There is "no bigger long-term question facing the global community" than the threat of climate change, Tony Blair has said.
"How do we get the world to think long term?" Mr Blair asked
The UK prime minister was speaking at the launch of the Climate Group, an international campaign aiming to speed up greenhouse gas emission reductions.
The charity is made up of businesses, governments and civil organisations.
But Friends of the Earth told BBC News the government was not doing enough to reduce carbon dioxide emissions.
At the launch on Tuesday, Mr Blair described the issue as "very critical indeed".
He said one of the first things he did on taking office was to ask scientists the scale of the global warming problem.
"One of the interesting things that came back to me was that this problem was greater than I had realised," Mr Blair said.
The issues of "some kind of trade-off between economic growth and environmental protection" had to be confronted, he added.
"How do we get the world to think long term?" Mr Blair asked.
Private companies and governments - including some individual states and cities in the United States - frustrated at the slow pace of international action to combat global warming formed the Climate Group.
Supporters include HSBC bank, oil giants Shell and BP, and environmental group WWF-UK.
Climate Group chief executive, Dr Steve Howard, said it was "looking beyond Kyoto" to drive reductions.
"There are many leading companies and governments dedicated to meeting or exceeding those targets," he added.
"By bringing the key players together for the first time, we believe that the world can turn the corner on climate change."
The Climate Group will hold a conference for leading "reducers" in Toronto in mid-May.
Further meetings in Europe, California and Australia are also planned and a "Carbon University" will be launched in early 2005.
Last year, Mr Blair pledged the UK government would cut emissions by 60% by 2050.
But speaking before Tuesday's launch, Friends of the Earth director, Tony Juniper, told BBC Radio 4's Today programme the "sad reality" was the UK had not progressed since 1997.
"We are only one fifth of 1% lower in our carbon dioxide emissions than we were when Labour came to power," he said.
"The difference between the speeches and the announcements and the carbon dioxide emissions is to that extent quite notable."
Environmental groups are urging the government to resist lobbying from industry to weaken targets due later this week on emissions from power stations and large factories.
Environment Secretary Margaret Beckett told Today progress had not been as good as the government would like but was "on the right general course".
"Where we have shown significant achievement... is in growing our economy while at the same time maintaining our performance on greenhouse gases," she added.