Arctic glacier’s galloping melt baffles scientists

Arctic glacier’s galloping melt baffles scientists

New satellite data analysis has produced evidence that rapid melting in the last three years has caused dramatic shrinkage of an Arctic ice cap.

LONDON, 31 January, 2015 – An ice cap in the high Arctic has lost what British scientists say is a significant amount of ice in an unusually short time.

It has thinned by more than 50 metres since 2012 – about one sixth of its original thickness – and the ice flow is now 25 times faster, accelerating to speeds of several kilometres per year.

Over the last two decades, thinning of the Austfonna ice cap in the Svalbard archipelago − , roughly half way between Norway and the North Pole − has spread more than 50km inland, to within 10km of the summit. .

A team led by the scientists from the UK Centre for Polar Observation and Modelling (CPOM) at the University of Leeds combined observations from eight satellite missions, including Sentinel-1A and CryoSat, with results from regional climate models, to understand what was happening.

Sea level rise

The study’s lead author, geophysicist Dr Mal McMillan, a member of the CPOM team, said: “These results provide a clear example of just how quickly ice caps can evolve, and highlight the challenges associated with making projections of their future contribution to sea level rise.”

The study, published in Geophysical Research Letters, is the first to make use of measurements from the European Space Agency’s latest Earth observation satellite, Sentinel-1A.

Dr McMillan said: “New satellites, such as the Sentinel-1A and CryoSat missions, are essential for enabling us to systematically monitor ice caps and ice sheets, and to better understand these remote polar environments.”

“Whether or not the warmer ocean water
and ice cap behaviour are directly linked
remains an unanswered question”

Melting ice caps and glaciers account for about a third of recent global sea level rise. Although scientists predict that they will continue to lose ice in the future, determining the exact amount is difficult, because of a lack of observations and the complex nature of how they interact with the climate around them.

The 20 years of satellite data that the scientists have amassed show some fairly small changes at the start of the study period, but these have since increased.

“Glacier surges, similar to what we have observed, are a well-known phenomenon”, said Professor Andrew Shepherd, the director of CPOM. “What we see here is unusual because it has developed over such a long period of time, and appears to have started when ice began to thin and accelerate at the coast.”

There is evidence that the surrounding ocean temperature has increased in recent years, which may have been the original trigger for the ice cap thinning.

Flow models

Prof Shepherd said: “Whether or not the warmer ocean water and ice cap behaviour are directly linked remains an unanswered question. Feeding the results into existing ice flow models may help us to shed light on the cause, and also improve predictions of global ice loss and sea level rise in the future.”

The team says long-term observations by satellites are the key to monitoring such climate-related phenomena.

Dr McMillan told Climate News Network he did not think what was happening in Austfonna suggested any sort of tipping point in the Arctic, which scientists say is warming more than twice as fast as anywhere else on Earth.

He said: “What I take from this work is that we don’t understand well enough what’s caused this sort of behaviour − natural variability, ocean temperatures or atmospheric temperatures. It reinforces the complexities and the challenges of the future.” – Climate News Network

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Increased carbon spill from glaciers sets new puzzle

Increased carbon spill from glaciers sets new puzzle

Samples taken from five continents indicate that a big rise in organic carbon released by melting glaciers could have serious implications for ecosystems.

LONDON, 28 January, 2015 − Researchers in the US have calculated that, thanks to climate change, melting glaciers will have spilled an extra 15 million tonnes of organic carbon into the seas by 2050.

The consequences for the ecosystems that depend on glacial meltwater are uncertain, but this burden of biological soot and sediment has potential implications for the global carbon cycle as well.

The researchers estimate that the dissolved organic carbon released by melting glaciers will be an increase of half as much again on the current flow − the equivalent of about half the annual flow of dissolved carbon down the mighty Amazon River. And their calculations have identified another puzzle for climate scientists trying to understand the carbon cycle.

The planet’s glaciers and ice sheets cover about 11% of the planet’s surface and hold about 70% of the world’s fresh water. Spread thinly through this frozen water is a significant amount of biological carbon, with the Antarctic ice sheet alone hosting 6 billion tonnes of it.

