"The hour is no longer for skepticism. It is time to act, and act urgently," Prince Albert II of Monaco said in announcing the project in Paris. He called global warming "the most important challenge we face in this century."
Scientists will use icebreakers, satellites, and submarines to study the effect of solar radiation on the polar atmosphere, the marine life swimming beneath the Antarctic ice, and the culture and politics of Arctic inhabitants.
The lifestyle of the Athabaskan, an indigenous group in northern Canada and Alaska, is already under threat, said James Allen of the Arctic Athabaskan Council.
"We are affected directly because we live off the land," he said in Paris. "People still fish, people still trap, and we still gather food and medicine from the land. So our food source is being affected."
In his tiny Arctic outpost of Ny-Alesund, the director of the Norwegian Polar Institute, Kim Holmen, described seeing glaciers melt at a faster rate in recent years.
The polar year is "important because it is concentrating the effort . . . to solve a major scientific problem of our time," Holmen said by telephone.
Schoolchildren with signs that said "Give us back winter" and "We want snow," built snowmen on the City Hall square and skirmished with snowballs in Oslo to mark the launch of the project. The weather warmed after a two-week cold snap, leaving sidewalks and the square slushy.
At a hotel made entirely of ice in Sweden, 125 miles north of the Arctic Circle, a giant hydrogen balloon was launched to ring in the polar year project. And in classrooms around the world, teachers conducted ice-related activities and experiments, organizers said.
Some scientists have warned the world could be heading for an ice-free Arctic.
"The projections are that ice in the Arctic will disappear in the summer months. . . . sometime within the next century," said Ian Allison, a cochair of the International Polar Year committee and researcher with the Australian Government Antarctic Commission.
Russian geographer Vladimir Kotlyakov, who has studied polar regions for 50 years and is a lead figure in the polar year project, was skeptical of predictions of an ice-free Arctic. But he did not deny climate changes were already affecting Russia.
"We'll have to change our agriculture, our industry, even our mentality as a frozen country," he said.
The last Polar Year was held in 1957-58, when Cold War tensions restricted some of that cooperation.
This year's project is sponsored by the UN's World Meteorological Organization and the International Council for Science. About $1.5 billion has been earmarked by various exploration agencies, but most of the money comes from existing polar research budgets.
The result, researchers hope, will be a more complete picture of the impact of global warming.
The project ends in March 2009.
