It is reported that the world's top climate watchdog, Dr Pachauri, chairing a conference in Mauritius, said that there was only a small window of time left for us to curb CO2 emissions and ensure the survival of humanity - pointing to the melting of the Arctic and dying coral reefs.

The Bush administration is hostile to this attitude, basically because the US is the principal world producer of CO2. As one US citizen put it on Channel 4 recently, "now that we own Iraq, I want petrol to be half the price it is now".

Unless Blair can stand up to the US, the Americans are set to choke the planet.

But it is highly probable that the Earth's climate is more like a spring-loaded mousetrap. Methane is a potent greenhouse gas, and there are millions of tons of it in compounds called hydrates in the sea, and stored in the permafrost of the Russian tundra. This will be triggered into the atmosphere by a temperature rise caused by CO2, thus greatly accelerating global warming and causing an even steeper rise in temperature thus releasing more methane. This is called "positive feedback".

As ice cover melts over vast areas, fewer of the sun's rays are reflected back, causing more warming. It becomes effectively a vicious circle, and the consequent effect on the global climate will be rapid and unstoppable.

So that brief "window of time" is now, and it is our only chance.

Chris Clayton,

Hempland Drive,

York.

Updated: 10:58 Thursday, January 27, 2005