Ominous Arctic Melt Worries Experts
The Associated Press, Dec. 11, 2007
WASHINGTON (AP)An already relentless melting of the
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 government's snow and ice data center in
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 said: "At this rate, the
So scientists in recent days have been asking themselves these questions: Was the record melt seen all over the
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
What happens in the
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.'
2007 shattered records for
_ 552 billion tons of ice melted this summer from the
_ A record amount of surface ice was lost over Greenland this year, 12 percent more than the previous worst year, 2005, according to data the
_ The surface area of summer sea ice floating in the
_ 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.
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
"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
Melting of sea ice and
"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 timebut it is going to require a quick turn in direction.'
Last year, Cecilia Bitz at the
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.