Tag Archives: Albedo

Arctic melt speeding up

FOR IMMEDIATE RELEASE It’s long been established that Arctic ice is on the retreat but it’s the pace of change that’s surprising scientists: latest studies show the region is at its warmest for 40,000 years.  LONDON, 9 March – Ice in the Arctic continues to retreat. The season without ice is getting longer by an average of five days every 10 years, according to a new study in Geophysical Research Letters.  And in some regions of the Arctic, the autumn freeze is now up to 11 days later every decade. This means that a greater proportion of the polar region for a longer timespan no longer reflects sunlight but absorbs it. This change in albedo – the scientist’s term for a planet’s reflectivity – means that open sea absorbs radiation, stays warmer, and freezes again ever later.

Warming accelerates

None of this is news: sea ice in the Arctic has been both retreating and thinning in volume for four decades. Researchers have tracked the retreat of the snow line to find tiny plants exposed that had been frozen over 40,000 years ago: the implication is that the Arctic is warmer now than it has been for 40 millennia. This warming threatens the animals that depend for their existence on a stable cycle of seasons  and is accelerating at such a rate that the polar ocean could be entirely free of ice in late summer in the next four decades. So Julienne Stroeve, of University College London and her colleagues have provided yet further confirmation of an increasing rate of change in the region in their latest study. The scientists examined satellite imagery of the Arctic for the last 30 years, on 25 square kilometer grid, to work out the albedo of each square for every month they had data. Their headline figure of five days is an average: in fact the pattern of freeze and thaw in the Arctic varies. In one region the melt season has been extended by 13 days, in another the melt season is actually getting shorter.

Energy increases

This increasing exposure to summer sunlight means that ever greater quantities of energy are being absorbed: several times the energy of the atomic bomb dropped on Hiroshima hits every square kilometer of the open Arctic Ocean. “The extent of sea ice in the Arctic has been declining for the last four decades,” said Professor Stroeve, “and the timing of when melt begins and ends has a large impact on the amount of ice lost each summer. With the Arctic region becoming more accessible for longer periods of time, there is a growing need for improved prediction of when the ice retreats and reforms in the water.” – Climate News Network  

FOR IMMEDIATE RELEASE It’s long been established that Arctic ice is on the retreat but it’s the pace of change that’s surprising scientists: latest studies show the region is at its warmest for 40,000 years.  LONDON, 9 March – Ice in the Arctic continues to retreat. The season without ice is getting longer by an average of five days every 10 years, according to a new study in Geophysical Research Letters.  And in some regions of the Arctic, the autumn freeze is now up to 11 days later every decade. This means that a greater proportion of the polar region for a longer timespan no longer reflects sunlight but absorbs it. This change in albedo – the scientist’s term for a planet’s reflectivity – means that open sea absorbs radiation, stays warmer, and freezes again ever later.

Warming accelerates

None of this is news: sea ice in the Arctic has been both retreating and thinning in volume for four decades. Researchers have tracked the retreat of the snow line to find tiny plants exposed that had been frozen over 40,000 years ago: the implication is that the Arctic is warmer now than it has been for 40 millennia. This warming threatens the animals that depend for their existence on a stable cycle of seasons  and is accelerating at such a rate that the polar ocean could be entirely free of ice in late summer in the next four decades. So Julienne Stroeve, of University College London and her colleagues have provided yet further confirmation of an increasing rate of change in the region in their latest study. The scientists examined satellite imagery of the Arctic for the last 30 years, on 25 square kilometer grid, to work out the albedo of each square for every month they had data. Their headline figure of five days is an average: in fact the pattern of freeze and thaw in the Arctic varies. In one region the melt season has been extended by 13 days, in another the melt season is actually getting shorter.

