Category Archives: Oceans

Warming seas cut marine mammals’ survival chances

Warmer waters force endangered whales to move into the danger zone to find food, and leave other marine mammals hungry.

LONDON, 13 September, 2021 − Thanks to climate change, things are going wrong for the right whale. As the Atlantic warms, one ocean giant has had to shift its feeding grounds − and into more dangerous unprotected waters. Other marine mammals will find it harder to survive.

Eubalaena glacialis, or the critically endangered North Atlantic right whale, may in the last decade have lost more than a quarter of its population. There could be only 356 individuals left.

And a second, separate study reports that, thanks to climate change, the future also looks lean for ringed seals and other Arctic marine predators: as greenhouse gas emissions continue to increase, and seas get warmer, the fish these mammals depend on will get smaller, and more scarce.

US scientists report in the journal Oceanography that, because of a shift in ocean temperatures in the Gulf of Maine − their traditional and protected habitat − the abundance of copepods or tiny crustaceans that nourish the giant mammals has fallen. This in turn has reduced the rates of calving, and forced the whales from their favourite mid-summer feeding grounds to the cooler waters of the Gulf of St Lawrence.

These new feeding grounds have no protection in place to prevent ship strikes, or entanglement in fishing gear. In 2017, biologists confirmed 17 right whale deaths in Canadian waters. Ten were found dead in 2019. In the last two years, there have been four identified deaths. The creature has a normal lifespan of about 70 years.

“We’ve never seen such drastic change so quickly. We’re rolling the dice, and we don’t know exactly what will happen”

The Gulf of Maine has been warming at depth, as ocean currents change in response to the climate emergency. The Atlantic Meridional Overturning Circulation, a part of the world climate powerhouse, could be changing, and with it the famous Gulf Stream that brings tropical waters into the North Atlantic.

That too has changed its trajectory in the last 10 years, and is now injecting warmer and saltier water into the Gulf of Maine, to alter the conditions that for most of human history provided food for the whales.

“Right whales continue to die each year,” said Erin Meyer-Gutbrod of the University of South Carolina, who led the study. “Protective policies must be strengthened immediately before this species declines past the point of no return.”

As the seas warm, the Artic ice retreats. The Arctic cod may be on the move, which is bad news not just for fishermen but for the seals and other creatures that depend on a rich energy source to maintain population numbers.

Smaller fish predominating

Canadian scientists report in the journal Ecology Letters that changes in the makeup, size and distribution of fish in Hudson Bay will begin to accelerate after 2025 and become rapidly more extreme unless humans drastically limit fossil fuel combustion.

And that would be bad news for the ringed seal, Phoca hispida: it would be left with a meaner food source. “We found that, by the end of the century, the large fatty Arctic cod may decline dramatically in terms of biomass and distribution.

“Then smaller fish like capelin and sand lance may become much more prevalent”, said Katie Florko, of the University of British Columbia, lead author. Warmer temperatures tend to favour smaller individuals. Arctic cod could shrink by up to 35%; they will also tend to move further north.

“It costs energy to forage. Does that mean the seals will need to spend more energy to get a larger number of these smaller fish for the same amount of energy as capturing a bigger fish?”

Her co-author Travis Tai, of the Pacific Climate Impacts Consortium, said: “We’ve never seen such drastic change so quickly. We’re rolling the dice, and we don’t know exactly what will happen. When we have dramatic shifts in food web structure, we can expect large changes not only to how species such as ringed seals use the oceans, but also how people use the oceans.” − Climate News Network

Warmer waters force endangered whales to move into the danger zone to find food, and leave other marine mammals hungry.

LONDON, 13 September, 2021 − Thanks to climate change, things are going wrong for the right whale. As the Atlantic warms, one ocean giant has had to shift its feeding grounds − and into more dangerous unprotected waters. Other marine mammals will find it harder to survive.

Eubalaena glacialis, or the critically endangered North Atlantic right whale, may in the last decade have lost more than a quarter of its population. There could be only 356 individuals left.

And a second, separate study reports that, thanks to climate change, the future also looks lean for ringed seals and other Arctic marine predators: as greenhouse gas emissions continue to increase, and seas get warmer, the fish these mammals depend on will get smaller, and more scarce.

US scientists report in the journal Oceanography that, because of a shift in ocean temperatures in the Gulf of Maine − their traditional and protected habitat − the abundance of copepods or tiny crustaceans that nourish the giant mammals has fallen. This in turn has reduced the rates of calving, and forced the whales from their favourite mid-summer feeding grounds to the cooler waters of the Gulf of St Lawrence.

These new feeding grounds have no protection in place to prevent ship strikes, or entanglement in fishing gear. In 2017, biologists confirmed 17 right whale deaths in Canadian waters. Ten were found dead in 2019. In the last two years, there have been four identified deaths. The creature has a normal lifespan of about 70 years.

“We’ve never seen such drastic change so quickly. We’re rolling the dice, and we don’t know exactly what will happen”

The Gulf of Maine has been warming at depth, as ocean currents change in response to the climate emergency. The Atlantic Meridional Overturning Circulation, a part of the world climate powerhouse, could be changing, and with it the famous Gulf Stream that brings tropical waters into the North Atlantic.

That too has changed its trajectory in the last 10 years, and is now injecting warmer and saltier water into the Gulf of Maine, to alter the conditions that for most of human history provided food for the whales.

“Right whales continue to die each year,” said Erin Meyer-Gutbrod of the University of South Carolina, who led the study. “Protective policies must be strengthened immediately before this species declines past the point of no return.”

As the seas warm, the Artic ice retreats. The Arctic cod may be on the move, which is bad news not just for fishermen but for the seals and other creatures that depend on a rich energy source to maintain population numbers.

Smaller fish predominating

Canadian scientists report in the journal Ecology Letters that changes in the makeup, size and distribution of fish in Hudson Bay will begin to accelerate after 2025 and become rapidly more extreme unless humans drastically limit fossil fuel combustion.

And that would be bad news for the ringed seal, Phoca hispida: it would be left with a meaner food source. “We found that, by the end of the century, the large fatty Arctic cod may decline dramatically in terms of biomass and distribution.

