Category Archives: Polar

End of Arctic sea ice by 2035 possible, study finds

How soon will the northern polar ocean be ice-free? New research expects the end of Arctic sea ice by 2035.

LONDON, 11 August, 2020 − The temperature of the Arctic matters to the entire world: it helps to keep the global climate fairly cool. Scientists now say that by 2035 there could be an end to Arctic sea ice.

The northern polar ocean’s sea ice is a crucial element in the Earth system: because it is highly reflective, it sends solar radiation back out into space. Once it’s melted, there’s no longer any protection for the darker water and rock beneath, and nothing to prevent them absorbing the incoming heat.

High temperatures in the Arctic during the last interglacial – the warm period around 127,000 years ago – have puzzled scientists for decades.

Now the UK Met Office’s Hadley Centre climate model has enabled an international research team to compare Arctic sea ice conditions during the last interglacial with the present day. Their findings are important for improving predictions of future sea ice change.

What is striking about the latest research is the date it suggests for a possible total melt − 2035. Many studies have thought a mid-century crisis likely, with another even carefully specifying 2044 as the year to watch. So a breathing space of only 15 years may surprise some experts.

“The prospect of loss of sea ice by 2035 should really be focussing all our minds on achieving a low-carbon world as soon as humanly feasible”

During spring and early summer shallow pools of water form on the surface of the Arctic sea ice. These “melt ponds” help to determine how much sunlight is absorbed by the ice and how much is reflected back into space. The new Hadley Centre model is the UK’s most advanced physical representation of the Earth’s climate and a critical tool for climate research, and it incorporates sea ice and melt ponds.

The researchers report their findings in the journal Nature Climate Change. Using the model to look at Arctic sea ice during the last interglacial, they concluded that the impact of intense springtime sunshine created many melt ponds, which played a crucial role in sea ice melt. A simulation of the future using the same model indicates that the Arctic may become sea ice-free by 2035.

The joint lead author of the team is Dr Maria Vittoria Guarino, an earth system modeller at the British Antarctic Survey (BAS) in Cambridge. She says: “High temperatures in the Arctic have puzzled scientists for decades. Unravelling this mystery was technically and scientifically challenging. For the first time, we can begin to see how the Arctic became sea ice-free during the last interglacial.

“The advances made in climate modelling mean that we can create a more accurate simulation of the Earth’s past climate which, in turn, gives us greater confidence in model predictions for the future.”

Dr Louise Sime, the group head of the palaeoclimate group and joint lead author at BAS, says: “We know the Arctic is undergoing significant changes as our planet warms. By understanding what happened during Earth’s last warm period we are in a better position to understand what will happen in the future.

Melt ponds crucial

“The prospect of loss of sea ice by 2035 should really be focussing all our minds on achieving a low-carbon world as soon as humanly feasible.”

Dr David Schroeder from the University of Reading, UK, who co-led the implementation of the melt pond scheme in the climate model, says: “This shows just how important sea ice processes like melt ponds are in the Arctic, and why it is crucial that they are incorporated into climate models.”

The extent of the areas sea ice covers varies between summer and winter. If more solar energy is absorbed at the surface, and temperatures rise further, a cycle of warming and melting occurs during summer months.

When the ice forms, the ocean water beneath becomes saltier and denser than the surrounding ocean. Saltier water sinks and moves along the ocean bottom towards the equator, while warm water from mid-depths to the surface travels from the equator towards the poles.

Scientists refer to this process as the ocean’s global “conveyor-belt”. Changes to the volume of sea ice can disrupt normal ocean circulation, with consequences for global climate. − Climate News Network

How soon will the northern polar ocean be ice-free? New research expects the end of Arctic sea ice by 2035.

LONDON, 11 August, 2020 − The temperature of the Arctic matters to the entire world: it helps to keep the global climate fairly cool. Scientists now say that by 2035 there could be an end to Arctic sea ice.

The northern polar ocean’s sea ice is a crucial element in the Earth system: because it is highly reflective, it sends solar radiation back out into space. Once it’s melted, there’s no longer any protection for the darker water and rock beneath, and nothing to prevent them absorbing the incoming heat.

High temperatures in the Arctic during the last interglacial – the warm period around 127,000 years ago – have puzzled scientists for decades.

Now the UK Met Office’s Hadley Centre climate model has enabled an international research team to compare Arctic sea ice conditions during the last interglacial with the present day. Their findings are important for improving predictions of future sea ice change.

What is striking about the latest research is the date it suggests for a possible total melt − 2035. Many studies have thought a mid-century crisis likely, with another even carefully specifying 2044 as the year to watch. So a breathing space of only 15 years may surprise some experts.

“The prospect of loss of sea ice by 2035 should really be focussing all our minds on achieving a low-carbon world as soon as humanly feasible”

During spring and early summer shallow pools of water form on the surface of the Arctic sea ice. These “melt ponds” help to determine how much sunlight is absorbed by the ice and how much is reflected back into space. The new Hadley Centre model is the UK’s most advanced physical representation of the Earth’s climate and a critical tool for climate research, and it incorporates sea ice and melt ponds.

The researchers report their findings in the journal Nature Climate Change. Using the model to look at Arctic sea ice during the last interglacial, they concluded that the impact of intense springtime sunshine created many melt ponds, which played a crucial role in sea ice melt. A simulation of the future using the same model indicates that the Arctic may become sea ice-free by 2035.

The joint lead author of the team is Dr Maria Vittoria Guarino, an earth system modeller at the British Antarctic Survey (BAS) in Cambridge. She says: “High temperatures in the Arctic have puzzled scientists for decades. Unravelling this mystery was technically and scientifically challenging. For the first time, we can begin to see how the Arctic became sea ice-free during the last interglacial.

“The advances made in climate modelling mean that we can create a more accurate simulation of the Earth’s past climate which, in turn, gives us greater confidence in model predictions for the future.”

Dr Louise Sime, the group head of the palaeoclimate group and joint lead author at BAS, says: “We know the Arctic is undergoing significant changes as our planet warms. By understanding what happened during Earth’s last warm period we are in a better position to understand what will happen in the future.

Melt ponds crucial

“The prospect of loss of sea ice by 2035 should really be focussing all our minds on achieving a low-carbon world as soon as humanly feasible.”

Dr David Schroeder from the University of Reading, UK, who co-led the implementation of the melt pond scheme in the climate model, says: “This shows just how important sea ice processes like melt ponds are in the Arctic, and why it is crucial that they are incorporated into climate models.”

The extent of the areas sea ice covers varies between summer and winter. If more solar energy is absorbed at the surface, and temperatures rise further, a cycle of warming and melting occurs during summer months.

When the ice forms, the ocean water beneath becomes saltier and denser than the surrounding ocean. Saltier water sinks and moves along the ocean bottom towards the equator, while warm water from mid-depths to the surface travels from the equator towards the poles.

Scientists refer to this process as the ocean’s global “conveyor-belt”. Changes to the volume of sea ice can disrupt normal ocean circulation, with consequences for global climate. − Climate News Network

Food shortage may finish polar bears by 2100

How long polar bears can survive depends on how long they can last without food. And that may be: not long enough.