Energy increases

This increasing exposure to summer sunlight means that ever greater quantities of energy are being absorbed: several times the energy of the atomic bomb dropped on Hiroshima hits every square kilometer of the open Arctic Ocean. “The extent of sea ice in the Arctic has been declining for the last four decades,” said Professor Stroeve, “and the timing of when melt begins and ends has a large impact on the amount of ice lost each summer. With the Arctic region becoming more accessible for longer periods of time, there is a growing need for improved prediction of when the ice retreats and reforms in the water.” – Climate News Network  

Arctic 'is set to reach 13°C by 2100'

FOR IMMEDIATE RELEASE
There is wide political agreement that global average temperatures should not rise more than 2°C above their level several centuries ago. The rise some scientists expect in the Arctic by 2100 is more than six times as great.

LONDON, 20 February – US scientists say that by the end of this century temperatures in the Arctic may for part of each year reach 13°C above pre-industrial levels. Global average temperatures have already risen by about 0.8°C over the level they were at in around 1750.

The Intergovernmental Panel on Climate Change said in its 2013 Fifth Assessment Report that it thought the probable global temperature rise by 2100 would be between 1.5 and 4°C under most scenarios. Most of the world’s governments have agreed the global rise should not be allowed to exceed a “safety level” of 2°C.

But James Overland, of the US National Oceanic and Atmospheric Administration, and colleagues, writing in the American Geophysical Union’s journal Earth’s Future, say average temperature projections show an Arctic-wide end of century increase of 13°C in the late autumn and 5°C in late spring for a business-as-usual emission scenario.

By contrast, a scenario based on climate mitigation would reduce these figures to 7°C and 3°C respectively. The team say they consider their estimates “realistic”, and they have used a large number of models in reaching them.

Ice fall

The Arctic is known to be warming fast, much faster than regions further south. The mean Arctic temperature is 1.5°C higher today than it was between 1971 and 2000, double the warming that occurred at lower latitudes during the same period.

The authors say Arctic sea ice volume has decreased by 75% since the 1980s. Reasons for the rapid warming include feedback processes linked to changes in albedo, which have caused a big drop in the ability of the Arctic’s snow and ice to reflect sunlight back into space.

As they melt they are replaced by darker rock and water, which, instead of reflecting the warmth away from the Earth, absorb it and help to raise the temperature. There are also changes taking place in ocean and land heat storage. These all help to amplify the effect of greenhouse gases in warming the Arctic.

Professor Overland and his colleagues say it is very likely that the Arctic Ocean will become nearly free of sea ice at some seasons of the year before 2050, and possibly within a decade or two. This in turn will further increase Arctic temperatures, economic access (for oil and gas exploitation and by shipping), and ecological shifts.

No agreement

The greenhouse gas emissions mitigation scenario the authors use (known as RCP4.5) assumes atmospheric concentrations of carbon dioxide (CO2) of about 538 parts per million (ppm). Before the Industrial Revolution concentrations were at about 280 ppm, and had changed little over many millennia. They are now at their highest in 15 million years, and rising at about 2 ppm annually, reaching almost 400 pp

Greenhouse gas emissions continue to rise, and so far world leaders have not managed to agree how to reduce them. Their efforts are now concentrated on next year’s UN climate change convention meeting, to be held in the French capital, Paris.

Professor Overland and his colleagues conclude that major changes in the Arctic climate are “very likely” over the decades until 2040, including “several additional months of open water in the Arctic Ocean, ever earlier snow melt, further loss of permafrost, increased economic access, and dramatic impacts on ecological systems.”

They say the large difference in surface air temperatures in the Arctic at the end of the century, which they are confident will happen, “makes a strong case to begin mitigation activities for greenhouse gases”. – Climate News Network

FOR IMMEDIATE RELEASE
There is wide political agreement that global average temperatures should not rise more than 2°C above their level several centuries ago. The rise some scientists expect in the Arctic by 2100 is more than six times as great.

LONDON, 20 February – US scientists say that by the end of this century temperatures in the Arctic may for part of each year reach 13°C above pre-industrial levels. Global average temperatures have already risen by about 0.8°C over the level they were at in around 1750.

The Intergovernmental Panel on Climate Change said in its 2013 Fifth Assessment Report that it thought the probable global temperature rise by 2100 would be between 1.5 and 4°C under most scenarios. Most of the world’s governments have agreed the global rise should not be allowed to exceed a “safety level” of 2°C.

