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Arctic sea ice is melting at a faster rate than previously believed, a group of scientists have claimed.
The European Space Agency say that new satellites they are using have revealed that 900 cubic kilometres of ice have disappeared over the last year.
This is 50 per cent higher than the current estimates from environmentalists, they claim.
Icicles from melting water form on ice in the Arctic. Scientists claim the ice is disappearing faster than previously though
It is suggested that the increase is down to global warming and rising greenhouse gas emissions.
The entire region could be eventually free of ice if the estimates prove accurate. This would trigger a 'gold rush' for oil reserves and fish stocks in the region.
'Preliminary analysis of our data indicates that the rate of loss of sea ice volume in summer in the Arctic may be far larger than we had previously suspected,' said Dr Seymour Laxon, of the Centre for Polar Observation and Modelling at University College London (UCL), where CryoSat-2 data is being analysed, told the Observer.
The scientists launched the CryoSat-2 probe in 2010 specifically to study ice thickness. Until then most studies had focused on the coverage of the ice.
Submarines were also sent into the water to analyse the ice. The methods are said to have given a picture of changes in the ice around the north pole since 2004.
The study revealed that the depth of ice had also been decreasing in addition to the amount of sea it stretched across.
Data from the exploration shows that in winter 2004, the volume of sea ice in the central Arctic was approximately 17,000 cubic km. This winter it was 14,000 km, according to CryoSat.
The amount of ice in summer 2004 was said to be 13,000 km and not it is 7,000.
Professor Chris Rapley of UCL added: 'Before CryoSat, we could see summer ice coverage was dropping markedly in the Arctic.
'But we only had glimpses of what was happening to ice thickness. Obviously if it was dropping as well, the loss of summer ice was even more significant.'
The findings come after study released earlier this month from the University of Copenhagen claimed that Greenland's ice is less vulnerable than feared to a runaway melt that would drive up world sea levels.
'It is too early to proclaim the 'ice sheet's future doom' caused by climate change', lead author Kurt Kjaer wrote in a statement of the findings in the journal Science.
An examination of old photos taken from planes revealed a sharp thinning of glaciers in north-west Greenland from 1985 to 1993, the experts in Denmark, Britain and the Netherlands wrote.
Sea ice in the Arctic is disappearing at a far greater rate than previously expected, according to data from the first purpose-built satellite launched to study the thickness of the Earth's polar caps.
Preliminary results from the European Space Agency's CryoSat-2 probe indicate that 900 cubic kilometres of summer sea ice has disappeared from the Arctic ocean over the past year.
This rate of loss is 50% higher than most scenarios outlined by polar scientists and suggests that global warming, triggered by rising greenhouse gas emissions, is beginning to have a major impact on the region. In a few years the Arctic ocean could be free of ice in summer, triggering a rush to exploit its fish stocks, oil, minerals and sea routes.
Using instruments on earlier satellites, scientists could see that the area covered by summer sea ice in the Arctic has been dwindling rapidly. But the new measurements indicate that this ice has been thinning dramatically at the same time. For example, in regions north of Canada and Greenland, where ice thickness regularly stayed at around five to six metres in summer a decade ago, levels have dropped to one to three metres.
"Preliminary analysis of our data indicates that the rate of loss of sea ice volume in summer in the Arctic may be far larger than we had previously suspected," said Dr Seymour Laxon, of the Centre for Polar Observation and Modelling at University College London (UCL), where CryoSat-2 data is being analysed. "Very soon we may experience the iconic moment when, one day in the summer, we look at satellite images and see no sea ice coverage in the Arctic, just open water."
If we see an increase in the amount of methane released from the Arctic Ocean clathrates again this September, it could happen in half that time.
The Arctic has lost more sea ice this year than at any time since satellite records began in 1979, Nasa says. Scientists involved in the calculations say it is part of a fundamental change. What is more, sea ice normally reaches its low point in September so it is thought likely that this year's melt will continue to grow. Nasa says the extent of sea ice was 1.58m sq miles (410m sq km) compared with a previous low of 1.61m sq miles (4.17m sq km) on 18 September 2007. The sea ice cap grows during the cold Arctic winters and shrinks when temperatures climb again, but over the last three decades, satellites have observed a 13% decline per decade in the summertime minimum.
The thickness of the sea ice is also declining, so overall the ice volume has fallen far - although estimates vary about the actual figure. Joey Comiso, senior research scientist at Nasa's Goddard Space Flight Center, said this year's ice retreat was caused by previous warm years reducing the amount of perennial ice - which is more resistant to melting. It's created a self-reinforcing trend. "Unlike 2007, temperatures were not unusually warm in the Arctic this summer. [But] we are losing the thick component of the ice cover," he said. "And if you lose [that], the ice in the summer becomes very vulnerable."
