This week, I'm one of four Conservative Shadow Cabinet ministers making speeches on climate change, talking about how we will take action to cut emissions and green our economy. This unprecedented series of speeches is a powerful demonstration that our commitment to the environment is as strong as ever.

It's significant that a Shadow Chancellor should be part of this. For, quite frankly, the Treasury has often been at best indifferent, and at worst obstructive. Alistair Darling has not given a major speech on the environment for two years. All this has got to change. Instead of the Treasury blocking green reform, I want a Conservative Treasury to lead the development of the low carbon economy and finance a green recovery. Let me explain how.

First, a Conservative Treasury will help the government to lead by example. For all Labour's fine rhetoric and mass of initiatives, the government's carbon emissions are higher today than they were in 1997. Despite Labour's target of cutting emissions by 12.5 per cent by 2010-11, the latest Sustainable Development Commission report found the total carbon emissions from central government departments have actually increased by 8 per cent since 1999. It's no good ministers telling the public what to do when they can't even get their own house in order.

Some of Britain's most successful companies have shown that it is possible to cut emissions and cut costs. I visited a B&Q store yesterday, and learned about how that company has cut their emissions by 10 per cent in recent years, and plans to go even further next year. We will follow their example by requiring government departments to cut their emissions by 10 per cent within 12 months of the election. And if any department needs encouraging to take action, a Conservative Treasury will simply give them less money to spend on energy bills. This isn't just good for the environment. It will save up to £300m a year. That's good for taxpayers too.

The second way that a Conservative Treasury will drive green growth is by financing a green recovery. The global market for green goods and technologies is worth trillions of dollars a year, but with less than a 5 per cent share of that market, Britain is failing to take advantage. In fact, we have a smaller share of the green market than France, Germany, Japan and the United States. This has got to change. That's why last year, I proposed the creation of the world's first green trading market, which would attract new investment from across the world. