and many millions of humans who depend on the oceans for income. And a new study by researchers from Australian universities reports that even a rise of 0.5°C is reflected in deaths during an outbreak of coral bleaching.

Corals live in symbiosis with algae: ocean warming periodically disturbs this normally beneficial relationship. The coral animals evert (turn out) the algae and once-lurid reefs will bleach, and become more vulnerable to disease.

Corals support the world’s richest ocean ecosystems so such changes are a challenge, both to the survival of biodiversity and to local incomes from the tourism linked to the beauty of the reefs.

Very warm water

“What we are seeing is that severe marine heatwave events can have a far more severe impact than coral bleaching: the water temperatures are so warm that that the coral animal doesn’t bleach – in terms of a loss of its symbiosis – the animal dies and its underlying skeleton is all that remains,” said Tracy Ainsworth of the University of New South Wales.

The researchers report in the journal Current Biology that they used computer tomography scanning techniques to explore the marine destruction. In 2016, more than 30% of the northern part of Australia’s Great Barrier Reef experienced temperatures higher than those in which corals can survive.

“We find that the skeleton is immediately overgrown by rapid growth of algae and bacteria,” said Bill Leggat of the University of Newcastle, a co-author.

“We show that this process is devastating not just for the animal tissue but also for the skeleton that is left behind, which is rapidly eroded and weakened.” − Climate News Network

Acid oceans may trigger mass extinction

A stable carbon cycle means life goes on. Too much carbon could wipe out many species. And acid oceans could hold the key.

LONDON, 23 July, 2019 − Catastrophically widespread die-offs of many creatures could be inevitable if human activities continue to lead to more acid oceans, a new study suggests.

Mass extinction may not be an enduring mystery. Instead, it may be an intrinsic property of the carbon cycle. Once levels of dissolved carbon dioxide in the oceans reach a certain threshold, life undergoes dramatic and catastrophic change.

If a US mathematician is right – and his argument is based on statistical reasoning and the evidence in the marine sediments – then once the seas become too acidic for marine organisms to form carbonate shells, a cascade of extinction begins.

And, he warns, the “unusually strong but geologically brief duration” of manmade carbon dioxide increase in the oceans can be matched with slow but devastating extinctions in the past.

In short, human combustion of fossil fuels, combined with the destruction of the forests, could be building up to extinctions on a scale so colossal that they will be visible in the fossil record hundreds of millions of years from now.

After a certain point, the carbon cycle will take over and decide life’s direction. It happened many times long before the emergence of the human species, and it could happen again, according to a new study in the  Proceedings of the National Academy of Sciences.

“It’s a positive feedback. More carbon dioxide leads to more carbon dioxide. Is such a feedback enough to render the system unstable?”

“Once we are over the threshold, how we got there may not matter,” said Daniel Rothman of the Massachusetts Institute of Technology. “Once you get over it, you’re dealing with how the Earth works, and it goes on its own ride.”

Professor Rothman developed his hypothesis in 2017, in the journal Science Advances, after he analysed 31 changes in the makeup of carbonate sediments laid down over the last 542 million years, and connected five great extinctions not just with carbon dioxide levels but with the rate at which these increased.

He may be for the moment a lone voice in linking four of the five major extinctions with critical levels of oceanic acidification as a consequence of a carbon dioxide threshold. But climate scientists and palaeontologists have been looking at possible links between carbon and extinction for decades.

They have also repeatedly warned that humans are about to precipitate a sixth mass extinction, chiefly on the basis that we are destroying natural habitat and erasing the conditions in which millions of species – many of them still not identified – were once able to flourish.

The carbon factor

But climate change driven by ever-increasing atmospheric carbon dioxide levels – powered in turn by ever-increasing combustion of fossil fuels – has also been a factor.

Whatever the risk to species or ecosystems, biologists and conservationists have warned that climate change driven by global heating can only make things worse.

And the more carefully researchers have looked at evidence of earlier catastrophic extinctions, the more bygone climate change has revealed itself. What caused the most dramatic and unequivocal of these – the “great dying” at the close of the Permian – is still hotly debated, but atmospheric conditions in one form or another have been repeatedly invoked and researchers have repeatedly drawn lessons for today.

But arguments so far have settled on whether such extinctions are a consequence of slow but inexorable episodes of volcanic discharge or some other geological shift.

Forget the trigger

Professor Rothman’s point is that the trigger itself may not be the important thing: what decides the fate of life on Earth is the level of carbon in the oceans and the rate at which it increases.

Once levels of acidification in the upper ocean reach a certain critical threshold, life is in for major disruption. If marine creatures cannot form shells, they are at risk. But even more dangerously, shells sink to the ocean floor, effectively removing carbon from circulation.

If there are fewer calcifying organisms, then less carbon dioxide is removed from the atmosphere and oceans become even more acidic. A vicious cycle has begun.

“It’s a positive feedback,” Professor Rothman said. “More carbon dioxide leads to more carbon dioxide. The question, from a mathematical point of view is, is such a feedback enough to render the system unstable?”

Balance restored

In his mathematical model, once carbon levels reached a critical threshold, a cascade of positive feedbacks amplified the effect. Severe ocean acidification set in.

The effect was not permanent. After tens of thousands of years, the carbon cycle did slip back to equilibrium and life could evolve and adapt again.

Carbon is now entering the oceans at an unprecedented rate, over what – in geological terms – is a very brief timespan. If human-triggered greenhouse gas emissions cross a critical threshold, the consequences could be as severe as any of the previous mass extinctions.

“It’s difficult to know how things will end up, given what is happening today,” he said. “But we are probably close to a critical threshold. Any spike would reach its maximum after about 10,000 years. Hopefully, that would give us time to find a solution.” − Climate News Network

A stable carbon cycle means life goes on. Too much carbon could wipe out many species. And acid oceans could hold the key.

LONDON, 23 July, 2019 − Catastrophically widespread die-offs of many creatures could be inevitable if human activities continue to lead to more acid oceans, a new study suggests.

Mass extinction may not be an enduring mystery. Instead, it may be an intrinsic property of the carbon cycle. Once levels of dissolved carbon dioxide in the oceans reach a certain threshold, life undergoes dramatic and catastrophic change.

If a US mathematician is right – and his argument is based on statistical reasoning and the evidence in the marine sediments – then once the seas become too acidic for marine organisms to form carbonate shells, a cascade of extinction begins.

And, he warns, the “unusually strong but geologically brief duration” of manmade carbon dioxide increase in the oceans can be matched with slow but devastating extinctions in the past.

In short, human combustion of fossil fuels, combined with the destruction of the forests, could be building up to extinctions on a scale so colossal that they will be visible in the fossil record hundreds of millions of years from now.

After a certain point, the carbon cycle will take over and decide life’s direction. It happened many times long before the emergence of the human species, and it could happen again, according to a new study in the  Proceedings of the National Academy of Sciences.

“It’s a positive feedback. More carbon dioxide leads to more carbon dioxide. Is such a feedback enough to render the system unstable?”

“Once we are over the threshold, how we got there may not matter,” said Daniel Rothman of the Massachusetts Institute of Technology. “Once you get over it, you’re dealing with how the Earth works, and it goes on its own ride.”

Professor Rothman developed his hypothesis in 2017, in the journal Science Advances, after he analysed 31 changes in the makeup of carbonate sediments laid down over the last 542 million years, and connected five great extinctions not just with carbon dioxide levels but with the rate at which these increased.

He may be for the moment a lone voice in linking four of the five major extinctions with critical levels of oceanic acidification as a consequence of a carbon dioxide threshold. But climate scientists and palaeontologists have been looking at possible links between carbon and extinction for decades.

They have also repeatedly warned that humans are about to precipitate a sixth mass extinction, chiefly on the basis that we are destroying natural habitat and erasing the conditions in which millions of species – many of them still not identified – were once able to flourish.

The carbon factor

But climate change driven by ever-increasing atmospheric carbon dioxide levels – powered in turn by ever-increasing combustion of fossil fuels – has also been a factor.

Whatever the risk to species or ecosystems, biologists and conservationists have warned that climate change driven by global heating can only make things worse.

And the more carefully researchers have looked at evidence of earlier catastrophic extinctions, the more bygone climate change has revealed itself. What caused the most dramatic and unequivocal of these – the “great dying” at the close of the Permian – is still hotly debated, but atmospheric conditions in one form or another have been repeatedly invoked and researchers have repeatedly drawn lessons for today.

But arguments so far have settled on whether such extinctions are a consequence of slow but inexorable episodes of volcanic discharge or some other geological shift.