'Inevitable death'
Walt Meier, from the National Snow and Ice Data Center that collaborates in the measurements, said: "In the context of what's happened in the last several years and throughout the satellite record, it's an indication that the Arctic sea ice cover is fundamentally changing." Professor Peter Wadhams, from Cambridge University, told BBC News: "A number of scientists who have actually been working with sea ice measurement had predicted some years ago that the retreat would accelerate and that the summer Arctic would become ice-free by 2015 or 2016. "I was one of those scientists - and of course bore my share of ridicule for daring to make such an alarmist prediction."
But Prof Wadhams said the prediction was now coming true, and the ice had become so thin that it would inevitably disappear. "Measurements from submarines have shown that it has lost at least 40% of its thickness since the 1980s, and if you consider the shrinkage as well it means that the summer ice volume is now only 30% of what it was in the 1980s," he added. "This means an inevitable death for the ice cover, because the summer retreat is now accelerated by the fact that the huge areas of open water already generated allow storms to generate big waves which break up the remaining ice and accelerate its melt. "Implications are serious: the increased open water lowers the average albedo [reflectivity] of the planet, accelerating global warming; and we are also finding the open water causing seabed permafrost to melt, releasing large amounts of methane, a powerful greenhouse gas, to the atmosphere."
Threats and opportunities
If we see an increase in the amount of methane released from the Arctic Ocean clathrates again this September, it could happen in half that time.
I kind of assume that your post was meant to be witty but unfortunately it comes across as kind of half-witty. Do you not even know what methane clathrates are?If we see an increase in the amount of methane released from the Arctic Ocean clathrates again this September, it could happen in half that time.
Are those damn seals farting again?
Yes of course I know the methane argument is a bunch of bullshit.
Yes of course I know the methane argument is a bunch of bullshit.
And the basis for that statement is?
More than 20 polar research teams have combined forces to produce estimates of the state of the ice in Greenland and Antarctica in a paper in Science. Until now different measurement means have produced a wide range of estimates with large uncertainties. But sea-level rise is now among the most pressing questions of our time. Polar ice has a tremendous capacity to cause massive rises - with huge potential impacts on coastal cities and communities around the world. But the remoteness and sheer size of the ice sheets mean accurate measurements are a serious challenge even for satellites which have to distinguish snow from ice, and the rise of the land from the shrinking of the ice.
One number
The new estimate shows that polar melting contributed about one-fifth of the overall global sea level rise since 1992; other factors include warming which causes the seawater to expand. The study does not seek to forecast future change. Supported by US and European space agencies NASA and ESA, the research brought together data from satellites measuring the surface altitude, the flow of the glaciers and the gravitational effect of the ice mass to produce the first joint assessment of how the ice sheets are changing. The results show that the largest ice sheet - that of East Antarctica - has gained mass over the study period of 1992-2011 as increased snowfall added to its volume.
However Greenland, West Antarctica and the Antarctic Peninsula were all found to be losing mass - and on a scale that more than compensates for East Antarctica's gain. The study's headline conclusion is that the polar ice sheets have overall contributed 11.1mm to sea level rise but with a "giver or take" uncertainty of 3.8mm - meaning the contribution could be as little as 7.3mm or as much as 14.9mm. The combined rate of melting from all the ice sheets has increased over the past 20 years with Greenland losing five times as much now as in 1992.
The lead author of the research, Prof Andrew Shepherd of Leeds University, said the study brings to an end 20 years of disagreement between different teams. "We can now say for sure that Antarctica is losing ice and we can see how the rate of loss from Greenland is going up over the same period as well," he said. "Prior to now there'd been 30 to 40 different estimates of how the ice sheets are changing, and what we realised was that most people just wanted one number to tell them what the real change was. "So we've brought everybody together to produce a single estimate and it turns out that estimate is two to three times more reliable than the last one."
On the rebound
Yes of course I know the methane argument is a bunch of bullshit.
And the basis for that statement is?
Yes of course I know the methane argument is a bunch of bullshit.
And the basis for that statement is?
The fact that the arctic was hotter during the holocene maximum, the roman warm period, the minoan warm period and the medieval warm period without the catastrophe that your models predict.
https://www2.ucar.edu/atmosnews/news/846/arctic-warming-overtakes-2000-years-natural-cooling
New research shows that the Arctic reversed a long-term cooling trend and began
https://www2.ucar.edu/atmosnews/news/846/arctic-warming-overtakes-2000-years-natural-cooling
New research shows that the Arctic reversed a long-term cooling trend and began
Damned interesting how your climate gurus and models happen to find the most warming where they have the least instrumentation.