“Then smaller fish like capelin and sand lance may become much more prevalent”, said Katie Florko, of the University of British Columbia, lead author. Warmer temperatures tend to favour smaller individuals. Arctic cod could shrink by up to 35%; they will also tend to move further north.

“It costs energy to forage. Does that mean the seals will need to spend more energy to get a larger number of these smaller fish for the same amount of energy as capturing a bigger fish?”

Her co-author Travis Tai, of the Pacific Climate Impacts Consortium, said: “We’ve never seen such drastic change so quickly. We’re rolling the dice, and we don’t know exactly what will happen. When we have dramatic shifts in food web structure, we can expect large changes not only to how species such as ringed seals use the oceans, but also how people use the oceans.” − Climate News Network

Extreme sea levels could soon become annual events

Extreme sea levels are inevitable. Researchers now know more about their scale. Prepare for high tides almost every year.

LONDON, 8 September, 2021 − Those who live by the sea could soon enough be at risk from it. Extreme sea levels − those episodes of high tide, storm surge and coastal flood − that now happen only once in every century could within a lifetime be happening every year.

And this is increasingly likely even if nations act on promises made six years ago and make drastic reductions in fossil fuel use. The global warming already inevitable because of the last decades of greenhouse gas emissions makes frequent flooding ever more likely.

US, European and Australian researchers report in the journal Nature Climate Change that they used computer projections to model what would be likely to happen to sea levels at 7,283 coastal locations worldwide over the next 70 years, under a range of scenarios that saw global temperatures rise to between 1.5°C and 5°C.

The bad news is that at least half of them face a massive increase in the frequency of extreme episodes by 2070.

“How much warming will it take to make a 100-year event an annual event? Not much more than what has already been documented”

The most vulnerable regions will be in the tropics and subtropics, including the Mediterranean Sea, the Arabian Peninsula, the southern part of North America’s Pacific Coast, Hawaii and the Caribbean, the Philippines, Indonesia and much of the southern hemisphere.

“One of our central questions driving this study was this: how much warming will it take to make what has been known as a 100-year event an annual event? Our answer is, not much more than what has already been documented,” said Claudia Tebaldi, of the Pacific Northwest National Laboratory in the US.

In the last century, the world has warmed by at least one degree Celsius above the average for most of human history: in 2015, in Paris, 195 nations vowed to contain global temperature rise to “well below” 2°C by 2100, and ideally to no more than 1.5°C. That promise has yet to be backed up by concerted, dramatic international action.

In fact, the planet could surpass the 1.5°C limit, at least temporarily, some time this decade. Within 70 years, at present rates of emissions, the world will be committed to a potentially catastrophic global average rise of 3°C.

Warmth in store

And, researchers have warned, and warned again, coastal flooding could reach devastating levels. So the latest study simply confirms an alarming future, and adds a little more certainty to the zones more at risk.

The research is also a reminder that although drastic cuts and a concerted effort to restore the natural world could limit the rise in global air temperatures, the world’s oceans are subject to a slower timetable: the warming that has already happened will increasingly be reflected in tide levels for decades to come.

Like all such projections, the potential outcome ranges from optimistic to very pessimistic. With a temperature rise of just 1.5°C, seven-tenths of the studied locations might experience little increase in flood frequency. At the gloomier end of the spectrum, 99% could see flooding multiply 100-fold.

“It’s not huge news that sea level rise will be dramatic even at 1.5°C and will have substantial effects on extreme sea level frequencies and magnitude,” Dr Tebaldi said. “This study gives a more complete picture around the globe. We were able to look at a wider range of warming levels in fine spatial detail.” − Climate News Network

Extreme sea levels are inevitable. Researchers now know more about their scale. Prepare for high tides almost every year.

LONDON, 8 September, 2021 − Those who live by the sea could soon enough be at risk from it. Extreme sea levels − those episodes of high tide, storm surge and coastal flood − that now happen only once in every century could within a lifetime be happening every year.

And this is increasingly likely even if nations act on promises made six years ago and make drastic reductions in fossil fuel use. The global warming already inevitable because of the last decades of greenhouse gas emissions makes frequent flooding ever more likely.

US, European and Australian researchers report in the journal Nature Climate Change that they used computer projections to model what would be likely to happen to sea levels at 7,283 coastal locations worldwide over the next 70 years, under a range of scenarios that saw global temperatures rise to between 1.5°C and 5°C.

The bad news is that at least half of them face a massive increase in the frequency of extreme episodes by 2070.

“How much warming will it take to make a 100-year event an annual event? Not much more than what has already been documented”

The most vulnerable regions will be in the tropics and subtropics, including the Mediterranean Sea, the Arabian Peninsula, the southern part of North America’s Pacific Coast, Hawaii and the Caribbean, the Philippines, Indonesia and much of the southern hemisphere.

“One of our central questions driving this study was this: how much warming will it take to make what has been known as a 100-year event an annual event? Our answer is, not much more than what has already been documented,” said Claudia Tebaldi, of the Pacific Northwest National Laboratory in the US.

In the last century, the world has warmed by at least one degree Celsius above the average for most of human history: in 2015, in Paris, 195 nations vowed to contain global temperature rise to “well below” 2°C by 2100, and ideally to no more than 1.5°C. That promise has yet to be backed up by concerted, dramatic international action.

In fact, the planet could surpass the 1.5°C limit, at least temporarily, some time this decade. Within 70 years, at present rates of emissions, the world will be committed to a potentially catastrophic global average rise of 3°C.

Warmth in store

And, researchers have warned, and warned again, coastal flooding could reach devastating levels. So the latest study simply confirms an alarming future, and adds a little more certainty to the zones more at risk.

The research is also a reminder that although drastic cuts and a concerted effort to restore the natural world could limit the rise in global air temperatures, the world’s oceans are subject to a slower timetable: the warming that has already happened will increasingly be reflected in tide levels for decades to come.

Like all such projections, the potential outcome ranges from optimistic to very pessimistic. With a temperature rise of just 1.5°C, seven-tenths of the studied locations might experience little increase in flood frequency. At the gloomier end of the spectrum, 99% could see flooding multiply 100-fold.

