The government has set out plans to cut carbon dioxide emissions by more than half. But what do they involve?
What targets have been set?
Ministers want to reduce emissions of carbon dioxide - one of the "greenhouse gases" thought to contribute to global warming. They want a cut of 60% by 2050 - and of between 26% and 32% by 2020 - compared with the level measured in 1990.
Who will monitor progress?
The draft Climate Change Bill says an independent panel should be established to set the government a "carbon budget" every five years, limiting the amount of emissions the UK can produce.
Will they be legally enforceable?
If the five-yearly targets are missed, a future government could be taken to a judicial review - where a court can look at its actions and, if necessary, hand out a punishment.
How will homes and businesses be affected?
The draft bill does not stipulate how carbon dioxide emissions will be reduced, just that there have to be cuts. Ministers argue that the five-year carbon budgets will give businesses long-term guidance on what has to be done. Other government actions - for instance banning high-energy light bulbs, increasing flight duties and fining heavy-polluting industry - will help the overall targets to be achieved, it is argued.
What alternatives are there?
The draft bill acknowledges that technological advances could create more fuel-efficient transport, industry and homes, creating less carbon dioxide. The government is also calling for more investment in wave, solar and wind power. Environment Secretary David Miliband said "big decisions" needed to be taken on nuclear power.
What is the point of the UK cutting emissions by 60% when the world's biggest polluters, such as China and the USA, will not?
The government argues that by setting an example, it will be able to persuade other countries to sign up to a new global agreement when the current Kyoto agreement runs out in 2012. The EU has committed itself to a 20% reduction in greenhouse gas emissions, compared with 1990 levels. Germany has invited Brazil, China, India, Mexico and South Africa to a G8 summit at Heiligendamm in June to lay the foundations for a replacement for Kyoto.
Who opposes the UK government's plans?
Some politicians - including former Conservative Chancellor and climate change sceptic Lord Lawson - say emissions targets will hit UK business unfairly, making it uncompetitive. But ministers say they are pushing countries such as China, India and the US to follow suit. Whether they will remains to be seen.
The UK Independence Party insists the government's plan is "deeply misguided" and is demanding more investment in nuclear energy as an alternative to using fossil fuels.
What do environmental campaigners think of the plans?
Friends of the Earth said it was pleased that a new law was proposed but called for more ambitious reduction targets. Christian Aid said the eventual Climate Change Bill should demand carbon dioxide cuts of at least 80% per cent by 2050 with annual carbon budgeting "milestones". Companies trading in the UK should have to report carbon dioxide emission levels, it added.
What do opposition parties say?
The Liberal Democrats and Conservatives have both welcomed the draft Climate Change Bill as a step in the right direction but they want carbon targets to be set every year. They fear the responsibility for keeping up progress will be too easily handed from one government to the next, with five yearly targets. Ministers say annual targets would be unworkable and unmeasurable because of fluctuations in the weather and carbon dioxide levels from one year to the next.
When will the draft bill become law?
The government is to consult environmental groups and Parliament and hopes to publish a full bill by the autumn, with an act in place by Easter 2008.