Increased meltwater

It is safe for the time being, but mountain glaciers almost everywhere in the world are in retreat, and meltwater flow from the glaciers that drain the Greenland icecap is on the increase.

Eran Hood, professor of environmental science at the University of Alaska Southeast in Juneau, and colleagues report in Nature Geoscience that they developed a database of dissolved organic carbon found in 300 samples collected from glaciers on five continents.

Some of it was clearly preserved from living things on the ice itself, some of was scraped up as the glaciers moved over old soils, and some of it was soot from fossil fuel combustion or distant forest fires.

There was a wide spread of carbon concentrations in the samples, but it was enough to estimate a global average.

“We know we are losing glaciers, but what does that mean for marine life, fisheries, things downstream
that we care about?”

They also knew that Greenland and Antarctic icebergs delivered 4,250 billion tonnes of water to the oceans each year, and that the run-off from retreating mountain glaciers was somewhere between 369-905 billion tonnes.

So they could begin to make an estimate of the rate at which dissolved organic carbon is re-entering the planetary system, and perhaps augmenting the carbon cycle.

The carbon cycle underwrites all life: plants and microbes withdraw carbon from the atmosphere and some of it gets stored in the soilspreserved as peat, or locked away as rock, or frozen as ice to be returned to the planetary system in all sorts of ways,

New questions

Research like this is basic: it adds another detail or two to an understanding of how the planet works. It starts to answer existing questions − but it also raises new ones.

“This research makes it clear that glaciers represent a substantial reservoir of organic carbon,” said Dr Hood. “As a result, the loss of glacier mass worldwide, along with the corresponding release of carbon, will affect high latitude marine ecosystems, particularly those surrounding the major ice sheets that now receive fairly limited land-to-ocean fluxes of carbon.”

His co-author Robert Spencer, assistant professor of oceanography at Florida State University, said: “The thing people have to think about is what this means for the Earth. We know we are losing glaciers, but what does that mean for marine life, fisheries, things downstream that we care about?” – Climate News Network

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Science gains from clearer sight of Greenland’s ice melt

Science gains from clearer sight of Greenland's ice melt

Research into how Greenland’s ice melts should lead to more accurate predictions of sea level rise and global warming.

LONDON, 18 January, 2015 − Scientists in the US have used on-the-ice measurements and military-grade satellite imagery to take a much closer look at just how Greenland’s icesheet melts.

They already knew that huge icebergs fall from the glaciers into the ocean, and that surface lakes drain suddenly in the summer warmth. But now they know considerably more about what happens to the network of streams, rivers and ponds that collect in the summer sunshine, and then flow across the top of the icesheet into moulins, or sinkholes.

They report in the Proceedings of the National Academy of Sciences that they used the data collected to chart 523 streams in a catchment area of about 6,800 square kilometres during the freak thaw of 2012, when almost the whole of the Greenland icecap was covered in slush. They measured the run-off at between 1,550 and 1,700 cubic metres per second − twice the average flow of the Colorado River.

Thereafter, all this water drained into moulins, and began to filter towards the base of the icesheet. What happened to it then is not yet certain, but the guess is that a percentage was soaked up within the iceshelf, while a proportion reached the sea.

Only the start

The study placed 11 researchers on the ice for six days in July 2012, during a massive and unusual melt. Only on one other occasion in the last 700 years, in 1889, did Greenland’s ice melt on such a scale.

The scientists were moved around by helicopter and equipped with a specially-designed automaton boat, buoys fitted with GPS technology, and sophisticated satellite imagery.

“It was a real preview of just how quickly that ice sheet can melt and the meltwater can escape”, said lead author Laurence Smith, Professor of Earth, Planetary, and Space Sciences at University of California Los Angeles. “The question was whether the ice sheet acts like a sponge or like Swiss cheese.”

The provisional answer is: both. Some meltwater stays, and some certainly escapes altogether. But it will take more than just one visit to arrive at more precise calculations.