“It’s not huge news that sea level rise will be dramatic even at 1.5°C and will have substantial effects on extreme sea level frequencies and magnitude,” Dr Tebaldi said. “This study gives a more complete picture around the globe. We were able to look at a wider range of warming levels in fine spatial detail.” − Climate News Network

Unknown waters ahead puzzle marine modellers

Climate change will alter the blue planet on an almost global scale. Marine life will change in the unknown waters ahead.

LONDON, 3 September, 2021 − By the close of this century, the world’s mariners may be sailing over unknown waters. Up to 95% of the ocean surface climates that Charles Darwin voyaged in the Beagle in the 19th century, and that became part of the global battleground during the wars of the 20th century, will have vanished.

And some − perhaps most − of these climates will be of a kind that have no precedent in human history, or prehistory.

Quite how sharply those familiar waters will disappear depends on what happens to global greenhouse emissions. But at the rates at which humans have been burning fossil fuels so far, somewhere between 35% and almost all the sea surface conditions will have changed, and so will the marine ecosystems that depend upon those conditions.

What happens to the algae and plankton, the pelagic fish and the predators that hunt them, is increasingly difficult to guess: another study has just concluded that even after more than a century of oceanography and marine biological research, humans still don’t know enough about how ocean ecosystems work to be able to be sure of the future.

US researchers write in the journal Scientific Reports that they looked at measurements that define marine surface climate: water temperature, the concentration of dissolved carbon dioxide that defines its pH value on the acid-alkaline chemical spectrum, and the water’s saturation with aragonite, a form of dissolved calcium carbonate, washed over the aeons by the rivers into the sea.

Telling comparisons

Put simply, as greenhouse gas emissions rise, so the oceans become both warmer and more acidic, and the saturation level of aragonite falls. And as this level falls, corals and other marine creatures find it harder to turn sea water into the shell structures that protect them.

The researchers report that they modelled the ocean climates for the years 1795 to 1834 − the years of Coleridge’s poem Rime of the Ancient Mariner, and of the British Royal Navy’s command of the high seas − and for the years 1963 to 2004, the years of the aircraft carrier and supertanker.

Then they compared their findings with what ocean surfaces will look like if carbon emissions peak in 2050, or − this is sometimes called the “business-as-usual” scenario − in 2100.

Under the first scenario, 35.6% of sea surface climates familiar for the last two centuries may have disappeared. Under the second, 95% will have gone, to be replaced by what the authors call ”novel climates.” And, they say in the constrained syntax of academic language, “the degree of global climate novelty at a location may … indicate how stressful novel conditions will be for all species.

“In contrast, the degree of global climate disappearance for a location may represent how hard it might be for species who are well-adapted to climate at that location to find a similar climate in the future.”

“Attempting to summarise the vast complexity of the global marine ecosystem in a handful of equations is enormously difficult”

That the marine world is changing is no surprise: scientists have reported again and again that once-valuable species are migrating, or growing smaller, or dwindling in number.

As temperatures rise, oxygen levels drop, leaving some species gasping. As breeding grounds warm, spawning becomes problematic. So researchers can see what is already happening. It’s much harder to guess what the oceans will be like decades from now.

And in a timely study in the journal Progress in Oceanography, a team from Australia, the US, Canada and Europe issues a similar warning: humans are about to voyage into unknown waters.

Global heating is already driving what they call “significant changes in the structure of marine ecosystems” worldwide. That is, the tiny creatures on which bigger fish ultimately depend will change. And that could be bad news for the millions of people who live by the sea, and seafood.

But, they warn, it is becoming difficult to calculate how the denizens of the deep, and the citizens of the shallows, will respond to ocean climate shifts. There is a lot more research to be done, and some complex mathematical challenges ahead.

Food supplies lessen

“We know the impact of climate change on both water temperature and primary production will alter marine ecosystems in fundamental ways. Fish and other marine animals will burn more energy in warmer waters, leaving less scope for growth and reproduction.

“At the same time, in regions where primary production from phytoplankton decreases there will be less food, which will drive marine biomass down further,” said Ryan Heneghan of Queensland University of Technology in Australia, who led the study.

“Between now and 2100, the change in global marine animal biomass across our models varied between a 30% decline and a small increase of 5%. Across all the models, there were biomass declines across most of the world’s oceans, but the models disagreed on where, why and by how much marine biomass would decline under climate change,” he said.

“Attempting to summarise the vast complexity of the global marine ecosystem in a handful of equations is enormously difficult, and global marine ecosystem modelling is a relatively new field of research; our oldest models are just over 10 years old, whereas the climate modelling community were developing their first models over 40 years ago. There is a lot of work to do.” − Climate News Network

Climate change will alter the blue planet on an almost global scale. Marine life will change in the unknown waters ahead.

LONDON, 3 September, 2021 − By the close of this century, the world’s mariners may be sailing over unknown waters. Up to 95% of the ocean surface climates that Charles Darwin voyaged in the Beagle in the 19th century, and that became part of the global battleground during the wars of the 20th century, will have vanished.

And some − perhaps most − of these climates will be of a kind that have no precedent in human history, or prehistory.

Quite how sharply those familiar waters will disappear depends on what happens to global greenhouse emissions. But at the rates at which humans have been burning fossil fuels so far, somewhere between 35% and almost all the sea surface conditions will have changed, and so will the marine ecosystems that depend upon those conditions.

What happens to the algae and plankton, the pelagic fish and the predators that hunt them, is increasingly difficult to guess: another study has just concluded that even after more than a century of oceanography and marine biological research, humans still don’t know enough about how ocean ecosystems work to be able to be sure of the future.

US researchers write in the journal Scientific Reports that they looked at measurements that define marine surface climate: water temperature, the concentration of dissolved carbon dioxide that defines its pH value on the acid-alkaline chemical spectrum, and the water’s saturation with aragonite, a form of dissolved calcium carbonate, washed over the aeons by the rivers into the sea.

Telling comparisons

Put simply, as greenhouse gas emissions rise, so the oceans become both warmer and more acidic, and the saturation level of aragonite falls. And as this level falls, corals and other marine creatures find it harder to turn sea water into the shell structures that protect them.