LONDON, 24 July, 2020 − As the Arctic sea ice dwindles, so will hope for the region’s most dramatic predator, its polar bears. A creature fashioned by evolution to fast a whole summer and gorge through the autumn and winter may not last, as the ice melts ever earlier and forms ever later.

That is because Ursus maritimus can find the food for the next generation of its cubs only by prowling the firm sea ice for a high-calorie diet of seal flesh and blubber.

And now a team of Canadian and US scientists has begun to establish the unknown of polar bear survival: how many days the creature can survive without food and still nourish its young and sustain life.

They call this the “fasting impact threshold” and the answer, they report in the journal Nature Climate Change, is not encouraging.

“Polar bears everywhere will face longer periods without food, and this will affect their ability to reproduce, survive and persist”

If warming continues at the present rate, then by the century’s end most of the sub-populations of this charismatic animal will not survive.

“The challenge is that the Arctic ice will keep disappearing as the world continues to warm,” said Péter Molnár, of the University of Toronto Scarborough, who led the research.

“This means polar bears everywhere will face longer periods without food, and this will affect their ability to reproduce, survive and persist as healthy populations.”

The researchers had to start with one big uncertainty: how much stored energy the bear has when the fasting season begins. Because the shelf ice has been thinning and shrinking for more than 40 years, hunting seasons have become shorter and bears now spend longer and longer on land.

Natural variability

That raised a second factor: some parts of the Arctic lose ice earlier than others. The third unknown is the health of the 19 sub-populations of Ursus maritimus, spread over four distinct eco-regions within the Arctic Circle, and how these separate populations would consider a “good” hunting season and a happy period of fasting.

In the southern Beaufort Sea, fewer than 127 ice-free days could be considered “good”, but even this seemingly assured number was based on only five years of systematic demographic data.

And then the researchers had to calculate the demands placed on individual bears: an adult male might be able to last 200 days; a solitary adult female up to 255 days. But a mother bear might begin to lose what it takes to get cubs through to maturity as early as 117 days, and certainly after 228 days.

But however incomplete, the scientists had data for about 80% of the polar bear populations, collected between 1979 and 2016, and report that what they politely call “recruitment and survival impact thresholds” may have already been exceeded in some populations.

Too hopeful?

That is, there are increasing numbers of bears in the Arctic no longer sure of having cubs or keeping them alive. That includes the polar bears of Hudson Bay and the Davis Strait in northern Canada: perhaps the most photographed bears in the world.

And if the world goes on warming, only a few creatures in the very high Arctic will see the next century.

“While our projections for the future of polar bears seem dire, the unfortunate thing is they might even be too optimistic. For example, we assumed that polar bears will use their available body energy in optimal ways when fasting. If that isn’t the case, the reality could be worse than our projections,” Dr Molnár said.

“What we do know is that becoming fat before a fasting season will be more difficult for polar bears as on-ice hunting seasons become shorter, so it’s likely that fasting impact thresholds will be crossed in the early years of our projected range.” − Climate News Network

How long polar bears can survive depends on how long they can last without food. And that may be: not long enough.

LONDON, 24 July, 2020 − As the Arctic sea ice dwindles, so will hope for the region’s most dramatic predator, its polar bears. A creature fashioned by evolution to fast a whole summer and gorge through the autumn and winter may not last, as the ice melts ever earlier and forms ever later.

That is because Ursus maritimus can find the food for the next generation of its cubs only by prowling the firm sea ice for a high-calorie diet of seal flesh and blubber.

And now a team of Canadian and US scientists has begun to establish the unknown of polar bear survival: how many days the creature can survive without food and still nourish its young and sustain life.

They call this the “fasting impact threshold” and the answer, they report in the journal Nature Climate Change, is not encouraging.

“Polar bears everywhere will face longer periods without food, and this will affect their ability to reproduce, survive and persist”

If warming continues at the present rate, then by the century’s end most of the sub-populations of this charismatic animal will not survive.

“The challenge is that the Arctic ice will keep disappearing as the world continues to warm,” said Péter Molnár, of the University of Toronto Scarborough, who led the research.

“This means polar bears everywhere will face longer periods without food, and this will affect their ability to reproduce, survive and persist as healthy populations.”

The researchers had to start with one big uncertainty: how much stored energy the bear has when the fasting season begins. Because the shelf ice has been thinning and shrinking for more than 40 years, hunting seasons have become shorter and bears now spend longer and longer on land.

Natural variability

That raised a second factor: some parts of the Arctic lose ice earlier than others. The third unknown is the health of the 19 sub-populations of Ursus maritimus, spread over four distinct eco-regions within the Arctic Circle, and how these separate populations would consider a “good” hunting season and a happy period of fasting.

In the southern Beaufort Sea, fewer than 127 ice-free days could be considered “good”, but even this seemingly assured number was based on only five years of systematic demographic data.

And then the researchers had to calculate the demands placed on individual bears: an adult male might be able to last 200 days; a solitary adult female up to 255 days. But a mother bear might begin to lose what it takes to get cubs through to maturity as early as 117 days, and certainly after 228 days.

But however incomplete, the scientists had data for about 80% of the polar bear populations, collected between 1979 and 2016, and report that what they politely call “recruitment and survival impact thresholds” may have already been exceeded in some populations.

Too hopeful?

That is, there are increasing numbers of bears in the Arctic no longer sure of having cubs or keeping them alive. That includes the polar bears of Hudson Bay and the Davis Strait in northern Canada: perhaps the most photographed bears in the world.

And if the world goes on warming, only a few creatures in the very high Arctic will see the next century.

“While our projections for the future of polar bears seem dire, the unfortunate thing is they might even be too optimistic. For example, we assumed that polar bears will use their available body energy in optimal ways when fasting. If that isn’t the case, the reality could be worse than our projections,” Dr Molnár said.

“What we do know is that becoming fat before a fasting season will be more difficult for polar bears as on-ice hunting seasons become shorter, so it’s likely that fasting impact thresholds will be crossed in the early years of our projected range.” − Climate News Network

Arctic Ocean is set for more turbulent future

The Arctic Ocean is about to become more violent, with higher storm waves and higher frequency, across a wide region.

LONDON, 20 July, 2020 − The Arctic Ocean is changing, and changing fast. By the century’s end, the maximum height of storm waves in the polar seas could have risen by twice or even three times the present height.

According to new research, wave heights could increase by two metres and coastal floods could become four times, or even 10 times, as frequent.

And a separate study has found that even the character of the water in the ocean is changing: warm salty water from the Atlantic is weakening the ice cover at an accelerating rate, but providing more nutrients for Arctic life, while extra river water from the Pacific has made the American-Asian part of the Arctic Ocean less likely to mix, and less biologically productive.

The Arctic is warming at twice the rate of the planet as a whole: the ice cover has been thinning and retreating for decades. And temperatures keep on rising.

One Siberian town recorded a temperature of 38°C in June, and the region has been hit by devastating forest fires.

“In many respects, the Arctic Ocean now looks like a new ocean”

And as the oceans warm, winds become more powerful and the ocean waves respond, with prospects of ever-greater hazard for shipping and coastal settlements.