“Greenland is really the big player for sea level rise in the future, so improving climate models is extremely crucial”

The scientists also took measurements of Greenland’s Isortoq river − just one of about 100 large terrestrial rivers delivering Greenland meltwater to the oceans.

They found that the Isortoq carries water from the ice sheet to the ocean at between 650 and 1,300 cubic metres per second, which is less than models have projected.

Such direct measurements are important because they make predictions of melt rate and sea level rise more accurate − and more credible.

“If we can get better estimates, then we can have better projections for the extent and impact of global warming”, said another of the report’s authors, Marco Tedesco, founder and director of the City College of New York’s Cryospheric Processes Laboratory. “Greenland is really the big player for sea level rise in the future, so improving climate models is extremely crucial.” – Climate News Network

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Trapped methane escapes as Pacific depths warm up

Trapped methane escapes as Pacific depths warm up

Oceanographers in the US warn that volumes of methane equivalent to a major oil spill are rising to the surface each year as warmer waters heat the frozen ocean bed.

LONDON, 11 January, 2015 – Researchers studying methane trapped in frozen layers below the Pacific Ocean seafloor predict that more and more of the potent greenhouse gas could bubble towards the surface as the deep water begins to warm.

“We calculate that methane equivalent in volume to the Deepwater Horizon oil spill [in 2010] is released every year off the Washington coast,” says Evan Solomon, assistant professor at the University of Washington School of Oceanography in the US.

Methane hydrates are the natural gas methane in solid form. Volume for volume, methane is at least 20 times more potent a greenhouse gas than carbon dioxide, although it is released in smaller quantities and has a much shorter lifespan in the atmosphere.

Vast quantities of the stuff are known to be trapped in sedimentary rocks and in the sea bed, in “frozen” form − held by a combination of temperature and pressure.

Fastest warming

Until now, most of the focus has been on the methane hydrates in the Arctic, the fastest warming region on the planet.

But Dr Solomon, oceanographer and lead author Susan Hautala and colleagues report in Geophysical Research Letters their calculations that between 1970 and 2013, some 4 million tonnes of methane have been released from the sea floor off the coast of Washington state.

This is about the equivalent of the natural gas released in 2010 when the Deepwater Horizon oil well blew out off the coast of Louisiana, and 500 times the rate of natural release from the sea floor.

Coring machine used to gather sediment samples from the Pacific. Image: Robert Cannata/University of Washington

Coring machine used to gather sediment samples from deep in the Pacific Ocean.
Image: Robert Cannata/University of Washington

The Pacific Northwest has high rates of biological activity, and methane is a natural biological product. At high ocean pressures and low sea temperatures, it “freezes” or crystallises in a solid state. And because the waters of the Pacific Northwest have been so rich in life, the seabed below is rich in methane hydrates.

But ocean waters have started to warm, at depth, and currents have carried the warming water across the ocean to the North American shelf.

Atmospheric warming

As water warms, the submarine methane “ice line” retreats further offshore − rather in the way that a snowline moves up hill, or a glacier retreats, in response to atmospheric warming.

The Washington scientists calculate that, since 1970, the boundary at which methane stays frozen has retreated by about a kilometre. By 2100, it will have moved perhaps another three kilometres off shore.

Their calculations suggest that, by the century’s end, 400,000 metric tonnes a year will escape. And the puzzle now is where the released methane will end up.

Some could be consumed by methane-eating bacteria in the seafloor ooze. But fishermen have also observed the stuff bubbling to the surface, to add to the burden of atmospheric greenhouse gases.

The finding, the researchers say, has “worldwide implications” for other oceanic reservoirs of the stuff, close to continental shelves and therefore vulnerable to large-scale melting. – Climate News Network

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Ocean warming speeds up cycle of climate change

Ocean warming speeds up cycle of climate change

British and German scientists have identified another consequence of global warming that is likely to accelerate climate change still further.

LONDON, 9 January, 2015 − The warming oceans could start to return more carbon dioxide to the atmosphere as the planet warms, according to new research.

And since 70% of the planet is covered by clear blue water, anything that reduces the oceans’ capacity to soak up and sequester carbon could only make climate change more certain and more swift.

