The clock face around which our minutes tick away is perhaps the single most potent symbol of the industrial era. It is the clock that allowed modern life to be cut precisely into the segments that the workplace requires and the individual seeks to protect.

On wrists and office walls, hanging from the vaults of railway stations, or squatting toadlike by the bedside to curtail our sleep, the clock and its face have become the near-universal embodiment of the always felt but hitherto seldom quantified march of time. As a result, it cries out for manipulation — whether by the hurried commuter who fools himself into punctuality by setting his watch five minutes fast, or by a government changing the clocks of a nation to make the most of the daylight hours.

There was a time — 1911, as it happens — when this journal was strongly against the latter practice, as embodied in the then radical idea of introducing daylight-saving time to Britain. Rather high-mindedly, we thought that “the scheme is unworthy of the dignity of a great nation, and if it were made compulsory by legislation, it would be a monument to national flaccidity”. In the subsequent 95 years, however, this stance has softened, and Nature welcomes the proposal currently before the British parliament to extend current daylight saving by putting Britain's clocks forward by one hour all year round. This would put Britain into the GMT+1 time zone in winter and GMT+2 in summer, bringing the nation into line with the rest of Europe.

The evidence is that lighter evenings make life safer and may well save energy too (see page 344). A three-year experiment along these lines, well monitored to ensure that the change lives up to its proponents' claims, seems a sensible idea.

Much less persuasive is a separate plan to move forward the time on the 'Doomsday clock', an icon cannily created by the editorial board of the Bulletin of the Atomic Scientists in 1947 to alert the world to the looming threat of nuclear annihilation. Last week the current board decided to broaden the clock's remit to include such developments as climate change, and to move its hands forward by two minutes to just five minutes to midnight.

This raises two concerns. A minor one is that 'nuclear war' means something rather different today to what it meant at the time of, say, the Cuban missile crisis (when the hands were set further from midnight than they are now). A nuclear war is no longer necessarily synonymous with an all-out exchange between superpowers, and may not lead to the doomsday envisaged by the creators of the doomsday clock. This is not to minimize the horrors of a limited nuclear exchange, but to acknowledge that the context for the still vital project of averting any military use of nuclear weapons has changed.

A greater misgiving comes from the addition of non-nuclear concerns to the doomsday calculus. This seriously muddies the waters. Climate change is undoubtedly a major challenge, but it does not threaten doomsday in the manner of a full-blown nuclear war. Global warming has no hair trigger, no tiny margin between safety and disaster, no doom that can be unleashed in the flight time of a missile — none of the characteristics, in fact, that made the fatal minutes on the face of the doomsday clock so iconic.

Climate change is a substantial threat, but it is quite different in character to nuclear war: it is the deterioration of land, the increase of drought, a billion livelihoods descending from backbreaking to impossible. The principal human cost of climate change is likely to be an intensification of global mortality due to poverty and ill health — mortality that already runs at a level that all would condemn as unacceptable were it not that, as a world, we accept it. This moral weight makes it pressing, but does not make it urgent in the 'time ticking away' sense the doomsday clock so powerfully evokes. It is more important that policies to reduce the harm done by climate change be sustainable over the long term than that action be taken precipitously.

To fight climate change, we do not need to alarm ourselves with clocks of doom. Instead we just need to use our time to good purpose. And the reduction in energy use to be expected from single–double daylight saving in Britain — or from the extended single daylight saving that is to be implemented in the United States this year — will be a marginal, but nonetheless welcome, step in the right direction.