Sean Kilpatrick via Reuters

Lowell Glacier rises from waters in Kluane National Park, near Haines Junction in Canada's Yukon Territory.

OSLO, Norway — Canadian glaciers that are the world's third biggest store of ice after Antarctica and Greenland seem headed for an irreversible melt that will push up sea levels, scientists said Thursday.

About 20 percent of the ice in glaciers, on islands such as Ellesmere or Devon off northern Canada, could vanish by the end of the 21st century in a melt that would add 1.4 inch (3.5 cm) to global sea levels, they said.

Governments are trying to understand every possible centimeter of sea level rise caused by global warming, to plan how to protect cities from New York to Shanghai or low-lying coasts from Ghana to Bangladesh. "We believe that the mass loss is irreversible in the foreseeable future," assuming continued climate change, the scientists, based in the Netherlands and the United States, wrote in the journal Geophysical Research Letters.

Lead author Jan Lenaerts of the University of Utrecht told Reuters that the trend seemed unstoppable because a thaw of white glaciers would expose dark-colored tundra that would soak up more of the sun's heat and further accelerate the melt.

A total melt of the glaciers would take several centuries. Climate change is warming the Arctic faster than the global average.

Most past estimates of Canada's glaciers, based on less precise data of their size and melt rates, pointed to a smaller contribution to sea level rise of perhaps three-quarters of an inch (2 centimeters) this century, Lenaerts said.

The U.N. panel of climate scientists has projected that world sea levels will rise by 7 to 23 inches (18 to 59 centimeters) this century, or more if a thaw of vast ice sheets in Antarctica or Greenland accelerates.

Canada's glaciers are little-studied and often lumped into the panel's estimates with ice in Alaska, Patagonia, Russia and Svalbard off north Norway.

"These glaciers are a significant part of the whole equation and of future sea level rise," David Vaughan, head of the ice2sea program for studying global warming based at the British Antarctic Survey in England, told Reuters. "We can't afford to ignore them." Vaughan was not among the authors of Thursday's study.

"Most attention goes out to Greenland and Antarctica, which is understandable because they are the two largest ice bodies in the world," Michiel van den Broeke, a co-author of the study at Utrecht University, said in a statement. "We want to show that the Canadian ice caps should be included in the calculations."

The experts used satellite data of the extent of Canadian glaciers over the past decade to work out a model to project their decline. The projection of a 20 percent loss of volume was based on a scenario in which world temperatures would rise by 3 degrees Celsius (5.4 degrees Fahrenheit) this century and by 8 degrees C (14.4 degrees F) in the Canadian Arctic. That's well within most U.N. scenarios.

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Lucas Jackson / Reuters, file

U.S. Navy safety swimmers stand on the deck of the Virginia class submarine USS New Hampshire after it surfaced through thin ice during exercises underneath ice in the Arctic Ocean north of Prudhoe Bay, Alaska March 19, 2011.

YOKOSUKA, Japan -- To the world's military leaders, the debate over climate change is long over. They are preparing for a new kind of Cold War in the Arctic, anticipating that rising temperatures there will open up a treasure trove of resources, long-dreamed-of sea lanes and a slew of potential conflicts. 

By Arctic standards, the region is already buzzing with military activity, and experts believe that will increase significantly in the years ahead. 

Last month, Norway wrapped up one of the largest Arctic maneuvers ever — Exercise Cold Response — with 16,300 troops from 14 countries training on the ice for everything from high intensity warfare to terror threats. Attesting to the harsh conditions, five Norwegian troops were killed when their C-130 Hercules aircraft crashed near the summit of Kebnekaise, Sweden's highest mountain.

The U.S., Canada and Denmark held major exercises two months ago, and in an unprecedented move, the military chiefs of the seven main Arctic powers — Canada, the U.S., Russia, Iceland, Denmark, Sweden and Finland — are to gather at a Canadian military base in May to specifically discuss regional security issues. 

None of this means a shooting war is likely at the North Pole any time soon. But as the number of workers and ships increases in the High North to exploit oil and gas reserves, so will the need for policing, border patrols and — if push comes to shove — military muscle to enforce rival claims. 

High stakes
The U.S. Geological Survey estimates that 13 percent of the world's undiscovered oil and 30 percent of its untapped natural gas is in the Arctic.

Shipping lanes could be regularly open across the Arctic by 2030 as rising temperatures continue to melt the sea ice, according to a National Research Council analysis commissioned by the U.S. Navy last year. 

UK report analyzes risks of Arctic development

What countries should do about climate change remains a heated political debate. But that has not stopped north-looking militaries from moving ahead with strategies that assume current trends will continue. 

Russia, Canada and the United States have the biggest stakes in the Arctic. With its military budget stretched thin by Iraq, Afghanistan and more pressing issues elsewhere, the United States has been something of a reluctant northern power, though its nuclear-powered submarine fleet, which can navigate for months underwater and below the ice cap, remains second to none. 

Lucas Jackson / Reuters, file

U.S. Navy watch a display in the control room of the Virginia class submarine USS New Hampshire as it surfaces during exercises underneath ice in the Arctic Ocean north of Prudhoe Bay, Alaska March 20, 2011.

