Some news about Greenland/Arctic melting

Record ice melt seen on Greenland in 2007
Expert: Equivalent to layer of water half-mile deep covering Washington, D.C.
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The amount of melt on Greenland's ice sheet last summer broke the previous measured record by 10 percent, according to new data analyzed by researchers at Colorado University.

The 2007 melt was the largest ever recorded since satellite measurements began in 1979, researcher Konrad Steffen told colleagues at a conference of the American Geophysical Union this week.

"The amount of ice lost by Greenland over the last year is the equivalent of two times all the ice in the Alps, or a layer of water more than one-half mile deep covering Washington, D.C.," he said in a statement released in conjunction with the new study.

The melting has increased by about 30 percent for west Greenland from 1979 to 2006, with record melt years in 1987, 1991, 1998, 2002, 2005 and 2007, said Steffen, director of the Cooperative Institute for Research in Environmental Sciences at Colorado University.

Air temps increased as well
He added that air temperatures on the Greenland ice sheet have increased by about 7 degrees Fahrenheit since 1991.

His team used data from military and weather satellites to chart the melt. It also maintains 22 monitoring stations on the ice sheet that transmit hourly data via satellites to Colorado University at Boulder.

Steffen noted that while Greenland has been thickening at higher elevations due to more snow, the gain is more than offset by accelerating loss where glaciers meet the sea.

One of those, he said, is the Jacobshavn Glacier, which drains 8 percent of the ice sheet. The drainage rate has sped up nearly twofold in the last decade, he said.

"The more lubrication there is under the ice, the faster that ice moves to the coast," said Steffen. "Those glaciers with floating ice 'tongues' also will increase in iceberg production."

Sea level predictions underestimated?
Steffen said recent research on ice dynamics "will likely show" that U.N. predictions "underestimated sea-level projections for the end of the 21st century."

Of particular concern is an increase in shafts known as moulins, which drain melt water from surface ponds down to bedrock.

"These melt-water drains seem to allow the ice sheet to respond more rapidly than expected to temperature spikes at the beginning of the annual warm season," Steffen said. "In recent years the melting has begun earlier than normal."

"We know the number of moulins is increasing," he added. "The bigger question is how much water is reaching the bed of the ice sheet, and how quickly it gets there."

The current contribution of Greenland ice melt to global sea levels is about .02 inches a year, Steffen's institute noted, but the potential impact is enormous. About a quarter the size of the United States, Greenland has about one-twentieth of the world's ice — the equivalent of about 21 feet of global sea rise were it to completely melt into the sea.

That process could take centuries to complete, but once started would be difficult to reverse.
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Rate of ice melt shocks warming experts
'The Arctic is screaming,' says one; another calls 2007 a 'watershed year'

WASHINGTON - An already relentless melting of the Arctic greatly accelerated this summer, a warning sign that some scientists worry could mean global warming has passed an ominous tipping point. One even speculated that summer sea ice would be gone in five years.

Greenland's ice sheet melted nearly 19 billion tons more than the previous high mark, and the volume of Arctic sea ice at summer's end was half what it was just four years earlier, according to new NASA satellite data obtained by The Associated Press.

"The Arctic is screaming," said Mark Serreze, senior scientist at the U.S. government's National Snow and Ice Data Center in Boulder, Colo.
Sea ice, which floats on water, is a key climate signal as well as prime habitat for walruses and polar bears in the Arctic. Ice sheets, for their part, lock water on land but raise sea levels if that ice starts to melt.

Changes in Arctic weather, especially warmer temperatures, also has implications for the rest of the world.

In the United States, a weakened Arctic blast moving south to collide with moist air from the Gulf of Mexico can mean less rain and snow in some areas, including the drought-stricken Southeast, said Michael MacCracken, a former federal climate scientist who now heads the nonprofit Climate Institute. Some regions, like Colorado, would likely get extra rain or snow.

Just last year, two top scientists surprised their colleagues by projecting that the Arctic sea ice was melting so rapidly that it could disappear entirely by the summer of 2040.

This week, after reviewing his own new data, NASA climate scientist Jay Zwally warned that "at this rate, the Arctic Ocean could be nearly ice-free at the end of summer by 2012, much faster than previous predictions."

So scientists in recent days have been asking themselves these questions: Was the record melt seen all over the Arctic in 2007 a blip amid relentless and steady warming? Or has everything sped up to a new climate cycle that goes beyond the worst case scenarios presented by computer models?