Forget the trigger

Professor Rothman’s point is that the trigger itself may not be the important thing: what decides the fate of life on Earth is the level of carbon in the oceans and the rate at which it increases.

Once levels of acidification in the upper ocean reach a certain critical threshold, life is in for major disruption. If marine creatures cannot form shells, they are at risk. But even more dangerously, shells sink to the ocean floor, effectively removing carbon from circulation.

If there are fewer calcifying organisms, then less carbon dioxide is removed from the atmosphere and oceans become even more acidic. A vicious cycle has begun.

“It’s a positive feedback,” Professor Rothman said. “More carbon dioxide leads to more carbon dioxide. The question, from a mathematical point of view is, is such a feedback enough to render the system unstable?”

Balance restored

In his mathematical model, once carbon levels reached a critical threshold, a cascade of positive feedbacks amplified the effect. Severe ocean acidification set in.

The effect was not permanent. After tens of thousands of years, the carbon cycle did slip back to equilibrium and life could evolve and adapt again.

Carbon is now entering the oceans at an unprecedented rate, over what – in geological terms – is a very brief timespan. If human-triggered greenhouse gas emissions cross a critical threshold, the consequences could be as severe as any of the previous mass extinctions.

“It’s difficult to know how things will end up, given what is happening today,” he said. “But we are probably close to a critical threshold. Any spike would reach its maximum after about 10,000 years. Hopefully, that would give us time to find a solution.” − Climate News Network

Arctic sea ice loss affects the jet stream

The jet stream affects northern hemisphere climates. And global warming affects the behaviour of the jet stream. Prepare for yet more extremes of seasonal weather.

LONDON, 6 June, 2019 − Did you shiver in a winter ice storm? Could you wilt in a protracted heatwave this summer? German scientists have just identified the guilty agency and delivered the evidence implicating the jet stream.

Blame it on Arctic warming, they conclude: the retreat of the sea ice over the polar ocean has distorted the pattern of flow of the stratospheric winds usually known as the jet stream.

It is not a new idea. But this time, scientists have employed artificial intelligence and a machine-learning programme to accurately model the changes in the jet stream and then link these to changes in the chemistry of the upper atmosphere, and increasing patterns of twisting waves in the high altitude winds which then distort seasonal weather in the northern hemisphere mid-latitudes. They describe their research in the journal Scientific Reports.

“Our study shows that the changes in the jet stream are at least partly due to the loss of Arctic sea ice. If the ice cover continues to dwindle, we believe that both the frequency and intensity of the extreme weather events previously observed in the middle latitudes will increase,” said Markus Rex, who heads atmospheric research at the Alfred Wegener Institute in Potsdam, Germany.

Cold bouts explained

“In addition, our findings confirm that the more frequently occurring cold phases in winter in the USA, Europe and Asia are by no means a contradiction to global warming; rather they are part of anthropogenic climate change.”

The jet stream – exploited by jet aircraft on the trans-Atlantic routes – is made up of westerly winds that, at an altitude of 10 kilometres, stream around the planet in the mid-latitudes, at speeds of up to 500 km an hour, and push weather systems from west to east.

But researchers have already observed this: they have been changing, in response to global warming and in particular to the rapid warming of the Arctic, as greenhouse gas ratios in the atmosphere rise, and go on rising, in response to profligate human combustion of fossil fuels.

Rather than stick to a course more or less parallel to the Equator, these winds have been observed describing dramatic waves.

“If the ice cover continues to dwindle, we believe that both the frequency and intensity of the extreme weather events previously observed in the middle latitudes will increase”

These twists of direction have been linked to blasts of Arctic air into regions that could normally expect relatively mild winters: in particular to the ferocious cold that hit the US Midwest in January 2019.

These winds have also weakened and been linked to prolonged drought and extremes of heat that hit Europe in 2003, 2006, 2015 and 2018.

But association is not the same as demonstration of cause-and-effect. The Potsdam scientists wanted surer evidence. And their new climate simulations now include a machine-learning component that accounts for ozone chemistry at high altitudes.

And what their new model found was that as the Arctic sea ice retreats, the atmospheric waves have warmed the polar stratosphere in ways that have been amplified by the behaviour of the ozone layer.

Ozone response

Since what powers the jet stream is the difference between the cold Arctic and the warm tropics, the jet stream has weakened, and begun to meander, like a river flowing across a flood plain towards the sea.

In effect, the new study introduces a new piece to the climate puzzle: the response of the ozone layer and its role in the play of winds around the planet. The pay-off could be a clearer picture of things to come.

“We are now for the first time employing artificial intelligence in climate modelling, helping us arrive at more realistic model systems,” said Professor Rex.

“This holds tremendous potential for future climate models, which we believe will deliver more reliable climate projections and therefore a more robust basis for political decision-making.” − Climate News Network

The jet stream affects northern hemisphere climates. And global warming affects the behaviour of the jet stream. Prepare for yet more extremes of seasonal weather.

LONDON, 6 June, 2019 − Did you shiver in a winter ice storm? Could you wilt in a protracted heatwave this summer? German scientists have just identified the guilty agency and delivered the evidence implicating the jet stream.

Blame it on Arctic warming, they conclude: the retreat of the sea ice over the polar ocean has distorted the pattern of flow of the stratospheric winds usually known as the jet stream.

It is not a new idea. But this time, scientists have employed artificial intelligence and a machine-learning programme to accurately model the changes in the jet stream and then link these to changes in the chemistry of the upper atmosphere, and increasing patterns of twisting waves in the high altitude winds which then distort seasonal weather in the northern hemisphere mid-latitudes. They describe their research in the journal Scientific Reports.

“Our study shows that the changes in the jet stream are at least partly due to the loss of Arctic sea ice. If the ice cover continues to dwindle, we believe that both the frequency and intensity of the extreme weather events previously observed in the middle latitudes will increase,” said Markus Rex, who heads atmospheric research at the Alfred Wegener Institute in Potsdam, Germany.

Cold bouts explained

“In addition, our findings confirm that the more frequently occurring cold phases in winter in the USA, Europe and Asia are by no means a contradiction to global warming; rather they are part of anthropogenic climate change.”

The jet stream – exploited by jet aircraft on the trans-Atlantic routes – is made up of westerly winds that, at an altitude of 10 kilometres, stream around the planet in the mid-latitudes, at speeds of up to 500 km an hour, and push weather systems from west to east.

But researchers have already observed this: they have been changing, in response to global warming and in particular to the rapid warming of the Arctic, as greenhouse gas ratios in the atmosphere rise, and go on rising, in response to profligate human combustion of fossil fuels.

Rather than stick to a course more or less parallel to the Equator, these winds have been observed describing dramatic waves.

“If the ice cover continues to dwindle, we believe that both the frequency and intensity of the extreme weather events previously observed in the middle latitudes will increase”

These twists of direction have been linked to blasts of Arctic air into regions that could normally expect relatively mild winters: in particular to the ferocious cold that hit the US Midwest in January 2019.

These winds have also weakened and been linked to prolonged drought and extremes of heat that hit Europe in 2003, 2006, 2015 and 2018.

But association is not the same as demonstration of cause-and-effect. The Potsdam scientists wanted surer evidence. And their new climate simulations now include a machine-learning component that accounts for ozone chemistry at high altitudes.

And what their new model found was that as the Arctic sea ice retreats, the atmospheric waves have warmed the polar stratosphere in ways that have been amplified by the behaviour of the ozone layer.

Ozone response

Since what powers the jet stream is the difference between the cold Arctic and the warm tropics, the jet stream has weakened, and begun to meander, like a river flowing across a flood plain towards the sea.

In effect, the new study introduces a new piece to the climate puzzle: the response of the ozone layer and its role in the play of winds around the planet. The pay-off could be a clearer picture of things to come.

“We are now for the first time employing artificial intelligence in climate modelling, helping us arrive at more realistic model systems,” said Professor Rex.

“This holds tremendous potential for future climate models, which we believe will deliver more reliable climate projections and therefore a more robust basis for political decision-making.” − Climate News Network

Unstable polar glaciers lose ice ever faster

As oceans warm, Antarctica’s ice sheets are at growing risk, with polar glaciers losing ice at rates to match the height of global monuments.

LONDON, 31 May, 2019 – Almost a quarter of all the glaciers in West Antarctica have been pronounced “unstable”. This means, in the simplest terms, that they are losing ice to the ocean faster than they can gain it from falling snow.

