Category Archives: Arctic

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A comparison of sea ice extent before the melting period began in 
March 2012 and after the melting period ended in September 2012. 
Purple line in these photos represents 1979-2000 median for 
Arctic ice. Image Credit: NOAA

The NOAA recently released its 2012 Arctic Report. I can’t recall how many times I’ve gotten into a conversation with someone who, in the most blasé sort of way, always has this sort of thing to say: “Oh, the Earth will just get rid of us” or “Yes, it is terrible but the Earth will go on even if we don’t”. Fuck you. It’s not about the earth going on you dimwit. Of course, yes, it will go on in one way or another. Never mind the fact that more often than not these folks I’m referring to actually have children and possibly grand children… but there are these little details that they seem incapable of thinking about. It’s as though they just can’t be bothered… yes dear, it’ll all just come out in the wash. Well fuck you again.

From the post at Earth Sky:

At the end of each year, the National Oceanic and Atmospheric Administration (NOAA) releases a report card on the state of the Arctic. In 2012, NOAA reports record low levels of sea ice extent, lower than we’ve seen before since the satellite era began in 1979. Plus, in June 2012, the Arctic experienced record low snow extent across the region. Greenland saw extreme melting during the summer of 2012, and the warmer temperatures and decreasing ice provided massive phytoplankton to grow. NOAA scientists said that air temperatures were on a par with the (relatively high) temperatures of the last decade, leading to, among other things, an increase in the length of the growing season along with tundra greenness in the Arctic. Climate models suggest that, in a warming climate, high latitudes such as the Arctic will be affected first, and so it seems to be. The 2012 Arctic Report Card is a peer-reviewed report that consists of 141 authors from 15 countries. If you ask a scientist who travels periodically to the Arctic or across Greenland, he or she will tell you that the landscape there is changing dramatically from year to year.

Arctic fox at Svalbard, Norway. In Fennoscandia,
fewer than 200 individuals are estimated to remain. 

What’s being lost, due to our insistence on the casual use of cars and lawn mowers and over consumption and homes kept at 72, are actual SPECIES. Other species that we share the planet with that should exist. But WE just can’t be bothered to stop and consider how it is that WE are destroying this fragile planet that hosts such amazing diversity.

We, as a species, are nothing short of criminal.

Melting ice cap triggering earthquakes in Greenland

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As a follow up to yesterday’s post regarding an ice-free Arctic, there is this regarding the land-bound ice of Greenland melting so fast that it is now starting to cause earthquakes.

The Guardian reports that the Melting ice cap triggering earthquakes:

The Greenland ice cap is melting so quickly that it is triggering earthquakes as pieces of ice several cubic kilometres in size break off.

Scientists monitoring events this summer say the acceleration could be catastrophic in terms of sea-level rise and make predictions this February by the Intergovernmental Panel on Climate Change far too low.

…

He had flown over the Ilulissat glacier and “seen gigantic holes in it through which swirling masses of melt water were falling. I first looked at this glacier in the 1960s and there were no holes. These so-called moulins, 10 to 15 metres across, have opened up all over the place. There are hundreds of them.”

This melt water was pouring through to the bottom of the glacier creating a lake 500 metres deep which was causing the glacier “to float on land. These melt-water rivers are lubricating the glacier, like applying oil to a surface and causing it to slide into the sea. It is causing a massive acceleration which could be catastrophic.”

The glacier is now moving at 15km a year into the sea although in surges it moves even faster. He measured one surge at 5km in 90 minutes – an extraordinary event.

Veli Kallio, a Finnish scientist, said the quakes were triggered because ice had broken away after being fused to the rock for hundreds of years. The quakes were not vast – on a magnitude of 1 to 3 – but had never happened before in north-west Greenland and showed potential for the entire ice sheet to collapse.

Dr Corell said: “These earthquakes are not dangerous in themselves but the fact that they are happening shows that events are happening far faster than we ever anticipated.”

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An ice-free Arctic in just 23 years?

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Big fucking surprise. Or not. Look… how many times do we have to see these words over and over? “Sooner than expected”, “much worse than previously thought”. I’ve said it before, this is happening at a pace far faster than even the worst predictions. We have got to start thinking of climate change as RIGHT FUCKING NOW. This is NOW. This is not 100 years from now. This is not great grand children or the next generation. FUCK. Stop eating meat. Stop driving. Stop consuming. FUCKING STOP.

