Tamara Rud, 70, fishes in the River Polui in the arctic city of Salekhard some 2000 km (1242 miles) northeast of Moscow November 25, 2007. REUTERS/Vasily Fedosenko (RUSSIA)It’s hard to imagine how big some of the cracks are on this link to satellite images of the Arctic ice during winter – dark lines hundreds of miles (km) long abruptly appear off the Canadian islands at the bottom right of the picture as the ice swirls through the winter.

At the top right, vast amounts of ice are flowing out of the Arctic basin southwards along the coast of Greenland.

“As of the middle of March, most of the basin, including the pole itself, appears to be covered only by seasonal ice,” it says. The image comes from Koji Shimada of the Japan Agency for Marine-Earth Science and Technology, via a link supplied by Thomas Homer Dixon, an environmental expert at the Trudeau Centre for Peace and Conflict Studies at the University of Toronto.

The summer sea ice in the Arctic shrank to a record low extent in September 2007, outstripping the previous 2005 record, according to satellite observations since the 1970s. Dark water, once exposed, soaks up ever more heat than reflective ice and snow, accelerating the process. A less chill Arctic in turn would tend to heat the rest of the globe. British long distance swimmer Lewis Pugh trains in Cape Town, South Africa, in a small pool filled with chunks of ice to bring the water temperature down to below 1 degree celsius (34 F), December 1, 2005. Pugh , who braved the Arctic Ocean in August, now plans three long distance swims in the Antarctic, and hopes to become the first to accomplish such a feat in both of the world’s coldest seas. Picture taken December 1, 2005. REUTERS/Mike Hutchings

And some researchers say that the Arctic ice may have reached a “tipping point” because of global warming and that it is destined to vanish in summers within decades — earlier than projected by the U.N. Climate Panel.