In the last 25 years most of the largest flows have accelerated the loss of ice fivefold.

And in places some glaciers, including those known as Pine Island and Thwaites, have “thinned” by 122 metres. That means that the thickness of the ice between the surface and the bedrock over which glaciers flow has fallen by almost the height of the Great Pyramid of Cheops in Egypt, and far more than the Statue of Liberty in New York or the tower of Big Ben in London.

The conclusions are based on climate simulation matched against 800 million measurements of the Antarctic ice sheet recorded by the altimeters aboard four orbiting satellites put up by the European Space Agency between 1992 and 2017. The conclusion is published in the journal Geophysical Research Letters.

“A wave of thinning has spread rapidly across some of Antarctica’s most vulnerable glaciers, and their losses are driving up sea levels around the planet”

Antarctic research is challenging. The continent is enormous – nearly twice the size of Australia – and frozen: 99.4% of it is covered by ice, to huge depths. It is also defined as a desert.

Snowfalls are low, but over millions of years these have built up to a reservoir of about nine-tenths of the planet’s fresh water, in the form of snow and ice.

It is also the coldest place on Earth and – even more of a problem for climate scientists – no observations or measurements of anything in Antarctica date back much further than the beginning of the 19th century. Most of the on-the-ground science is possible only in the Antarctic summer.

The latest study confirms a succession of alarming finds. The West Antarctic ice sheet is not just losing ice, it is doing so at ever-faster speeds. Scientists have already suggested that the rate of loss for the Pine Island and Thwaites glaciers could be irreversible. So much has already been lost that the bedrock, crushed by its burden of ice for aeons, is actually beginning to bounce up in response.

Huge ice losses

“In parts of Antarctica the ice sheet has thinned by extraordinary amounts, and we set out to show how much was due to changes in climate and how much was due to weather,” said Andrew Shepherd of the University of Leeds, UK, who led the research.

Changes in snowfall tended, they found, to be reflected over changes in height over large areas for a few years. But the most pronounced changes have persisted for decades: it’s the climate that is changing things, not the weather.

“Knowing how much snow has fallen has really helped us to detect the underlying change in glacier ice within the satellite record. We can see clearly now that a wave of thinning has spread rapidly across some of Antarctica’s most vulnerable glaciers, and their losses are driving up sea levels around the planet”, Professor Shepherd says.

“Altogether, ice losses from East and West Antarctica have contributed 4.6mm to global sea level rise since 1992.” – Climate News Network

As oceans warm, Antarctica’s ice sheets are at growing risk, with polar glaciers losing ice at rates to match the height of global monuments.

LONDON, 31 May, 2019 – Almost a quarter of all the glaciers in West Antarctica have been pronounced “unstable”. This means, in the simplest terms, that they are losing ice to the ocean faster than they can gain it from falling snow.

In the last 25 years most of the largest flows have accelerated the loss of ice fivefold.

And in places some glaciers, including those known as Pine Island and Thwaites, have “thinned” by 122 metres. That means that the thickness of the ice between the surface and the bedrock over which glaciers flow has fallen by almost the height of the Great Pyramid of Cheops in Egypt, and far more than the Statue of Liberty in New York or the tower of Big Ben in London.

The conclusions are based on climate simulation matched against 800 million measurements of the Antarctic ice sheet recorded by the altimeters aboard four orbiting satellites put up by the European Space Agency between 1992 and 2017. The conclusion is published in the journal Geophysical Research Letters.

“A wave of thinning has spread rapidly across some of Antarctica’s most vulnerable glaciers, and their losses are driving up sea levels around the planet”

Antarctic research is challenging. The continent is enormous – nearly twice the size of Australia – and frozen: 99.4% of it is covered by ice, to huge depths. It is also defined as a desert.

Snowfalls are low, but over millions of years these have built up to a reservoir of about nine-tenths of the planet’s fresh water, in the form of snow and ice.

It is also the coldest place on Earth and – even more of a problem for climate scientists – no observations or measurements of anything in Antarctica date back much further than the beginning of the 19th century. Most of the on-the-ground science is possible only in the Antarctic summer.

The latest study confirms a succession of alarming finds. The West Antarctic ice sheet is not just losing ice, it is doing so at ever-faster speeds. Scientists have already suggested that the rate of loss for the Pine Island and Thwaites glaciers could be irreversible. So much has already been lost that the bedrock, crushed by its burden of ice for aeons, is actually beginning to bounce up in response.

Huge ice losses

“In parts of Antarctica the ice sheet has thinned by extraordinary amounts, and we set out to show how much was due to changes in climate and how much was due to weather,” said Andrew Shepherd of the University of Leeds, UK, who led the research.

Changes in snowfall tended, they found, to be reflected over changes in height over large areas for a few years. But the most pronounced changes have persisted for decades: it’s the climate that is changing things, not the weather.

“Knowing how much snow has fallen has really helped us to detect the underlying change in glacier ice within the satellite record. We can see clearly now that a wave of thinning has spread rapidly across some of Antarctica’s most vulnerable glaciers, and their losses are driving up sea levels around the planet”, Professor Shepherd says.

“Altogether, ice losses from East and West Antarctica have contributed 4.6mm to global sea level rise since 1992.” – Climate News Network

Sea level rise may double forecast for 2100

Scientists say global sea level rise could far exceed predictions because of faster melting in Greenland and Antarctica.

LONDON, 22 May, 2019 − If you are among the many millions of people who live near the world’s coasts, it will probably be worth your while to read this: sea level rise could be much greater than we expect.

A team of international scientists led by the University of Bristol, UK, has looked again at the estimates of how much the world’s oceans are likely to rise during this century. It concludes that the figure could be far higher than previous studies suggested.

In an extreme case, the members say, sea level rise over the next 80 years could mean that by 2100 the oceans will have risen by around six feet (two metres) − roughly twice the level thought likely till now, with “pretty unimaginable” consequences

In its fifth assessment report, published in 2013, the Intergovernmental Panel on Climate Change (IPCC) said the continued warming of the Earth, if there were no major reductions in greenhouse gas emissions, would see the seas rising by between 52cm and 98cm by 2100.

Sombre prospect

Many climate scientists have argued that this was a conservative estimate. The possibility that the eventual figure could be around double the forecast, threatening hundreds of millions of people with having to leave their homes, is sobering. It is published in the Proceedings of the National Academy of Sciences (PNAS).

The Bristol team used a different way of trying to gauge the possible effect of the way the ice is melting in Greenland, West and East Antarctica, not relying simply on projections from numerical models.

Their method used a technique called a structured expert judgement study, which involved 22 ice sheet experts in estimating plausible ranges for future sea level rise caused by the projected melting of the ice sheets in each of the three areas studied, under low and high future global temperature rise scenarios.

If emissions continue on their current path, the business-as-usual scenario, the researchers say, then the world’s seas would be very likely to rise by between 62cm and 238cm by 2100. This would be in a world that had warmed by around 5°C, one of the worst-case scenarios for global warming.

 

“I think that a 5% probability, crikey − I think that’s a serious risk. If we see something like that in the next 80 years we are looking at social breakdown on scales that are pretty unimaginable”

“For 2100, the ice sheet contribution is very likely in the range of 7-178cm but once you add in glaciers and ice caps outside the ice sheets and thermal expansion of the seas, you tip well over two metres,” said the lead author, Jonathan Bamber, of the University of Bristol.

He added: “Such a rise in global sea level could result in land loss of 1.79 million sq km, including critical regions of food production, and potential displacement of up to 187 million people.”

For temperature rises expected up to 2°C Greenland’s ice sheet makes the single biggest contribution to sea level rise. But as temperatures climb further the much larger Antarctic ice sheets become involved.

“When you start to look at these lower-likelihood but still plausible values, then the experts believe that there is a small but statistically significant probability that West Antarctica will transition to a very unstable state, and parts of East Antarctica will start contributing as well,” said Professor Bamber.

“But it’s only at these higher probabilities for 5°C that we see those types of behaviours kicking in.”

Mass exodus

Globally important food-growing areas such as the Nile delta would be liable to vanish beneath the waves, and large parts of Bangladesh. Major global cities including London, New York, Rio de Janeiro and Shanghai would face significant threats.

“To put this into perspective, the Syrian refugee crisis resulted in about a million refugees coming into Europe,” said Professor Bamber.

Polar science is making striking advances in understanding what is happening to the Greenland and Antarctic ice sheets. New satellite measurements are showing ice mass loss happening faster than models expected, and there is also something called the marine ice-cliff instability hypothesis, which assumes that coastal ice cliffs can rapidly collapse after ice shelves disintegrate, as a result of surface and sub-shelf melting caused by global warming.