It is a process that engineers call “positive feedback”. And under such a cycle of feedback, the world will continue to get even warmer, accelerating the process yet again.

Many such studies are, in essence, computer simulations. But Chris Marsay − a marine biochemist at the UK’s National Oceanography Centre in Southampton − and colleagues based their results on experiments at sea.

Sediment traps

They report in the Proceedings of the National Academy of Sciences that they examined sediment traps in the North Atlantic to work out what happens to organic carbon – the tissue of the living things that exploit photosynthesis, directly or indirectly, to convert carbon dioxide – as it sinks to the depths.

Sooner or later, much of this stuff gets released into the sea water as carbon dioxide. This is sometimes called the ocean’s biological carbon pump. In deep, cold waters, the process is slow. In warmer, shallower waters, it accelerates.

And as there is evidence that the ocean is responding to atmospheric changes in temperature, both at the surface and at depth, the study suggests that “predicted future increases in ocean temperatures will result in reduced CO2 storage by the oceans”.

The research was conducted on a small scale, in a limited stretch of ocean, so the conclusion is still provisional − and, like all good science, will be confirmed by replication. But it is yet another instance of the self-sustaining momentum of global warming.

Such positive feedbacks are already at work in high latitudes. Ice reflects sunlight, and therefore the sun’s heat. So as the Arctic ice sheet steadily diminishes over the decades, more and more blue water is available to absorb heat − and accelerate warming.

“The world is at a crossroads in terms of climate health and climate change”

The same gradual warming has started to release another greenhouse gas trapped at the ocean’s edge. Natural “marsh gas”, or methane, is stored in huge masses, “frozen” as methane hydrate in cold continental shelves.

Methane exists in much smaller quantities than carbon dioxide, and has a shorter life in the atmosphere, but is far more potent, volume for volume, as a greenhouse gas.

Researchers at the Arctic University of Norway in Tromso reported last month in Geophysical Research Letters that once-frozen methane gas was leaking from thawing ocean floor off Siberia. Some of this thaw is natural, and perhaps inevitable. But some is connected with human influence and could accelerate.

Alexei Portnov, a geophysicists at the university’s Centre for Arctic Gas Hydrate, Climate and Environment  says: “If the temperature of the oceans increases by two degrees, as suggested by some reports, it will accelerate the thawing to the extreme. A warming climate could lead to an explosive gas release from the shallow areas.”

Biological origin

Arctic methane, like ocean organic carbon, has a biological origin. It is released by decaying vegetation under marshy conditions and tends to form as a kind of ice at low temperatures and high pressures, much of it along continental shelves that, at the height of the Ice Ages, were above sea level.

The International Union for Conservation of Nature also reminded the world last month that the ocean plays a vital role in climate, and that plankton, fish and crustaceans could be considered as “mobile carbon units”.

In this sense, the fish in the sea are not just suppers waiting to be caught, but are important parts of the planetary climate system. The healthier the oceans, and the richer they are in living things, the more effective they become at soaking up atmospheric carbon.

“The world is at a crossroads in terms of climate health and climate change,” said Dan Laffoley, vice-chairman of the IUCN World Commission on Protected Areas, introducing a new report on the marine role in the carbon cycle.

“Neglect the ocean and wonder why our actions are not effective, or manage and restore the ocean to boost food security and reduce the impact of climate change. The choice should be an easy one.” – Climate News Network

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Satellite provides sharper picture of shrinking ice sheet

Satellite provides sharper picture of shrinking ice sheet

The most detailed study yet of the Greenland ice sheet illustrates the complex process that is causing billions of tonnes to melt ever year.

LONDON, 27 December, 2014 − Greenland’s ice sheet shrank by an average of 243 billion tonnes a year between 2003 and 2009 – a rate of melting that is enough to raise the world’s sea levels by 0.68 mm per year.