The researchers report that they modelled the ocean climates for the years 1795 to 1834 − the years of Coleridge’s poem Rime of the Ancient Mariner, and of the British Royal Navy’s command of the high seas − and for the years 1963 to 2004, the years of the aircraft carrier and supertanker.

Then they compared their findings with what ocean surfaces will look like if carbon emissions peak in 2050, or − this is sometimes called the “business-as-usual” scenario − in 2100.

Under the first scenario, 35.6% of sea surface climates familiar for the last two centuries may have disappeared. Under the second, 95% will have gone, to be replaced by what the authors call ”novel climates.” And, they say in the constrained syntax of academic language, “the degree of global climate novelty at a location may … indicate how stressful novel conditions will be for all species.

“In contrast, the degree of global climate disappearance for a location may represent how hard it might be for species who are well-adapted to climate at that location to find a similar climate in the future.”

“Attempting to summarise the vast complexity of the global marine ecosystem in a handful of equations is enormously difficult”

That the marine world is changing is no surprise: scientists have reported again and again that once-valuable species are migrating, or growing smaller, or dwindling in number.

As temperatures rise, oxygen levels drop, leaving some species gasping. As breeding grounds warm, spawning becomes problematic. So researchers can see what is already happening. It’s much harder to guess what the oceans will be like decades from now.

And in a timely study in the journal Progress in Oceanography, a team from Australia, the US, Canada and Europe issues a similar warning: humans are about to voyage into unknown waters.

Global heating is already driving what they call “significant changes in the structure of marine ecosystems” worldwide. That is, the tiny creatures on which bigger fish ultimately depend will change. And that could be bad news for the millions of people who live by the sea, and seafood.

But, they warn, it is becoming difficult to calculate how the denizens of the deep, and the citizens of the shallows, will respond to ocean climate shifts. There is a lot more research to be done, and some complex mathematical challenges ahead.

Food supplies lessen

“We know the impact of climate change on both water temperature and primary production will alter marine ecosystems in fundamental ways. Fish and other marine animals will burn more energy in warmer waters, leaving less scope for growth and reproduction.

“At the same time, in regions where primary production from phytoplankton decreases there will be less food, which will drive marine biomass down further,” said Ryan Heneghan of Queensland University of Technology in Australia, who led the study.

“Between now and 2100, the change in global marine animal biomass across our models varied between a 30% decline and a small increase of 5%. Across all the models, there were biomass declines across most of the world’s oceans, but the models disagreed on where, why and by how much marine biomass would decline under climate change,” he said.

“Attempting to summarise the vast complexity of the global marine ecosystem in a handful of equations is enormously difficult, and global marine ecosystem modelling is a relatively new field of research; our oldest models are just over 10 years old, whereas the climate modelling community were developing their first models over 40 years ago. There is a lot of work to do.” − Climate News Network

Hotter water leaves smaller and less mobile fish

The catch with warming oceans is that there’ll be less of a catch. Smaller and less mobile fish will leave less to eat.

LONDON, 18 August, 2021 − Climate change could be about to get the world’s tastiest fish into hot water. The double jeopardy of global heating and overfishing could already be resulting in smaller and less mobile fish, turning sardines and herring, anchovies and pilchards into ever-smaller servings.

It has happened before: a new study of the evolution of fish species over the past 150 million years has found clear evidence of the ups and downs of time: as the ocean temperatures rise, fish tend to get smaller and travel less.

“Warming waters are a double whammy for fish, as they not only cause them to evolve to a smaller size, but also reduce their ability to move to more suitable environments,” said Chris Venditti, of the University of Reading, UK.

“Our research supports the theory that fish will get smaller as oceans warm under climate change, but reveals the worrying news that they will also not be able to evolve to cope as efficiently as first thought.

“This has serious implications for all fish and our food security”

“With sea temperatures rising faster than ever, fish will very quickly get left behind in evolutionary terms and struggle to survive.”

Professor Venditti and colleagues in Chile and Peru report in the journal Nature Climate Change that they applied subtle statistical techniques to evidence of fish evolution amassed in an international database called The Fish Tree of Life to learn about the link between temperature and size in one seafaring order, the Clupeiforms.

This group embraces both Atlantic and Pacific herring, the Japanese and South American pilchard, the anchovy and so on. But what is true for one order is likely to be true for almost all fish: warmer oceans mean more stress.

And stress is on the way. Over the last 150 million years, fish have had to adjust to changing temperatures, but only at rates of around 0.8°C per thousand years. Since 1981, according to the US National Oceanic and Atmospheric Administration, the seas have been warming at 0.18°C per decade.

Evolution at risk

So the finding supports what biologists already know: that animals confronted with higher temperatures tend to evolve to smaller sizes.

It’s not as if fish were not already feeling the heat. As waters warm, their capacity for dissolved oxygen dwindles. Spawning becomes more problematic. Migration becomes more urgent, but for smaller creatures with lower energy reserves also more difficult.

In the world’s traditional fishing grounds, overall catch sizes are shrinking: so too are the sizes of individual fish. And, the latest research suggests, warming waters could limit the capacity to evolve to new species that can adapt to changing conditions.

“This has serious implications for all fish and our food security,” Professor Venditti said, “as many of the species we eat could become increasingly scarce or even non-existent in decades to come.” − Climate News Network

The catch with warming oceans is that there’ll be less of a catch. Smaller and less mobile fish will leave less to eat.

LONDON, 18 August, 2021 − Climate change could be about to get the world’s tastiest fish into hot water. The double jeopardy of global heating and overfishing could already be resulting in smaller and less mobile fish, turning sardines and herring, anchovies and pilchards into ever-smaller servings.

It has happened before: a new study of the evolution of fish species over the past 150 million years has found clear evidence of the ups and downs of time: as the ocean temperatures rise, fish tend to get smaller and travel less.

“Warming waters are a double whammy for fish, as they not only cause them to evolve to a smaller size, but also reduce their ability to move to more suitable environments,” said Chris Venditti, of the University of Reading, UK.

“Our research supports the theory that fish will get smaller as oceans warm under climate change, but reveals the worrying news that they will also not be able to evolve to cope as efficiently as first thought.

