The Arctic Ocean could be largely ice-free and open to shipping¹ during the summer in as little as ten years' time, a top polar specialist has said.

一位顶级极地专家称，再过短短10年的时间，北冰洋的夏季将不会出现大的海冰，这将使货运成为可能。

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The yellow SPRITE radar was the expedition's key piece of kit³

"It's like man is taking the lid off（揭开盖子） the northern part of the planet," said Professor Peter Wadhams, from the University of Cambridge.

Professor Wadhams has been studying the Arctic ice since the 1960s.

He was speaking in central London at the launch of the findings of the Catlin Arctic Survey.

The expedition trekked⁴（艰苦跋涉） across 435km of ice earlier this year.

Led by explorer Pen Hadow, the team's measurements found that the ice-floes were on average 1.8m thick - typical of so-called "first year" ice formed during the past winter and most vulnerable to melting.

The survey route - to the north of Canada - had been expected to cross areas of older "multi-year" ice which is thicker and more resilient（弹回的，愉快的）.

When the ridges⁵ of ice between floes are included, the expedition found an average thickness of 4.8m.

Professor Wadhams said: "The Catlin Arctic Survey data supports the new consensus⁶（一致，合意） view - based on seasonal⁷ variation of ice extent and thickness, changes in temperatures, winds and especially ice composition - that the Arctic will be ice-free in summer within about 20 years, and that much of the decrease will be happening within 10 years.

"That means you'll be able to treat the Arctic as if it were essentially⁸ an open sea in the summer and have transport across the Arctic Ocean."

According to Professor Wadhams, faster shipping and easier access to oil and gas reserves（储量） were among short-term benefits of the melting.

But in the longer-term, losing a permanent（永久的，持久的） feature of the planet risked accelerated warming, changing patterns of circulation（流通，循环） in the oceans and atmosphere, and having unknown effects on ecosystems⁹ through the acidification（酸化） of waters.

Pen Hadow and his companions Ann Daniels and Martin Hartley endured ferocious¹⁰（残忍的，凶猛的） weather - including a wind chill of minus 70 - delayed resupply flights and starvation rations¹¹ during the expedition from 1 March to 7 May.

When I met them on the ice, as part of a BBC team that joined the pick-up flight, all three had lost weight and were evidently tired from the ordeal¹².

The expedition had been blighted¹³（枯萎，摧残） by equipment failures. A pioneering radar system, designed to measure the ice while being dragged over the ice, broke down within days. Another device to measure the water beneath the ice never functioned at all.