Greenland ice melting faster than thought

Satellite examination of the Greenland ice cap shows it is melting twice as fast as it was five years ago, according to a top NASA climate scientist. Jim Hansen said that holds dramatic and potentially disastrous implications for sea levels and climate change.

Hansen said: “This new satellite data is a remarkable advance. We are seeing for the first time the detailed behavior of the ice streams that are draining the Greenland ice sheet. They show that Greenland seems to be losing at least 200 cubic kilometers of ice a year. It is different from even two years ago, when people still said the ice sheet was in balance.”

He said once an ice sheet begins to disintegrate, it will reach a tipping point after which the break-up accelerates. The question, Hansen said, is how close are we to that tipping point? His answer is that we may be on the edge of it.

Hansen said once the ice begins to melt at the surface, it forms lakes that flow down through crevasses to the bottom of the ice pack, and rivers of water run under the ice, causing it to slide toward the open ocean.

“Our NASA scientists have measured this in Greenland,” Hansen said. “And once these ice streams start moving, their influence stretches right to the interior of the ice sheet. Building an ice sheet takes a long time, because it is limited by snowfall. But destroying it can be explosively rapid.”

The NASA scientist said he expects sea level rise to become a major issue in the near future, more so even than global warming.

How much time do we have to alter this course of events? “We have to stabilize emissions of carbon dioxide within a decade,” Hansen said, “or temperatures will warm by more than 1 degree. That will be warmer than it has been for half-a-million years, and many things could become unstoppable. If we are to stop that, we cannot wait for new technologies. We have to act with what we have.”

A new NASA report, released late last month, said 2005 was the warmest year on record and is more notable because there was no boost in temperature from a powerful El Nino that year.

The report, an annual analysis by the Goddard Institute for Space Studies, said the planet’s highest surface temperature in more than a century of such measurements was marked in 2005. Measurements were taken on land, by satellite on the surface of the sea and by ship-based analyses.

There were other analyses, however, that did not put 2005 as the warmest year. A report by Britain’s Meteorological Office held 2005 was the second-warmest year on record. NASA spokesmen said their report differed from others because it included temperature estimates up to 1200 kilometers from the nearest measurement station.

In that way, they said, they were able to include data from the Arctic where very few weather stations exist. That made 2005 the record holder. Researchers said: “We believe the remarkable Arctic warmth of 2005 is real, and the inclusion of estimated Arctic temperatures is the primary reason for our rank of 2005 as the warmest year.

The greatest warming in the past 50 years has taken place in Alaska, Siberia and the Antarctic Peninsula, scientists said.

While 2005 was tagged the warmest year on record, the early part of this year brought extreme cold to parts of Europe and Asia. Russia, Ukraine and Poland have attributed scores of deaths to the freezing weather.

Note: While CBS’s 60 Minutes covered this story last Sunday, in our Nov. 23-29, 2005 issue’s “Glaciers pose massive threat to millions”, Senior Editor Joe Baker addressed the issue of glacial melt in the Himalayas, Argentina and Chile. In last week’s issue’s “Brits panicking at global warming, U.S. yawns,” Baker noted the lack of alarm and action by our government.

From the Feb. 22-28, 2006, issue

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