The reflective Arctic sea ice that serves as a heat shield for the planet has melted to a new record low and government-backed scientists on Monday said the Arctic may be largely ice-free as soon as 2020.

This month, up to 100,000 square miles of sea ice a day disappeared, bringing overall shrinkage over the past three decades to 40 per cent, according to data analysed over the weekend at the National Snow and Ice Data Centre, located at the University of Colorado in Boulder.

The data show the area covered by sea ice shrank to 1.58 million square miles, its lowest ebb in 32 years. That’s about 27,000 square miles less than the previous low of 1.61 million square miles recorded Sept 18, 2007.

Another 150,000 square miles of sea ice could melt before the middle of next month, when refreezing typically begins, NSIDC research scientist Walt Meier said, during a conference call with colleagues at NASA.

The past six years have brought the six lowest levels of sea ice since 1979, when measurements began. The climate scientists said the melting will open shipping routes for energy companies hoping to claim untapped oil and gas, while also worsening climate change worldwide.

“The Arctic is not like Las Vegas,” Mr. Meier said. “What happens in the Arctic does not stay in the Arctic.” Arctic summers may be mostly ice-free by 2020 to 2050, he said.

A previous Intergovernmental Panel on Climate Change report, published in 2007, projected ice-free conditions around 2100. “The observations show us going quicker than that,” Mr. Meier said.

NASA senior scientist Joey Comiso said some residual sea ice, around 10 per cent, likely will remain. However, the data in recent years show not only summertime declines, he noted, “but also quite significant declines in the sea ice cover during winter”.

The dissolving of White Sea ice into darker open water means reduced reflection. More sunlight is absorbed into oceans, raising water temperatures. This ocean warming is seen by some as related to climate change, affecting ocean currents, air currents and storm paths.

“The ocean warms when the ice cover is not there, so you get a lot of warming within the Arctic Ocean that, from the ocean, can then feed back and melt the ice,” Mr. Meier said.

“As far as the larger scale, when you’re heating up a region of the world, compared to what it used to be, you’re changing the balance of the climate system,” he said.

“Now, your air conditioner is losing coolant, so to speak. It’s not as efficient as it used to be.”

Sea ice also is thinning, the scientists said. And this sea ice capping the planet, as they described it, increasingly resembles slush.

The ice is more easily broken apart by storms, melted by summer sunlight and reduced by warming waters. Climate-change modellers not involved in the ice-observation project link the melting sea ice to global warming driven in part by human use of fossil fuels.

The melting is working in favour of ships that haul drilling rigs for extraction of new oil from the Arctic. U.S. Department of the Interior officials is expected to approve exploratory drilling this year in the Chukchi and other Arctic seas. — New York Times News Service