Climate change was one of the key issues to be raised by British Prime Minister Tony Blair during a summit with Bush at the White House.

Bush told a press conference afterwards, "I've always said it's a serious long long-term issue that needs to be dealt with, and my administration isn't waiting around to deal with the issue.

"We lead the world when it comes to dollars spent, millions spent on research about climate change," the US president said.

"We want to know more about it. It's easier to solve a problem when you know a lot about it."

The United States has been widely criticised for withdrawing from a commitment to ratify the Kyoto protocol on climate change, which set targets for reducing pollution that causes global warming.

But Bush said that the United States will have to change its high energy consuming habits and move away from "a hydrocarbon society".

He said he hoped gas-guzzling American drivers would turn to alternatives such as hydrogen fuel powered cars.

"Our country is going to have to diversify away from the type of automobiles we drive. It's beginning to happen here. We'll have more fuel cells, cars driven by fuel cells on the road next year than the past year, and more after that. We're beginning to change."

Bush also said the United States was spending a lot of money on producing coal that creates less pollution.

"That's going to be very important for a country like ours and a country like China. And one of the issues we've got to figure out how to deal with is how we share that technology with developing nations."