LONDON — Prime Minister Brown of Britain said yesterday he is determined to raise Britain’s already ambitious targets for cutting carbon emissions and to push the nation to the forefront of global efforts to tackle climate change.

Mr. Brown, making his first major environment speech since taking office, also said Britain would encourage allies such as America to make similar pledges.

Britain has already committed to cutting carbon emissions by 60% of 1990 levels by 2050, though lawmakers have warned that the country will likely miss a steppingstone target of a 20% reduction by 2010. Mr. Brown, who took office in June, said he will ask a committee of advisers to consider whether Britain can meet a 80% cut in emissions by 2050.

“The climate change crisis is the product of many generations, but overcoming it must be the great project of this generation,” Mr. Brown told a meeting of the World Wide Fund for Nature.

“While the richest countries have caused climate change, it is the poorest who are already suffering its worst effects,” he said.

Any successor pact to the Kyoto Protocol — which set targets for industrialized nations to reduce emissions by 2012 — must pledge to hold the rise in global average temperatures to no more than 3.6 degrees Fahrenheit, Mr. Brown said. The British leader has used talks with President Bush to press Washington to accept a new global deal on reducing carbon emissions. America has declined to sign up to the Kyoto Protocol.

“It is not overdramatic to say that the character and course of the coming century will be set by how we measure up to that challenge,” Mr. Brown said.

Following talks last week with Jim Connaughton, chairman of the White House Council on Environmental Quality, the British climate change minister, Phil Woolas, said he believed Washington is “at the tipping point” of taking on a deal on emission reduction.

Mr. Brown said the British government hoped to build one of the world’s first carbon capture facilities — a process that involves collecting carbon dioxide and pumping it in liquid form into porous rock layers underground, where it cannot contribute to trapping sunlight and warming the atmosphere.

He said he would meet business leaders to discuss phasing out single-use plastic bags and will launch an information service for homeowners offering them tips on recycling and reducing energy consumption.