Tony Blair has warned world leaders they have less than seven years to save the planet. But he ruled out a "ticket tax" on British airline passengers to combat global warming.
The Prime Minister was accused of double standards over climate change after he urged the US, China and India to join a global offensive to tackle the problem.
Mr Blair told the liaison committee of senior MPs: "I think that if we don't get the right agreement internationally for the period after which the Kyoto protocol will have expired - that's 2012 - we are in serious trouble."
He said there was "the beginnings of an international consensus" and praised President George Bush for last week acknowledging America's "addiction to oil" but called on the US to go further.
Mr Blair dismissed calls for a levy on air travel to cut carbon emissions caused by the rise in cheap flights. A tax would need to be "hefty" to be effective, he said.
"It is unrealistic to think that you will get some restriction on air travel at an international level. The best way to go is to recognise that it is a reality, and see how you can develop the technology that is able to reduce the harmful emissions."
Peter Ainsworth, the shadow Environment Secretary, said: "Aviation is probably the hardest part of the climate change challenge, but we must face up to it. To walk away with a defeatist shrug is irresponsible."
Norman Baker, environment spokesman for the Liberal Democrats, said: "Emissions from aviation represent the greatest challenge in tackling climate change. For the Prime Minister to wash his hands in this way is unbelievable. If aviation continues to grow, the increase in emissions will cancel out cuts from all other sectors."Reuse content