It seems unthinkable, but for the first time in human history, ice is on course to disappear entirely from the North Pole this year.

The disappearance of the Arctic sea ice, making it possible to reach the Pole sailing in a boat through open water, would be one of the most dramatic – and worrying – examples of the impact of global warming on the planet. Scientists say the ice at 90 degrees north may well have melted away by the summer.

Human-generated climate change made flowers bloom sooner and autumn leaves fall later, turned some polar bears into cannibals and some birds into early breeders, a vast global study reported on Wednesday.

Hundreds of previous studies have noted these specific changes and most suggested a link to so-called anthropogenic global warming, but a new analysis published in the journal Nature correlated these earlier studies with changes in temperature, the study’s lead author said.

Rising oil prices, global food shortages and the economic crisis are proof for many survivalists that society is on the brink of meltdown. But are their predictions all gloom and doom - or a chance to create new communities?

As many as one billion people could lose their homes by 2050 because of the devastating impact of global warming, scientists and political leaders will be warned today.

They will hear that the steady rise in temperatures across the planet could trigger mass migration on unprecedented levels.

Hundreds of millions could be forced to go on the move because of water shortages and crop failures in most of Africa, as well as in central and southern Asia and South America, the conference in London will be told.

You know when climate change is biting hard when instead of a vast expanse of snow the North Pole is a vast expanse of water. This year, for the first time, Arctic scientists are preparing for that possibility.

“The set-up for this summer is disturbing,” says Mark Serreze, of the US National Snow and Ice Data Center (NSIDC). A number of factors have this year led to most of the Arctic ice being thin and vulnerable as it enters its summer melting season.

In September 2007, Arctic sea ice reached a record low, opening up the fabled North-West passage that runs from Greenland to Alaska.