Rage at the dying of the ice

In 1982, with his travelling companion Charles Burton, the celebrated explorer Sir Ranulph Fiennes became the first man to reach both the north and south poles. Since then he has set several records in his efforts to reach the north pole without a support crew

The news that the melting of sea ice in the Arctic has reached record levels is alarming, but not primarily for practical reasons of travelling there, of course: most people don't make a habit of floating around on ice floes. In 1982, though, Charles Burton and I did spend months camped on ice floes, floating along, 600 miles north of land, in our efforts to reach the north pole. We measured the ablation levels (to monitor for melting) by putting measured prods into little pools of ice on our ice floe, recording the results and sending them back to the UK. Back then, nobody was particularly alarmed. Since then, though, those same records from scientists floating around up there have been increasingly interpreted as bad news.

Practically, for expedition people wanting to go to the north pole from land, this means they're more likely to face big, watery expanses between the ice floes - that will become the major obstacle, rather than the ridges formed through ice floes colliding with each other. It becomes a question of whether you have a canoe instead of a sledge. You'll have to paddle, instead of worrying about skis and blisters.

This is very bad news for wildlife, too - for the polar bears and for the Arctic foxes that follow them. It will mean, sadly, fewer floes for them to travel on, and fewer opportunities to catch the seals that pop up through seal holes in the ice: the bears can't do that by swimming around in vast areas of sea. There were plenty of bears in the 80s, although of course we rather hoped to avoid them. We had a .44 Magnum with us. The first thing we'd do if a bear came up to us was to bang cooking pots together loudly. Most bears haven't heard that noise before, and would scarper. If a bear didn't, it meant it was hungry, and we'd fire bullets over its head. Of the 19 bears who showed an interest in us, we only had to shoot one, and though I aimed at its chest, I hit its ankle - I must have been nervous - and it took flight.

The most worrying geographical factor of all, though, in terms of polar global warming, is the huge ice sheet in Antarctica. The ice is up to two miles deep, and it's sitting on top of high mountains. If the bottom of that ice gets slightly warmer, there will be an oily subsurface between the rock and the ice, and it's placed in such a way that the whole ice sheet - a vast area, bigger than several American states - is liable to head out to the ocean. The displacement of the seas, in that case, would be enormous.

· Interview by Oliver Burkeman