But James Overland, of the US National Oceanic and Atmospheric Administration, and colleagues, writing in the American Geophysical Union’s journal Earth’s Future, say average temperature projections show an Arctic-wide end of century increase of 13°C in the late autumn and 5°C in late spring for a business-as-usual emission scenario.

By contrast, a scenario based on climate mitigation would reduce these figures to 7°C and 3°C respectively. The team say they consider their estimates “realistic”, and they have used a large number of models in reaching them.

Ice fall

The Arctic is known to be warming fast, much faster than regions further south. The mean Arctic temperature is 1.5°C higher today than it was between 1971 and 2000, double the warming that occurred at lower latitudes during the same period.

The authors say Arctic sea ice volume has decreased by 75% since the 1980s. Reasons for the rapid warming include feedback processes linked to changes in albedo, which have caused a big drop in the ability of the Arctic’s snow and ice to reflect sunlight back into space.

As they melt they are replaced by darker rock and water, which, instead of reflecting the warmth away from the Earth, absorb it and help to raise the temperature. There are also changes taking place in ocean and land heat storage. These all help to amplify the effect of greenhouse gases in warming the Arctic.

Professor Overland and his colleagues say it is very likely that the Arctic Ocean will become nearly free of sea ice at some seasons of the year before 2050, and possibly within a decade or two. This in turn will further increase Arctic temperatures, economic access (for oil and gas exploitation and by shipping), and ecological shifts.

No agreement

The greenhouse gas emissions mitigation scenario the authors use (known as RCP4.5) assumes atmospheric concentrations of carbon dioxide (CO2) of about 538 parts per million (ppm). Before the Industrial Revolution concentrations were at about 280 ppm, and had changed little over many millennia. They are now at their highest in 15 million years, and rising at about 2 ppm annually, reaching almost 400 pp

Greenhouse gas emissions continue to rise, and so far world leaders have not managed to agree how to reduce them. Their efforts are now concentrated on next year’s UN climate change convention meeting, to be held in the French capital, Paris.

Professor Overland and his colleagues conclude that major changes in the Arctic climate are “very likely” over the decades until 2040, including “several additional months of open water in the Arctic Ocean, ever earlier snow melt, further loss of permafrost, increased economic access, and dramatic impacts on ecological systems.”

They say the large difference in surface air temperatures in the Arctic at the end of the century, which they are confident will happen, “makes a strong case to begin mitigation activities for greenhouse gases”. – Climate News Network

Arctic ‘is set to reach 13°C by 2100’

FOR IMMEDIATE RELEASE There is wide political agreement that global average temperatures should not rise more than 2°C above their level several centuries ago. The rise some scientists expect in the Arctic by 2100 is more than six times as great. LONDON, 20 February – US scientists say that by the end of this century temperatures in the Arctic may for part of each year reach 13°C above pre-industrial levels. Global average temperatures have already risen by about 0.8°C over the level they were at in around 1750. The Intergovernmental Panel on Climate Change said in its 2013 Fifth Assessment Report that it thought the probable global temperature rise by 2100 would be between 1.5 and 4°C under most scenarios. Most of the world’s governments have agreed the global rise should not be allowed to exceed a “safety level” of 2°C. But James Overland, of the US National Oceanic and Atmospheric Administration, and colleagues, writing in the American Geophysical Union’s journal Earth’s Future, say average temperature projections show an Arctic-wide end of century increase of 13°C in the late autumn and 5°C in late spring for a business-as-usual emission scenario. By contrast, a scenario based on climate mitigation would reduce these figures to 7°C and 3°C respectively. The team say they consider their estimates “realistic”, and they have used a large number of models in reaching them.