Extreme wave events that once occurred in the Arctic at average intervals of once every 20 years could by the end of the century happen every two to five years, according a study in the Journal of Geophysical Research: Oceans.

“It increases the risk of flooding and erosion. It increases drastically almost everywhere”, said Mercè Casas-Prat, a researcher with Environment and Climate Change Canada. “This can have a direct impact on communities that live close to the shoreline.”

She and a colleague used computer simulations and a range of climate predictions to work out what will happen to those ocean surfaces not covered by ice as the seas warm in response to greenhouse gas emissions from fossil fuel combustion.

They found that almost everywhere in the Arctic would experience greater wave height. The hardest-hit would be the Greenland Sea, bounded by the largest body of ice in the northern hemisphere, and the Svalbard Archipelago.

More salty water

Maximum annual wave heights could increase by as much as six metres.
“At the end of the century, the maximum will on average come later in the year and also be more extreme,” Dr Casas-Prat said.

The Arctic Ocean covers only about 3% of the planet’s surface, but it is vulnerable to change in ocean regions much nearer the Equator. US and Scandinavian scientists report in the journal Frontiers in Marine Science that they looked at 37 years of direct observation and measurement to find that not only are Arctic waters changing: they are changing in different ways.

Flows of increasingly warm salty water from the Atlantic have begun to mix at depth, weaken sea ice and bring deeper, nutrient-rich water to the surface. At the other entrance to the partly landlocked expanse of water, an increasing flow from rivers has begun to make the separation of surface and deep layers even more pronounced.

This limits the movement of nutrients to the surface, protentially making that part of the sea less biologically rich. Many marine creatures from low latitudes are moving north, in some cases replacing local species. The changes could affect fisheries, tourism, navigation and of course the people who live in the Arctic.

“In many respects, the Arctic Ocean now looks like a new ocean,” said Igor Polyakov, an oceanographer at the University of Fairbanks, Alaska, who led the research. − Climate News Network

The Arctic Ocean is about to become more violent, with higher storm waves and higher frequency, across a wide region.

LONDON, 20 July, 2020 − The Arctic Ocean is changing, and changing fast. By the century’s end, the maximum height of storm waves in the polar seas could have risen by twice or even three times the present height.

According to new research, wave heights could increase by two metres and coastal floods could become four times, or even 10 times, as frequent.

And a separate study has found that even the character of the water in the ocean is changing: warm salty water from the Atlantic is weakening the ice cover at an accelerating rate, but providing more nutrients for Arctic life, while extra river water from the Pacific has made the American-Asian part of the Arctic Ocean less likely to mix, and less biologically productive.

The Arctic is warming at twice the rate of the planet as a whole: the ice cover has been thinning and retreating for decades. And temperatures keep on rising.

One Siberian town recorded a temperature of 38°C in June, and the region has been hit by devastating forest fires.

“In many respects, the Arctic Ocean now looks like a new ocean”

And as the oceans warm, winds become more powerful and the ocean waves respond, with prospects of ever-greater hazard for shipping and coastal settlements.

Extreme wave events that once occurred in the Arctic at average intervals of once every 20 years could by the end of the century happen every two to five years, according a study in the Journal of Geophysical Research: Oceans.

“It increases the risk of flooding and erosion. It increases drastically almost everywhere”, said Mercè Casas-Prat, a researcher with Environment and Climate Change Canada. “This can have a direct impact on communities that live close to the shoreline.”

She and a colleague used computer simulations and a range of climate predictions to work out what will happen to those ocean surfaces not covered by ice as the seas warm in response to greenhouse gas emissions from fossil fuel combustion.

They found that almost everywhere in the Arctic would experience greater wave height. The hardest-hit would be the Greenland Sea, bounded by the largest body of ice in the northern hemisphere, and the Svalbard Archipelago.

More salty water

Maximum annual wave heights could increase by as much as six metres.
“At the end of the century, the maximum will on average come later in the year and also be more extreme,” Dr Casas-Prat said.

The Arctic Ocean covers only about 3% of the planet’s surface, but it is vulnerable to change in ocean regions much nearer the Equator. US and Scandinavian scientists report in the journal Frontiers in Marine Science that they looked at 37 years of direct observation and measurement to find that not only are Arctic waters changing: they are changing in different ways.

Flows of increasingly warm salty water from the Atlantic have begun to mix at depth, weaken sea ice and bring deeper, nutrient-rich water to the surface. At the other entrance to the partly landlocked expanse of water, an increasing flow from rivers has begun to make the separation of surface and deep layers even more pronounced.

This limits the movement of nutrients to the surface, protentially making that part of the sea less biologically rich. Many marine creatures from low latitudes are moving north, in some cases replacing local species. The changes could affect fisheries, tourism, navigation and of course the people who live in the Arctic.

“In many respects, the Arctic Ocean now looks like a new ocean,” said Igor Polyakov, an oceanographer at the University of Fairbanks, Alaska, who led the research. − Climate News Network

South Pole warms faster than anywhere − but why?

The coldest place on Earth, the South Pole, is mysteriously heating a lot faster than the rest of the planet.

LONDON, 16 July, 2020 − The South Pole is warming, and warming fast. In the last 30 years, the place furthest from the summer sun, the place where one winter’s night lasts for 179 days, has been warming at 0.6°C per decade. This is three times the speed of average warming for the whole planet.

The finding is unexpected. The geographic South Pole is not only the most extreme location in the southern hemisphere, it is also at Alpine altitude. The Amundsen-Scott research station at the pole is at 2,835 metres, perched on a sheet of glacier ice 2,700 metres above the bedrock, and moving towards the sea at 10 metres a year.

Winter temperatures have fallen to minus 82.8°C. The warmest summer day ever recorded was minus 13.6°C.

And yet this unforgiving spot, with an annual average temperature of minus 49°C, still registers a measure of global warming. Whether this warming is fuelled by a natural climate cycle or by the profligate human use of fossil fuels, or by both, is not certain.

Systematic record-keeping began only in 1957 and for most of the late 20th century, while the rest of the planet started to warm, the South Pole continued to cool. West Antarctica is getting warmer, and melting at an accelerating rate, thanks in part to human-fuelled climate change.

“Antarctica experiences some of the most extreme weather and variability on the planet, and due to its remote location we actually know very little about the continent”

But scientists from New Zealand and the US report in the journal Nature that between 1989 and 2018, the South Pole had warmed by 1.8°C, partly because warm waters in the western Pacific had affected the South Atlantic winds and stepped up the delivery of warm air to the heart of the continent.

And this most extreme of environments goes on presenting puzzles. In April researchers announced the discovery of the remains of a 90-million-year-old swampy temperate forest within 900kms of the South Pole: it was once so warm that even in a winter night that lasted for months, foliage could flourish.

The latest research from the South Pole data suggests that researchers would like to know a lot more before they can say if the warming trend will continue, and why.

“Antarctica experiences some of the most extreme weather and variability on the planet,” said Kyle Clem, of Victoria University in Wellington, New Zealand, who led the research, “and due to its remote location we actually know very little about the continent, so there are constant surprises and new things to learn about Antarctica every year.” − Climate News Network

The coldest place on Earth, the South Pole, is mysteriously heating a lot faster than the rest of the planet.