I hate humanity and truthfully, I think I’m starting to take pleasure in seeing people suffer from weather related catastrophes. If only that suffering were more focused on the U.S. and other primary contributors of atmospheric carbon. It’s harsh I know but FUCK. How stupid, shortsighted and selfish can we be?

seaice1979-2007sep05.jpg
Comparison of sea ice area on September 5, 1979 and September 5, 2007.

Sea ice area in early September has declined 42% in the 28 years since 1979.
Image credit: University of Illinois Polar Research Group.

Jeff Masters over at Wunderground discusses the issue:

None of our computer climate models predicted that such a huge loss in Arctic ice would occur so soon. Up until this year, the prevailing view among climate scientists was that an ice-free Arctic ocean would occur in the 2070-2100 time frame. The official word on climate change, the February 2007 report from the U.N.-sponsored Intergovernmental Panel on Climate Change (IPCC), warned that without drastic changes in greenhouse gas emissions, Arctic sea ice will “almost entirely” disappear by the end of the century. This projection is now being radically revised. Earlier this year, I blogged about a new study that predicted abrupt losses of Arctic sea ice were possible as early as 2015, and that we could see an ice-free Arctic Ocean as early as 2040. Well, the Arctic Ocean has suffered one of the abrupt losses this study warned about–eight years earlier than this most radical study suggested. It is highly probable that a complete loss of summer Arctic sea ice will occur far earlier than any scientist or computer model predicted. In an interview published yesterday in The Guardian Dr. Mark Serreze, and Arctic ice expert with the National Snow and Ice Data Center, said: “If you asked me a couple of years ago when the Arctic could lose all of its ice, then I would have said 2100, or 2070 maybe. But now I think that 2030 is a reasonable estimate. It seems that the Arctic is going to be a very different place within our lifetimes, and certainly within our children’s lifetimes.” While natural fluctuations in wind and ocean circulation are partly to blame for this loss of sea ice, human-caused global warming is primarily to blame. In the words of Dr. Serreze: “The rules are starting to change and what’s changing the rules is the input of greenhouse gases. This year puts the exclamation mark on a series of record lows that tell us something is happening.”

The implications
The melting of the Arctic sea ice will not raise ocean levels appreciably, since the ice is made up of frozen sea water that is floating in the ocean. Sea ice melt does contribute slightly to sea level rise, since the fresh melt water is less dense than the salty ocean water it displaces. According to Robert Grumbine’s sea level FAQ, if all the world’s sea ice melted, it would contribute to about 4 millimeters of global sea level rise. This is a tiny figure compared to the 20 feet of sea level rise locked up in the ice of the Greenland ice sheet, which is on land.

The biggest concern about Arctic sea ice loss is the warmer average temperatures it will bring to the Arctic in coming years. Instead of white, reflective ice, we will now have dark, sunlight-absorbing water at the pole, leading to a large increase in average temperature. Warmer temperatures will accelerate the melting of the Greenland ice sheet, which holds enough water to raise sea level 20 feet. The official word on climate, the 2007 IPCC report, predicted only a 0.6-1.9 foot sea level rise by 2100, due to melting of the Greenland ice sheet and other factors. I believe these estimates will need to be revised sharply upwards in light of the unexpectedly high Arctic sea ice loss this summer.

One more point–global warming skeptics often criticize using computer model climate predictions as a basis for policy decisions. These models are too uncertain, they say. Well, the uncertainty goes both way–sometimes the models will underestimate climate change. We should have learned this lesson when the ozone hole opened up–another case where the models failed to predict a major climate change. The atmosphere is not the well-behaved, predictable entity the models try to approximate it as. The atmosphere is wild, chaotic, incredibly complex, and prone to sudden unexpected shifts. By pumping large amounts of greenhouse gases into the air, we have destabilized the climate and pushed the atmosphere into a new state it has never been in before. We can expect many more surprises that the models will not predict. Some of these may be pleasant surprises, but I am expecting mostly nasty surprises.

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Climate Change Round-up

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I suppose it is a good sign that I’m having a hard time keeping up with all of the recent media coverage of climate change. I would like to point out though that while the coverage is now consistent via the web I’m not seeing it nearly as much on the television. I don’t watch much but when I do flip on the TV and CNN I’m much more likely to see discussion of stupid, irrelevant celebrity gossip than I am discussion of climate change. That’s just plain fucked up. Until the corporate media stop the daily bullshit coverage of Anna Nicole’s baby’s daddy and replace it with daily discussion of peak oil, climate change, and sustainable development they are as much a part of the problem as they have always been.