Ice fall

The Arctic is known to be warming fast, much faster than regions further south. The mean Arctic temperature is 1.5°C higher today than it was between 1971 and 2000, double the warming that occurred at lower latitudes during the same period. The authors say Arctic sea ice volume has decreased by 75% since the 1980s. Reasons for the rapid warming include feedback processes linked to changes in albedo, which have caused a big drop in the ability of the Arctic’s snow and ice to reflect sunlight back into space. As they melt they are replaced by darker rock and water, which, instead of reflecting the warmth away from the Earth, absorb it and help to raise the temperature. There are also changes taking place in ocean and land heat storage. These all help to amplify the effect of greenhouse gases in warming the Arctic. Professor Overland and his colleagues say it is very likely that the Arctic Ocean will become nearly free of sea ice at some seasons of the year before 2050, and possibly within a decade or two. This in turn will further increase Arctic temperatures, economic access (for oil and gas exploitation and by shipping), and ecological shifts.

No agreement

The greenhouse gas emissions mitigation scenario the authors use (known as RCP4.5) assumes atmospheric concentrations of carbon dioxide (CO2) of about 538 parts per million (ppm). Before the Industrial Revolution concentrations were at about 280 ppm, and had changed little over many millennia. They are now at their highest in 15 million years, and rising at about 2 ppm annually, reaching almost 400 pp Greenhouse gas emissions continue to rise, and so far world leaders have not managed to agree how to reduce them. Their efforts are now concentrated on next year’s UN climate change convention meeting, to be held in the French capital, Paris. Professor Overland and his colleagues conclude that major changes in the Arctic climate are “very likely” over the decades until 2040, including “several additional months of open water in the Arctic Ocean, ever earlier snow melt, further loss of permafrost, increased economic access, and dramatic impacts on ecological systems.” They say the large difference in surface air temperatures in the Arctic at the end of the century, which they are confident will happen, “makes a strong case to begin mitigation activities for greenhouse gases”. – Climate News Network

FOR IMMEDIATE RELEASE There is wide political agreement that global average temperatures should not rise more than 2°C above their level several centuries ago. The rise some scientists expect in the Arctic by 2100 is more than six times as great. LONDON, 20 February – US scientists say that by the end of this century temperatures in the Arctic may for part of each year reach 13°C above pre-industrial levels. Global average temperatures have already risen by about 0.8°C over the level they were at in around 1750. The Intergovernmental Panel on Climate Change said in its 2013 Fifth Assessment Report that it thought the probable global temperature rise by 2100 would be between 1.5 and 4°C under most scenarios. Most of the world’s governments have agreed the global rise should not be allowed to exceed a “safety level” of 2°C. But James Overland, of the US National Oceanic and Atmospheric Administration, and colleagues, writing in the American Geophysical Union’s journal Earth’s Future, say average temperature projections show an Arctic-wide end of century increase of 13°C in the late autumn and 5°C in late spring for a business-as-usual emission scenario. By contrast, a scenario based on climate mitigation would reduce these figures to 7°C and 3°C respectively. The team say they consider their estimates “realistic”, and they have used a large number of models in reaching them.

Ice fall

The Arctic is known to be warming fast, much faster than regions further south. The mean Arctic temperature is 1.5°C higher today than it was between 1971 and 2000, double the warming that occurred at lower latitudes during the same period. The authors say Arctic sea ice volume has decreased by 75% since the 1980s. Reasons for the rapid warming include feedback processes linked to changes in albedo, which have caused a big drop in the ability of the Arctic’s snow and ice to reflect sunlight back into space. As they melt they are replaced by darker rock and water, which, instead of reflecting the warmth away from the Earth, absorb it and help to raise the temperature. There are also changes taking place in ocean and land heat storage. These all help to amplify the effect of greenhouse gases in warming the Arctic. Professor Overland and his colleagues say it is very likely that the Arctic Ocean will become nearly free of sea ice at some seasons of the year before 2050, and possibly within a decade or two. This in turn will further increase Arctic temperatures, economic access (for oil and gas exploitation and by shipping), and ecological shifts.

