Environmental expert warns against global warming...

I think it's clear we should listen to the experts.

And, as delegates at the United Nations conference in Montreal negotiate the future of the Kyoto protocol this week, campaigners have received a timely boost from the actor Leonardo DiCaprio who has announced he is to make a documentary about environmental issues.

Mr DiCaprio, a keen environmentalist who drives a hybrid car, has started production of the documentary, called 11th Hour, about efforts to stop global warming. The actor is not present in Montreal, but in a statement he said: "Global warming is not only the number one environmental challenge we face today, but one of the most important issues facing all of humanity."