Serious risk

The chances of sea level rise as devastating as this are small, the Bristol team say − about 5%. But they should be taken seriously.

“If I said to you that there was a one in 20 chance that if you crossed the road you would be squashed you wouldn’t go near it,” Professor Bamber said.

“Even a 1% probability means that a one in a hundred year flood is something that could happen in your lifetime. I think that a 5% probability, crikey − I think that’s a serious risk.

“If we see something like that in the next 80 years we are looking at social breakdown on scales that are pretty unimaginable.” − Climate News Network

Scientists say global sea level rise could far exceed predictions because of faster melting in Greenland and Antarctica.

LONDON, 22 May, 2019 − If you are among the many millions of people who live near the world’s coasts, it will probably be worth your while to read this: sea level rise could be much greater than we expect.

A team of international scientists led by the University of Bristol, UK, has looked again at the estimates of how much the world’s oceans are likely to rise during this century. It concludes that the figure could be far higher than previous studies suggested.

In an extreme case, the members say, sea level rise over the next 80 years could mean that by 2100 the oceans will have risen by around six feet (two metres) − roughly twice the level thought likely till now, with “pretty unimaginable” consequences

In its fifth assessment report, published in 2013, the Intergovernmental Panel on Climate Change (IPCC) said the continued warming of the Earth, if there were no major reductions in greenhouse gas emissions, would see the seas rising by between 52cm and 98cm by 2100.

Sombre prospect

Many climate scientists have argued that this was a conservative estimate. The possibility that the eventual figure could be around double the forecast, threatening hundreds of millions of people with having to leave their homes, is sobering. It is published in the Proceedings of the National Academy of Sciences (PNAS).

The Bristol team used a different way of trying to gauge the possible effect of the way the ice is melting in Greenland, West and East Antarctica, not relying simply on projections from numerical models.

Their method used a technique called a structured expert judgement study, which involved 22 ice sheet experts in estimating plausible ranges for future sea level rise caused by the projected melting of the ice sheets in each of the three areas studied, under low and high future global temperature rise scenarios.

If emissions continue on their current path, the business-as-usual scenario, the researchers say, then the world’s seas would be very likely to rise by between 62cm and 238cm by 2100. This would be in a world that had warmed by around 5°C, one of the worst-case scenarios for global warming.

 

“I think that a 5% probability, crikey − I think that’s a serious risk. If we see something like that in the next 80 years we are looking at social breakdown on scales that are pretty unimaginable”

“For 2100, the ice sheet contribution is very likely in the range of 7-178cm but once you add in glaciers and ice caps outside the ice sheets and thermal expansion of the seas, you tip well over two metres,” said the lead author, Jonathan Bamber, of the University of Bristol.

He added: “Such a rise in global sea level could result in land loss of 1.79 million sq km, including critical regions of food production, and potential displacement of up to 187 million people.”

For temperature rises expected up to 2°C Greenland’s ice sheet makes the single biggest contribution to sea level rise. But as temperatures climb further the much larger Antarctic ice sheets become involved.

“When you start to look at these lower-likelihood but still plausible values, then the experts believe that there is a small but statistically significant probability that West Antarctica will transition to a very unstable state, and parts of East Antarctica will start contributing as well,” said Professor Bamber.

“But it’s only at these higher probabilities for 5°C that we see those types of behaviours kicking in.”

Mass exodus

Globally important food-growing areas such as the Nile delta would be liable to vanish beneath the waves, and large parts of Bangladesh. Major global cities including London, New York, Rio de Janeiro and Shanghai would face significant threats.

“To put this into perspective, the Syrian refugee crisis resulted in about a million refugees coming into Europe,” said Professor Bamber.

Polar science is making striking advances in understanding what is happening to the Greenland and Antarctic ice sheets. New satellite measurements are showing ice mass loss happening faster than models expected, and there is also something called the marine ice-cliff instability hypothesis, which assumes that coastal ice cliffs can rapidly collapse after ice shelves disintegrate, as a result of surface and sub-shelf melting caused by global warming.

Serious risk

The chances of sea level rise as devastating as this are small, the Bristol team say − about 5%. But they should be taken seriously.

“If I said to you that there was a one in 20 chance that if you crossed the road you would be squashed you wouldn’t go near it,” Professor Bamber said.

“Even a 1% probability means that a one in a hundred year flood is something that could happen in your lifetime. I think that a 5% probability, crikey − I think that’s a serious risk.

“If we see something like that in the next 80 years we are looking at social breakdown on scales that are pretty unimaginable.” − Climate News Network

Marine microbes may fuel ocean warming

Warmer air means warmer seas, and marine microbes in warmer seas could mean yet warmer air. The climate cycle could get increasingly vicious.

LONDON, 6 May, 2019 − US scientists say marine microbes are the cause of yet another potentially positive feedback that could accelerate global warming.

As the oceans warm, marine microbial life might start to pump yet more carbon dioxide into the air. This process would of course increase the greenhouse gas levels still further and warm the oceans to increasing temperatures.

The finding is a reminder that the atmosphere, oceans, ice caps, rocks, algae, bacteria and forests are all intricate parts of the planetary climate machinery, and researchers still have a long way to go before they understand all the working parts in detail. But it is also a reminder that every small rise in planetary average temperatures in some way feeds back into this complex system.

The new study, based on analysis of data gathered during a research cruise in 2013 from Peru to Tahiti, is published in the Proceedings of the National Academy of Sciences.

“Warming will cause faster recycling of carbon in many areas, and that means less carbon will reach the deep ocean and get stored”

The shipboard scientists looked in depth at processes in highly productive waters off the South American coasts, and at the more or less barren waters south of the equator that cycle in a set of currents known as the South Pacific Gyre.

They did so to estimate the fate of tiny green plants – plankton – as they flourished in the ocean surface, and then perished and sank to the depths.

In the great and far-from-complete reckoning of the planet’s carbon budget – from atmosphere to plants to animals and back to the air, or to the rocks – climate scientists think that the oceans absorb around one fourth of all the extra carbon dioxide that humans burn as fossil fuels to power economic growth.

Plankton produce about 40 to 50 billion tonnes of organic carbon as they flourish, and then perish. Microbes set to work and begin the process of decay, recycling the carbon into the atmosphere. But somewhere between 8bn and 10bn tonnes of green tissue sink below 100 metres, into waters increasingly starved of oxygen, and decay stops.

Long sojourn

Once the dead plankton reach the ocean bottom, they could be there for centuries. More heat, however, could alter the balance of recycling and long-term storage.

“The results are telling us that warming will cause faster recycling of carbon in many areas, and that means less carbon will reach the deep ocean and get stored,” said Robert Anderson, of Columbia University’s Lamont-Doherty Earth Observatory, and one of the authors.

The fear is that as the oceans warm, the oxygen-low zones will increase and expand. That could suggest more long-term carbon burial. But as the surface waters warm, the microbial activity could accelerate, and release even more carbon into the atmosphere. In which case, the world would warm more swiftly.

Research like this is necessarily inconclusive: marine biologists have a lot more to do before they get a convincing answer to a global puzzle. Climate scientists started worrying about oxygen depletion in the oceans years ago, but they have been more bothered by evidence that in a warmer world microbial scavengers and recyclers work ever harder, and not just on land.

Positive feedbacks

As the polar ice retreats, there are more emissions of potent greenhouse gases from the tundra. And as high latitude ice and snow retreats, the levels of radiation back into space are reduced, while deep blue sea and brown rock absorb ever higher doses of sunlight.

All these are instances of positive feedback: planetary responses that seem overall to make climate change more likely, and climate extremes more hazardous. And the increasing evidence of oxygen depletion in the oceans provides no comfort: as the seas warm, less oxygen is available for the ocean’s animals: including of course the huge hauls of fish on which millions depend for income and nourishment.

As the scientists say, in the opaque language of a research journal: “Our findings imply that climate warming will result in reduced ocean carbon storage due to expanding oligotrophic gyres, but opposing effects on ocean carbon storage from expanding suboxic waters will require modelling and future work to disentangle.”

In other words, there is more research to be done. − Climate News Network

Warmer air means warmer seas, and marine microbes in warmer seas could mean yet warmer air. The climate cycle could get increasingly vicious.

LONDON, 6 May, 2019 − US scientists say marine microbes are the cause of yet another potentially positive feedback that could accelerate global warming.

