Climate change is as great a threat to the world as international terrorism and nuclear war, Professor Stephen Hawking said yesterday.

The cosmologist and mathematician said that the twin dangers of global warming and nuclear proliferation needed to be tackled urgently.

Professor Hawking, of the University of Cambridge, was speaking as the group of scientists who run the Doomsday Clock — a countdown to Armageddon that was begun in 1947 — was moved two minutes closer to stand at five minutes to midnight to reflect climate change and the nuclear programmes of North Korea and Iran.

“Since Hiroshima and Nagasaki, no nuclear weapons have been used in war, though the world has come uncomfortably close to disaster on more than one occasion,” Professor Hawking said. “But for good luck, we would all be dead.

“As we stand at the brink of a second nuclear age and a period of unprecedented climate change, scientists have a special responsibility once again to inform the public and advise leaders about the perils that humanity faces.

“We foresee great peril if governments and society do not take action now to render nuclear weapons obsolete and prevent further climate change.

“As scientists, we understand the dangers of nuclear weapons and their devastating effects, and we are learning how human activities and techno- logies are affecting climate systems in ways that may for ever change life on Earth.

“As citizens of the world, we have a duty to alert the public to the unnecessary risks that we live with every day, and to the perils we foresee if governments and societies do not take action now to render nuclear weapons obsolete and to prevent further climate change.”

The Doomsday Clock is operated by the Bulletin of the Atomic Scientists (BAS) and has been adjusted only 17 times in its 60-year history, most recently in 2002 when it was advanced to seven minutes to midnight after the events of September 11, 2001, and the US withdrawal from the Anti- Ballistic Missile Treaty.

“The dangers posed by climate change are nearly as dire as those posed by nuclear weapons,” the BAS said. “The effects may be less dramatic in the short term than the destruction that could be wrought by nuclear explosions, but over the next three to four decades climate change could cause irremediable harm to the habitats upon which human societies depend for survival.”

The threat of climate change was also emphasised yesterday by a new set of maps that show in detail how it is likely to affect different parts of the world.

The atlas, compiled using a new index method that combines natural climate variation with global warming predictions, suggests that years like 2006, the warmest on record in Britain, will be normal by 2100.

Michèle Bättig, of the Swiss Federal Institute of Technology, in Zurich, led the research. She told New Scientist magazine: “We hope it will help policymakers gain a quick overview of the scientific facts without getting lost in the detail.”

The study is published in the journal Geophysical Research Letters. The results are presented on nine maps of the world, each assessing change as a single factor such as rainfall, drought and temperature.

The areas that will experience the most significant changes are coloured red. One of the most striking images, showing temperature changes, shows regions close to the Arctic Circle and the Equator covered in dark red, denoting the highest predicted increases.

Europe and the United States are coloured mainly yellow and orange, denoting mid-range scores of 6 to 7 on the scale, whereas regions such as the Amazon rainforest and the Congo basin are coloured red and score about 11.

Another map shows the world almost covered in crimson. It measures the frequency with which abnormally hot years that have been occuring once every two decades will be recorded by 2100, and suggests that such events will be become annual almost everywhere.

Tom Downing of the Stockholm Environment Institute, said: “It focuses the debate on the big events we ought to be worrying about.”

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