No agreement

The greenhouse gas emissions mitigation scenario the authors use (known as RCP4.5) assumes atmospheric concentrations of carbon dioxide (CO2) of about 538 parts per million (ppm). Before the Industrial Revolution concentrations were at about 280 ppm, and had changed little over many millennia. They are now at their highest in 15 million years, and rising at about 2 ppm annually, reaching almost 400 pp Greenhouse gas emissions continue to rise, and so far world leaders have not managed to agree how to reduce them. Their efforts are now concentrated on next year’s UN climate change convention meeting, to be held in the French capital, Paris. Professor Overland and his colleagues conclude that major changes in the Arctic climate are “very likely” over the decades until 2040, including “several additional months of open water in the Arctic Ocean, ever earlier snow melt, further loss of permafrost, increased economic access, and dramatic impacts on ecological systems.” They say the large difference in surface air temperatures in the Arctic at the end of the century, which they are confident will happen, “makes a strong case to begin mitigation activities for greenhouse gases”. – Climate News Network

Arctic albedo loss threatens wildlife

FOR IMMEDIATE RELEASE The rapid thawing of the region’s sea ice is affecting virtually every species of Arctic wildlife – and a new study of how the rate of melting is accelerating shows the problem is set to worsen. LONDON, 7 August – The loss of Arctic sea ice is bad news for the Pacific walrus, and for polar bears: the walrus has further to swim to dig for clams on the sea floor, and the polar bear has less chance of catching seals. But the real problems begin at the base of the food chain. Since the end of the last century, more than two million square kilometres of sea ice have disappeared, and the loss of summer ice is accelerating. Researchers call this “a stunning loss of habitat for sea ice algae and sub-ice plankton which together account for 57% of the total annual primary production in the Arctic Ocean.” Eric Post, a biologist at Penn State University in the US, and colleagues report in Science that the seasonal timing of the ice algae bloom is critical to the successful reproduction of the zooplankton copepods (small crustaceans) that graze on the algae, and the bloom in phytoplankton that follows the normal seasonal retreat of the sea ice delivers food for the copepod offspring. These two “pulses” in productivity in the Arctic are the basis of the food web for all the higher creatures. The copepod explosion provides breakfast, lunch and supper for whales, seabirds, small fish, crustaceans and so on. But the fact that the total area under ice each summer has been shrinking at 86,000 square kilometres a year, and the annual ice melt season has been extended by at least 20 days, could have profound consequences for the entire ecosystem, and for the big, warm-blooded creatures at the top of the food chain.

Hybrid polar bears

“Our team set out to explore the domino effects of sea ice loss on marine mammals, as well as on land-dwelling species living adjacent to the ice”, said Post. The ice shelf is habitat for large mammals: as the ice thins and dwindles so does the habitat, and therefore the hunting opportunities. Walrus forage for food in shallow waters, and use the sea ice to rest, and to dive from, between foraging. As the ice melts and retreats from the shoreline the ice edge moves over deeper waters, and the walrus community increasingly has to crowd together on the shoreline rather than the ice, making the spread of infection easier, and increasing the dangers of trampling for the young. As the ice retreats, polar bears have less access to seal populations – and supplies of blubber – and they too have begun to mingle populations: there have been increasing reports of hybridisation with grizzly bears. Because sea ice in Arctic Canada is decreasing, there is a greater likelihood of contact between eastern and western Arctic seal populations, and a greater chance that phocine distemper virus will spread from the eastern seals to the western population. Sea ice loss could affect the populations of Arctic fox and wolf – because the loss of ice will increase genetic isolation – and the warming of the land surfaces in the Arctic is beginning to alter the vegetation, with consequences for caribou and other grazers.

Cooling mechanism falters

Another important consequence of sea ice loss is a change in the Arctic albedo – the measure of radiation that normally bounces off the ice and back into space, keeping the Arctic cold. In Nature Climate Change Aku Riihelä of the Finnish Meteorological Institute in Helsinki and colleagues report that they looked at satellite data from 1989 to 2002, during the summer months, for both open water and sea ice regions of the Arctic. They found that all albedo trends show a significant reduction, which is another way of saying that more sunlight is being absorbed into the land and ocean of the Arctic – which will accelerate the rate of warming and the loss of further ice. The consequences of this for the whole Arctic ecosystem will be considerable, warns Professor Post. As the seas open, they become accessible to shipping traffic and drilling rigs, and any increase in this could affect both terrestrial and marine creatures, among them the bowhead whales and the Pacific walrus. “By viewing sea ice as essential habitat and a substrate for important species interactions, rather than as a lifeless blank surface, its loss as a result of warming becomes a rather stunning prospect,” he says. – Climate News Network