As the oceans warm, marine microbial life might start to pump yet more carbon dioxide into the air. This process would of course increase the greenhouse gas levels still further and warm the oceans to increasing temperatures.

The finding is a reminder that the atmosphere, oceans, ice caps, rocks, algae, bacteria and forests are all intricate parts of the planetary climate machinery, and researchers still have a long way to go before they understand all the working parts in detail. But it is also a reminder that every small rise in planetary average temperatures in some way feeds back into this complex system.

The new study, based on analysis of data gathered during a research cruise in 2013 from Peru to Tahiti, is published in the Proceedings of the National Academy of Sciences.

“Warming will cause faster recycling of carbon in many areas, and that means less carbon will reach the deep ocean and get stored”

The shipboard scientists looked in depth at processes in highly productive waters off the South American coasts, and at the more or less barren waters south of the equator that cycle in a set of currents known as the South Pacific Gyre.

They did so to estimate the fate of tiny green plants – plankton – as they flourished in the ocean surface, and then perished and sank to the depths.

In the great and far-from-complete reckoning of the planet’s carbon budget – from atmosphere to plants to animals and back to the air, or to the rocks – climate scientists think that the oceans absorb around one fourth of all the extra carbon dioxide that humans burn as fossil fuels to power economic growth.

Plankton produce about 40 to 50 billion tonnes of organic carbon as they flourish, and then perish. Microbes set to work and begin the process of decay, recycling the carbon into the atmosphere. But somewhere between 8bn and 10bn tonnes of green tissue sink below 100 metres, into waters increasingly starved of oxygen, and decay stops.

Long sojourn

Once the dead plankton reach the ocean bottom, they could be there for centuries. More heat, however, could alter the balance of recycling and long-term storage.

“The results are telling us that warming will cause faster recycling of carbon in many areas, and that means less carbon will reach the deep ocean and get stored,” said Robert Anderson, of Columbia University’s Lamont-Doherty Earth Observatory, and one of the authors.

The fear is that as the oceans warm, the oxygen-low zones will increase and expand. That could suggest more long-term carbon burial. But as the surface waters warm, the microbial activity could accelerate, and release even more carbon into the atmosphere. In which case, the world would warm more swiftly.

Research like this is necessarily inconclusive: marine biologists have a lot more to do before they get a convincing answer to a global puzzle. Climate scientists started worrying about oxygen depletion in the oceans years ago, but they have been more bothered by evidence that in a warmer world microbial scavengers and recyclers work ever harder, and not just on land.

Positive feedbacks

As the polar ice retreats, there are more emissions of potent greenhouse gases from the tundra. And as high latitude ice and snow retreats, the levels of radiation back into space are reduced, while deep blue sea and brown rock absorb ever higher doses of sunlight.

All these are instances of positive feedback: planetary responses that seem overall to make climate change more likely, and climate extremes more hazardous. And the increasing evidence of oxygen depletion in the oceans provides no comfort: as the seas warm, less oxygen is available for the ocean’s animals: including of course the huge hauls of fish on which millions depend for income and nourishment.

As the scientists say, in the opaque language of a research journal: “Our findings imply that climate warming will result in reduced ocean carbon storage due to expanding oligotrophic gyres, but opposing effects on ocean carbon storage from expanding suboxic waters will require modelling and future work to disentangle.”

In other words, there is more research to be done. − Climate News Network

Heat makes ocean winds and waves fiercer

The seas are rising. Ocean winds and waves are growing in speed and force. The oceans could be feeling the heat.

LONDON, 1 May, 2019 − The great swells of the Pacific are beginning to swell even more as fiercer ocean winds and waves leave their mark. The breakers that crash on the storm beaches now do so with greater force. The white horses are gathering pace.

A 33-year-study of data from 31 satellites and 80 ocean buoys has confirmed suspicions. The extreme ocean winds are now fiercer, and the waves are getting measurably higher.

It is a given of global warming that as average planetary temperatures rise, then more energy is available for storm, rainfall and drought.

In the past century, because of ever-increasing combustion of fossil fuels that release growing quantities of greenhouse gases, average global temperatures have crept higher by 1°C and in three decades the speed of extreme winds in the Southern Ocean has increased by 8%, or 1.5 metres per second. Extreme waves have increased by 30cms, or 5%, over the same period.

“These changes have impacts that are felt all over the world. Storm waves can increase coastal erosion, putting coastal settlements and infrastructures at risk”

“Although increases of 5 and 8% might not seem like much, if sustained into the future such changes to our climate will have major impacts,” said Ian Young, an engineer at the University of Melbourne in Australia

He and a colleague report in the journal Science that they reached their conclusion on the basis of 4 billion observations made between 1985 and 2018.

“Flooding events are caused by storm surge and associated breaking waves. The increased sea level makes these events more serious and more frequent,” said Professor Young. “Increases in wave height, and changes in other properties such as wave direction, will further increase the probability of coastal flooding.”

Sea levels have been creeping ever higher, in large part because of the retreat of most of the planet’s great glaciers and the ever-increasing meltwater from Greenland and West Antarctica, and also as a simple matter of physics: as the oceans warm, the waters become less dense and sea levels rise.

Difficult measurements

Surfers and pleasure-seekers began to worry about the impact of global warming and climate change on wave patterns years ago. But seemingly simple phenomena such as the effects wave height and wind speed have in the open oceans on a world-wide basis are harder to measure.

Spanish oceanographers reported earlier this year that they were sure that ocean waves were gathering in force and strength, and European engineers have warned of the impact of more intense storms backed up by rising seas on the Atlantic ports and coastlines of the continent.

But there are problems: precision measurements have been made only recently. Oceanographers cannot be sure that they are not witnessing a natural cycle of ocean change, in which storm intensities slowly vary over a pattern of decades.

Since 1985 earth observation satellites have been equipped with altimeters to measure wave height and wind speed, radiometers to measure wind speed, and scatterometers to record wind speed and direction. The next problem has been calibrating data from a range of different satellites, and indeed the slightly different stories told by instruments on the same satellite.

Worse to come

But the Australian engineers report that they are now 90% confident that they can measure ocean change: violent storms now arrive with higher wave crests and more dangerous winds than they did in 1985, and although this is true worldwide, the effect is most pronounced in the great ocean that swirls around Antarctica.

The next challenge is to make estimates of how much more violent the worst sea storms are likely to become later in the century, as planetary average temperatures – and sea levels – continue to rise.

“These changes have impacts that are felt all over the world. Storm waves can increase coastal erosion, putting coastal settlements and infrastructures at risk,” Professor Young said.

“We need a better understanding of how much this change is due to long-term climate change, and how much is due to multi-decadal fluctuations or cycles.” − Climate News Network

The seas are rising. Ocean winds and waves are growing in speed and force. The oceans could be feeling the heat.

LONDON, 1 May, 2019 − The great swells of the Pacific are beginning to swell even more as fiercer ocean winds and waves leave their mark. The breakers that crash on the storm beaches now do so with greater force. The white horses are gathering pace.

A 33-year-study of data from 31 satellites and 80 ocean buoys has confirmed suspicions. The extreme ocean winds are now fiercer, and the waves are getting measurably higher.

It is a given of global warming that as average planetary temperatures rise, then more energy is available for storm, rainfall and drought.

In the past century, because of ever-increasing combustion of fossil fuels that release growing quantities of greenhouse gases, average global temperatures have crept higher by 1°C and in three decades the speed of extreme winds in the Southern Ocean has increased by 8%, or 1.5 metres per second. Extreme waves have increased by 30cms, or 5%, over the same period.

“These changes have impacts that are felt all over the world. Storm waves can increase coastal erosion, putting coastal settlements and infrastructures at risk”

“Although increases of 5 and 8% might not seem like much, if sustained into the future such changes to our climate will have major impacts,” said Ian Young, an engineer at the University of Melbourne in Australia

He and a colleague report in the journal Science that they reached their conclusion on the basis of 4 billion observations made between 1985 and 2018.

“Flooding events are caused by storm surge and associated breaking waves. The increased sea level makes these events more serious and more frequent,” said Professor Young. “Increases in wave height, and changes in other properties such as wave direction, will further increase the probability of coastal flooding.”

Sea levels have been creeping ever higher, in large part because of the retreat of most of the planet’s great glaciers and the ever-increasing meltwater from Greenland and West Antarctica, and also as a simple matter of physics: as the oceans warm, the waters become less dense and sea levels rise.

