OSLO, Norway (Reuters) -- More than 60 nations launch the broadest scientific investigation yet of the Arctic and Antarctic on Thursday to chart polar regions on the front lines of global warming.

About 3,000 children will build snowmen in Oslo, top scientists will meet in Paris and researchers will gather on a polar research vessel in Cape Town harbor in South Africa as part of ceremonies starting International Polar Year (IPY).

During the U.N.-backed year, about 50,000 people will be involved in 228 projects such as studying marine life in the Antarctic, mapping how winds carry pollutants to the Arctic, or examining the health of people, polar bears or penguins.

David Carlson, director of the IPY Programme Office, said the icy ends of the earth had been overlooked too long. "This part of the planet has its problems and it needs to get a higher level of attention," he told Reuters.

Many scientists say that warming of the Arctic, where indigenous hunting cultures and animals are under threat from receding ice, may be a portent of damaging shifts elsewhere on the planet linked to global warming.

And a melt of ice sheets on Greenland or Antarctica in coming centuries would raise world sea levels, threatening cities from Tokyo to New York and low lying coral atolls in the Pacific.

Polar vulnerability

"These regions are highly vulnerable to rising temperatures," Michel Jarraud, head of the U.N.'s World Meteorological Organization, said in a statement. He said more monitoring stations were needed in polar regions.

Arctic temperatures are rising fast, apparently because water or ground, once exposed, soak up far more heat from the sun than ice or snow. Antarctica is staying cooler, with its far bigger volume of ice acting as a deep freeze.

The world's top climate scientists said in a U.N. report last month that "average Arctic temperatures increased at almost twice the global average rate in the past 100 years".

They projected that sea levels could rise by 18 to 59 cm (7.1 to 23.2 inches) by 2100, by when Arctic sea ice may disappear in summers.

Nordic nations, with Arctic territories, fear businesses including tourism are vulnerable to warming.

In Finland, scientists will meet on Thursday in Rovaniemi, a town which draws thousands of tourists every year with a claim to be the home of Santa Claus. In northern Sweden, a giant balloon will be released by a hotel carved from blocks of ice.

Countries ranging from China to Brazil will stage ceremonies on Thursday -- some countries such as the United States and Britain marked the start of polar year earlier this week.

The world has had polar years before, in 1882-83, 1932-33 and 1957-58. The "year" will last until 2009 -- it often takes two seasons to reach remote polar regions, set up equipment, leave to avoid the winter and then return to collect the gear.

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