In what looks to be another sign the Arctic is heating up quickly, British explorers in Canada's Far North reported that they had been hit by a three-minute rain shower over the weekend. The rain fell on the team's ice base off Ellef Rignes island, about 3,900 kilometres north of the Canadian capital, Ottawa.

"It's definitely a shocker... the general feeling within the polar community is that rainfall in the high Canadian Arctic in April is a freak event," said Pen Hadow, the team's expedition director.

"Scientists would tell us that we can expect increasingly to experience these sorts of outcomes as the climate warms," he told Reuters in a telephone interview from London.