Environment: Arctic sea ice melts to new low

Latest satellite data shows that on August 26, the vast blanket of ice shrank to 1.58 million square miles.

The extent of the ice is 27,000 square miles less than the previous melt record set on September 18, 2007.

Such extreme ice loss has not been seen since satellite measurements began in 1979.

It is especially alarming since the seasonal summer Arctic “sea ice minimum” normally does not occur until mid to late September.

Scientists expect the sea ice to continue to dwindle for the next two or three weeks.

Most experts agree that the retreat of Arctic sea ice is mostly tied to global warming caused by man-made greenhouse gas emissions, rather than natural climate variations.

Loss of sea ice does not raise sea levels but contributes to warming because of the loss of bright surfaces. Arctic ice reflects up to 80% of sunlight that hits it back into space.

With less ice, the oceans are allowed to heat up more, which in turn contributes to more melting.

US scientist Dr Walt Meier, from the University of Colorado’s National Snow and Ice Data Centre (NSIDC), which released the new figures, said: “It’s a little surprising to see the 2012 Arctic sea ice extent in August dip below the record low 2007 sea ice extent in September. It’s likely we are going to surpass the record decline by a fair amount this year by the time all is said and done.

“By itself it’s just a number, and occasionally records are going to get set. But 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 is fundamentally changing.”

Since 1979, September Arctic sea ice cover has declined by around 12% per decade.

On September 18, 2007, the sea ice minimum reached a five-day running average of 1.61 million square miles. Compared with the long-term minimum from 1979 to 2000, the ice cover was lower by about a million square miles - roughly 10 times the size of the UK.

“The years from 2007 to 2012 are the six lowest years in terms of Arctic sea ice extent in the satellite record,” Dr Meier added. “In the big picture, 2012 is just another year in the sequence of declining sea ice. We have been seeing a trend toward decreasing minimum Arctic sea ice extents for the past 34 years, and there’s no reason to believe this trend will change.”

He and other experts believe the Arctic could be experiencing ice-free summers within the next several decades.

John Sauven, executive director of the environmentalist group Greenpeace, said government representatives attending the United Nation’s General Assembly in New York next month “should arrive with an image of the melting Arctic ice etched on their memory”.

He added: “These preliminary figures provide irrefutable evidence that greenhouse gas emissions leading to global warming are damaging one of the planet’s critical environments, one that helps maintain the stability of the global climate for every citizen of the world.

“Today’s news should trigger a year of emergency action to save the Arctic, including unprecedented investments in renewable energy and energy efficiency, and agreement to create a global sanctuary in the far north, safeguarding its beleaguered and fragile ecosystem.”

Professor Jeff Kargel, a glaciologist at the University of Arizona, said: “This latest dramatic season of record-fast meltback of sea ice is an indisputable indicator of historically unprecedented rapid climate change over a vast area. This is not a fluke, not an anomaly; it’s not a short-term random variation, some minor phenomenon with negligible impact, or something operative over geologic time scales. This is huge, and it’s fast.”

He wondered whether a “global ocean dynamics switch” had been thrown, or whether the Arctic Ocean was operating its own “little system”.

“I don’t know,” the professor added. “But even the layperson can see that climate far outside the Arctic of the last several years is different than climate of preceding decades. Now we are seeing it hit the Arctic very hard. It does make one wonder what’s next and how this Arctic shift will play out globally as feedbacks take hold.”

Bob Ward, policy and communications director at the Grantham Research Institute on Climate Change and the Environment at the London School of Economics and Political Science, said: “The record set today is a stark sign that global warming is radically altering the planet, with sea ice extent in the Arctic now 40% less than the average between 1979 and 2000.

“At the current rate of warming, we can expect within a few decades that Arctic sea ice will disappear completely during the summer months.”