The Doomsday Clock: Nuclear threat to world 'rising'

For 60 years, it has depicted how close the world is to nuclear disaster. Today, scientists will move its hands forward to show we are facing the gravest threat in at least 20 years

Five years of international headlines tell of growing turmoil in the Middle East, international terrorism in Western capitals and more countries seeking the ultimate national security insurance policy.

Now climate change and oil insecurity is driving countries to seek nuclear power, bringing with it new dangers of proliferation in volatile parts of the globe.

Today the Doomsday Clock, devised by the Chicago-based Bulletin of the Atomic Scientists in 1947 at the dawn of the nuclear age, will make official what most thinking citizens feel in their bones - that the world has edged closer to nuclear Armageddon than at any time since the most precarious moments of the Cold War in the early 1980s.

At 2.30pm, simultaneous events will take place in London and Washington at which the symbolic clock will be moved forward from its present seven minutes to midnight, where it has stood since 2002. The reasons for the time being advanced five years ago were crumbling arms control treaties and a terrorist threat brought into shattering relief by 9/11.

At the start of 2007, not only is the picture darker on both those scores. The nuclear threat has also acquired an added and unquantifiable dimension, thanks to global warming - prompting the Bulletin to warn of a "Second Nuclear Age". The existing dangers could not be more obvious: the problem is where to start. What about Iran's quest for nuclear weapons, and the thinly veiled warnings from the undeclared but assumed nuclear power Israel that it will strike first to remove what it sees as an existentialist threat comparable to the Holocaust?

Or the nuclear test last year by North Korea, a member of George Bush's "axis of evil", which could have neighbouring Japan and South Korea seeking protection with nuclear weapons of their own? Or the nuclear arsenal of unstable Pakistan, where Islamic extremists have staged several assassination attempts against President Pervez Musharraf?

Or - perhaps the greatest danger of all - that having visited conventional terror on an unprecedented scale upon New York City on 11 September 2001, al-Qa'ida or some similar organisation will either get hold of a ready-made nuclear device or build one of its own, and then use it?

And why not? Grave doubts surround Russia's ability to secure its nuclear materials, many of them dating from the Soviet era, and to prevent its nuclear scientists from selling their skills to the highest bidder. If a terrorist group did explode even a crude dirty bomb (and the US claims to have disrupted such plots) the taboo that has prevented states from using nuclear weapons in anger since 1945 might be broken.

And in this new nuclear age, the deterrence doctrine of "mutually assured destruction", or MAD, that kept the Cold War cold, would not apply. The US and Russia may have 2,000 launch-ready weapons between them - but these would be of no more use against an amorphous terrorist group than Israel's nuclear arsenal against the Palestinians. Even so, a threshold would have been crossed and a regional, even generalised nuclear war, would become conceivable.

In 1947, the Doomsday Clock was first set at seven minutes to midnight, exactly where it has stood since 2002. On the Bulletin's reckoning, the planet's closest brush thus far with Armageddon came in 1953, when the clock's hand moved to two minutes to midnight after the US and the Soviet Union tested hydrogen bombs within nine months of each other.

Thereafter the clock has tracked the chills and thaws of the Cold War, and the successive arrival of Britain, France, China, India and Pakistan as recognised nuclear powers. The hand reached its "safest" point - 17 minutes to Armageddon - in 1991 when the US and the soon-to-disappear Soviet Union signed the Strategic Arms Reduction Treaty (START), and that year's Gulf War, driving Saddam Hussein from Kuwait, seemed to herald an era when the great powers could work together under the auspices of the UN. The 2003 Iraq invasion destroyed any such illusions. Once there were five proven nuclear powers. Now there are nine.

Global warming, argues the Bulletin, indirectly increases this risk. Civil nuclear power, which produces no greenhouse gases, is back in fashion and hundreds of nuclear reactors will be built. Yet enriched uranium, to power them, and plutonium are also the vital raw materials for nuclear weapons.

In this Second Nuclear Age, there will be more of these deadly commodities around. Small wonder the hand on the Doomsday Clock will move towards midnight. The only question is, how close will it get?