Our leaders have been telling us for many years now how seriously they take the threat of global warming. This was the week we asked them to prove it, by demanding the inclusion of an ambitious climate change Bill in the forthcoming Queen's Speech. The response of the Government to our challenge will determine how history judges its environmental credentials. A watershed moment is approaching. We will soon know whether Tony Blair and his ministers are truly engaged with the issue, or whether their many fine speeches over the past decade have been plain old hot air.
The in-depth report on climate change by Sir Nicholas Stern, the head of the government economic service, is poised to arrive at exactly the right time to increase the pressure on ministers. We are told the report, which will be released on Monday, will contain a stark message for ministers. Sir Nicholas will reveal that by the end of the century, global warming could cost the world economy 20 per cent of its GDP. Massive population shifts prompted by rising sea levels and flooding could cause the biggest global recession since the 1930s. Yet there is hope. By sacrificing 1 per cent of our GDP to fight climate change now we could avoid such a catastrophe. If ever there was an argument designed to engage the attention of our number-crunching Chancellor, it is one framed in such clear cost-benefit terms.
The report also promises to be an important challenge to the conventional thinking on climate change in business circles. Measures proposed to curtail climate change - raising carbon taxes, fining industry for excessive pollution - have traditionally been regarded as "bad for the economy". But we now see that carrying on as normal will itself wreck growth in the long term. Preventing major climate change is about economic self-interest. Thus the Stern analysis becomes as relevant in a global context as it is in a British one. The wakening giants of China and India will not wish to see their own hard-won prosperity crumble just as it is finally achieved. Nor will the US, the main obstacle at present to a binding international treaty, want to see its wealth destroyed.
If the global economics of climate change are in the process of shifting, the politics here in Britain have already done so. The Liberal Democrats and the Conservatives are both calling for statutory annual reductions in carbon emissions. So too are 400 MPs, from across the parties. The public demand for action is growing too, as witnessed by the impressive response from our readers to The Independent's call this week for ideas on what should be in the Bill.
Mr Brown and Mr Blair have an unprecedented opportunity here. Yet both continue to resist tough action. The Prime Minister said this week that annual reductions would be "very, very difficult to deliver". The Chancellor is also reported to be unconvinced. Our leaders may not be in denial about the reality of climate change, but they are still very much in denial about the solution. Mr Blair and Mr Brown seem to believe that long-term targets, some minor tinkering with the tax system and the expansion of EU emissions trading schemes are enough to prevent disaster.
All the evidence suggests they are not. Only statutory annual limits on emissions will create an appropriate economic price for carbon - and genuine incentives for efficiency and renewable technologies. We are told that Britain will reduce emissions by 60 per cent below 1990 levels by 2050. How? The plain fact is that emissions are rising, not falling. It is time for a radical new approach. It is time for those who are serious about safeguarding the planet's future to stand up and be counted.