In what is claimed as the first detailed study, geologist Beata Csatho, of the University of Buffalo in the US, and colleagues report in the Proceedings of the National Academy of Sciences that they used satellite and aerial data to reconstruct changes in the ice sheet at 100,000 places, and to confirm that the process of losing 277 cubic kilometres of ice a year is more complex than anyone had predicted.

The Greenland ice sheet is the second biggest body of ice on Earth − second only to Antarctica − and its role in the machinery of the northern hemisphere climate is profound.

Careful measurements

It has been closely studied for decades, but such are the conditions in the high Arctic that researchers have tended to make careful measurements of ice melt and glacier calving in fixed locations – in particular, at four glaciers − and then try to estimate what that might mean for the island as a whole.

“The great importance of our data is that, for the first time, we have a comprehensive picture of how all of Greenland’s glaciers have changed over the past decade,” Dr Csatho said.

The study looked at readings from NASA’s ice, cloud and land elevation satellite ICESat, and from aerial surveys of 242 glaciers wider than 1.5 km at their outlets, to get a more complete picture of melting, loss and – in some cases – thickening of the ice sheet as a whole.

“When the ice sheet is thinner, it is at a slightly lower elevation and at the mercy of warmer air temperatures”

Previous studies have focused on the four glaciers. One of them, Jakobshavn, has doubled its speed of flow since 2003, and closer studies have begun to reveal more about the dynamics of individual flows.

But the real strength of the study is that it establishes the pattern of ice melt in more detail, and suggests that climate models may not give a clear enough picture of the future of the ice cap. To put it crudely, Greenland could lose ice faster in the future than any of today’s predictions suggest.

Meanwhile, a team from the UK has been trying to work out what is happening on the surface of the ice sheet. Each summer, of course, some of the ice melts. Some of this gets to the sea, but some freezes again in the natural seasonal order of things.

But glaciology researcher Amber Leeson, of the University of Leeds, and colleagues report in Nature Climate Change that the “supraglacial” lakes that form each summer could also affect ice flow.

Their computer simulations suggest that these lakes will migrate further inland as the century wears on and the world continues to warm. Ice reflects heat, water absorbs it. So the process could trigger further melting. Some of this extra meltwater could slide or drain to the base of the glacier, lubricating its flow and accelerating the process yet again.

Thin pancake

“Our research shows that, by 2060, the area of Greenland covered by them will double,” Dr Leeson said. “When you pour pancake batter into a pan, if it rushes quickly to the edge of the pan, you end up with a thin pancake. It’s similar to what happens with ice sheets. The faster it flows, the thinner it will be.

“When the ice sheet is thinner, it is at a slightly lower elevation and at the mercy of warmer air temperatures than it would be if it were thicker, increasing the size of the melt zone around the edge of the ice sheet.”

In the last 40 years, the band in which such supraglacial lakes can form has crept 56 km inland. By 2060, the simulations now suggest, it could reach 110km inland, doubling the area of coverage and delivering yet more meltwater to fuel further warming.

Once again, the research suggests that current models underestimate the rate of ice loss. – Climate News Network

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Rapid increase in Arctic temperature is spreading south

Rapid increase in Arctic temperature is spreading south

Rising temperatures in Finland illustrate the increasingly rapid pace of warming in high northern latitudes − a trend that has accelerated over the last 40 years.

LONDON, 25 December 2014 − Climate scientists are confident that the Arctic is warming more than twice as fast as any other part of the planet, but now comes evidence from researchers in Finland that the rising temperatures are being felt further south than the polar regions.

Most governments have agreed that the global temperature should not be allowed to rise more than 2°C above its pre-industrial level in order to prevent the onset of dangerous climate change. Finland’s experience shows how fast this threshold may be reached.

The marked rise is reported in a study by researchers from the University of Eastern Finland and the Finnish Meteorological Institute, published in the journal Stochastic Environmental Research and Risk Assessment. They say their study “exhibits a statistically significant trend, which is consistent with human-induced global warming”.

Trees affected

Records show that, over the past 166 years, the average temperature in Finland has risen by more than two degrees Celsius. The average increase observed was 0.14°C per decade, which is nearly twice the global average. Since the 1960s, the temperature has risen faster than ever before, with the rise varying between 0.2 and 0.4°C per decade.