“This has serious implications for all fish and our food security”

“With sea temperatures rising faster than ever, fish will very quickly get left behind in evolutionary terms and struggle to survive.”

Professor Venditti and colleagues in Chile and Peru report in the journal Nature Climate Change that they applied subtle statistical techniques to evidence of fish evolution amassed in an international database called The Fish Tree of Life to learn about the link between temperature and size in one seafaring order, the Clupeiforms.

This group embraces both Atlantic and Pacific herring, the Japanese and South American pilchard, the anchovy and so on. But what is true for one order is likely to be true for almost all fish: warmer oceans mean more stress.

And stress is on the way. Over the last 150 million years, fish have had to adjust to changing temperatures, but only at rates of around 0.8°C per thousand years. Since 1981, according to the US National Oceanic and Atmospheric Administration, the seas have been warming at 0.18°C per decade.

Evolution at risk

So the finding supports what biologists already know: that animals confronted with higher temperatures tend to evolve to smaller sizes.

It’s not as if fish were not already feeling the heat. As waters warm, their capacity for dissolved oxygen dwindles. Spawning becomes more problematic. Migration becomes more urgent, but for smaller creatures with lower energy reserves also more difficult.

In the world’s traditional fishing grounds, overall catch sizes are shrinking: so too are the sizes of individual fish. And, the latest research suggests, warming waters could limit the capacity to evolve to new species that can adapt to changing conditions.

“This has serious implications for all fish and our food security,” Professor Venditti said, “as many of the species we eat could become increasingly scarce or even non-existent in decades to come.” − Climate News Network

Ancient sea level rises may have been fairly minimal

Maybe ancient sea level rises were not so dramatic. But they’d still have been pretty frightening.

LONDON, 12 August, 2021 − Earth scientists have measured the rising tides of a warmer world more than 100 millennia ago and found a glimmer of good news: ancient sea level rises during a warm spell in the last Ice Age were quite possibly only about 1.2 metres higher than they are today.

Since, between 128,000 and 117,000 years ago, the world was perhaps as much as 2°C warmer than it would become for most of human history, this really is encouraging. Right now, climate scientists project a rise of somewhere between 60cm and 1.5m later this century, as global temperature levels rise 2°C or more above those normal before the Industrial Revolution.

But until now, geological orthodoxy has proposed that during the last “interglacial” or sudden warming, sea levels rose by six metres or possibly even nine metres. This could only happen if the Antarctic or Greenland ice sheets had collapsed.

And although these are indeed already losing ice at an accelerating rate, it doesn’t seem possible for such a colossal quantity of ice to melt in only a handful of decades.

Missing factor

So there was a mismatch between the predictions of the world’s scientists and the apparent evidence from the past.

Now a new study in the Proceedings of the National Academy of Sciences offers a solution: calculations about past sea level heights may have been perhaps too gloomy because they did not fully factor in sea level’s other great uncertainty — the movement of the continents lapped by the sea.

This bedevils all predictions about sea level rise. Seas rise and fall with global temperatures, but so do landmasses. Right now, although sea level is creeping up at a rate measured in millimetres per year, the land under a number of great coastal cities is sinking dramatically, as humans build  ever more massive cities and abstract ever more groundwater. So predictions warn that millions could be at risk of coastal flooding.

But there is another, deeper reason for the uncertainty: as rising temperatures remove the massive burden of ice from glaciated land, and wind and rain erode mountains, so the subterranean rocks in the Earth’s mantle, far below the crust, respond by inching upwards. Even the seemingly solid rocks are elastic, subsiding under pressure and rising when the mass is removed.

“Models of ice sheets are still in their toddlerhood”

All this means that, unless researchers can make an accurate estimate of land movement as well, sea level estimates are riven with uncertainties.

So a team from Columbia University in the US has looked at evidence of sea level rise and fall preserved in fossilised reefs and dunes in just one 1200km chain of islands − the Bahamas in the Atlantic − to come up with a new set of projections.

In the next 100 years, sea levels will rise by about 1.2 metres. This could be too modest: sea levels could just possibly rise by perhaps 5.3 metres, but this doesn’t seem likely. And a nine-metre rise is highly improbable.

“To get to nine metres of sea level rise, you’d have to melt large parts of Greenland and Antarctica,” said Blake Dyer, of the university’s Lamont-Doherty Earth Observatory.

Tricky calculation

“This suggests that didn’t happen. So maybe we should feel not so bad about the future. On the other hand, our lower estimate is bad, and our upper one is really bad.”

At the heart of the puzzle is a phenomenon known to geophysicists as isostasy: vast tracts of continental landmass have been heaving up and down, imperceptibly, over periods of tens of thousands of years, in response to ice and erosion.

So calculating sea level rise and fall when the thing on which sea level measurements are recorded − the land − is itself always shifting becomes tricky. That has always been why climate projections of sea levels contain a range of forecasts, rather than a hard number.

The argument is that changes recorded along the north-south lie of the Bahamas would provide a new and more sophisticated way of reconstructing sea heights in the relatively recent past.

Melting not guaranteed

The study doesn’t settle the question: estimates of past sea level change on a dramatic scale come from many parts of the planet, and glaciologists still have to reconstruct the rate at which the northern ice, for instance, may have retreated while the southern ice cap continued to advance during the last interglacial: that too would have limited sea level rise.

“This is still a question. Models of ice sheets are still in their toddlerhood,” said Maureen Raymo, director of the Earth Observatory and a co-author.

Human carbon emissions are now heating the globe far more rapidly and evenly than during the last interglacial, so there is no guarantee of any melting at different rates in two hemispheres

“That makes it more difficult to apply the results to today. The easy thing to say would be, ‘Oh we showed that sea levels were not so bad, and that’s terrific.’  The harder answer, the more honest answer, is that maybe things were different then, and we’re not in the clear.” − Climate News Network

Maybe ancient sea level rises were not so dramatic. But they’d still have been pretty frightening.

LONDON, 12 August, 2021 − Earth scientists have measured the rising tides of a warmer world more than 100 millennia ago and found a glimmer of good news: ancient sea level rises during a warm spell in the last Ice Age were quite possibly only about 1.2 metres higher than they are today.

