The collapse of an ice bridge yesterday, in the remote vastness of the Antarctic, was a moment of terrible significance. It matters much more than its size may immediately suggest. This 25-mile strip of ice is believed to underpin the enormous Wilkins ice shelf, one of ten Antarctic ice shelves that have been in place for 10,000 years, but which have shrunk or collapsed in the past half-century. There is no longer any reasonable doubt that climate change is the cause: temperatures have risen by 2.5C (4.5F) in the Antarctic Peninsula in 50 years, faster than the global average.

It is important not to misread what is happening. The collapse of ice shelves does not raise sea level significantly, because the ice contracts as it melts. The real danger is that these shelves cease to act as buffers between warmer ocean currents and the land ice in the Antarctic interior. Even a 1 per cent loss of that ice could raise sea levels by 65cm (25in), the Norwegian Polar Institute said yesterday. That may not sound like much: only 2 per cent of the world's land is less than 10m above sea level. But that land is inhabited by a tenth of the world's population. This is one reason why the Netherlands has been at the forefront of developing renewable energy and floating houses: more than half the Dutch population lives at or below sea level.

What is most alarming about the events in the Antarctic is their speed, which has taken scientists by surprise. These ice shelves are collapsing far more rapidly than most scientists had predicted only 15 years ago. This is also true at the other pole. In the Arctic, summer sea ice is disappearing much faster than was thought even two years ago. Then, the Intergovernmental Panel on Climate Change (IPCC) predicted that this ice would disappear towards the end of this century. Now, scientists at the US National Snow and Ice Data Centre, the US National Centre for Atmospheric Research and elsewhere are predicting that the summer seas may be ice-free in only 20 years. This matters because ice reflects sunlight, while a dark iceless sea absorbs it. Scientists such as Jim Hansen, of Nasa, fear that the IPCC models that expect gradual change may be misleading, because of the risk of an “albedo flip” from light to dark, which would raise sea levels and melt parts of the Arctic permafrost that are keeping the lid on large quantities of greenhouse gases.

The changes in the Antarctic have demonstrated the bravery and ingenuity of the explorers and scientific investigators who go out into the furthest wildernesses to see what is happening and who try to make up for their small numbers and sparse budgets by, for example, equipping seals with monitoring devices. They also demonstrate the fragility of scientific models that attempt to predict incredibly complex natural interactions. Nature still has the edge on us, and it may be too optimistic to assume that the Earth will respond gradually to gradual increases in temperature.

The disappearance of parts of Antarctica from the map is a warning that the world should not ignore. The need for polar research and for concerted action against climate change has never been greater. In Bonn tomorrow, 175 countries conclude climate change talks that are intended to help to devise a new climate pact in the run-up to the crucial UN summit in Copenhagen at the end of this year. But the pace is glacial. President Obama warned on his sixth day in office that unchecked climate change could lead to “irreversible catastrophe”. Those were strong words. They need to be matched by dramatic action to move to a more carbon-neutral world. Events in Antarctica may seem remote: but they should send a chill through all of us.