LONDON, 16 July, 2020 − The South Pole is warming, and warming fast. In the last 30 years, the place furthest from the summer sun, the place where one winter’s night lasts for 179 days, has been warming at 0.6°C per decade. This is three times the speed of average warming for the whole planet.

The finding is unexpected. The geographic South Pole is not only the most extreme location in the southern hemisphere, it is also at Alpine altitude. The Amundsen-Scott research station at the pole is at 2,835 metres, perched on a sheet of glacier ice 2,700 metres above the bedrock, and moving towards the sea at 10 metres a year.

Winter temperatures have fallen to minus 82.8°C. The warmest summer day ever recorded was minus 13.6°C.

And yet this unforgiving spot, with an annual average temperature of minus 49°C, still registers a measure of global warming. Whether this warming is fuelled by a natural climate cycle or by the profligate human use of fossil fuels, or by both, is not certain.

Systematic record-keeping began only in 1957 and for most of the late 20th century, while the rest of the planet started to warm, the South Pole continued to cool. West Antarctica is getting warmer, and melting at an accelerating rate, thanks in part to human-fuelled climate change.

“Antarctica experiences some of the most extreme weather and variability on the planet, and due to its remote location we actually know very little about the continent”

But scientists from New Zealand and the US report in the journal Nature that between 1989 and 2018, the South Pole had warmed by 1.8°C, partly because warm waters in the western Pacific had affected the South Atlantic winds and stepped up the delivery of warm air to the heart of the continent.

And this most extreme of environments goes on presenting puzzles. In April researchers announced the discovery of the remains of a 90-million-year-old swampy temperate forest within 900kms of the South Pole: it was once so warm that even in a winter night that lasted for months, foliage could flourish.

The latest research from the South Pole data suggests that researchers would like to know a lot more before they can say if the warming trend will continue, and why.

“Antarctica experiences some of the most extreme weather and variability on the planet,” said Kyle Clem, of Victoria University in Wellington, New Zealand, who led the research, “and due to its remote location we actually know very little about the continent, so there are constant surprises and new things to learn about Antarctica every year.” − Climate News Network

Antarctic melting could bring a much hotter future

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

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

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

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

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

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

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

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

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

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

Tell-tale line

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

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

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

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

Faster change ahead

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Tell-tale line

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

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

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

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

Faster change ahead

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

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

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

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

North Pole may be clear water by mid-century

This story is a part of Covering Climate Now’s week of coverage focused on Climate Solutions, to mark the 50th anniversary of Earth Day. Covering Climate Now is a global journalism collaboration committed to strengthening coverage of the climate story.

 

Within 30 years, there could be clear blue water over the North Pole – not good news for most of the planet.

LONDON, 25 April, 2020 – Within three decades, the North Pole could be free of sea ice in the late summer. The latest and most advanced climate simulations, tested by 21 research institutes from around the world, predict that if humans go on emitting ever-greater volumes of carbon dioxide from fossil fuel combustion and other actions, then before 2050, for the first time in human history, there could be no ice over the North Pole.

And a team of research scientists aboard a ship intent on spending a year observing the drift of sea ice across the Arctic Ocean has been warned that they may have to finish early: the ice supposed to hold the ship fast could melt too soon.

The loss of sea ice promises devastating consequences for the rich life in the most northern waters. The ice reflects sunlight back into space and keeps the Arctic cool. It also provides space for seals on which to haul out, and hunting grounds for blubber-hungry polar bears.

And although human inaction in the climate emergency makes the loss of polar ice ever more probable, so much greenhouse gas has already built up in the planetary atmosphere that it could happen anyway.

Taken aback

“If we reduce global emissions rapidly and substantially, and thus keep our warming below 2°C relative to pre-industrial levels, sea ice will nevertheless likely disappear occasionally in summer even before 2050,” said Dirk Notz, of the University of Hamburg in Germany, who led the study. “This really surprised us.”

Climate scientists first warned of the accelerating loss of Arctic sea ice two decades ago, and have repeatedly re-examined the climate predictions, each time with much the same outcome.

The loss of ice promises new trade routes between Atlantic and Pacific Oceans, but the cost of a warming Arctic could have catastrophic economic consequences.

The pattern of the northern hemisphere climate is driven by the temperature difference between the Arctic and the tropics, and rapid polar warming both disturbs temperate climate regimes and brings ever higher sea levels, with accelerating ice loss from Greenland, which right now bears enough ice to raise global sea levels by more than seven metres.

“The changes in the Arctic system are so incredibly rapid that even our satellite observations from 15 years ago are unlike the Arctic today”

Dr Notz and his co-authors report in the journal Geophysical Research Letters that they used the very latest climate model developed for the Intergovernmental Panel on Climate Change and tested it on a range of 40 possible climate outcomes.

In most simulations, the Arctic sea ice was reduced to less than a million square kilometres – polar researchers call this “practically sea-ice free” – in the month of September for the first time before 2050. Even if human fossil fuel use was sharply reduced, the ocean could be free of ice some years; if not, the pole could become open water most years.

And a second study, in the journal The Cryosphere, offers a measure of the sea ice loss even now. More than a century ago, the great explorer Fridtjof Nansen sailed his ship the Fram into the polar ice, became fast, and travelled with the floe across the Arctic Ocean.

His became the first scientific observation of a phenomenon called the trans-Polar drift, which takes algae, sediments and nutrients – and increasingly, plastic pollution – across the Arctic from Siberia to Canada and Greenland.

Melted out

In October a team of international researchers boarded a vessel called Polarstern with the intention of measuring the ice movement in the modern Arctic in more detail. They had planned for a year fast in the ice. Their project even has a name: Mosaic, or Multidisciplinary drifting Observatory for the Study of Arctic Climate.

But climate simulations by the US scientists reveal that in every sense, the project is on thin ice and could end prematurely. The flow of ice could be faster, and carry the ship further, than expected: nearly one in five of the simulations also predicted that the ship could melt out of the ice in less than a year.

“The changes in the Arctic system are so incredibly rapid that even our satellite observations from 15 years ago are unlike the Arctic today,” said one of the authors, Marika Holland of the US National Center for Atmospheric Research.

“Now there is thinner ice, which moves more quickly, and there is less snow cover. It is a totally different ice regime.” – Climate News Network

This story is a part of Covering Climate Now’s week of coverage focused on Climate Solutions, to mark the 50th anniversary of Earth Day. Covering Climate Now is a global journalism collaboration committed to strengthening coverage of the climate story.

 

Within 30 years, there could be clear blue water over the North Pole – not good news for most of the planet.

LONDON, 25 April, 2020 – Within three decades, the North Pole could be free of sea ice in the late summer. The latest and most advanced climate simulations, tested by 21 research institutes from around the world, predict that if humans go on emitting ever-greater volumes of carbon dioxide from fossil fuel combustion and other actions, then before 2050, for the first time in human history, there could be no ice over the North Pole.

And a team of research scientists aboard a ship intent on spending a year observing the drift of sea ice across the Arctic Ocean has been warned that they may have to finish early: the ice supposed to hold the ship fast could melt too soon.

