Britain will publish a climate change bill on Tuesday that will set targets for carbon dioxide emissions cuts and could make the country the first to limit greenhouse gases by law.
The draft bill, which is part of Britain's bid to tackle global warming, is expected to make a 60 percent cut in carbon emissions by 2050 a legal requirement but rule out annual goals.
The bill comes after European Union leaders agreed to reduce carbon emissions from burning fossil fuels for transport and power by 20 percent by 2020.
Most scientists predict that global average temperatures will rise between 1.8 and 4.0 degrees Celsius this century as a direct result of burning fossil fuels.
"We need to ensure that the U.K.'s emissions?are placed on a sustained downward path," Finance Minister Gordon Brown said in a major speech on the environment on Monday, months before he is expected to take over from British Prime Minister Tony Blair.
Environment Minister David Miliband, who has pledged to include the 60 percent target in the draft bill, will present it to parliament on Tuesday, triggering a review process.
Environmentalists and some lawmakers, including the leader of the main opposition party, have vowed to press for more stringent goals.
"The Climate Change Bill could make the U.K. a world leader in tackling climate change," said Friends of the Earth director Tony Juniper.
"However, if we are to set a global example, we need a bill which is strong enough to ensure successive governments deliver the cuts in carbon dioxide emissions which are needed," he said, calling for emission cuts of 3 percent a year.
Such annual cuts would lead to a total reduction of 80 percent by 2050. The government has so far resisted calls for a target above 60 percent.
"We are not going for annual targets," Miliband told Reuters last month. "We think annual targets are silly--they are gesture politics rather than real policy."
Miliband has declined to comment on widespread speculation the government would opt for five-year rolling targets.
However, he has said the government would create an independent oversight committee to monitor the annual progress of successive governments in cutting carbon dioxide emissions and set "appropriate" interim targets along the way.
Brown on Monday said the government would phase out high-energy lightbulbs, make it easier for people to insulate their homes and try to persuade the EU to ban wasteful electrical devices such as standby switches.
Writing in the Sunday Times newspaper, Miliband said energy efficiency measures had to be paramount, and nuclear power had a role to play alongside renewable energy in meeting the targets.
An advocate of personal carbon budgets, he said the bill would open the way for the extension of carbon emissions trading to all British businesses from only half now.