The International Atomic Energy Agency (IAEA), which exists to spread the peaceful use of the atom, reveals in a new report that it could not grow fast enough over the next decades to slow climate change - even under the most favorable circumstances.

The report - published to celebrate yesterday's 50th anniversary of nuclear power - contradicts a recent surge of support for the atom as the answer to global warming.

That surge was provoked by an article in The Independent last month by Professor James Lovelock - the creator of the Gaia theory - who said that only a massive expansion of nuclear power as the world's main energy source could prevent climate change overwhelming the globe.

Professor Lovelock, a long-time nuclear supporter, wrote: "Civilization is in imminent danger and has to use nuclear - the one safe, available, energy source - now or suffer the pain soon to be inflicted by our outraged planet."

His comments were backed by Sir Bernard Ingham, Lady Thatcher's former PR chief, and other commentators, but have now been rebutted by the most authoritative organization on the matter.

Unlike fossil fuels, nuclear power emits no carbon dioxide, the main cause of climate change. However, it has long been in decline in the face of rising public opposition and increasing reluctance of governments and utilities to finance its enormous construction costs.

No new atomic power station has been ordered in the US for a quarter of a century, and only one is being built in Western Europe - in Finland. Meanwhile, Germany, Belgium, the Netherlands and Sweden have all pledged to phase out existing plants.

The IAEA report considers two scenarios. In the first, nuclear energy continues to decline, with no new stations built beyond those already planned. Its share of world electricity - and thus its relative contribution to fighting global warming - drops from its current 16 per cent to 12 per cent by 2030.

Surprisingly, it made an even smaller relative contribution to combating climate change under the IAEA's most favorable scenario, seeing nuclear power grow by 70 per cent over the next 25 years. This is because the world would have to be so prosperous to afford the expansions that traditional ways of generating electricity from fossil fuels would have grown even faster. Climate change would doom the planet before nuclear power could save it.

Alan McDonald, an IAEA nuclear energy analyst, told The Independent on Sunday last night: "Saying that nuclear power can solve global warming by itself is way over the top." But he added that closing existing nuclear power stations would make tackling climate change harder.