Mr Bush says new technology will help lower emissions
US President George W Bush says he is setting an "ambitious" new target of halting growth in US greenhouse gas emissions by 2025.
Citing new technology as the key, he said emissions in the US needed to reach a peak within 15 years and decline after that.
Environmentalists were quick to sharply criticise the new targets.
The three main challengers to replace Mr Bush in January all favour more aggressive climate change policies.
Mr Bush said the new target should require emissions "well below" projections given in the 2002 climate strategy.
"There are a number of ways to achieve these reductions, but all responsible approaches depend on accelerating the development and deployment of new technologies."
He added: "If we fully implement our strong new laws, adhere to the principles I've outlined, and adopt appropriate incentives, we will put America on an ambitious new track for greenhouse gas reductions."
The new technology would combine with nuclear power and "clean coal" to help meet the targets, Mr Bush said.
However, there was no indication of any new legislation to target emitters, and his statement warned Congress not to pass laws that could "impose tremendous costs on our economy and American families".
The US took part in climate change talks in Bali, Indonesia, last year when it was agreed to work towards setting new targets by the end of 2009, ahead of the expiry of the Kyoto emissions agreement in 2012. The US always rejected Kyoto.
Environmentalists rounded on Mr Bush's new plan.
Carl Pope, the executive director of the largest US environmental group, the Sierra Club, said: "Under the president's plan we'll need a real miracle to save us from global warming."
The three rivals for the US presidency - John McCain, Barack Obama and Hillary Clinton - all favour tougher climate change policies.
They include a cap on industrial carbon dioxide gases and an emissions trading system like that in the European Union.