Since, between 128,000 and 117,000 years ago, the world was perhaps as much as 2°C warmer than it would become for most of human history, this really is encouraging. Right now, climate scientists project a rise of somewhere between 60cm and 1.5m later this century, as global temperature levels rise 2°C or more above those normal before the Industrial Revolution.

But until now, geological orthodoxy has proposed that during the last “interglacial” or sudden warming, sea levels rose by six metres or possibly even nine metres. This could only happen if the Antarctic or Greenland ice sheets had collapsed.

And although these are indeed already losing ice at an accelerating rate, it doesn’t seem possible for such a colossal quantity of ice to melt in only a handful of decades.

Missing factor

So there was a mismatch between the predictions of the world’s scientists and the apparent evidence from the past.

Now a new study in the Proceedings of the National Academy of Sciences offers a solution: calculations about past sea level heights may have been perhaps too gloomy because they did not fully factor in sea level’s other great uncertainty — the movement of the continents lapped by the sea.

This bedevils all predictions about sea level rise. Seas rise and fall with global temperatures, but so do landmasses. Right now, although sea level is creeping up at a rate measured in millimetres per year, the land under a number of great coastal cities is sinking dramatically, as humans build  ever more massive cities and abstract ever more groundwater. So predictions warn that millions could be at risk of coastal flooding.

But there is another, deeper reason for the uncertainty: as rising temperatures remove the massive burden of ice from glaciated land, and wind and rain erode mountains, so the subterranean rocks in the Earth’s mantle, far below the crust, respond by inching upwards. Even the seemingly solid rocks are elastic, subsiding under pressure and rising when the mass is removed.

“Models of ice sheets are still in their toddlerhood”

All this means that, unless researchers can make an accurate estimate of land movement as well, sea level estimates are riven with uncertainties.

So a team from Columbia University in the US has looked at evidence of sea level rise and fall preserved in fossilised reefs and dunes in just one 1200km chain of islands − the Bahamas in the Atlantic − to come up with a new set of projections.

In the next 100 years, sea levels will rise by about 1.2 metres. This could be too modest: sea levels could just possibly rise by perhaps 5.3 metres, but this doesn’t seem likely. And a nine-metre rise is highly improbable.

“To get to nine metres of sea level rise, you’d have to melt large parts of Greenland and Antarctica,” said Blake Dyer, of the university’s Lamont-Doherty Earth Observatory.

Tricky calculation

“This suggests that didn’t happen. So maybe we should feel not so bad about the future. On the other hand, our lower estimate is bad, and our upper one is really bad.”

At the heart of the puzzle is a phenomenon known to geophysicists as isostasy: vast tracts of continental landmass have been heaving up and down, imperceptibly, over periods of tens of thousands of years, in response to ice and erosion.

So calculating sea level rise and fall when the thing on which sea level measurements are recorded − the land − is itself always shifting becomes tricky. That has always been why climate projections of sea levels contain a range of forecasts, rather than a hard number.

The argument is that changes recorded along the north-south lie of the Bahamas would provide a new and more sophisticated way of reconstructing sea heights in the relatively recent past.

Melting not guaranteed

The study doesn’t settle the question: estimates of past sea level change on a dramatic scale come from many parts of the planet, and glaciologists still have to reconstruct the rate at which the northern ice, for instance, may have retreated while the southern ice cap continued to advance during the last interglacial: that too would have limited sea level rise.

“This is still a question. Models of ice sheets are still in their toddlerhood,” said Maureen Raymo, director of the Earth Observatory and a co-author.

Human carbon emissions are now heating the globe far more rapidly and evenly than during the last interglacial, so there is no guarantee of any melting at different rates in two hemispheres

“That makes it more difficult to apply the results to today. The easy thing to say would be, ‘Oh we showed that sea levels were not so bad, and that’s terrific.’  The harder answer, the more honest answer, is that maybe things were different then, and we’re not in the clear.” − Climate News Network

Arctic’s coldest sea ice is vulnerable to melting

Every year an ice floe as big as Austria simply vanishes. That’s climate change, as the Arctic’s coldest sea ice risks melting.

LONDON, 6 July, 2021 − The frozen world is dwindling fast. New research suggests that the cryosphere − the area of the planet covered by snow and ice − is dwindling by around 87,000 square kilometres every year. This is an area bigger than Austria, almost as big as Hungary, or Jordan. Even the Arctic’s coldest sea ice is threatened.

A second, separate study warns that what glacier scientists call the Last Ice Refuge − the tract of Arctic Ocean that will stay frozen when the rest of it becomes open water during some summers in the next decades − is itself at risk: the coldest and most secure reaches of sea ice just north of Greenland and Canada could be vulnerable to summer melt.

That the polar regions and the high-altitude frozen rivers and lakes are at risk is not news: climate scientists have been warning for decades of accelerating melt in Antarctica, ever-higher losses of ice mass from Greenland, and a loss of northern polar sea ice so comprehensive that by 2050, much of the Arctic Ocean could be clear blue water most summers.

The cryosphere matters: it is a reservoir of two-thirds of the planet’s fresh water. Its gleaming white surface acts as planetary insulation: most of the sunlight that falls upon it is reflected back into space. As the ice thins and retreats, the exposed darker ocean below it warms up, to accelerate global heating and trigger yet more ice loss.

“In years when you replenish the ice cover in this region with older, thicker ice, that doesn’t seem to help as much as you might expect”

Scientists from Lanzhou University in China report in the journal Earth’s Future that they tried to look at the picture of change on a planetary scale. The cryosphere has always expanded and shrunk with the seasons in both hemispheres. Scientists calculated the daily extent of all the world’s snow and ice cover and then averaged it to get yearly estimates.

The Arctic is perhaps the fastest-warming zone on the planet and the northern hemisphere cover has been losing 102,000 sq kms a year, every year. This is an area bigger than Iceland, or Eritrea. The southern hemisphere ice however has been expanding by about 14,000 sq kms a year − think of the Bahamas − to offset a little of the loss.