One of the study’s co-authors, Professor Ari Laaksonen, said: “The biggest temperature rise has coincided with November, December and January. Temperatures have also risen faster than the annual average in March, April and May. In the summer months, however, the temperature rise has not been as significant.”

One consequence of the rising temperature is that Finnish lakes now freeze over later in the year than they used to, while the ice cover melts earlier each spring. Some of Finland’s trees are also beginning to blossom earlier than before.

“The area of higher warming is reaching further south than it has been recorded before”

The study found that the temperature has risen in two phases − the first lasting from the start of the observation period in 1847 to the late 1930s, and the second from the late 1960s until now. During the intervening 30 years or so, the temperature remained nearly steady.

Dr Santtu Mikkonen, the lead author, said: “The stop in the temperature rise can be explained by several factors, including long-term changes in solar activity and the post-World War II growth of human-derived aerosols in the atmosphere. When looking at recent years’ observations, it seems that the temperature rise is not slowing down.”

He told the Climate News Network: “Our study shows that the warming is taking place all over Finland. In addition to the results shown in the paper we made some tests with data only from southern Finland  and from individual stations in different parts of the country, and the trend was similar in all these analyses. The area of higher warming is reaching further south than it has been recorded before.”

The temperature time series was created by averaging the data produced by all Finnish weather stations across the country. Because the Finnish weather network did not cover the entire country in the early years, data obtained from weather stations in neighbouring countries was also used.

Finland, lying between the Atlantic and the Eurasian continent, is subject to very variable weather. The researchers say they used a method that made it possible for them to take into consideration the seasonal changes typical of Nordic conditions, as well as significant annual variation. − Climate News Network

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Polar bears feel the heat as frozen habitat shrinks

Polar bears feel the heat as frozen habitat shrinks

As climate change increasingly affects the Arctic, some polar bear populations are suffering because rising temperatures are reducing the sea ice vital for their survival.

LONDON, 19 December, 2014 − The Arctic is changing faster under the influence of the warming climate than anywhere else on Earth, scientists have confirmed.

The US National Oceanic and Atmospheric Administration (NOAA) says Arctic air temperatures continue to rise more than twice as fast as they do globally − a phenomenon known as Arctic amplification.

The extent of snow cover in April 2014 in Eurasia was the lowest since 1967, and sea ice extent in September was the sixth lowest since 1979.

Badly affected

Some Arctic polar bear populations have been badly affected by the progressive shrinking of Arctic sea ice.

But NOAA says: “Natural variation remains, such as the slight increase in March 2014 sea ice thickness and only a slight decrease in total mass of the Greenland ice sheet in summer 2014.”

Increasing air and sea surface temperatures, a decline in the reflectivity of the ice at the surface of the Greenland ice sheet, shrinking spring snow cover on land and summer ice on the ocean, and the declining populations and worsening health of some bear populations are among the findings described in NOAA’s Arctic Report Card 2014.

“Arctic warming is setting off changes that affect people and the environment in this fragile region, and has broader effects beyond the Arctic on global security, trade and climate,” Craig McLean, of NOAA, told the annual American Geophysical Union Fall meeting in San Francisco.

“This year’s Arctic Report Card shows the importance of international collaboration on long-term observing programmes that can provide vital information to citizens, policymakers and industry.”

“Arctic warming has broader effects beyond the Arctic on global security, trade and climate”

The Report Card, published annually since 2006, updates changes affecting the Arctic. This year’s report − written by 63 US and other authors − covers key indicators, and also includes a new report on the status of the bears.

This section, written by the Norwegian Polar Institute and Polar Bears International, assesses the animals’ populations in some areas where there is good long-term data available. There are clear variations between areas.

Ice break-up

The most recent data shows that a population decline in western Hudson Bay, Canada, was caused by earlier sea ice break-up and later freeze-up.

The bears depend on sea ice to travel, hunt, mate and, in some areas, to den. But in the southern Beaufort Sea, north of Alaska, their numbers have now stabilised after a decline of about 40% since 2001.

