(Recasts, adds quotes, details) By Alister Doyle, Environment Correspondent OSLO, March 1 (Reuters) - More than 60 nations started the biggest scientific investigation of the Arctic and Antarctic on Thursday amid new evidence that global warming is thawing polar ice and raising sea levels. About 3,000 children made slushy snowmen and waved banners saying "give us back the winter" in Oslo, scientists met in Paris and other experts gathered on a research vessel in Cape Town to mark the start of International Polar Year (IPY). "The polar year is important for everyone on the planet," Norwegian Prime Minister Jens Stoltenberg told Reuters when asked if people living in places such as Africa or Asia should be interested in science at the icy ends of the earth. "We are seeing climate change most clearly in the polar areas and research there can give us decisive knowledge in the fight against global warming," he said. During the U.N.-backed year, about 50,000 experts 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. Scientists will fly planes into storms off Greenland, others will measure ice from satellites and still others will see how reindeer are faring when warmer weather damages lichen pastures. "This part of the planet has its problems and it needs to get a higher level of attention," David Carlson, director of the IPY Programme Office, told Reuters. THAW GATHERS PACE The Norwegian Polar Institute said in a report that a melt of glaciers in Svalbard, an Arctic chain of islands about 1,000 km (620 miles) from the North Pole, was quickening. "The melting has clearly accelerated in the past five years," it said. "Therefore Svalbard ice is contributing more than before to raising world sea levels." Rising seas could end up threatening cities from Tokyo to New York. Many scientists say warming of the Arctic, where indigenous hunting cultures and animals are under threat from receding ice, may be a portent of damaging changes elsewhere linked to global warming stoked by human use of fossil fuels. Arctic temperatures are rising at about twice the global average, apparently because water or ground, once exposed, soak up more heat than reflective ice or snow. Antarctica is staying cooler because its huge volume of ice acts as a deep freeze. The world's top climate scientists said in a U.N. report last month that it was "very likely" that human activities were the main cause of global warming and projected that sea levels could rise by 18 to 59 cm (7.1 to 23.2 inches) by 2100. By that time, Arctic sea ice may disappear in summers. Nordic nations, with Arctic territories, fear businesses including tourism are vulnerable. In Finland, scientists met 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, they were releasing a giant balloon outside a hotel carved from blocks of ice.
