In his letter (November 26) Neil Craig said: "We know for a fact that no unprecedented warming is taking place." Sir David King, the UK's chief scientist, would refute that, saying: "The weight of evidence for climate change, and the causal link with greenhouse gas emissions is unarguable and the science is clear that this rise in temperatures will continue and accelerate."

Physical evidence is widely available. In this month's Geographical, the magazine of the Royal Geographical Society, the facts are that most of the world's glaciers are melting, accelerating their rate of loss, and many have disappeared. The reduced summer meltwater will translate to lower river water flows, affecting millions of people who rely on them for drinking and agriculture. The loss of glacier mass is transferred to the sea, forcing sea levels up, affecting those who live by the sea.

As the ability of the Earth to reflect the sun's heat is reduced through decreasing ice coverage, combined with reduced vegetative cover because of continued deforestation and increased desertification, combined with increasing methane emissions from Siberia, carbon dioxide release from our own peat bogs and continued man-made emissions, it becomes possible to glimpse the looming catastrophe not many years from now as the Earth's temperature begins to spiral out of control. Yet many are not persuaded by the arguments.

So, do we do nothing and see what happens? Unfortunately, that's not an option because the earth is warming and we have to plan contingencies. Do we take the risk and not bother to reduce emissions? That's not an option either because oil prices are going up. Or is it best to minimise the risk by setting tough reduction targets for emissions, because surely by doing that we're encouraging man's innovative capabilities to find more sustainable energy sources and means of transport? Why not be united in encouraging world leaders to take drastic measures in Bali because in the end that will be good for all of us?

Paul Shaw, 20 Argyle Way, Dunblane.