In the Chukchi Sea, between Alaska and Russia and immediately to the west of the Beaufort, the condition of the bears and their reproductive rates have been stable for 20 years.

The Report Card says there are now twice as many ice-free days in the southern Beaufort as there are in the Chukchi Sea.

It notes that polar bears have been through “long and dramatic periods of population decline” during the last million years, and that during periods with little sea ice, polar bears and brown bears have often interbred.

The report says Alaska recorded temperature anomalies more than 10°C higher than the January average during 2014.

Snow cover across the Arctic during the spring was below the long-term average for 1981-2010, with a new record low set in April for Eurasia. North America’s June snow extent was the third lowest on record.

Snow disappeared three to four weeks earlier than normal in western Russia, Scandinavia, the Canadian sub-Arctic and western Alaska because of below-average accumulation and above-normal spring temperatures.

The eight lowest sea ice extents since 1979 have occurred in the last eight years (2007-2014). There is still much less of the oldest, thickest (greater than 13 feet, or four metres) and most resilient ice than in 1988, when it made up 26% of the ice pack. This year’s figure is 10%.

Extent of melting

As sea ice retreats in summer, sea surface temperature across the Arctic Ocean is increasing. In the Chukchi Sea, it is increasing at 0.5°C per decade.

Melting occurred across almost 40% of the surface of the Greenland ice sheet in summer 2014. For 90% of the summer, the extent of melting was above the long-term average for 1981-2010.

In August 2014, the reflectivity (albedo) of the ice sheet was the lowest recorded since satellite observations began in 2000. When less of the sun’s energy is reflected by ice, melting increases. The total mass of the ice sheet remained essentially unchanged between 2013 and 2014.

Declining sea ice allows more sunlight to reach the upper layers of the ocean, triggering increased photosynthesis and greater production of phytoplankton − the tiny marine plants that form the base of the food chain for fish and marine mammals. − Climate News Network

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Canada’s polar bears face food crisis by 2100

Canada's polar bears face food crisis by 2100

The survival of polar bears in Canada’s Arctic Archipelago may be in question in around 80 years’ time, because of the shrinkage of the sea ice.

LONDON, 30 November 2014 − The polar bears of the Canadian Arctic – at present they make their home in the nation’s huge, frozen archipelago – face starvation and reproductive failure by the close of this century.

New research in the Public Library of Science Journal PLOS One confirms that the continuing loss of sea ice in the Arctic ocean puts pressures on the region’s most iconic predator. By 2100, polar bears in the high Arctic may have to endure between two and five months without access to any sea ice.

Ursus maritimus has evolved under harsh circumstances, can swim huge distances, and can survive long periods without eating. However, it can only do so if it has been able to build up energy reserves and to do this, the bear needs access to a rich source of fat and calories.

So it hunts seals, and to hunt seals, it must be able to get onto the sea ice. The ice is where it hunts, where it mates and where it migrates.

No ice, no seals

Stephen Hamilton of the University of Alberta and colleagues used climate models to work out the likely pattern of sea ice in the Canadian Arctic during the rest of the century. The Canadian archipelago is home to at least seven populations of polar bear, a species already declared vulnerable.

Researchers have measured a steady shrinking of the north polar ice sheet over the last 30 years and have also found that the remaining sea ice is becoming thinner. By mid-century, according to some researchers, the Arctic could be navigable one summer in two.

This is not likely to be good news for an animal that needs the ice to hunt to gain fat and to provide the energy for the next breeding cycle. Hamilton and colleagues put their message bleakly:  “Under business-as-usual climate projections, polar bears may face starvation and reproductive failure across the entire Archipelago by the year 2100.”

“By 2100 all regions of the study area may cross the critical point-of-no-return”

This may not mean the end of the species, but there are only 19 populations of polar bears in the world, and the seven populations that hunt or den in the Canadian Arctic Archipelago make up probably a quarter of all the planet’s polar bears, even though the Canadian islands make up less than 10% of the polar bear’s range. So what happens in the Canadian Arctic could be critical.

