
The government has unveiled plans to set a "legally binding" target to cut carbon emissions by 60% by 2050.
The draft Climate Change Bill calls for "carbon budgets" to be set every five years and for ministers to give annual progress reports on cutting emissions.
Environment Secretary David Miliband said the plans, which also include more investment in wind and wave power, provided "clarity" for businesses.
But he rejected opposition calls for annual targets on reducing emissions.
"Changing your policy on the basis of one year's weather isn't a sensible way of doing things," he told the BBC.
The government's plans include:
But its overall effect on emissions would be limited without a new international agreement to replace the Kyoto protocol, which expires in 2012, he added.
Under the proposals, an independent body would advise on the setting of carbon budgets.
Future policies to control emissions would also be made "quicker and easier" to introduce.
Launching the draft bill, Mr Miliband said: "With climate change we can't just close our eyes and cross our fingers.
"We need to step up our action to tackle it, building on our considerable progress so far. And time isn't on our side."
A full Climate Change Bill is set to be published in the autumn.
At the weekend, the Conservatives unveiled environmental proposals including VAT or fuel duty on domestic flights.
But Mr Miliband said more focus was needed on cutting carbon emissions from homes, citing government plans to make all new houses carbon-neutral by 2016 and encourage the use of energy-efficient light bulbs.
He told BBC Radio 4's Today programme: "At the moment, domestic buildings account for 25% of the UK emissions.
"Aviation represents 5%, so aviation is important but it's one fifth as important for this big problem as domestic emissions."
Mr Miliband added: "If we are going to fly more, we've got to do something else less.
"In the end the planet doesn't mind whether it's an aviation emission or another emission."
He also said that "criminalising aviation won't save the planet".
Chancellor Gordon Brown said the bill would mean governments would "manage our carbon budgets with the same prudence and discipline" as economic budgets.
But BBC environment correspondent Sarah Mukherjee said opposition MPs were planning to table amendments which would force the government to accept annual targets.
Shadow environment secretary Peter Ainsworth said: "To be truly effective, any bill should have three elements: annual emission reduction targets; an independent body to set as well as monitor these targets; and an annual carbon budget report from the secretary of state.
"We've got to stop having a system whereby targets are set 10 years in advance, ignored up until year eight, and then are quietly dropped in year nine."
Liberal Democrat environment spokesman Chris Huhne said his party was "certainly supporting the bill" but that the 60% target may "not be good enough".
"We may well need to aim more towards about 80%, but it's a good first start and the framework is broadly right," he told BBC News.