It falls to the Committee on Climate Change to tell a truth that politicians dare not mention. Unencumbered by the need to win elections, the committee can say what we must do to meet our legally binding targets to cut greenhouse gas emissions.

Ministers are fond of saying how Britain is leading the world by promising to cut emissions by 34 per cent on 1990 levels by 2020 and 80 per cent by 2050. They are less fond of outlining the sacrifices required.

The committee makes clear that the apparent good progress to date is a “false impression” created by the recession and, before that, the closure of much of manufacturing industry. “Where CO2 emissions have fallen, the extent to which this has been through implementation of measures to improve energy or carbon efficiency is very limited.” Emissions will continue to fall this year but once the economy starts to recover, they will rise unless the Government uses “stronger levers”.

The committee takes vague government aspirations and explains exactly what will have to be achieved. For example, while ministers have waffled about an electric car revolution, it sets tough targets: 240,000 electric cars by 2015, 1.7 million by 2020.

The committee’s resolution to be honest is shown by its call for road pricing to be reconsidered – not just to reduce congestion but also to cut emissions. It knows that motoring taxes are politically tricky. By recommending the charge – with no reduction in fuel duty – the committee is making it harder for the Tories to pitch for the motoring vote by promising lower taxes.

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