Difficult measurements

Surfers and pleasure-seekers began to worry about the impact of global warming and climate change on wave patterns years ago. But seemingly simple phenomena such as the effects wave height and wind speed have in the open oceans on a world-wide basis are harder to measure.

Spanish oceanographers reported earlier this year that they were sure that ocean waves were gathering in force and strength, and European engineers have warned of the impact of more intense storms backed up by rising seas on the Atlantic ports and coastlines of the continent.

But there are problems: precision measurements have been made only recently. Oceanographers cannot be sure that they are not witnessing a natural cycle of ocean change, in which storm intensities slowly vary over a pattern of decades.

Since 1985 earth observation satellites have been equipped with altimeters to measure wave height and wind speed, radiometers to measure wind speed, and scatterometers to record wind speed and direction. The next problem has been calibrating data from a range of different satellites, and indeed the slightly different stories told by instruments on the same satellite.

Worse to come

But the Australian engineers report that they are now 90% confident that they can measure ocean change: violent storms now arrive with higher wave crests and more dangerous winds than they did in 1985, and although this is true worldwide, the effect is most pronounced in the great ocean that swirls around Antarctica.

The next challenge is to make estimates of how much more violent the worst sea storms are likely to become later in the century, as planetary average temperatures – and sea levels – continue to rise.

“These changes have impacts that are felt all over the world. Storm waves can increase coastal erosion, putting coastal settlements and infrastructures at risk,” Professor Young said.

“We need a better understanding of how much this change is due to long-term climate change, and how much is due to multi-decadal fluctuations or cycles.” − Climate News Network

Cold-blooded sealife runs double heat risk

Extremes of heat are twice as risky for cold-blooded sealife as for other ectotherms. A hot rock could be safer than the deep sea.

LONDON, 29 April, 2019 – When it comes to global warming, there may no longer be plenty of fish in the sea: new research suggests that cold-blooded sealife may be twice as likely to be at risk in its natural habitat as land-dwelling ectotherms.

This finding is unexpected: the ocean is, in both area and volume, the single biggest living space on the planet. Fish that feel the heat can move towards the poles when temperatures get too high.

But when US researchers took a closer look at the data available on the thermal discomfort zones – those moments when cold-blooded creatures begin to overheat and need to find a safe, cool place in which to lie low – those spiders and lizards that survive in the tropics and temperate zones actually stand a better chance of finding somewhere to hide, and thus living through heatwaves, than their marine cousins.

“New conservation efforts will be needed if the ocean is going to continue supporting human well-being, nutrition and economic activity”

“We find that, globally, marine species are being eliminated from their habitats by warming temperatures twice as often as land species,” said Malin Pinsky, of Rutgers University in New Brunswick.

“The findings suggest that new conservation efforts will be needed if the ocean is going to continue supporting human well-being, nutrition and economic activity.”

He and colleagues report in the journal Nature that they searched the literature for detailed information on 400 species, and calculated the safe conditions for 88 marine and 294 land animals. They also identified the coolest temperatures available to each species during the hottest parts of the year.

More terrestrial refuges

And they found that, on average, fish and marine animals were more likely to live on the edge of temperatures that could become dangerously high. Land animals – insects and reptiles – could disappear into the forests, seek the shade or go underground: something sea creatures could not do.

That terrestrial reptiles and amphibians and marine animals are at risk is not news: researchers have already recorded significant movements of sea species in response to heat extremes off the Californian coast.

There has been repeated evidence that rising global temperature, as a consequence of greenhouse gas emissions from fossil fuel use, has begun to affect commercial fisheries, and other researchers have made it emphatically clear that only determined human action to contain global warming and protect breeding grounds can keep fish on the family supper table.

What most would not have expected was to find that land animals were less at risk, simply because they were land-dwellers.

Limited evidence

Research of this kind tends to deliver findings that can be challenged, and the authors concede that their conclusions are limited by the available evidence. Of 159 separate studies, 153 were in the northern hemisphere and 137 were from the temperate latitudes. Of their marine ectotherms, only 7% were pelagic: these are the fish – among them cod and tuna – that can swim to deeper, cooler layers when surface temperatures soar.

The remaining 93% included slow-moving bottom-dwellers such as lobsters, horseshoe crabs, abalone and snails, which may have nowhere left to go when life locally gets too hot to handle. The researchers make it clear that they are not talking about complete global extinctions of species: they choose the phrase “local extirpations”.

And they make it clear that land-dwelling cold-blooded animals are by no means safe from increasingly frequent, intense episodes of heat extremes driven by climate change: they would continue to be vulnerable to loss of what the researchers call “local refugia” – for example woodland cover – which “would make habitat fragmentation and changes in land use critical drivers of species loss on land.” – Climate News Network

Extremes of heat are twice as risky for cold-blooded sealife as for other ectotherms. A hot rock could be safer than the deep sea.

LONDON, 29 April, 2019 – When it comes to global warming, there may no longer be plenty of fish in the sea: new research suggests that cold-blooded sealife may be twice as likely to be at risk in its natural habitat as land-dwelling ectotherms.

This finding is unexpected: the ocean is, in both area and volume, the single biggest living space on the planet. Fish that feel the heat can move towards the poles when temperatures get too high.

But when US researchers took a closer look at the data available on the thermal discomfort zones – those moments when cold-blooded creatures begin to overheat and need to find a safe, cool place in which to lie low – those spiders and lizards that survive in the tropics and temperate zones actually stand a better chance of finding somewhere to hide, and thus living through heatwaves, than their marine cousins.

“New conservation efforts will be needed if the ocean is going to continue supporting human well-being, nutrition and economic activity”

“We find that, globally, marine species are being eliminated from their habitats by warming temperatures twice as often as land species,” said Malin Pinsky, of Rutgers University in New Brunswick.

“The findings suggest that new conservation efforts will be needed if the ocean is going to continue supporting human well-being, nutrition and economic activity.”

He and colleagues report in the journal Nature that they searched the literature for detailed information on 400 species, and calculated the safe conditions for 88 marine and 294 land animals. They also identified the coolest temperatures available to each species during the hottest parts of the year.

More terrestrial refuges

And they found that, on average, fish and marine animals were more likely to live on the edge of temperatures that could become dangerously high. Land animals – insects and reptiles – could disappear into the forests, seek the shade or go underground: something sea creatures could not do.

That terrestrial reptiles and amphibians and marine animals are at risk is not news: researchers have already recorded significant movements of sea species in response to heat extremes off the Californian coast.

There has been repeated evidence that rising global temperature, as a consequence of greenhouse gas emissions from fossil fuel use, has begun to affect commercial fisheries, and other researchers have made it emphatically clear that only determined human action to contain global warming and protect breeding grounds can keep fish on the family supper table.

What most would not have expected was to find that land animals were less at risk, simply because they were land-dwellers.

Limited evidence

Research of this kind tends to deliver findings that can be challenged, and the authors concede that their conclusions are limited by the available evidence. Of 159 separate studies, 153 were in the northern hemisphere and 137 were from the temperate latitudes. Of their marine ectotherms, only 7% were pelagic: these are the fish – among them cod and tuna – that can swim to deeper, cooler layers when surface temperatures soar.

The remaining 93% included slow-moving bottom-dwellers such as lobsters, horseshoe crabs, abalone and snails, which may have nowhere left to go when life locally gets too hot to handle. The researchers make it clear that they are not talking about complete global extinctions of species: they choose the phrase “local extirpations”.

And they make it clear that land-dwelling cold-blooded animals are by no means safe from increasingly frequent, intense episodes of heat extremes driven by climate change: they would continue to be vulnerable to loss of what the researchers call “local refugia” – for example woodland cover – which “would make habitat fragmentation and changes in land use critical drivers of species loss on land.” – Climate News Network

Fast Arctic melt could cost $70 trillion

Polar change, notably the fast Arctic melt, could impose huge costs on world economies. New evidence shows how rapidly the frozen north is changing.

LONDON, 26 April, 2019 – The northern reaches of the planet are undergoing very rapid change: the fast Arctic melt means the region is warming at twice the speed of the planetary average.

The loss of sea ice and land snow could tip the planet into a new and unprecedented cycle of climatic change and add yet another $70 trillion (£54 tn) to the estimated economic cost of global warming.

In yet another sombre statement of the challenge presented by climate change, driven by ever-increasing emissions of greenhouse gases from the fossil fuels that power the global economy, British, European and US researchers took a look at two manifestations of warming.

One is the growing levels of ancient carbon now being released into the atmosphere as the Arctic permafrost begins to melt. The other is the reduced reflection of solar radiation back into space as what had once been an expanse of snow and ice melts, to expose ever greater areas of light-absorbing blue sea, dark rock and scrubby tundra.