The loss of sea ice promises devastating consequences for the rich life in the most northern waters. The ice reflects sunlight back into space and keeps the Arctic cool. It also provides space for seals on which to haul out, and hunting grounds for blubber-hungry polar bears.

And although human inaction in the climate emergency makes the loss of polar ice ever more probable, so much greenhouse gas has already built up in the planetary atmosphere that it could happen anyway.

Taken aback

“If we reduce global emissions rapidly and substantially, and thus keep our warming below 2°C relative to pre-industrial levels, sea ice will nevertheless likely disappear occasionally in summer even before 2050,” said Dirk Notz, of the University of Hamburg in Germany, who led the study. “This really surprised us.”

Climate scientists first warned of the accelerating loss of Arctic sea ice two decades ago, and have repeatedly re-examined the climate predictions, each time with much the same outcome.

The loss of ice promises new trade routes between Atlantic and Pacific Oceans, but the cost of a warming Arctic could have catastrophic economic consequences.

The pattern of the northern hemisphere climate is driven by the temperature difference between the Arctic and the tropics, and rapid polar warming both disturbs temperate climate regimes and brings ever higher sea levels, with accelerating ice loss from Greenland, which right now bears enough ice to raise global sea levels by more than seven metres.

“The changes in the Arctic system are so incredibly rapid that even our satellite observations from 15 years ago are unlike the Arctic today”

Dr Notz and his co-authors report in the journal Geophysical Research Letters that they used the very latest climate model developed for the Intergovernmental Panel on Climate Change and tested it on a range of 40 possible climate outcomes.

In most simulations, the Arctic sea ice was reduced to less than a million square kilometres – polar researchers call this “practically sea-ice free” – in the month of September for the first time before 2050. Even if human fossil fuel use was sharply reduced, the ocean could be free of ice some years; if not, the pole could become open water most years.

And a second study, in the journal The Cryosphere, offers a measure of the sea ice loss even now. More than a century ago, the great explorer Fridtjof Nansen sailed his ship the Fram into the polar ice, became fast, and travelled with the floe across the Arctic Ocean.

His became the first scientific observation of a phenomenon called the trans-Polar drift, which takes algae, sediments and nutrients – and increasingly, plastic pollution – across the Arctic from Siberia to Canada and Greenland.

Melted out

In October a team of international researchers boarded a vessel called Polarstern with the intention of measuring the ice movement in the modern Arctic in more detail. They had planned for a year fast in the ice. Their project even has a name: Mosaic, or Multidisciplinary drifting Observatory for the Study of Arctic Climate.

But climate simulations by the US scientists reveal that in every sense, the project is on thin ice and could end prematurely. The flow of ice could be faster, and carry the ship further, than expected: nearly one in five of the simulations also predicted that the ship could melt out of the ice in less than a year.

“The changes in the Arctic system are so incredibly rapid that even our satellite observations from 15 years ago are unlike the Arctic today,” said one of the authors, Marika Holland of the US National Center for Atmospheric Research.

“Now there is thinner ice, which moves more quickly, and there is less snow cover. It is a totally different ice regime.” – Climate News Network

Cloudless skies hasten Greenland’s ice loss

This story is a part of Covering Climate Now’s week of coverage focused on Climate Solutions, to mark the 50th anniversary of Earth Day. Covering Climate Now is a global journalism collaboration committed to strengthening coverage of the climate story.

 

The bad news about Greenland’s ice loss has just got even worse. Blame it on mischief by blue skies all day long.

LONDON, 22 April, 2020 – Greenland’s ice loss reached record levels in 2019, and scientists think they’ve identified the culprit: the good weather which normally brings the snow-bearing clouds to the High Arctic.

The huge island, the biggest bank of ice in the northern hemisphere, has been losing ice at an ever-increasing rate in a rapidly warming world. Last year it shed more ice than ever, and this time because the skies were unusually clear.

There is enough ice on Greenland to raise global sea levels by more than seven metres. A recent study established that in the years between 1992 and 2018, rates of polar ice loss have risen six-fold, and so much water has flowed off the Greenland ice surface that sea levels have risen by more than 10mm everywhere.

Now a new study by US and Belgian scientists in the journal The Cryosphere confirms that 2019 was even worse. Because of good weather and cloudless skies, only enough snow fell to deposit 50 billion tonnes of ice into the island’s profit-and-loss ice account. The average annual deposit between 1981 and 2010 was about 375bn tonnes.

But glaciers still flowed towards the sea at an ever-increasing rate, summer snow melt continued to flow off the ice sheet, and icebergs continued to calve, so on balance the island lost 600 billion tonnes of ice: enough to raise global sea levels by 1.5mm. This is the biggest overall loss of ice since records in Greenland began in 1948.

“These atmospheric conditions are becoming more and more frequent over the past few decades. It is very likely that this is due to the waviness of the jet stream”

The cause: unusual spells of high atmospheric pressure over the island for unusually long periods of time. That stopped the formation of clouds, and that meant less precipitation, in the form of snow. Snow reflects solar radiation more effectively than ice, so the surface absorbed more heat and melting also accelerated.

The pattern of warm moist clouds trapped over northern Greenland by the heat that would normally radiate off the ice, instead of releasing snow, also emitted their own heat, to make things worse. The worst year for surface melting remains 2012, but the summer of 2019 was a good second.

The implication is that things could get worse, and losses of Greenland ice could accelerate.

“These atmospheric conditions are becoming more and more frequent over the past few decades,” said Marco Tedesco, of the Lamont-Doherty Earth Observatory at the University of Columbia in the US, the lead author.

“It is very likely that this is due to the waviness of the jet stream, which we think is related to, among other things, the disappearance of snow cover in Siberia, the disappearance of sea ice, and the difference in the rate at which temperature is increasing in the Arctic versus the mid-latitudes.” – Climate News Network

This story is a part of Covering Climate Now’s week of coverage focused on Climate Solutions, to mark the 50th anniversary of Earth Day. Covering Climate Now is a global journalism collaboration committed to strengthening coverage of the climate story.

 

The bad news about Greenland’s ice loss has just got even worse. Blame it on mischief by blue skies all day long.

LONDON, 22 April, 2020 – Greenland’s ice loss reached record levels in 2019, and scientists think they’ve identified the culprit: the good weather which normally brings the snow-bearing clouds to the High Arctic.

The huge island, the biggest bank of ice in the northern hemisphere, has been losing ice at an ever-increasing rate in a rapidly warming world. Last year it shed more ice than ever, and this time because the skies were unusually clear.

There is enough ice on Greenland to raise global sea levels by more than seven metres. A recent study established that in the years between 1992 and 2018, rates of polar ice loss have risen six-fold, and so much water has flowed off the Greenland ice surface that sea levels have risen by more than 10mm everywhere.

Now a new study by US and Belgian scientists in the journal The Cryosphere confirms that 2019 was even worse. Because of good weather and cloudless skies, only enough snow fell to deposit 50 billion tonnes of ice into the island’s profit-and-loss ice account. The average annual deposit between 1981 and 2010 was about 375bn tonnes.

