REYKJAVIK, Iceland -- Get ready to order those beach umbrellas in Barrow. One of the leading authorities on the physics of northern seas is predicting an ice-free Arctic Ocean by the year 2020.

That's about two decades sooner than various models for climatic warming have indicated the Arctic might fully open.

"No models here," Peter Wadhams, professor of applied mathematics and theoretical physics at the University of Cambridge in England, told the Arctic Circle Assembly on Sunday. "This is data."

Wadhams has access to data not only on the extent of ice covering the Arctic, but on the thickness of that ice. The latter comes from submarines that have been beneath the ice collecting measurements every year since 1979.

This data shows ice volume "is accelerating downward," Wadhams said. "There doesn't seem to be anything to stop it from going down to zero.

"By 2020, one would expect the summer sea ice to disappear. By summer, we mean September. ... (but) not many years after, the neighboring months would also become ice-free."

Wadhams later clarified that by "ice-free" he didn't exactly mean the Arctic was going to look like the Baltic Sea in summer.

The scientific definition of "ice-free" is complicated. It is basically based on the amount of ice found in a number of grids when looking at the Arctic from space.

An "ice-free" Arctic, as defined by scientists, would remain full of floating ice in the summer, but the ice would be broken up enough that a ship could push through it.

Wadhams' pronouncement was angrily challenged by one of the scientists modeling sea ice decline, but the elderly physicist stuck to his guns. He admitted he is predicting a very early opening of the Arctic, but this is "not a model.

"I wasn't issuing any threats to anyone."

The modelers, he told Alaska Dispatch News later, are very sensitive about their models. But he added that it's hard to deny the actual data. He had plotted the ice decline as a graph curving steadily and increasingly downward since the 1970s and hitting zero in 2020.

Former Alaska North Slope Borough Mayor Edward Itta, on hand for the conference, liked the graph.

"It made it easy to understand," he said.

Wadhams -- who has spent much of his life working in, on or under the Arctic ice -- said he is not suggesting the Arctic is on its way to becoming the new Mediterranean. He is only suggesting the polar ice cap that has locked the region under ice year-round for centuries is going to go away, at least in summer.

"In fact, it (the Arctic) could become nastier" because of that, he added, citing the weather conditions that can develop as rain, wind and snow whip over vast expanses of broken ice.

Wadhams has previously made predictions that Arctic melt would occur faster than most models estimate; in 2012, he said that the Arctic could be ice-free by the summer of 2015 or 2016. That prediction appears unlikely now, but many climate authorities believe the Arctic may have already reached a tipping point at which the release of methane gas from thawing permafrost will greatly accelerate warming. Methane is a greenhouse gas said to be about 30 times more efficient in trapping heat on Earth than the carbon dioxide pouring into the atmosphere from the homes, motor vehicles and businesses of the modern industrial world.

Even with the continued melt, there is no indication the climate of the Arctic will get all that much friendlier to humans anytime soon, and as Okalik Eegeesiak, chair of the Inuit Circumpolar Council observed Sunday, "the climate is not for everyone."

The loss of Arctic ice might actually have more of an impact on the climate than on humans over the short term. Without ice cover to reflect sunlight back into space, the summer Arctic will begin to absorb a lot of solar energy.

The effect of that, Wadhams said, "is like increasing our emissions by a quarter."

This and Wadhams' other pronouncements came on the same day the United Nations' Intergovernmental Panel on Climate Change issued a report saying global warming is real and irreversible.

"The planet faces a future of extreme weather, rising sea levels and melting polar ice from soaring levels of carbon dioxide and other gases," the Washington Post reported.

One of those "other gases" is Arctic methane, about which there has been a lot of talk here at the Arctic Circle Assembly, a three-day conference organized by Iceland President Olafur Ragnar Grimsson and Alaska Dispatch News Publisher Alice Rogoff.

There is a lot of methane locked in the frozen ground or beneath the seas in the Arctic, but that is changing.

Along the Russian coast, Wadhams noted, "offshore permafrost is thawing."

As it thaws, methane is bubbling to the surface. Russian scientists report that significant volumes appear to have already escaped into the atmosphere. A University of Alaska Fairbanks professor at one forum Saturday showed photos of a student lighting off a big plume of the gas bubbling out of the ice.

Dan White, director of the Institute of Northern Engineering at UAF, warned there is enough gas bubbling up under the ice of some Arctic lakes in winter that one must be careful not to hurt oneself when lighting the gas.

The Arctic methane, Wadhams said, "could cause a large amount of warming in a short time."

Igor Semiletov, a professor at the International Arctic Research Center at UAF, estimates there might be 500 times as much methane trapped beneath the Arctic as there is currently in the atmosphere.

If a lot of it got loose fast, the planet could really heat up.

Contact Craig Medred at