The researchers also found that much of the cryosphere was now frozen for shorter periods: the day of first freezing now happens about 3.6 days later than it did in 1979, and the ice thaws 5.7 days earlier than it did 40 years ago.

But until now, one stretch of Arctic sea ice had shown no particular signs of change. When glaciologists repeatedly warned that the Arctic could be ice-free in summer by mid-century, they meant that the region would be down to its last million sq km of ice floe. This would be the last stronghold of the frozen world: the last place where seals, walruses and polar bears could find the surfaces they needed for survival.

Essential Refuge

But researchers aboard the German icebreaker Polarstern observed that the ice cover of the Wandel Sea off Greenland and Canada in the summer of 2020 was at a record low. This was a surprise, because at the beginning of the season it had been as dense as ever.

Permanent ice is a matter of life and death to the Arctic’s apex mammal predators: seals haul out onto the ice, to become potential prey for polar bears. Walruses use the ice as a platform for foraging. As the summer sea ice thins and shrinks a little more every year over the rest of the Arctic, the Last Ice Refuge becomes ever more important for their survival as species. The big question is: were the weather conditions unusual, or was this a sign of global heating?

“During the winter and spring of 2020 you had patches of older, thicker ice that had drifted into there, but there was enough thinner, newer ice that melted to expose open ocean,” said Axel Schweiger of the University of Washington in the US, who led the research.

“That began a cycle of absorbing heat energy to melt more ice, in spite of the fact that there was some thick ice. So in years when you replenish the ice cover in this region with older, thicker ice, that doesn’t seem to help as much as you might expect.” − Climate News Network

Every year an ice floe as big as Austria simply vanishes. That’s climate change, as the Arctic’s coldest sea ice risks melting.

LONDON, 6 July, 2021 − The frozen world is dwindling fast. New research suggests that the cryosphere − the area of the planet covered by snow and ice − is dwindling by around 87,000 square kilometres every year. This is an area bigger than Austria, almost as big as Hungary, or Jordan. Even the Arctic’s coldest sea ice is threatened.

A second, separate study warns that what glacier scientists call the Last Ice Refuge − the tract of Arctic Ocean that will stay frozen when the rest of it becomes open water during some summers in the next decades − is itself at risk: the coldest and most secure reaches of sea ice just north of Greenland and Canada could be vulnerable to summer melt.

That the polar regions and the high-altitude frozen rivers and lakes are at risk is not news: climate scientists have been warning for decades of accelerating melt in Antarctica, ever-higher losses of ice mass from Greenland, and a loss of northern polar sea ice so comprehensive that by 2050, much of the Arctic Ocean could be clear blue water most summers.

The cryosphere matters: it is a reservoir of two-thirds of the planet’s fresh water. Its gleaming white surface acts as planetary insulation: most of the sunlight that falls upon it is reflected back into space. As the ice thins and retreats, the exposed darker ocean below it warms up, to accelerate global heating and trigger yet more ice loss.

“In years when you replenish the ice cover in this region with older, thicker ice, that doesn’t seem to help as much as you might expect”

Scientists from Lanzhou University in China report in the journal Earth’s Future that they tried to look at the picture of change on a planetary scale. The cryosphere has always expanded and shrunk with the seasons in both hemispheres. Scientists calculated the daily extent of all the world’s snow and ice cover and then averaged it to get yearly estimates.

The Arctic is perhaps the fastest-warming zone on the planet and the northern hemisphere cover has been losing 102,000 sq kms a year, every year. This is an area bigger than Iceland, or Eritrea. The southern hemisphere ice however has been expanding by about 14,000 sq kms a year − think of the Bahamas − to offset a little of the loss.

The researchers also found that much of the cryosphere was now frozen for shorter periods: the day of first freezing now happens about 3.6 days later than it did in 1979, and the ice thaws 5.7 days earlier than it did 40 years ago.

But until now, one stretch of Arctic sea ice had shown no particular signs of change. When glaciologists repeatedly warned that the Arctic could be ice-free in summer by mid-century, they meant that the region would be down to its last million sq km of ice floe. This would be the last stronghold of the frozen world: the last place where seals, walruses and polar bears could find the surfaces they needed for survival.

Essential Refuge

But researchers aboard the German icebreaker Polarstern observed that the ice cover of the Wandel Sea off Greenland and Canada in the summer of 2020 was at a record low. This was a surprise, because at the beginning of the season it had been as dense as ever.

Permanent ice is a matter of life and death to the Arctic’s apex mammal predators: seals haul out onto the ice, to become potential prey for polar bears. Walruses use the ice as a platform for foraging. As the summer sea ice thins and shrinks a little more every year over the rest of the Arctic, the Last Ice Refuge becomes ever more important for their survival as species. The big question is: were the weather conditions unusual, or was this a sign of global heating?

“During the winter and spring of 2020 you had patches of older, thicker ice that had drifted into there, but there was enough thinner, newer ice that melted to expose open ocean,” said Axel Schweiger of the University of Washington in the US, who led the research.

“That began a cycle of absorbing heat energy to melt more ice, in spite of the fact that there was some thick ice. So in years when you replenish the ice cover in this region with older, thicker ice, that doesn’t seem to help as much as you might expect.” − Climate News Network

Orkney’s renewable energy to fuel foreign needs

The tough climate of the North Atlantic is an ideal proving ground for Orkney’s renewable energy boom.

LONDON, 2 July, 2021 − A surplus of electricity from renewable sources is a luxury that many communities in a world threatened by climate change might wish for. This is the happy situation of Orkney, a wind-swept archipelago 10 miles (16 kms) north of the Scottish mainland on the edge of the Atlantic. Orkney’s renewable energy, a success at home, may soon be supplying consumers further afield.

Using a combination of wind, sun, tides and waves, the islands have been producing more than 100% of the electricity the residents need since 2013, and have now reached 130%.

The islanders are exploiting their renewable riches by developing a variety of pioneering schemes. Many are being installed by Scottish engineering companies that hope they will be scaled up and will benefit the rest of Europe, and of the entire world.

Orkney is home to the European Marine Energy Centre, which is successfully testing wave and tidal machines. But the islands are also pioneering other technologies and putting the surplus electricity to good use.