Summary of the latest installment of the Intergovernmental Panel on Climate Change (IPCC) report: Climate Change 2007: Climate Change Impacts, Adaptation and Vulnerability [PDF – 547KB]

Billions face climate change risk:

Billions face climate change risk

The impact of climate change has been a major source of dispute
Billions of people face shortages of food and water and increased risk of flooding, experts at a major climate change conference have warned.

Damage already done for some natural wonders

BRUSSELS, Belgium (AP) — While governments grapple with the politics of global warming, some of the world’s greatest treasures already are being damaged and threatened with destruction.

Conservationists have drawn up priorities for action to salvage some of nature’s wonders that are feeling the heat of climate change — from the Himalayan glaciers to the Amazon rain forests and the unique ecosystem of the Mexican desert.

Many of the regions at risk were singled out in a report by the Intergovernmental Panel on Climate Change, an authoritative body of 2,500 scientists. The report is undergoing governmental review at a five-day conference in Brussels.

On Thursday, diplomats and scientists were negotiating the text of a 21-page summary of the full 1,572-page scientific report. It projects specific consequences for each degree of rising global temperatures, which the IPCC agrees is largely caused by human activity.

On the sidelines of the conference, the World Wildlife Fund for Nature issued a list of 10 regions suffering irreversible damage from climate change. The group also listed where it has projects to limit further damage or help people adapt to new conditions.

“What we are talking about are the faces of the impacts of climate change,” said Lara Hansen, WWF’s chief scientist on climate issues.

The WWF is among the largest of many nongovernment organizations to take up the challenge of climate change.

The Nature Conservancy, based in Arlington, Virginia, is another. It has projects to protect coral reefs off Florida, in the coral triangle of Indonesia and in Papua New Guinea. It also is trying to preserve native alpine meadows in China and conserve vegetation in California’s Sierra Nevada mountains.

Though climate change has been discussed for decades, Hansen said the effects were now becoming visible. “It’s only in the past decade that we can go outside and see for ourselves what’s happening,” she told The Associated Press.

Some damage is reversible, Hansen said. Although melted glaciers cannot be restored, some coral reefs can recover.

But as natural landmarks deteriorate, she said more attention will have to be paid to adapting to change, not only trying to prevent it, and not enough experts are being trained to help people acclimatize.

“There’s a massive void ahead of us in getting new people,” she said.

U.N.: Warming ruining society, nature:

Top climate experts warned on Friday that global warming will cause faster and wider damage than previously forecast, ranging from hunger in Africa and Asia to extinctions and rising ocean levels.

Study: Climate change could bring new U.S. Dust Bowl

Changing climate will mean increasing drought in the southwestern United States, where water already is in short supply, according to a new study.

“The bottom line message for the average person and also for the states and federal government is that they’d better start planning for a Southwest region in which the water resources are increasingly stretched,” said Richard Seager of Columbia University’s Lamont Doherty Earth Observatory.

Seager is lead author of the study published online Thursday by the journal Science.

Researchers studied 19 computer models of the climate, using data dating back to 1860 and projecting into the future. The same models were used in preparing the reports of the Intergovernmental Panel on Climate Change.

The consensus of the models was that climate in the southwestern United States and parts of northern Mexico began a transition to drier conditions late in the 20th century and is continuing the trend in this century, as climate change alters the movement of storms and moisture in the atmosphere.

The reduction in rainfall could reach levels of the 1930s Dust Bowl that ranged throughout the Midwestern United States, Seager said in a telephone interview.

Arctic lost part of its perennial sea ice in 2005: NASA

Global warming may already be having an effect on the Arctic which in 2005 only replaced a little of the thick sea ice it loses and usually replenishes annually, a NASA study said Tuesday.

Scientists from the US space agency used satellite images to analyze six annual cycles of Arctic sea ice from 2000 to 2006.

Sea ice is essential to maintaining and stabilizing the Arctic’s ice cover during its warmer summer months.

But “recent studies indicate Arctic perennial ice is declining seven to 10 percent each decade,” said Ron Kwok from NASA’s Jet Propulsion Laboratory in Pasadena, California.

“Our study gives the first reliable estimates of how perennial ice replenishment varies each year at the end of the summer.