Russia — one-third of which lies within the Arctic Circle — has been the most aggressive in establishing itself as the emerging region's superpower. 

Rob Huebert, an associate political science professor at the University of Calgary in Canada, said Russia has recovered enough from its economic troubles of the 1990s to significantly rebuild its Arctic military capabilities, which were a key to the overall Cold War strategy of the Soviet Union, and has increased its bomber patrols and submarine activity. 

Huebert said that has in turn led other Arctic countries — Norway, Denmark and Canada — to resume regional military exercises that they had abandoned or cut back on after the Soviet collapse. Even non-Arctic nations such as France have expressed interest in deploying their militaries to the Arctic. 

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"We have an entire ocean region that had previously been closed to the world now opening up," Huebert said. "There are numerous factors now coming together that are mutually reinforcing themselves, causing a buildup of military capabilities in the region. This is only going to increase as time goes on." 

Noting that the Arctic is warming twice as fast as the rest of the globe, the U.S. Navy in 2009 announced a beefed-up Arctic Roadmap by its own task force on climate change that called for a three-stage strategy to increase readiness, build cooperative relations with Arctic nations and identify areas of potential conflict. 

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"We want to maintain our edge up there," said Cmdr. Ian Johnson, the captain of the USS Connecticut, which is one of the U.S. Navy's most Arctic-capable nuclear submarines and was deployed to the North Pole last year. "Our interest in the Arctic has never really waned. It remains very important." 

US 'inadequately prepared'
But the U.S. remains ill-equipped for large-scale Arctic missions, according to a simulation conducted by the U.S. Naval War College. A summary released last month found the Navy is "inadequately prepared to conduct sustained maritime operations in the Arctic" because it lacks ships able to operate in or near Arctic ice, support facilities and adequate communications.

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The findings indicate the Navy is entering a new realm in the Arctic," said Walter Berbrick, a War College professor who participated in the simulation. "Instead of other nations relying on the U.S. Navy for capabilities and resources, sustained operations in the Arctic region will require the Navy to rely on other nations for capabilities and resources." 

He added that although the U.S. nuclear submarine fleet is a major asset, the Navy has severe gaps elsewhere — it doesn't have any icebreakers, for example. The only one in operation belongs to the Coast Guard. The U.S. is currently mulling whether to add more icebreakers.

US: 56 coral species face extinction danger

Acknowledging the need to keep apace in the Arctic, the United States is pouring funds into figuring out what climate change will bring, and has been working closely with the scientific community to calibrate its response. 

"The Navy seems to be very on board regarding the reality of climate change and the especially large changes we are seeing in the Arctic," said Mark C. Serreze, director of the National Snow and Ice Data Center at the Cooperative Institute for Research in Environmental Sciences University of Colorado. "There is already considerable collaboration between the Navy and civilian scientists and I see this collaboration growing in the future." 

The most immediate challenge may not be war — both military and commercial assets are sparse enough to give all countries elbow room for a while — but whether militaries can respond to a disaster. 

Heather Conley, director of the Europe program at the London-based Center for Strategic and International Studies, said militaries probably will have to rescue their own citizens in the Arctic before any confrontations arise there. 

"Catastrophic events, like a cruise ship suddenly sinking or an environmental accident related to the region's oil and gas exploration, would have a profound impact in the Arctic," she said. "The risk is not militarization; it is the lack of capabilities while economic development and human activity dramatically increases that is the real risk."

POLENET

This GPS sensor on Greenland is one of nearly 50 spread across the island.

A network of GPS stations across southern Greenland has detected that the area lost 100 billion tons of ice due to an unusually warm summer in 2010, researchers report. What's more, removing that much weight has raised parts of the bedrock by a quarter inch more than in recent years.

Greenland's ice sheet has been seeing a steady melt during the summer months, and those GPS stations in years prior to 2010 typically detected an uplift of 0.59 inches.

"But a temperature spike in 2010 lifted the bedrock a detectably higher amount over a short five-month period -- as high as 20 mm (0.79 inches) in some locations," Ohio State University said in explaining the research by Michael Bevis, one of its geologists, and others that are part of the POLENET research network.

Bevis described the findings last Friday at a conference of the American Geophysical Union, saying he's convinced that the uplift is due to the ice loss.

"Really, there is no other explanation. The uplift anomaly correlates with maps of the 2010 melting day anomaly. In locations where there were many extra days of melting in 2010, the uplift anomaly is highest."

He added that the findings also have implications for sea levels.

"Pulses of extra melting and uplift imply that we'll experience pulses of extra sea level rise. The process is not really a steady process," he said.

Experts had earlier estimated that Greenland between 1961 and 2003 saw years that ranged from 25 billion tons of new ice to years where 60 billion tons were lost. Years since then have seen even higher shrinkage.

100 billion tons of ice melting from Greenland's ice sheet translates into a global sea level increase of about .01 inches.

The team first reported that ice sheets, which can be thousands of feet thick, suppress bedrock in 2008, when they discussed findings from similar GPS sensors on Antarctica.