But glaciers still flowed towards the sea at an ever-increasing rate, summer snow melt continued to flow off the ice sheet, and icebergs continued to calve, so on balance the island lost 600 billion tonnes of ice: enough to raise global sea levels by 1.5mm. This is the biggest overall loss of ice since records in Greenland began in 1948.

“These atmospheric conditions are becoming more and more frequent over the past few decades. It is very likely that this is due to the waviness of the jet stream”

The cause: unusual spells of high atmospheric pressure over the island for unusually long periods of time. That stopped the formation of clouds, and that meant less precipitation, in the form of snow. Snow reflects solar radiation more effectively than ice, so the surface absorbed more heat and melting also accelerated.

The pattern of warm moist clouds trapped over northern Greenland by the heat that would normally radiate off the ice, instead of releasing snow, also emitted their own heat, to make things worse. The worst year for surface melting remains 2012, but the summer of 2019 was a good second.

The implication is that things could get worse, and losses of Greenland ice could accelerate.

“These atmospheric conditions are becoming more and more frequent over the past few decades,” said Marco Tedesco, of the Lamont-Doherty Earth Observatory at the University of Columbia in the US, the lead author.

“It is very likely that this is due to the waviness of the jet stream, which we think is related to, among other things, the disappearance of snow cover in Siberia, the disappearance of sea ice, and the difference in the rate at which temperature is increasing in the Arctic versus the mid-latitudes.” – Climate News Network

Ancient ice-free polar forest could soon return

An ice-free polar forest once flourished, helped by enough heat and ample greenhouse gas. It could come back.

LONDON, 10 April, 2020 – Many millions of years ago, the southern continent wasn’t frozen at all, but basked in heat balmy enough for an ice-free polar forest to thrive. And ancient pre-history could repeat itself.

Climate scientists can tell you what the world could be like were today’s greenhouse gas concentrations to triple – which they could do if humans go on clearing tropical forests and burning fossil fuels.

They know because, 90 million years ago, the last time when carbon dioxide levels in the atmosphere went past the 1200 ppm (parts per million) mark, sea levels were 170 metres higher than today and the world was so warm that dense forests grew in what is now Antarctica.

At latitude 82 South, a region where the polar night lasts for four months, there was no icecap. Instead, the continental rocks were colonised by conifer forest, with a mix of tree ferns and an understorey of flowering shrubs.

Even though at that latitude the midday sun would have been relatively low in the sky, and the forests would have had to survive sustained winter darkness for a dozen weeks or more, average temperatures would have been that of modern day Tasmania, and a good 2C° warmer than modern Germany.

“Even during months of darkness, swampy temperate forests were able to grow close to the South Pole, revealing an even warmer climate than we expected”

German and British researchers report in the journal Nature that they took a closer look at a sequence of strangely-coloured mudstone in a core drilled 30 metres below the bottom of the sea floor, off West Antarctica.

The section of sediment had been preserved from the mid-Cretaceous, around 90 million years ago, in a world dominated by dinosaurs. By then, the first mammals may have evolved, the grasses were about to emerge, and seasonal flowering plants had begun to colonise a planet dominated for aeons by evergreens.

And in the preserved silt were pollens, spores, tangled roots and other plant material so well preserved that the researchers could not just identify the plant families, but even take a guess at parallels with modern forests. Before their eyes was evidence of something like the modern rainforests of New Zealand’s South Island, but deep inside the Antarctic Circle.

“The preservation of this 90 million-year-old forest is exceptional, but even more surprising is the world it reveals,” said Tina van de Flierdt, of Imperial College London.

“Even during months of darkness, swampy temperate forests were able to grow close to the South Pole, revealing an even warmer climate than we expected.”

British rain levels

Somewhere between 115 and 85 million years ago, the whole world was a lot hotter: in the tropics temperatures reached 35°C and the average temperature of that part of the Antarctic was 13°C. This is at least two degrees higher than the average temperature for modern Germany.

Average temperatures in summer went up to 18.5°C, and the water temperatures in the swamps and rivers tipped 20°C, only 900 kms from the then South Pole. Modern Antarctica is classed as desert, with minimal precipitation: then it would have seen 1120 mm a year. People from southwestern Scotland or parts of Wales would have felt at home.

It is an axiom of earth science that the present is key to the past: if such forests today can flourish at existing temperatures, then the same must have been true in the deep past.

So climate scientists from the start have taken a close interest in the evidence of intensely warm periods in the fossil record: a mix of plant and animal remains, the ratio of chemical isotopes preserved in rock, and even the air bubbles trapped in deep ice cores can help them reconstruct the temperatures, the composition of the atmosphere and the rainfall of, for example, the warmest periods of the Pliocene, when carbon dioxide levels in the atmosphere tipped the 1000 ppm mark, and average planetary temperatures rose by 9°C.

Prehistoric encore approaching?

In the past century, atmospheric CO2 levels have swollen from 285 ppm to more than 400 ppm, and the planetary thermometer has already crept up by 1°C above the level for most of human history. If human economies continue burning fossil fuels at an ever-increasing rate, the conditions that prevailed 56 million years ago could return by 2159.

The Cretaceous evidence will help climate scientists calibrate their models of a world in which greenhouse gas emissions go on rising.

“Before our study, the general assumption was that the global carbon dioxide concentration in the Cretaceous was roughly 1000 ppm,” said Johann Klages, of the Alfred Wegener Institute centre for polar and marine research in Germany, who led the study.

“But in our model-based experiments, it took concentration levels of 1120 to 1680 ppm to reach the average temperatures back then in Antarctica.” – Climate News Network

An ice-free polar forest once flourished, helped by enough heat and ample greenhouse gas. It could come back.

LONDON, 10 April, 2020 – Many millions of years ago, the southern continent wasn’t frozen at all, but basked in heat balmy enough for an ice-free polar forest to thrive. And ancient pre-history could repeat itself.

Climate scientists can tell you what the world could be like were today’s greenhouse gas concentrations to triple – which they could do if humans go on clearing tropical forests and burning fossil fuels.

They know because, 90 million years ago, the last time when carbon dioxide levels in the atmosphere went past the 1200 ppm (parts per million) mark, sea levels were 170 metres higher than today and the world was so warm that dense forests grew in what is now Antarctica.

At latitude 82 South, a region where the polar night lasts for four months, there was no icecap. Instead, the continental rocks were colonised by conifer forest, with a mix of tree ferns and an understorey of flowering shrubs.

Even though at that latitude the midday sun would have been relatively low in the sky, and the forests would have had to survive sustained winter darkness for a dozen weeks or more, average temperatures would have been that of modern day Tasmania, and a good 2C° warmer than modern Germany.

“Even during months of darkness, swampy temperate forests were able to grow close to the South Pole, revealing an even warmer climate than we expected”

German and British researchers report in the journal Nature that they took a closer look at a sequence of strangely-coloured mudstone in a core drilled 30 metres below the bottom of the sea floor, off West Antarctica.

The section of sediment had been preserved from the mid-Cretaceous, around 90 million years ago, in a world dominated by dinosaurs. By then, the first mammals may have evolved, the grasses were about to emerge, and seasonal flowering plants had begun to colonise a planet dominated for aeons by evergreens.

