THE possibility that, in an Obama administration, science will drive rational public policy provides an unprecedented opportunity to deal with a gnawing yet persistently neglected threat to the world: nuclear weapons.
No government is likely to declare how many strategic nuclear warheads it has, but the US and Russia are thought to possess at least 5000 apiece. The 2002 Strategic Offensive Reductions Treaty required each nation to have no more than 2200 "operationally deployed" strategic warheads by 2012, yet this represents no real progress towards disarmament, as the target number is essentially identical to that proposed at the 1997 summit on nuclear arms reduction between Bill Clinton and Boris Yeltsin in Helsinki, Finland.
As we object to Iran's apparent efforts to join the club of nuclear weapons states we should remember that the US, Russia, France, the UK and China have failed to meet their obligations to disarm, some four decades after they all signed the 1970 Nuclear Non-Proliferation Treaty (NPT).
Reducing the size of our nuclear weapons stockpile would not reduce our ability to deter a nuclear attack - a fact acknowledged by politicians such as Henry Kissinger, George Schultz and William Perry. Even 500 active warheads would be sufficient to kill hundreds of millions of people around the world. Reducing the size of the nuclear stockpile would bring one key benefit, though. Maintaining a huge and complex nuclear infrastructure is not cheap. In a time of increasing budget concerns, this is one area where savings could be achieved with little or no cost to security.
The terrorist attacks in Mumbai underscore the danger of a nuclear confrontation between India and Pakistan. Yet the US has turned a blind eye to an ongoing Pakistani project to build a plutonium reactor that would be capable of making enough fuel each year for up to 50 nuclear weapons. In 2006, Congress approved a nuclear cooperation pact with India that would help promote that country's bomb-making capacity. Neither India nor Pakistan has signed the NPT. The new administration needs to defuse the situation by encouraging disarmament in this region, not proliferation.
Aside from the direct sociopolitical and economic consequences of a regional nuclear war, it is now clear that the longer-term impact of even a localised nuclear conflict between Pakistan and India would be more severe than previously estimated. A study published last year shows that global temperatures and growing seasons could decline significantly following as few as 50 15-kiloton explosions, as might result from such a regional war (Physics Today, vol 61, p 37).
Finally, the new administration might bring some rationality to the US's efforts to deploy ballistic missile defence systems here and elsewhere in the world. It has been estimated that over the past 40 years the US has spent upwards of $600 billion on missile defence. Yet despite this, the US is not significantly closer to producing a workable system than it was in 1972 when it signed the Anti-Ballistic Missile Treaty.
Common sense suggests, as the US physics community did in 2003, that we should not use a missile defence system until it is shown to be workable against a realistic threat. Yet the US has nevertheless deployed a currently untested system at a cost of close to $10 billion per year - and the Bush administration complicated relations with Russia by declaring its intent to install it in Poland.
In this new year, as the country and the world look to Barack Obama with hope, he has signalled his intent to address one clear global threat, namely climate change. Leading the world away from the nuclear precipice will require at least as much sound thinking and political courage.
Lawrence Krauss is director of the Origins initiative at Arizona State University in Phoenix
- From issue 2692 of New Scientist magazine, page 27.