Pen Hadow, Ann Daniels and Martin Hartley were flown from a position on the ice approximately 500 kilometers from the North Geographic Pole to Eureka in Northern Canada, the world's second-northernmost permanent research station. They will return to their London headquarters this week, Catlin reported.

The expedition ended several weeks ahead of schedule because of concerns that the spring melting of the Arctic sea ice would make it too dangerous for aircraft to land at a later date, it was explained.

Speaking from the Arctic just prior to his return from the ice, survey leader Pen Hadow said in a statement that, the expedition was "grueling but successful." He noted the team captured about 16,000 observations and took 1,500 physical measurements of the thickness and density of the ice and snow.

Peter Wadhams, professor of ocean physics and head of the Polar Ocean Physics Group in the Department of Applied Mathematics and Theoretical Physics at the University of Cambridge, said the group's findings will be helpful.

"The data already sent back show the team have been travelling on first-year ice and provide an insight into its rate of growth this year. The rest of the data the team will provide on their return will help us to process and interpret it further and make a valuable contribution to data available to sea ice scientists."

According to a preliminary report, first-year ice is typically thinner multi-year ice. The amount of multi-year ice in the Arctic Ocean is an indication of how much sea ice has remained at the end of the last summer melt season.

Because it's thicker, the report said, multi-year ice is more likely to survive the summer season than first-year ice (which is thinner). Multi-year ice that is thinner than expected, however, may not survive a summer melt season, the report said.

Current estimates as to how long ice will remain a year-round feature at the North Pole vary considerably, with scientific predictions ranging from five to 100 years. More accurate information is essential if scientists and decision makers are to anticipate fully the potential impact of the loss of the Arctic sea ice on the world's population, Catlin said.

The data will now be analyzed by the Catlin Arctic Survey's scientific partners, which include the University of Cambridge and the United States Navy's Department of Oceanography.

The conclusions drawn from this analysis are expected to be presented at the United Nations Climate Change Conference, to be held in December in Copenhagen.

Negotiating teams from countries around the world will meet in Copenhagen to attempt to replace the Kyoto protocol agreement.