Kalaallit Nunaat Ice Sheet formed very fast The WE News Archives

A record loss of sea ice in the Arctic summer 2005 has convinced scientists that the northern hemisphere may have crossed a critical threshold beyond which the climate may never recover.

Scientists fear that the Arctic has now entered an irreversible phase of warming which will accelerate the loss of the polar sea ice that has helped to keep the climate stable for thousands of years.

Dr Serreze: "This will be four Septembers in a row that we've seen a downward trend. The feeling is we are reaching a tipping point or threshold beyond which sea ice will not recover."

Professor Wadhams: "As the sea ice melts, and more of the sun's energy is absorbed by the exposed ocean, a positive feedback is created leading to the loss of yet more ice."

"If anything we may be underestimating the dangers. The computer models may not take into account collaborative positive feedback."

"Sea ice keeps a cap on frigid water, keeping it cold and protecting it from heating up."

"Losing the sea ice of the Arctic is likely to have major repercussions for the climate."

"There could be dramatic changes to the climate of the northern region due to the creation of a vast expanse of open water where there was once effectively land."

"You're essentially changing land into ocean and the creation of a huge area of open ocean where there was once land will have a very big impact on other climate parameters."

Global warming point of no return

Tuesday, 17 August, 2004

Ice yields ancient 'plant matter'

Some of the material looks like pine needles or blades of grass

Scientists drilling ice cores in Greenland have recovered what appear to be plant remains from nearly 3km (two miles) below the surface.

Team members said reddish clumps of material, found in the muddy ice in the cores, contain what appear to be pine needles or blades of grass.

If confirmed, it will be the first organic material to be recovered from a deep ice core drilling project.

Scientists think the material could be several million years old.

The suspected plant material was recovered between the ice sheet and the bedrock at a drilling site in central Greenland, by a team belonging to the North Greenland Ice Core Project (NGrip).

Several of the pieces look very much like blades of grass or pine needles

James White, University of Colorado

"Several of the pieces look very much like blades of grass or pine needles," said Professor James White, a principal investigator on the NGrip project from the University of Colorado at Boulder.

They may date to before the ice sheet covered the island during the last Ice Age. Samples of the material will now be sent off to several laboratories for analysis.

Ancient relics

"There is a big possibility that this material is several million years old, from a time when trees covered Greenland," said Professor Dorthe Dahl-Jensen of the University of Copenhagen's Niels Bohr Institute.

She added that, if the remains are indeed organic, their presence would suggest that the Greenland ice sheet formed very fast.

The cores were recovered from about 3km beneath the ice

In summer 2003, the drilling team reached the bedrock at a depth of 3085m. Trapped gas in the cores could help researchers determine how the area's climate varied year on year over the past 123,000 years.

After reaching the bedrock, reddish water flooded the lowest 45m of the bore hole. At this site, the ice sheet is melting at the bottom due to high geothermal heat.

The water is running in channels in and under the ice, and is part of a sub-glacial system that may have been isolated from the surface for several million years.

Deep freeze

This year, the researchers returned to drill down into the reddish refrozen water and retrieved the ice cores with the suspected organic material. These ice cores also have a very high content of trapped gas.

Some of the project members even think there is a possibility exotic life forms might survive in this ice.

The cores are cylinders of ice four inches in diameter that have been drilled in the ice and brought to the surface in 3.5m (11.5 feet) lengths. The researchers work to recover the cores in subsurface trenches where temperatures frequently fall to minus 30C (-22F).

Each yearly record of ice can reveal past temperatures and precipitation levels, the content of ancient atmospheres and even evidence for the timing, direction and magnitude of distant storms, fires and volcanic eruptions.

NGrip is an international project with members from the US, Japan and Europe.