“The amount of first-year ice that survives the summer directly influences how thick the ice cover will be at the start of the next melt season.”

The team observed that only 4.0 percent, about 2.5 million square kilometers (965,000 square miles) of thin ice survived the 2005 summer melt to replenish the perennial cover.

It was the weakest ice cover since 2000, and so there was 14 percent less permanent ice cover in January 2006 than in the corresponding period the year before.

“The winters and summers before fall 2005 were unusually warm,” Kwok said. “The low replenishment seen in 2005 is potentially a cumulative effect of these trends.

“If the correlations between replenishment area and numbers of freezing and melting temperature days hold long-term, it is expected the perennial ice coverage will continue to decline.”

Records dating back to 1958 have shown a gradual warming of Arctic temperatures which speeded up in the 1980s.

“Our study suggests that on average the area of seasonal ice that survives the summer may no longer be large enough to sustain a stable, perennial ice cover, especially in the face of accelerating climate warming and Arctic sea ice thinning,” Kwok added.

Scientists say Antarctic ice sheet is thinning

A Texas-sized piece of the Antarctic ice sheet is thinning, possibly due to global warming, and could cause the world’s oceans to rise significantly, polar ice experts said on Wednesday.

They said “surprisingly rapid changes” were occurring in Antarctica’s Amundsen Sea Embayment, which faces the southern Pacific Ocean, but that more study was needed to know how fast it was melting and how much it could cause the sea level to rise.

The warning came in a joint statement issued at the end of a conference of U.S. and European polar ice experts at the University of Texas in Austin.

The scientists blamed the melting ice on changing winds around Antarctica that they said were causing warmer waters to flow beneath ice shelves.

The wind change, they said, appeared to be the result of several factors, including global warming, ozone depletion in the atmosphere and natural variability.

The thinning in the two-mile-(3.2-km)- thick ice shelf is being observed mostly from satellites, but it is not known how much ice has been lost because data is difficult to obtain on the remote ice shelves, they said.

Study is focusing on the Amundsen Sea Embayment because it has been melting quickly and holds enough water to raise world sea levels six meters, or close to 20 feet, the scientists said.

Antarctic Glaciers’ Sloughing Of Ice Has Scientists at a Loss

Some of the largest glaciers in Antarctica and Greenland are moving in unusual ways and are losing increased amounts of ice to the sea, researchers said yesterday.

—
Complicating the situation for those studying Antarctica, some parts of the continent are gaining ice depth through snowfall while temperatures on the tip of the Antarctic peninsula, the continent’s closest point to South America, are rising faster than almost anywhere else on the planet. The surprisingly fast-moving glaciers are largely on the West Antarctic ice sheet.

Wingham, of University College London, and Andrew Shepherd of the University of Edinburgh said satellite radar readings show that overall, each year the ice loss from Greenland and Antarctica amounts to about 10 percent of the rise in the global sea level, which totals about one-tenth of an inch per year. The net loss of Antarctic ice is estimated to be 25 billion metric tons a year, despite the growth of the ice sheet in East Antarctica.

Because such a large percentage of the world’s ice is found in those two locations, scientists are carefully watching for signs of increased ice loss. If that process accelerates, researchers say, it could result in a substantial, and highly disruptive, increase in sea levels worldwide.

In Greenland, glaciers appear to be moving more quickly to sea because melting ice has allowed the sheet to slide more easily over the rock and dirt below. In Antarctica, the loss is believed to be associated with the breaking off into seawater of ice deep under the ice sheet with little-understood internal dynamics that put increased pressure on the massive ice streams.

Southern Ocean current faces slowdown threat

The impact of global warming on the vast Southern Ocean around Antarctica is starting to pose a threat to ocean currents that distribute heat around the world, Australian scientists say, citing new deep-water data.

Melting ice-sheets and glaciers in Antarctica are releasing fresh water, interfering with the formation of dense “bottom water,” which sinks 4-5 kilometers to the ocean floor and helps drive the world’s ocean circulation system.

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Ice shelf collapses in Canada

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Guardian Unlimited reports that a Giant ice island breaks off Arctic shelf. You’ll note those magic words that I’ve been pointing out as a common phrase in all climate change news: “What surprised us was how quickly it happened.”

An ice island the size of a small city is adrift in the Arctic after breaking free from one of Canada’s largest ice shelves, scientists said today.