What seems to govern polar bear behaviour is the concentration of sea ice: if the concentration falls below between 30 to 50%, the bears abandon the ice and move ashore to await the return of winter. The longer the bears stay ashore, the briefer the access to seal blubber.

At this point the extent of the ice-free period becomes critical. If the ice-free period lasts 120 days, two or three bears in every hundred could perish. If it lasts 180 days, then 20 out of 100 could starve. If the ice breaks up too early, between 55 and 100% of pregnant females could lose their cubs.

The scientists’ research is intended to help conservation programmes, but there may not be much future for the bears in the far north of Canada.

“By 2100 all regions of the study area may cross the critical point-of-no-return,” the authors say,  “putting the persistence of the Canadian Arctic Archipelago polar bear populations in jeopardy.” – Climate  News Network

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IPCC’s urgent warning to tackle climate change

IPCC’s urgent warning to tackle climate change

The UN panel of climate scientists says some consequences of global warming will become irreversible unless greenhouse gas emissions fall to zero by the end of the century − but latest research suggests the reality may be even more urgent than that.

LONDON, 3 November, 2014 − Climate change threatens to become “severe, pervasive and irreversible”, according to the latest report from the Intergovernmental Panel on Climate Change (IPCC).

Without drastic cuts in greenhouse gas emissions, the report says, global average temperatures will probably increase by another 2°C by mid-century on their 1986-2005 levels. This implies temperatures nearly 4°C higher by 2100.

The warnings come in the Summary for Policymakers of the IPCC’s Climate Change 2014 Synthesis Report, itself a distillation of the three distinct volumes of the Panel’s Fifth Assessment Report (on climate science, impacts and mitigation) published since September 2013.

Will to change

The IPCC chair, Dr R K Pachauri, said at the Summary’s launch in Copenhagen: “We have the means to limit climate change. The solutions are many, and allow for continued economic and human development. All we need is the will to change. . .”

The Panel insists that adapting to climate change will not be enough, and that the world must make “substantial and sustained reductions of greenhouse gas emissions”.

Dr Pachauri said: “To keep a good chance of staying below 2ºC [the international threshold for temperature rise], and at manageable costs, our emissions should drop by 40% to 70% globally between 2010 and 2050, falling to zero or below by 2100.”

“A large fraction of anthropogenic climate change resulting from CO2 emissions is irreversible . . .”

The Summary, spelling out in careful terms what this means, says: “A large fraction of anthropogenic climate change resulting from CO2 emissions is irreversible on a multi-century to millennial timescale, except in the case of a large net removal of CO2 from the atmosphere over a sustained period.”

Put more simply, this means that without an effective way to clean up the main greenhouse gas, the world will face permanent changes. Unfortunately, the method proposed for cleaning the atmosphere − carbon capture and storage − has not yet proved itself at scale.

So Dr Pachauri’s plea that the world finds “the will to change“ is fine, so far as it goes. The problem is that there are also several technological hurdles still to surmount.

And that’s not the only problem with this report. As with previous major IPCC reports, it unavoidably trails some way behind the facts. The authors of the three volumes on which the Summary is based, published in the last 14 months, were able to consider only climate science published up till 15 March, 2013.

Serious consequences

But among research published since then − and too late to be considered by the IPCC teams − was a NASA report suggesting that the melting glaciers of West Antarctica may have passed the point of no return, with serious consequences for global sea levels.

Yet the IPCC Summary says simply: “Abrupt and irreversible ice loss from the Antarctic ice sheet is possible, but current evidence and understanding is insufficient to make a quantitative assessment.”

Other recent advances in climate science that were published too late for the Panel to consider relate to the Greenland ice sheet and to the Amazon.

This is not to blame the IPCC for producing a report that has serious gaps. Its assessment reports appear only once every six or seven years, and are written by unpaid volunteers, supported by a permanent staff of around 12 people.

But if you hear the IPCC being accused − as it often is − of alarmism, consider how truly alarming the Summary would have been if the authors had been able to digest all we now know about the effects of climate change. − Climate News Network

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