Abrupt surprises

The concern is with what the scientists like to call “non-linear transitions”. The fear is not that global warming will simply get more pronounced as more snow and ice disappears. The fear is that at some point the melting will reach a threshold that could tip the planet into a new climate regime that would be irreversible, and for which there has been no parallel in human history.

And if so, the costs in terms of climate disruption, heat waves, rising sea levels, harvest failures, more violent storms and more devastating floods and so on could start to soar.

The scientists report in the journal Nature Communications that if the nations of the world were to keep a promise made in Paris in 2015 to contain planetary warming to “well below” 2°C above the average for most of human history by the year 2100, the extra cost of Arctic ice loss would still tip $24 tn.

But on the evidence of national plans tabled so far, the world seems on course to hit 3°C by the century’s end, and the extra cost to the global economies is estimated at almost $70 tn.

“What we are witnessing is a major transport current faltering, which is bringing the world one step closer to a sea ice-free summer in the Arctic”

If the world goes on burning more and more fossil fuels – this is called the business-as-usual scenario – then global temperatures could rise to 4°C above the historic average by 2100. The bill for what the scientists call “the most expensive and least desirable scenario” is set at $2197 tn. And, they stress, their forecast $70 tn is just the extra cost of the melting Arctic.

They have not factored in all the other much-feared potential “tipping points” such as the loss of the tropical rainforests that absorb so much of the atmospheric carbon, the collapse of the great Atlantic current that distributes equatorial heat to temperate climates, the loss of the West Antarctic ice sheet, and other irreversible changes.

As they see it, even to contain global warming to 1.5°C by 2100 could cost a global $600 trillion.

And although the thawing of the permafrost and the opening of the Arctic Ocean would deliver mining and shipping opportunities, any such rewards would be dwarfed by the cost of the emissions from the thawing permafrost, and the reduction of what scientists call albedo: the reflectivity of pristine ice and snow that helps keep the Arctic frozen.

Model-based estimates

Research of this kind is based on vast numbers of simulations of the global economies under a range of scenarios, and the calculations of cost remain just that, estimates based on models of what nations might or might not do. The price economies must pay will be real enough, but the advanced accounting of what has yet to happen remains academic.

But the changes in the Arctic are far from academic, according to a series of new studies of what has been happening, and is happening right now.

●Researchers in California report in the Proceedings of the National Academy of Sciences that they have now reconstructed change in the Greenland ice sheet between 1972 and 2018, to estimate the loss of ice.

Fifty years ago, the northern hemisphere’s greatest sheet of ice was losing 47 billion tonnes of ice every year, and by the next decade 50 bn tonnes annually.

Sea levels raised

Since then the losses have risen almost six-fold, and since 2010 the island has been losing ice at the rate of 290 billion tonnes a year. So far, ice from Greenland alone has raised sea levels by almost 14 mm.

●German scientists have looked at the results of 15 years of observations by the Grace satellite system – the acronym stands for Gravity Recovery and Climate Experiment – which ended in 2018. They calculate that between April 2002 and June 2017, Greenland lost about 260 bn tonnes of ice each year, and Antarctica 140 bn tonnes.

They warn in the journal Nature Climate Change that melting at this rate could accelerate sea level rise to 10 mm a year – faster than at any time in the last 5,000 years – as a direct consequence of a warming climate.

●And the traffic of sea ice across the Arctic ocean has begun to falter, according to German oceanographers. The Transpolar Drift is a slow flow of new sea ice from the Siberian Arctic across the pole to the Fram Strait east of Greenland.

Melting too early

It has its place in the history of polar exploration: in 1893 the Norwegian explorer Fridtjof Nansen deliberately sailed his ship the Fram into the ice pack off Siberia and went with the floes across the Arctic.

The Drift is a kind of frozen ocean conveyor that carries nutrients, algae and sediments across the pole. But, researchers say in the journal Scientific Reports, this flow has started to vary. Most of the young ice off the Siberian coast now melts before it can leave its “nursery”. Once, half the ice from the Russian shelf completed the journey. Now, only one-fifth does.

“What we are witnessing is a major transport current faltering, which is bringing the world one step closer to a sea ice-free summer in the Arctic,” said Thomas Krumpen of the Alfred Wegener Institute, who led the study.

“The ice now leaving the Arctic through the Fram Strait is, on average, 30% thinner than it was 15 years ago.” – Climate News Network

Polar change, notably the fast Arctic melt, could impose huge costs on world economies. New evidence shows how rapidly the frozen north is changing.

LONDON, 26 April, 2019 – The northern reaches of the planet are undergoing very rapid change: the fast Arctic melt means the region is warming at twice the speed of the planetary average.

The loss of sea ice and land snow could tip the planet into a new and unprecedented cycle of climatic change and add yet another $70 trillion (£54 tn) to the estimated economic cost of global warming.

In yet another sombre statement of the challenge presented by climate change, driven by ever-increasing emissions of greenhouse gases from the fossil fuels that power the global economy, British, European and US researchers took a look at two manifestations of warming.

One is the growing levels of ancient carbon now being released into the atmosphere as the Arctic permafrost begins to melt. The other is the reduced reflection of solar radiation back into space as what had once been an expanse of snow and ice melts, to expose ever greater areas of light-absorbing blue sea, dark rock and scrubby tundra.

Abrupt surprises

The concern is with what the scientists like to call “non-linear transitions”. The fear is not that global warming will simply get more pronounced as more snow and ice disappears. The fear is that at some point the melting will reach a threshold that could tip the planet into a new climate regime that would be irreversible, and for which there has been no parallel in human history.

And if so, the costs in terms of climate disruption, heat waves, rising sea levels, harvest failures, more violent storms and more devastating floods and so on could start to soar.

The scientists report in the journal Nature Communications that if the nations of the world were to keep a promise made in Paris in 2015 to contain planetary warming to “well below” 2°C above the average for most of human history by the year 2100, the extra cost of Arctic ice loss would still tip $24 tn.

But on the evidence of national plans tabled so far, the world seems on course to hit 3°C by the century’s end, and the extra cost to the global economies is estimated at almost $70 tn.

“What we are witnessing is a major transport current faltering, which is bringing the world one step closer to a sea ice-free summer in the Arctic”

If the world goes on burning more and more fossil fuels – this is called the business-as-usual scenario – then global temperatures could rise to 4°C above the historic average by 2100. The bill for what the scientists call “the most expensive and least desirable scenario” is set at $2197 tn. And, they stress, their forecast $70 tn is just the extra cost of the melting Arctic.

They have not factored in all the other much-feared potential “tipping points” such as the loss of the tropical rainforests that absorb so much of the atmospheric carbon, the collapse of the great Atlantic current that distributes equatorial heat to temperate climates, the loss of the West Antarctic ice sheet, and other irreversible changes.

As they see it, even to contain global warming to 1.5°C by 2100 could cost a global $600 trillion.

And although the thawing of the permafrost and the opening of the Arctic Ocean would deliver mining and shipping opportunities, any such rewards would be dwarfed by the cost of the emissions from the thawing permafrost, and the reduction of what scientists call albedo: the reflectivity of pristine ice and snow that helps keep the Arctic frozen.

Model-based estimates

Research of this kind is based on vast numbers of simulations of the global economies under a range of scenarios, and the calculations of cost remain just that, estimates based on models of what nations might or might not do. The price economies must pay will be real enough, but the advanced accounting of what has yet to happen remains academic.

But the changes in the Arctic are far from academic, according to a series of new studies of what has been happening, and is happening right now.

●Researchers in California report in the Proceedings of the National Academy of Sciences that they have now reconstructed change in the Greenland ice sheet between 1972 and 2018, to estimate the loss of ice.

Fifty years ago, the northern hemisphere’s greatest sheet of ice was losing 47 billion tonnes of ice every year, and by the next decade 50 bn tonnes annually.

Sea levels raised

Since then the losses have risen almost six-fold, and since 2010 the island has been losing ice at the rate of 290 billion tonnes a year. So far, ice from Greenland alone has raised sea levels by almost 14 mm.

●German scientists have looked at the results of 15 years of observations by the Grace satellite system – the acronym stands for Gravity Recovery and Climate Experiment – which ended in 2018. They calculate that between April 2002 and June 2017, Greenland lost about 260 bn tonnes of ice each year, and Antarctica 140 bn tonnes.