The ice island is 37 metres (120ft) thick and measures 9 miles by 3 miles, according to the CanWest News Service. It broke clear from Ellesmere island, about 500 miles south of the North Pole, 16 months ago, triggering tremors so powerful they were picked up by earthquake monitors 155 miles away.

Scientists have only just released details about the island after piecing together the break-up from seismic monitors and satellite images.

Within days of breaking free from its fjord on Ellesmere, the floating ice island had drifted a few miles offshore. It travelled west for 31 miles until it froze into the sea ice in early winter.

The island was part of the Ayles ice shelf, one of six major ice shelves in Canada’s Arctic. Scientists believe the shelf’s break-up – the largest of its kind in the Canadian Artic in 30 years – is the result of global warming.

The Artic expert Warwick Vincent, of Laval University in Quebec, said he had never seen such a dramatic loss of sea ice and suggested the break-up indicated that climate change was accelerating.

Dr Vincent, who has travelled to the ice island, said yesterday: “This is a dramatic and disturbing event. It shows that we are losing remarkable features of the Canadian North that have been in place for many thousands of years. We are crossing climate thresholds, and these may signal the onset of accelerated change ahead.

“We think this incident is consistent with global climate change. We aren’t able to connect all of the dots … but unusually warm temperatures definitely played a major role.”

He said Canada’s remaining ice shelves were 90% smaller than when they were first discovered 100 years ago.

…
Using US and Canadian satellite images, as well as data from seismic monitors, Professor Copland discovered that the ice shelf collapsed on the afternoon of August 13 2005.

“What surprised us was how quickly it happened,” he said. “It’s pretty alarming. Even 10 years ago scientists assumed that when global warming changes occur that it would happen gradually so that perhaps we expected these ice shelves just to melt away quite slowly, but the big surprise is that, for one they are going, but secondly, that when they do go, they just go suddenly, it’s all at once, in a span of an hour.”

More from CNN: Ancient ice shelf breaks free from Canadian Arctic:

A giant ice shelf the size of 11,000 football fields has snapped free from Canada’s Arctic, scientists said.

The mass of ice broke clear 16 months ago from the coast of Ellesmere Island, about 800 kilometers (497 miles) south of the North Pole, but no one was present to see it in Canada’s remote north.
…
The Ayles Ice Shelf, roughly 66 square kilometers (41 square miles) in area, was one of six major ice shelves remaining in Canada’s Arctic.

Scientists say it is the largest event of its kind in Canada in 30 years and point their fingers at climate change as a major contributing factor.

And this from the Montreal Gazette Ice shelf collapse sends chill:

Canada’s North changing. Global warming suspected cause of huge breakup on Ellesmere Island
An ancient ice shelf has cracked off northern Ellesmere Island, creating an enormous 66-square-kilometre ice island and leaving a trail of icy blocks in its wake.

“It really is incredible,” said Warwick Vincent of Universite Laval, one of the few people to have laid eyes on the scene. “It’s like a cruise missile has come down and hit the ice shelf.”
…
“We are seeing incredible changes,” said Vincent, whose group is studying the island’s disappearing ice shelves and their unique ecosystems. “People talk of endangered animals – well, these are endangered landscape features and we’re losing them.”

The Ayles ice shelf was one of six ice shelves left in Canada, remnants of a vast icy fringe that used to cover the top end of Ellesmere.

Scientists consider the Canadian shelves, located about 800 kilometres south of the North Pole, sentinels that reflect the accelerating change in the Arctic.

In 2002, one of Vincent’s graduate students, Derek Mueller, discovered that Ellesmere’s Ward Hunt ice shelf had cracked in half. The researchers have also seen the sudden collapse of ice dams and the draining of 30-kilometre-long lakes into the sea.

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Polar bears to get ‘threatened’ listing thanks to climate change

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And to think I know people that still think global warming is a natural cycle… they much prefer to gloss over the effects of what we are doing. Much easier to watch tv, go shopping, etc. and pretend that this is all natural… no need for guilt or responsibility. It’s far too much trouble to consider reality and the possible need to change one’s lifestyle.

I’m increasingly convinced that human beings are fucking monsters. At the very least, we’ve become nature’s delete key. Sad to say but it will be a good thing for the rest of the planet when we manage the task of deleting ourselves… something that will not likely come soon enough.

Polar bears to get ‘threatened’ listing:

WASHINGTON (AP) — Polar bears are in deep trouble because of global warming and other factors and deserve federal protection under the Endangered Species Act, the Bush administration is proposing Wednesday.

