Urgent action is needed now to combat the world's "greatest environmental challenge" - global warming, the prime minister has said.
The environment is again climbing the political agenda
The effects of climate change would be felt within a generation unless action was taken now, he warned.
In a key speech delivered on Tuesday, he said the world's richest nations had a responsibility to "lead the way".
Tory leader Michael Howard attacked Mr Blair's "fine words but no action", but some campaigners welcomed his stance.
Mr Blair pledged that Britain would argue for aviation emissions to be brought into the EU emissions trading scheme.
But action could not be taken by one country alone, he warned, as he set out government plans to tackle the issue during a speech to the Prince of Wales' Business and the Environment charity.
"No one nation alone can resolve it. It has no definable boundaries," he said.
"Short of international action commonly agreed and commonly followed through, it is hard even for a large country to make a difference on its own.
"But there is no doubt that the time to act is now.
"It is now that timely action can avert disaster. It is now that with foresight and will such action can be taken without disturbing the essence of our way of life, by adjusting behaviour, not altering it entirely," he said.
"There's no doubt that in my mind that the time to act is now.
"If there is one message I want to leave with you it is one of urgency," he said.
But Mr Howard, who has accused Mr Blair of squandering the chance to lead efforts against climate change, told the BBC that the prime minister's speech was "nothing new at all".
Mr Howard said: "Once again what we have had from Mr Blair are fine words but no action.
"He talked about the challenge of global warming but you would never guess from his speech that carbon emissions which were falling before Labour came to government have been rising again since."
The Green Party's Keith Taylor also questioned Mr Blair's commitment to change.
He said: "His own government is undermining its aspirations towards reducing climate change gases because it is, for instance, embarking on a £30bn road building programme."
Parts of the UK have been affected by extreme weather this year
Liberal Democrat environment spokesman Norman Baker said if Mr Blair was sincere he would scrap government plans for more roads and airport terminals.
Mr Baker asked: "How many hurricanes and tornadoes will it take for the prime minister to realise that paying lip service to the environment is just no use?"
Environmental campaigners broadly welcomed the speech but suggested Mr Blair should focus on policies at home in order to lead the world.
A spokesman for the WWF said the prime minister's credibility would be "fatally undermined" unless he tackled UK emissions through energy, housing and transport.
And Greenpeace executive director Stephen Tindale urged Mr Blair to show the way "by launching a clear energy revolution here at home".
The prime minister told the meeting he did not think the US Senate would ratify the Kyoto agreement on climate change.
But at the G8 summits, which Britain chairs next year, governments had to accept the scientific evidence explicitly and say how to take the process forward.
The prime minister also faces pressure to take action to push US President George Bush to take climate change more seriously.
The US has repudiated the Kyoto Protocol under which industrialised nations agreed to limit their greenhouse gas emissions.
The UK's chief scientist Sir David King said earlier this year that climate change was a bigger problem than the threat of terrorism.