'The canary has died'
"The Arctic is often cited as the canary in the coal mine for climate warming," said Zwally, who as a teenager hauled coal. "Now as a sign of climate warming, the canary has died. It is time to start getting out of the coal mines."

It is the burning of coal, oil and other fossil fuels that produces carbon dioxide and other greenhouse gases, responsible for man-made global warming. For the past several days, government diplomats have been debating in Bali, Indonesia, the outlines of a new climate treaty calling for tougher limits on these gases.

More than 18 scientists told The AP that they were surprised by the level of ice melt this year.

"I don't pay much attention to one year ... but this year the change is so big, particularly in the Arctic sea ice, that you've got to stop and say, 'What is going on here?' You can't look away from what's happening here," said Waleed Abdalati, NASA's chief of cyrospheric sciences. "This is going to be a watershed year."

Unfortunate records
2007 shattered records for Arctic melt in the following ways:

* 552 billion tons of ice melted this summer from the Greenland ice sheet, according to preliminary satellite data to be released by NASA Wednesday. That's 15 percent more than the annual average summer melt, beating 2005's record.
* A record amount of surface ice was lost over Greenland this year, 10 percent more than the previous worst year, 2005, according to data the University of Colorado released Monday. That's nearly quadruple the amount that melted just 15 years ago. It's an amount of water that could cover Washington, D.C., a half-mile deep, researchers calculated.
* The surface area of summer sea ice floating in the Arctic Ocean this summer was nearly 23 percent below the previous record. The dwindling sea ice already has affected wildlife, with 6,000 walruses coming ashore in northwest Alaska in October for the first time in recorded history. Another first: the Northwest Passage was open to navigation.
* Still to be released is NASA data showing the remaining Arctic sea ice to be unusually thin, another record. That makes it more likely to melt in future summers. Combining the shrinking area covered by sea ice with the new thinness of the remaining ice, scientists calculate that the overall volume of ice is half of 2004's total.
* Alaska's frozen permafrost is warming, not quite thawing yet. But temperature measurements 66 feet deep in the frozen soil rose nearly four-tenths of a degree from 2006 to 2007, according to measurements from the University of Alaska. While that may not sound like much, "it's very significant," said University of Alaska professor Vladimir Romanovsky.
* Surface temperatures in the Arctic Ocean this summer were the highest in 77 years of record-keeping, with some places 8 degrees Fahrenheit above normal, according to research to be released Wednesday by the University of Washington’s Michael Steele.
Greenland, in particular, is a significant bellwether. Most of its surface is covered by ice. If it completely melted — something key scientists think would likely take centuries, not decades — it could add more than 21 feet to the world's sea level.

However, for nearly the past 30 years, the data pattern of its ice sheet melt has zigzagged. A bad year, like 2005, would be followed by a couple of lesser years.

According to that pattern, 2007 shouldn't have been a major melt year, but it was, said Konrad Steffen, of the University of Colorado, which gathered the latest data.
"I'm quite concerned," he said. "Now I look at 2008. Will it be even warmer than the past year?"

Other new data, from a NASA satellite, measures ice volume. NASA geophysicist Scott Luthcke, reviewing it and other Greenland numbers, concluded: "We are quite likely entering a new regime."

Melting of sea ice and Greenland's ice sheets also alarms scientists because they become part of a troubling spiral.

White sea ice reflects about 80 percent of the sun's heat off Earth, NASA's Zwally said. When there is no sea ice, about 90 percent of the heat goes into the ocean which then warms everything else up. Warmer oceans then lead to more melting.

"That feedback is the key to why the models predict that the Arctic warming is going to be faster," Zwally said. "It's getting even worse than the models predicted."

NASA scientist James Hansen, the lone-wolf researcher often called the godfather of global warming, on Thursday will tell scientists and others at a meeting of researchers in San Francisco that in some ways Earth has hit one of his so-called tipping points, based on Greenland melt data.
"We have passed that and some other tipping points in the way that I will define them," Hansen said in an e-mail. "We have not passed a point of no return. We can still roll things back in time — but it is going to require a quick turn in direction."

Last year, Cecilia Bitz at the University of Washington and Marika Holland at the National Center for Atmospheric Research in Colorado startled their colleagues when they predicted an Arctic free of sea ice in just a few decades. Both say they are surprised by the dramatic melt of 2007.

Bitz, unlike others at NASA, believes that "next year we'll be back to normal, but we'll be seeing big anomalies again, occurring more frequently in the future." And that normal, she said, is still a "relentless decline" in ice.

A NASA multimedia presentation on climate "tipping points" is online at www.nasa.gov/topics/earth/tipping_points.html