Pollution and overhunting also threaten their existence. Greenland and Norway have the most polar bears, but almost 5,000 live mainly in Alaska and travel to Canada and Russia.

Interior Secretary Dirk Kempthorne plans to announce later Wednesday that polar bears should be listed as a “threatened” species on the government list of imperiled species, a department official confirmed Wednesday. The “endangered” category is reserved for species more likely to become extinct.

Such a decision would prevent the U.S. government from allowing any activity that could jeopardize polar bears or the sea ice where they live.

Thinner sea ice reduces the amount of food polar bears can find, including ice seals that are their main prey.

Environmentalists hope that invoking the Endangered Species Act protections eventually might provide impetus for the government to cut back on its emissions of carbon dioxide and other heat-trapping “greenhouse” gases that are warming the atmosphere.

The proposed listing also marks a potentially significant departure for the administration from its cautious rhetoric about the effects of global warming.

President Bush’s steadfast refusal to go along with United Nations-brokered mandatory controls on carbon dioxide, the chief global warming gas, has contributed to international tension between the United States and other nations.

Polar bears, an iconic and cold-dependent animal, are dropping in numbers and weight in the Arctic. In July, the House approved a U.S.-Russia treaty to help protect polar bears from overhunting and other threats to their survival.

That vote put into effect a 2000 treaty that sets quotas on polar bear hunting by native populations in the two countries and establishes a bilateral commission to analyze how best to sustain sea ice. It also approved spending $2 million a year through 2010 for the polar bear program.

The Polar Bear Specialist Group of the World Conservation Union, based in Gland, Switzerland, has estimated that the polar bear population in the Arctic has dwindled to 20,000 to 25,000.

The group lists the polar bear among more than 16,000 species threatened for survival worldwide, and projects a 30 percent decline in their numbers over the next 45 years. It says sea ice is expected to decrease 50 percent to 100 percent over the next 50 to 100 years.”

The Interior Department plans to allow up to 90 days of public comment on its proposal, which was first reported by The Washington Post on its Web site on Tuesday night.

A little over a year ago, three environmental groups — the Center for Biological Diversity, Natural Resources Defense Council and Greenpeace — filed suit to force such a proposal from Interior’s Fish and Wildlife Service, which oversees endangered species. Fish and Wildlife officials have been reviewing the status of polar bears more than two years.

They were pleased by the decision Wednesday.

“This is a victory for the polar bear, and all wildlife threatened by global warming,” Kassie Siegel, a lawyer for the Center for Biological Diversity, said Wednesday. “There is still time to save polar bears but we must reduce greenhouse gas pollution immediately.”

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Sea level rise ‘under-estimated’

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I’m definitely seeing a pattern with the reporting on climate change stories. Seems that with every single story on every new report it is always we underestimated the effects or this particular effect is happening much sooner than we thought it would. The BBC reports that Sea level rise ‘under-estimated’:

Current sea level rise projections could be under-estimating the impact of human-induced climate change on the world’s oceans, scientists suggest.

By plotting global mean surface temperatures against sea level rise, the team found that levels could rise by 59% more than current forecasts.

The researchers say the possibility of greater increases needs be taken into account when planning coastal defences.

The findings have been published in the online edition of the journal Science.

The team from Germany and the US found that for the timescale relevant to human-induced climate change, the observed rate of sea level rise through the 20th Century held a strong correlation with the rate of warming.

When applied to the possible scenarios outlined by the Intergovernmental Panel on Climate Change (IPCC), the researchers found that in 2100 sea levels would be 0.5-1.4m above 1990 levels.

This projection is much greater than the 9-88cm forecast made by the IPCC itself in its Third Assessment Report, published in 2001.

…

He writes in Science Express: “Understanding global sea level changes is a difficult physical problem, as a number of complex mechanisms with different timescales play a role.”

These include:

* thermal expansion of water through heat absorption
* water entering the oceans from glaciers and ice sheets
* increased ice flows after the removal of buttressing ice shelves

Professor Rahmstorf said he decided to use observational data because computer models of climate significantly under-estimated the sea level rise that had already occurred.

“The fact that we get such differences using different methods shows how uncertain our sea level forecasts still are,” he said.

Greenland’s glaciers have been sliding faster towards the sea

He added that the main uncertainty was the response of large ice sheets in Greenland and Antarctica to rising temperatures, which was difficult to predict.

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