Ice in the ocean surrounding the Arctic is thinner than it`s been in 30 years, and there`s much less of it, say scientists who are monitoring the effects of climate change, The San Francisco Chronicle reported.
At the same time, another team of climate scientists is predicting from earlier data that the Arctic`s ice cover has been melting so rapidly over the past few years that much of it could be gone within another three decades.
"Ice extent is an important measure of the health of the Arctic," said Walter Fowler of the University of California`s Snow and Ice Data Center. "It is critical for animals that live on the ice and for the humans who use its resources for subsistence."
The 31st annual end-of-winter survey of Arctic sea ice conditions was reported Monday during a teleconference by researchers from NASA and the Snow and Ice Data Center, who monitor the ice continuously by satellite. Their assessment was not reassuring.
The ice that begins freezing every autumn over the vast ocean surrounding the pole is so thin it may last only a year. By contrast, ice that doesn`t thaw during the spring and summer becomes perennial ice that grows thicker and thicker year by year.
By the end of February, the survey team found that ice cover over the far north had reached 5.85 million square miles this winter, representing the fifth-lowest area of ice cover since satellite surveys began in 1979, according to Walter Meier of the Snow and Ice Data Center.
This year, though, the cover is mostly thinner than normal and will not last the summer season, said Ronald Kwok of NASA`s Jet Propulsion Laboratory. Thin ice made up more than 70 percent of the total cover this winter, compared to 4o to 50 percent in the 1980s, according to Fowler.
The older thick ice - ice that lasts two years or longer - made up 30 to 40 percent of the Arctic ice cover in the 1980s, Kwok said, while this year it amounts to only 10 percent of the total.
The severity of the problem is underscored by the fact that all ice cover - thick or thin - reflects the sun`s radiation back into space and keeps the ocean surface water cold, just the way white clothing on a sunny summer day keeps a human body cool.
But when the ice melts - as it is doing more and more each year in the Arctic - it opens up more stretches of the ocean`s surface to absorb the sun`s radiation. The result is a warmer ocean, which creates a "feedback loop" that speeds up the pace of global warming.
In the earlier report published in the current issue of the journal Geophysical Research Letters, Muyin Wang of the University of Washington and James E. Overland of the National Oceanic and Atmospheric Administration in Seattle predicted that the entire Arctic could become nearly ice-free in less than 30 years.
The Arctic, they said, is losing sea ice far more rapidly than the world`s experts had predicted in the last report from the IPCC, the Intergovernmental Panel on Climate Change, the agency whose members provide crucial data for government policy actions on global warming.
The rapid loss of Arctic sea ice over the three years from 2005 to 2008 marked "a new milestone," Wang and Overland said, and the warming ocean has caused summer air temperatures across the Arctic to rise by as much as 9 degrees Fahrenheit more than the IPCC had predicted, they said.
"We predict a nearly sea-ice-free Arctic in September (at the end of the melting season and the beginning of the next year`s freeze) by the year 2037," the two climate scientists said.