FOR IMMEDIATE RELEASE The rapid thawing of the region’s sea ice is affecting virtually every species of Arctic wildlife – and a new study of how the rate of melting is accelerating shows the problem is set to worsen. LONDON, 7 August – The loss of Arctic sea ice is bad news for the Pacific walrus, and for polar bears: the walrus has further to swim to dig for clams on the sea floor, and the polar bear has less chance of catching seals. But the real problems begin at the base of the food chain. Since the end of the last century, more than two million square kilometres of sea ice have disappeared, and the loss of summer ice is accelerating. Researchers call this “a stunning loss of habitat for sea ice algae and sub-ice plankton which together account for 57% of the total annual primary production in the Arctic Ocean.” Eric Post, a biologist at Penn State University in the US, and colleagues report in Science that the seasonal timing of the ice algae bloom is critical to the successful reproduction of the zooplankton copepods (small crustaceans) that graze on the algae, and the bloom in phytoplankton that follows the normal seasonal retreat of the sea ice delivers food for the copepod offspring. These two “pulses” in productivity in the Arctic are the basis of the food web for all the higher creatures. The copepod explosion provides breakfast, lunch and supper for whales, seabirds, small fish, crustaceans and so on. But the fact that the total area under ice each summer has been shrinking at 86,000 square kilometres a year, and the annual ice melt season has been extended by at least 20 days, could have profound consequences for the entire ecosystem, and for the big, warm-blooded creatures at the top of the food chain.

Hybrid polar bears

“Our team set out to explore the domino effects of sea ice loss on marine mammals, as well as on land-dwelling species living adjacent to the ice”, said Post. The ice shelf is habitat for large mammals: as the ice thins and dwindles so does the habitat, and therefore the hunting opportunities. Walrus forage for food in shallow waters, and use the sea ice to rest, and to dive from, between foraging. As the ice melts and retreats from the shoreline the ice edge moves over deeper waters, and the walrus community increasingly has to crowd together on the shoreline rather than the ice, making the spread of infection easier, and increasing the dangers of trampling for the young. As the ice retreats, polar bears have less access to seal populations – and supplies of blubber – and they too have begun to mingle populations: there have been increasing reports of hybridisation with grizzly bears. Because sea ice in Arctic Canada is decreasing, there is a greater likelihood of contact between eastern and western Arctic seal populations, and a greater chance that phocine distemper virus will spread from the eastern seals to the western population. Sea ice loss could affect the populations of Arctic fox and wolf – because the loss of ice will increase genetic isolation – and the warming of the land surfaces in the Arctic is beginning to alter the vegetation, with consequences for caribou and other grazers.

Cooling mechanism falters

Another important consequence of sea ice loss is a change in the Arctic albedo – the measure of radiation that normally bounces off the ice and back into space, keeping the Arctic cold. In Nature Climate Change Aku Riihelä of the Finnish Meteorological Institute in Helsinki and colleagues report that they looked at satellite data from 1989 to 2002, during the summer months, for both open water and sea ice regions of the Arctic. They found that all albedo trends show a significant reduction, which is another way of saying that more sunlight is being absorbed into the land and ocean of the Arctic – which will accelerate the rate of warming and the loss of further ice. The consequences of this for the whole Arctic ecosystem will be considerable, warns Professor Post. As the seas open, they become accessible to shipping traffic and drilling rigs, and any increase in this could affect both terrestrial and marine creatures, among them the bowhead whales and the Pacific walrus. “By viewing sea ice as essential habitat and a substrate for important species interactions, rather than as a lifeless blank surface, its loss as a result of warming becomes a rather stunning prospect,” he says. – Climate News Network