The week began with David Miliband's leaked wish-list of possible green taxes. It continued with the publication of the Stern report - the first authoritative economic analysis of climate change. It hit its mid-point with the Government promising a climate-change Bill. And it has ended with a march through London highlighting the dangers of irreversible climate change. If ever there were a tipping point when the political classes finally woke up to climate change, this week was surely it. Or was it?
At the launch of the Stern report, we saw both Gordon Brown and Tony Blair proudly trumpeting their view that the UK is "leading the world on climate change".
It is true that Labour raised the level of debate when they first came to power. In 1997, a fresh-faced Tony Blair promised to put the environment at the heart of his Government. Gordon Brown pledged to "shift the burden of taxation from goods to bads". John Prescott embarked on a policy of "integrated transport" to get people out of their cars and on to public transport.
It's time to get real. None of the above has happened. In fact, carbon emissions are higher today than they were when the Government came to power in 1997. Labour has gone backwards on climate change.
Take renewable energy. Just 4.2 per cent of UK electricity comes from renewable sources; this puts us at the bottom of the EU league, alongside Malta. Margaret Beckett may lecture India about climate change, but around 6 per cent of Indian energy comes from renewable sources. We are in no position to lecture anybody.
Take energy efficiency. A new home made to current building regulations will use on average 40 per cent more energy than a home built in Sweden. Despite the fact that a third of new buildings fail to meet even our own pitiful official standards, there has not been a single prosecution for failure.
Take transport. Average emissions from new cars sold in the UK are 171.4g/km, and nobody pretends that we will hit the target of 100g/km by 2010. Since Mr Prescott's grand design for transport, car use has increased by around 11 per cent, with a quarter of all car journeys under two miles. And then there is aviation, the fastest-growing source of emissions. The Government is stubbornly sticking to its discredited plan to treble airport capacity. So much for joined-up thinking.
Even in government-owned buildings - the one area directly and irrevocably under government control - carbon emissions are rising. As the Sustainable Development Commission so aptly stated: "Leading by example? Not exactly."
It is clear that business as usual has failed. This is precisely why the Conservative Party, along with the remarkable Stop Climate Chaos coalition, has called for a climate-change Bill in the next session of Parliament. We need a binding legal framework to guarantee emission reductions, whichever party is in power.
We await the Government's proposals for such a Bill with interest. We hope to be able to support it, but we will not accept a watered-down version.
To be effective, any climate-change Bill will need to include these elements: rolling year-on-year emission targets; an independent body to set and monitor them; and an annual carbon budget report, with any new measures being subject to approval in Parliament.
The best argument for annual targets is Labour's own record.
Three times the Government has promised to reduce Britain's 1990 level of emissions by 20 per cent before 2010. The Government accepted in 2000 that "the goal is challenging, but that is its purpose. It is designed to give a clear signal of the direction in which policy is moving, allowing long-term planning and stimulating innovative responses."
The "clear signal" was evidently not received in Whitehall. Emissions have risen steadily since the commitment was made. As a result, in March of this year, it was quietly dropped.
Yearly targets would allow us to check that policy is working, and to tweak it if it isn't. This approach would provide a rather more effective discipline than the current one, which, as we have seen, involves waiting 10 years for policy to fail and then surreptitiously walking away.
In this newspaper a week ago, the Environment Secretary David Miliband argued that "it is not serious to pretend that annual targets on carbon emissions are the answer. Emissions are affected by things beyond the control of government: short-term fluctuations in energy prices; severe weather; the economic cycle."
But, in the Tory party, we have built the necessary flexibility into the way we have structured our proposals. In practice, emission cuts may come in fits and starts - the dash for gas under John Major quickly led to a 7 per cent reduction. Conversely, a combination of cold weather and gas shortages led to greater coal use last winter, resulting in an increase in emissions that the Government hadn't planned for. We do not expect the Government to meet the annual targets precisely each year. Instead, we have proposed rolling targets, independently set and monitored.
In other words, the Government can miss the targets for whatever reason it wants, but it will be held accountable for its decisions by the independent commission, and by the public. If there were genuine economic reasons why one year was especially difficult, the commission would take that into account and readjust the following year's targets to keep us on track for a cut of at least 60 per cent by 2050.
However, if failure to meet carbon obligations arose - as over the past nine years - from government ineptitude or inertia, this would be exposed. Heads should roll. This is the kind of external discipline we need if we are to make real progress.
In the end, only a global solution will work. But if Messrs Blair and Brown are to achieve the moral authority required to tackle the greatest threat we face, they must start to show some true leadership at home. This is not just for the health of our environment and our economy, but for the health of the world itself. Mr Blair's international musings have made the UK an eagerly watched test case. Unfortunately, it is a test the Government is currently failing.
Peter Ainsworth MP is shadow Secretary of State for the Environment