Spare power is already used to make hydrogen and oxygen. The Orcadians plan to use hydrogen to power the fleet of small boats they need to connect the populations of nine of the largest inhabited islands, and the fleet of larger ferries linking them to mainland Scotland.

“Where you have a coastline and some waves, there is an opportunity”

The 22,000 people of the islands have enthusiastically embraced renewable energy, with more than 1,000 households generating their own power, covering over 10% of the population. There is also a high take-up of electric vehicles – 267 at the last count.

The Orkney Islands Council is pushing for an interconnector linking Orkney and the mainland to export its surplus energy, which a recent report suggests could be worth up to £807 million (€938m) annually to the local economy.

This would mean building more wind turbines in the outlying islands, and also connecting tidal and wave energy installations to the grid.

The Orkney Renewable Energy Forum promotes all forms of renewables on the islands and details more than a dozen pioneering projects that have come to Orkney for testing.

Costs to dive

Because of the frequently stormy weather and exposure to the Atlantic rollers, Orkney has been attractive for companies needing especially to test novel wave power machines and undersea turbine installations. The sheer number of experiments allows Orkney to claim to be a world leader in the field.

Underwater turbines, known also as tidal stream turbines, were first tried in the islands. They exploit strong undersea currents and are now a proven technology. MeyGen began by successfully installing four 1.5 megawatt turbines between Orkney and the mainland. They performed better than expected, and a much larger development is now under way.

Although the United Kingdom has now left the European Union, the tidal technology developed in Orkney and Shetland – the island group to the north – is destined for wider European use. The EU has ambitious targets for generating tidal energy and companies are racing to exploit the many undersea tidal resources along the Atlantic and North Sea coastlines.

They believe that costs will fall as the technology develops, and predictable tidal currents will produce the regular output highly desirable for keeping electricity grids stable.

Wave machines, however, have not been so successful. Although some have clearly worked and produced power, the last push to full commercial deployment has proved difficult, and some companies have gone bankrupt.

South Seas beckon

Engineers have not given up, however, and the latest wave machine, 20 metres long and weighing 38 tonnes, has been towed to the islands and is currently being installed before tests start.

There are ambitious plans to connect it to the grid to prove that the technology lives up the maker’s claims that hundreds of such machines could power millions of homes.

Cameron McNatt of Mocean Energy, which is developing the machine, has high hopes for Orkney’s renewable energy. He said: “Scotland and the North Sea are really good proving grounds for this technology, and where you have a coastline and some waves, there is an opportunity.

“We anticipate our technology being used all over the world. Outside of Europe, the United States is a big target market for us, as is Australia and the Oceania region.” − Climate News Network

The tough climate of the North Atlantic is an ideal proving ground for Orkney’s renewable energy boom.

LONDON, 2 July, 2021 − A surplus of electricity from renewable sources is a luxury that many communities in a world threatened by climate change might wish for. This is the happy situation of Orkney, a wind-swept archipelago 10 miles (16 kms) north of the Scottish mainland on the edge of the Atlantic. Orkney’s renewable energy, a success at home, may soon be supplying consumers further afield.

Using a combination of wind, sun, tides and waves, the islands have been producing more than 100% of the electricity the residents need since 2013, and have now reached 130%.

The islanders are exploiting their renewable riches by developing a variety of pioneering schemes. Many are being installed by Scottish engineering companies that hope they will be scaled up and will benefit the rest of Europe, and of the entire world.

Orkney is home to the European Marine Energy Centre, which is successfully testing wave and tidal machines. But the islands are also pioneering other technologies and putting the surplus electricity to good use.

Spare power is already used to make hydrogen and oxygen. The Orcadians plan to use hydrogen to power the fleet of small boats they need to connect the populations of nine of the largest inhabited islands, and the fleet of larger ferries linking them to mainland Scotland.

“Where you have a coastline and some waves, there is an opportunity”

The 22,000 people of the islands have enthusiastically embraced renewable energy, with more than 1,000 households generating their own power, covering over 10% of the population. There is also a high take-up of electric vehicles – 267 at the last count.

The Orkney Islands Council is pushing for an interconnector linking Orkney and the mainland to export its surplus energy, which a recent report suggests could be worth up to £807 million (€938m) annually to the local economy.

This would mean building more wind turbines in the outlying islands, and also connecting tidal and wave energy installations to the grid.

The Orkney Renewable Energy Forum promotes all forms of renewables on the islands and details more than a dozen pioneering projects that have come to Orkney for testing.

Costs to dive

Because of the frequently stormy weather and exposure to the Atlantic rollers, Orkney has been attractive for companies needing especially to test novel wave power machines and undersea turbine installations. The sheer number of experiments allows Orkney to claim to be a world leader in the field.

Underwater turbines, known also as tidal stream turbines, were first tried in the islands. They exploit strong undersea currents and are now a proven technology. MeyGen began by successfully installing four 1.5 megawatt turbines between Orkney and the mainland. They performed better than expected, and a much larger development is now under way.

Although the United Kingdom has now left the European Union, the tidal technology developed in Orkney and Shetland – the island group to the north – is destined for wider European use. The EU has ambitious targets for generating tidal energy and companies are racing to exploit the many undersea tidal resources along the Atlantic and North Sea coastlines.

They believe that costs will fall as the technology develops, and predictable tidal currents will produce the regular output highly desirable for keeping electricity grids stable.

Wave machines, however, have not been so successful. Although some have clearly worked and produced power, the last push to full commercial deployment has proved difficult, and some companies have gone bankrupt.

South Seas beckon

Engineers have not given up, however, and the latest wave machine, 20 metres long and weighing 38 tonnes, has been towed to the islands and is currently being installed before tests start.

There are ambitious plans to connect it to the grid to prove that the technology lives up the maker’s claims that hundreds of such machines could power millions of homes.

Cameron McNatt of Mocean Energy, which is developing the machine, has high hopes for Orkney’s renewable energy. He said: “Scotland and the North Sea are really good proving grounds for this technology, and where you have a coastline and some waves, there is an opportunity.

“We anticipate our technology being used all over the world. Outside of Europe, the United States is a big target market for us, as is Australia and the Oceania region.” − Climate News Network

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