The scientists huddled in Vostok StationA Russian research station 800 miles from the South Pole. last Thursday stared at the temperature gauge in amazement. It had registered extreme cold the day before; now it had sunk even further, to -79.4C. If it fell by another 0.6 degrees, it would match the lowest October temperature ever recorded anywhere in the world. Yet on most of the planet climate change was pushing temperatures up. What was going on?

Elsewhere in Antarctica, American scientists were grappling with data as bizarre as their Russian counterparts. They had calculated the average temperature at the Amundsen-ScottIn 1911 Norway's Roald Amundsen became the first person to reach the South Pole, a month ahead of Britain's Robert Falcon Scott, who died with his companions on the way back. South Pole Station between April and September at -61C - the lowest since records began in 1957, and a whole 2.5C lower than the average for the last 30 years.

A scientist who has often visited Antarctica, Matthew Lazzara, put the extreme conditions in perspective.  "At these temperatures, it is difficult to operate aircraft," he told The Washington Post. "Between -50C and -58C you put the aircraft at risk, with the hydraulics freezing up or fuel turning into a jelly."

The effects on humans are terrifying. In 1911, three members of an expedition to collect penguin eggs endured temperatures that averaged -40C and sometimes fell to -60C. One of them, Apsley Cherry-Garrard, called his book about the experience The Worst Journey In The World.

At one point his teeth chattered so violently that they shattered. According to his biographer Sara WheelerA travel writer whose books include Terra Incognita: Travels in Antarctica., "It took him 45 minutes to chip his way into his sleeping bag each night, as during the day it froze flat like a slab of tombstone granite." When the three men returned to base camp after five weeks, their frozen clothes had to be cut from their bodies.

Scientists attribute the current temperatures to the polar vortex - a ring of strong winds which forms in the autumn and lasts until spring.

"Basically, the winds in the polar stratosphereA layer of the atmosphere which extends for 31 miles above the Earth's surface. have been stronger than normal, which is associated with shifting the jet streamA fast-moving current of air. toward the pole," says atmospheric scientist Amy Butler. "This keeps the cold air locked up over much of Antarctica."

But according to Professor Robert Matthews of Aston University, we are lucky that the whole planet is not equally cold.  "Oddly enough," he explains, "an Ice Age has gripped the Earth for most of the last 2.6 million years, and we're currently experiencing an unusually warm break from this so-called QuaternaryA geological period which began two million years ago. glaciation, which temporarily lifted around 12,000 years ago."

How long the break continues depends on changes in the Earth's orbit around the Sun, which affect how much sunlight it receives, and also on global warming. Scientists estimate that man-made global warmingSome global warming occurs naturally, produced by the combination of sunlight and CO2 in the atmosphere. has delayed it by 50,000 years.

The effect of global warming on climate has become easier to predict thanks to the work of three outstanding scientists: Japan's Syukuro Manabe, Germany's Klaus Hasselmann and Italy's Giorgio Parisi. Yesterday they were jointly awarded the Nobel Prize for physics.

Some say, yes: ice ages are controlled by cyclical changes in the Earth's orientation towards the Sun, and another one should have begun several thousand years ago. Analysis of air trapped deep in existing ice indicates that a build-up of CO2 and methane began between 5,000 and 8,000 years ago, when farming and deforestation by humans increased - so the two must be related.   

Others believe that global warming is actually hastening the next Ice Age. They argue that rapidly melting glaciers have formed a "cold blob" of water south of Greenland which could obstruct the flow of the Gulf Stream, causing the temperature in Europe to drop dramatically. The result, according to William H Calvin of Washington University, would be a "global climate flip-flop".