Global warming "is an important issue," Bush said alongside British Prime Minister Tony Blair at a summit of the G8 meeting in Gleneagles, Scotland.
"It's an issue where there has been disagreement in the past, but I think if people can look at what the prime minister and his leadership has achieved, there is a consensus that we need to move forwards together," Bush said.
"The way to move forwards together is to recognise, one, there's a problem, which I have since I've been the president. Two, that there's a constructive way to deal with the problem."
The Kyoto Protocol, which runs out in 2012, was signed in 1997, but Bush declared in one of his first acts after taking office that he would never ratify it.
It requires industrialised countries to trim their output of greenhouse gases - the carbon pollution from fossil fuels that scientists say is warming the planet's surface and damaging its climate.
Bush said in March 2001 that the deal was too costly for the oil-dependent US economy and insisted he would only accept voluntary measures rather than binding caps on emissions.
And, he argued, Kyoto was unfair because fast-growing, populous developing countries such as China and India were not required to join the targeted emissions cuts.
"The most constructive way to deal with the problem from our perspective is one, to not only include the United States in discussions, but also include developing countries in discussion, countries like India and China"
US President George Bush
"The most constructive way to deal with the problem from our perspective is one, to not only include the United States in discussions, but also include developing countries in discussion, countries like India and China," Bush said on Thursday.
Asked whether he had changed his stance, Bush said: "My position has been pretty steady."
Global warming is the most contentious topic at a Group of Eight summit gathering the leaders of Britain, Canada, France, Germany, Italy, Japan, Russia and the US in Gleneagles, Scotland.
The US and British leaders, close allies in the Iraq war, were speaking after a working breakfast to try to get their positions in sync before the opening of formal G8 talks.
In pre-summit negotiations, Bush took a consistently hard line on climate change, refusing text that described the problem as urgent and gutting it of any pledges on funding or emissions cuts, sources close to the talks said.
Leaders from Brazil, China, India, Mexico and South Africa were to join Thursday's meeting.
Bush said the US spent $20 billion a year on global warming and alternatives to hydrocarbons, including a project for research into hydrogen.
He also highlighted the link between national security and weaning the US off its dependence on imported oil and gas.