They warn in the journal Nature Climate Change that melting at this rate could accelerate sea level rise to 10 mm a year – faster than at any time in the last 5,000 years – as a direct consequence of a warming climate.

●And the traffic of sea ice across the Arctic ocean has begun to falter, according to German oceanographers. The Transpolar Drift is a slow flow of new sea ice from the Siberian Arctic across the pole to the Fram Strait east of Greenland.

Melting too early

It has its place in the history of polar exploration: in 1893 the Norwegian explorer Fridtjof Nansen deliberately sailed his ship the Fram into the ice pack off Siberia and went with the floes across the Arctic.

The Drift is a kind of frozen ocean conveyor that carries nutrients, algae and sediments across the pole. But, researchers say in the journal Scientific Reports, this flow has started to vary. Most of the young ice off the Siberian coast now melts before it can leave its “nursery”. Once, half the ice from the Russian shelf completed the journey. Now, only one-fifth does.

“What we are witnessing is a major transport current faltering, which is bringing the world one step closer to a sea ice-free summer in the Arctic,” said Thomas Krumpen of the Alfred Wegener Institute, who led the study.

“The ice now leaving the Arctic through the Fram Strait is, on average, 30% thinner than it was 15 years ago.” – Climate News Network

Gulf Stream slowdown may bring later cold

The Gulf Stream is weakening, and Europe could expect a prolonged cold spell as the world warms – but not the day after tomorrow.

LONDON, 25 March, 2019 – As the Gulf Stream weakens in a rapidly warming world, north-western Europe could paradoxically become cooler. There is, however, a time lag between those two climate change-related events, and US scientists now think they know how long that could be.
It could be as much as 400 years.

They know this because the world has warmed and cooled before, and as the difference between tropics and Arctic narrows, there is a change in the so-called Atlantic conveyor, an important part of the climate machine.

This vast Atlantic current carries a steady flow of warm water to the far north, making north-western Europe up to 5°C warmer than its latitude would otherwise dictate. Then, as it meets colder, denser Arctic waters, it dives, to carry its burden of surface carbon to the depths, and then flows southwards again.

This phenomenon, known as the Atlantic Meridional Overturning Circulation, or AMOC, is in effect Europe’s bespoke heating system: Britain’s chief scientific adviser once calculated that it delivers to the UK alone the warmth of 27,000 power stations.

“There are some precursors in the ocean, so we should be watching the ocean”

But evidence from climate history shows that this heating has been turned off a number of times. Europe was plunged into a cold snap 13,000 years ago during a period known as the Younger Dryas and then warmed up about 11,000 years ago.

New and sophisticated studies of fossil carbon show that anybody taking notes at the time might have observed the warning signs. About 400 years before the abrupt shift to a frosty spell, the Atlantic current weakened. And it started to strengthen again about four centuries before the world warmed.

The study, published in the journal Nature Communications, confirms what climate scientists have always known: any sudden catastrophic return of the Ice Ages – dramatised in Hollywood’s notorious 2004 climate change movie The Day After Tomorrow – won’t happen at action movie pace. But it will happen over decades, and now seemingly with several centuries of advance notice.

“Our reconstructions indicate that there are clear climate precursors provided by the ocean state – like warning signs, so to speak,” said Francesco Muschitiello, then of the Lamont-Doherty Earth Observatory at Columbia University, US, and now at the University of Cambridge in the UK, who led the research.

Timing established

Climate scientists have clear dates for the timing of the Younger Dryas event: ice cores from the Arctic show both that Greenland’s temperature fell by 6°C or more at the beginning of the cycle, and that it rose by at least 8°C at its end.

To time the changes in the ocean current, they used carbon-dating techniques to identify a pattern of change in the marine sediments in the Norwegian Sea.

Since marine sediments settle very slowly, over very long periods of time, they needed a more precise “clock” to help calibrate their calculations: they found this in the fossilised ancient plants in a Scandinavian lake.

The isotope carbon-14 is pulled directly from the atmosphere each season by growing foliage. It decays at a predictable rate, and the amount of surviving C14 delivered a reliable clock. The identification of two volcanic ash layers from eruptions in Iceland, in both lake and seabed, provided yet more confidence in the timings. From these factors, the researchers were able to identify a slowdown in the transport of carbon from surface to the deep – and thus a slowdown in the current.

Long wait

The research confirms a link between ocean circulation patterns and northern hemisphere climate shifts: it provides evidence of what could be a considerable interval between the two.

Researchers have repeatedly warned that the Atlantic current seemed to be slowing, in response to global warming driven by profligate fossil fuel use by humankind, and that the consequences of continued slowdown could be very uncomfortable for hundreds of millions.

If the evidence from the Younger Dryas provides a sure parallel to today’s conditions, then Europeans might have time to prepare.

“It is clear that there are some precursors in the ocean, so we should be watching the ocean,” said Dr Muschitiello. “The mere fact that AMOC has been slowing down, that should be a concern based on what we have found.” – Climate News Network

The Gulf Stream is weakening, and Europe could expect a prolonged cold spell as the world warms – but not the day after tomorrow.

LONDON, 25 March, 2019 – As the Gulf Stream weakens in a rapidly warming world, north-western Europe could paradoxically become cooler. There is, however, a time lag between those two climate change-related events, and US scientists now think they know how long that could be.
It could be as much as 400 years.

They know this because the world has warmed and cooled before, and as the difference between tropics and Arctic narrows, there is a change in the so-called Atlantic conveyor, an important part of the climate machine.

This vast Atlantic current carries a steady flow of warm water to the far north, making north-western Europe up to 5°C warmer than its latitude would otherwise dictate. Then, as it meets colder, denser Arctic waters, it dives, to carry its burden of surface carbon to the depths, and then flows southwards again.

This phenomenon, known as the Atlantic Meridional Overturning Circulation, or AMOC, is in effect Europe’s bespoke heating system: Britain’s chief scientific adviser once calculated that it delivers to the UK alone the warmth of 27,000 power stations.

“There are some precursors in the ocean, so we should be watching the ocean”

But evidence from climate history shows that this heating has been turned off a number of times. Europe was plunged into a cold snap 13,000 years ago during a period known as the Younger Dryas and then warmed up about 11,000 years ago.

New and sophisticated studies of fossil carbon show that anybody taking notes at the time might have observed the warning signs. About 400 years before the abrupt shift to a frosty spell, the Atlantic current weakened. And it started to strengthen again about four centuries before the world warmed.

The study, published in the journal Nature Communications, confirms what climate scientists have always known: any sudden catastrophic return of the Ice Ages – dramatised in Hollywood’s notorious 2004 climate change movie The Day After Tomorrow – won’t happen at action movie pace. But it will happen over decades, and now seemingly with several centuries of advance notice.

“Our reconstructions indicate that there are clear climate precursors provided by the ocean state – like warning signs, so to speak,” said Francesco Muschitiello, then of the Lamont-Doherty Earth Observatory at Columbia University, US, and now at the University of Cambridge in the UK, who led the research.

Timing established

Climate scientists have clear dates for the timing of the Younger Dryas event: ice cores from the Arctic show both that Greenland’s temperature fell by 6°C or more at the beginning of the cycle, and that it rose by at least 8°C at its end.

To time the changes in the ocean current, they used carbon-dating techniques to identify a pattern of change in the marine sediments in the Norwegian Sea.

Since marine sediments settle very slowly, over very long periods of time, they needed a more precise “clock” to help calibrate their calculations: they found this in the fossilised ancient plants in a Scandinavian lake.

The isotope carbon-14 is pulled directly from the atmosphere each season by growing foliage. It decays at a predictable rate, and the amount of surviving C14 delivered a reliable clock. The identification of two volcanic ash layers from eruptions in Iceland, in both lake and seabed, provided yet more confidence in the timings. From these factors, the researchers were able to identify a slowdown in the transport of carbon from surface to the deep – and thus a slowdown in the current.

Long wait

The research confirms a link between ocean circulation patterns and northern hemisphere climate shifts: it provides evidence of what could be a considerable interval between the two.

Researchers have repeatedly warned that the Atlantic current seemed to be slowing, in response to global warming driven by profligate fossil fuel use by humankind, and that the consequences of continued slowdown could be very uncomfortable for hundreds of millions.

If the evidence from the Younger Dryas provides a sure parallel to today’s conditions, then Europeans might have time to prepare.

“It is clear that there are some precursors in the ocean, so we should be watching the ocean,” said Dr Muschitiello. “The mere fact that AMOC has been slowing down, that should be a concern based on what we have found.” – Climate News Network