And in the preserved silt were pollens, spores, tangled roots and other plant material so well preserved that the researchers could not just identify the plant families, but even take a guess at parallels with modern forests. Before their eyes was evidence of something like the modern rainforests of New Zealand’s South Island, but deep inside the Antarctic Circle.

“The preservation of this 90 million-year-old forest is exceptional, but even more surprising is the world it reveals,” said Tina van de Flierdt, of Imperial College London.

“Even during months of darkness, swampy temperate forests were able to grow close to the South Pole, revealing an even warmer climate than we expected.”

British rain levels

Somewhere between 115 and 85 million years ago, the whole world was a lot hotter: in the tropics temperatures reached 35°C and the average temperature of that part of the Antarctic was 13°C. This is at least two degrees higher than the average temperature for modern Germany.

Average temperatures in summer went up to 18.5°C, and the water temperatures in the swamps and rivers tipped 20°C, only 900 kms from the then South Pole. Modern Antarctica is classed as desert, with minimal precipitation: then it would have seen 1120 mm a year. People from southwestern Scotland or parts of Wales would have felt at home.

It is an axiom of earth science that the present is key to the past: if such forests today can flourish at existing temperatures, then the same must have been true in the deep past.

So climate scientists from the start have taken a close interest in the evidence of intensely warm periods in the fossil record: a mix of plant and animal remains, the ratio of chemical isotopes preserved in rock, and even the air bubbles trapped in deep ice cores can help them reconstruct the temperatures, the composition of the atmosphere and the rainfall of, for example, the warmest periods of the Pliocene, when carbon dioxide levels in the atmosphere tipped the 1000 ppm mark, and average planetary temperatures rose by 9°C.

Prehistoric encore approaching?

In the past century, atmospheric CO2 levels have swollen from 285 ppm to more than 400 ppm, and the planetary thermometer has already crept up by 1°C above the level for most of human history. If human economies continue burning fossil fuels at an ever-increasing rate, the conditions that prevailed 56 million years ago could return by 2159.

The Cretaceous evidence will help climate scientists calibrate their models of a world in which greenhouse gas emissions go on rising.

“Before our study, the general assumption was that the global carbon dioxide concentration in the Cretaceous was roughly 1000 ppm,” said Johann Klages, of the Alfred Wegener Institute centre for polar and marine research in Germany, who led the study.

“But in our model-based experiments, it took concentration levels of 1120 to 1680 ppm to reach the average temperatures back then in Antarctica.” – Climate News Network

Poles attract marine life avoiding rising heat

In a warming ocean, some species will swim, others sink. But all agree: the poles attract marine life without exception.

LONDON, 3 April, 2020 − It’s the same the whole world over: everywhere in the oceans of this warming planet, the poles attract marine life.

Molluscs are on the move, haddock are feeling the heat, and penguins are shifting further south. Nautilus are heading north, and plankton are edging towards both poles.

New analysis of marine species has confirmed what commercial fishermen already know to their cost: that as the oceans warm, the sea’s citizens shift their grounds.

Researchers report in the journal Current Biology that they surveyed the evidence assembled in 540 records of 304 widely distributed marine animals over the last century, to find that all of them are shifting their range: away from the equatorial waters, and in both hemispheres nearer to the poles.

In the past century, overall, the world’s oceans have warmed by around 1°C. By 2050, the rise may reach 1.5°C, and all the evidence so far suggests fish and shellfish, along with the microbial creatures at the bottom of the food chain and the marine mammals and seabirds that prey on them all, will have shifted their latitudinal range.

“Both increasing and decreasing abundances may have harmful knock-on effects for the wider ecosystem”

The greatest abundance of any species, the researchers found, was likely to be at the poleward edge of the preferred range, and the sparsest nearest to the tropical waters.

“The main surprise is how pervasive the effects were. We found the same trend across all groups of marine life we looked at, from plankton to marine invertebrates, and from fish to seabirds,” said Martin Genner, an evolutionary ecologist at the University of Bristol in the UK.

“This matters because it means that climate change is not only leading abundance changes, but intrinsically affecting the performance of species locally. We see species such as the Emperor penguin becoming less abundant as the water becomes too warm at their equatorward edge, and we see some fish such as the European sea bass thriving at their poleward edge, where historically they were uncommon.”

Fish and many marine animals have a preferred range of temperatures, and even seemingly imperceptible shifts can have unpredictable effects. Both individual research and commercial catch data have confirmed a series of shifts in response to global heating.

Winners and losers

Tropical fish are shifting away from the hottest waters, North Sea catches are more likely to be found in north Atlantic waters, and some Mediterranean species have now shifted to the waters of Western Europe.

The latest research suggests that whole ecosystems may be on the move, and with them Atlantic herring and Adelie penguins, loggerhead turtles and phytoplankton.

“Some marine species appear to benefit from climate change, particularly some populations at the poleward limits that are now able to thrive,” said Louise Rutterford, another of the research team at Bristol.

“Meanwhile, some marine life suffers as it is not able to adapt fast enough to survive warming, and this is most noticeable in populations nearer the equator.

“This is concerning, as both increasing and decreasing abundances may have harmful knock-on effects for the wider ecosystem.” − Climate News Network

In a warming ocean, some species will swim, others sink. But all agree: the poles attract marine life without exception.

LONDON, 3 April, 2020 − It’s the same the whole world over: everywhere in the oceans of this warming planet, the poles attract marine life.

Molluscs are on the move, haddock are feeling the heat, and penguins are shifting further south. Nautilus are heading north, and plankton are edging towards both poles.

New analysis of marine species has confirmed what commercial fishermen already know to their cost: that as the oceans warm, the sea’s citizens shift their grounds.

Researchers report in the journal Current Biology that they surveyed the evidence assembled in 540 records of 304 widely distributed marine animals over the last century, to find that all of them are shifting their range: away from the equatorial waters, and in both hemispheres nearer to the poles.

In the past century, overall, the world’s oceans have warmed by around 1°C. By 2050, the rise may reach 1.5°C, and all the evidence so far suggests fish and shellfish, along with the microbial creatures at the bottom of the food chain and the marine mammals and seabirds that prey on them all, will have shifted their latitudinal range.

“Both increasing and decreasing abundances may have harmful knock-on effects for the wider ecosystem”

The greatest abundance of any species, the researchers found, was likely to be at the poleward edge of the preferred range, and the sparsest nearest to the tropical waters.

“The main surprise is how pervasive the effects were. We found the same trend across all groups of marine life we looked at, from plankton to marine invertebrates, and from fish to seabirds,” said Martin Genner, an evolutionary ecologist at the University of Bristol in the UK.

“This matters because it means that climate change is not only leading abundance changes, but intrinsically affecting the performance of species locally. We see species such as the Emperor penguin becoming less abundant as the water becomes too warm at their equatorward edge, and we see some fish such as the European sea bass thriving at their poleward edge, where historically they were uncommon.”

Fish and many marine animals have a preferred range of temperatures, and even seemingly imperceptible shifts can have unpredictable effects. Both individual research and commercial catch data have confirmed a series of shifts in response to global heating.

Winners and losers

Tropical fish are shifting away from the hottest waters, North Sea catches are more likely to be found in north Atlantic waters, and some Mediterranean species have now shifted to the waters of Western Europe.

The latest research suggests that whole ecosystems may be on the move, and with them Atlantic herring and Adelie penguins, loggerhead turtles and phytoplankton.

“Some marine species appear to benefit from climate change, particularly some populations at the poleward limits that are now able to thrive,” said Louise Rutterford, another of the research team at Bristol.

“Meanwhile, some marine life suffers as it is not able to adapt fast enough to survive warming, and this is most noticeable in populations nearer the equator.

“This is concerning, as both increasing and decreasing abundances may have harmful knock-on effects for the wider ecosystem.” − Climate News Network

Northern Europe’s warm water flow may falter

Global heating can stop the flow of Europe’s warm water from the tropics. Happening often during the Ice Ages, it could soon recur.

LONDON, 1 April, 2020 – Oceanographers have confirmed once again that global heating could slow or shut down the flow of currents such as the Gulf Stream, ending northern Europe’s warm water supply with an unexpected and prolonged cold snap.

This time the confidence is based neither on ocean measurements made now, nor complex computer simulations of the future. There is fresh evidence from the sea floor that such an ocean shutdown happened many times in the last half a million years of Ice Ages.

The Gulf Stream is part of a much larger flow of water called the Atlantic Meridional Overturning Circulation, an ocean recycling system that both nourishes marine life and moderates the climate in two hemispheres.

For the last 10,000 years of human history, tropical water has flowed north from the Caribbean and equatorial regions and washed the shores of Europe as far north as Norway, bringing equatorial heat to soften the impact of European winters.

A former UK chief scientist once calculated that the Gulf Stream delivered the warmth of 27,000 power stations and kept Britain about 5°C warmer than its citizens had any right to expect, given the latitude at which they lived.

“These findings suggest that our climate system, which depends greatly on deep ocean circulation, is critically poised near a tipping point for abrupt disruptions”

But as that stretch of the Gulf Stream known to oceanographers as the North Atlantic drift current reaches the Greenland Sea it becomes increasingly colder and saltier and thus more dense, and sinks to the ocean floor, loaded with dissolved atmospheric carbon dioxide and oxygen, to become a southward flow called the North Atlantic Deepwater formation.

And it also mingles with fresh water melting each summer from the Greenland ice sheet. But as the rate of Arctic melting accelerates, more fresh water will plunge into the same sea, with an increasing probability that it will disrupt the ocean cycle, turn off the flow of warm tropical water, and plunge Europe into a prolonged cold spell.

In its most dramatic form, this hypothesis was the basis for a 2004 Hollywood disaster movie called The Day After Tomorrow. Climate scientists are fairly sure that such an event would not mean the sudden advance of glacial ice over much of Europe and North America. But they have repeatedly identified evidence that the flow of the northward current is beginning to weaken.

And the journal Science now carries additional evidence that the ocean circulation was repeatedly interrupted for periods of a century or more during the warm spells or interglacials that have happened during the last 450,000 years.

Shells’ signatures

The signature of ocean change is there in the tiny sea shells from marine creatures called foraminifera that rain down onto the ocean floor to form annual layers of silent testimony to past climates.

When the mix of carbon isotope ratios preserved in them is high, that is a sign that the Atlantic circulation was once vigorous. When it is low, then this overturning circulation is feeble, or has stopped altogether.

The signal from the deep ocean is that when they happen, these disruptions seem to happen very swiftly, and to linger for 100 years or more. And, the scientists say, these interruptions in the flow of the ocean – and with it, the transport of heat from the tropics – happen more easily than previously appreciated, and they occurred in past climate conditions similar to those the world may soon face.

“These findings suggest that our climate system, which depends greatly on deep ocean circulation, is critically poised near a tipping point for abrupt disruptions,” said Yair Rosenthal of Rutgers University in the US, one of the authors.

“Although the disruptions in circulation and possible coolings may be relatively short-lived – lasting maybe a century or more – the consequences might be large.” – Climate News Network

Global heating can stop the flow of Europe’s warm water from the tropics. Happening often during the Ice Ages, it could soon recur.

LONDON, 1 April, 2020 – Oceanographers have confirmed once again that global heating could slow or shut down the flow of currents such as the Gulf Stream, ending northern Europe’s warm water supply with an unexpected and prolonged cold snap.

This time the confidence is based neither on ocean measurements made now, nor complex computer simulations of the future. There is fresh evidence from the sea floor that such an ocean shutdown happened many times in the last half a million years of Ice Ages.

The Gulf Stream is part of a much larger flow of water called the Atlantic Meridional Overturning Circulation, an ocean recycling system that both nourishes marine life and moderates the climate in two hemispheres.

For the last 10,000 years of human history, tropical water has flowed north from the Caribbean and equatorial regions and washed the shores of Europe as far north as Norway, bringing equatorial heat to soften the impact of European winters.

A former UK chief scientist once calculated that the Gulf Stream delivered the warmth of 27,000 power stations and kept Britain about 5°C warmer than its citizens had any right to expect, given the latitude at which they lived.

“These findings suggest that our climate system, which depends greatly on deep ocean circulation, is critically poised near a tipping point for abrupt disruptions”

But as that stretch of the Gulf Stream known to oceanographers as the North Atlantic drift current reaches the Greenland Sea it becomes increasingly colder and saltier and thus more dense, and sinks to the ocean floor, loaded with dissolved atmospheric carbon dioxide and oxygen, to become a southward flow called the North Atlantic Deepwater formation.

And it also mingles with fresh water melting each summer from the Greenland ice sheet. But as the rate of Arctic melting accelerates, more fresh water will plunge into the same sea, with an increasing probability that it will disrupt the ocean cycle, turn off the flow of warm tropical water, and plunge Europe into a prolonged cold spell.

In its most dramatic form, this hypothesis was the basis for a 2004 Hollywood disaster movie called The Day After Tomorrow. Climate scientists are fairly sure that such an event would not mean the sudden advance of glacial ice over much of Europe and North America. But they have repeatedly identified evidence that the flow of the northward current is beginning to weaken.

And the journal Science now carries additional evidence that the ocean circulation was repeatedly interrupted for periods of a century or more during the warm spells or interglacials that have happened during the last 450,000 years.

Shells’ signatures

The signature of ocean change is there in the tiny sea shells from marine creatures called foraminifera that rain down onto the ocean floor to form annual layers of silent testimony to past climates.

When the mix of carbon isotope ratios preserved in them is high, that is a sign that the Atlantic circulation was once vigorous. When it is low, then this overturning circulation is feeble, or has stopped altogether.

The signal from the deep ocean is that when they happen, these disruptions seem to happen very swiftly, and to linger for 100 years or more. And, the scientists say, these interruptions in the flow of the ocean – and with it, the transport of heat from the tropics – happen more easily than previously appreciated, and they occurred in past climate conditions similar to those the world may soon face.

“These findings suggest that our climate system, which depends greatly on deep ocean circulation, is critically poised near a tipping point for abrupt disruptions,” said Yair Rosenthal of Rutgers University in the US, one of the authors.

“Although the disruptions in circulation and possible coolings may be relatively short-lived – lasting maybe a century or more – the consequences might be large.” – Climate News Network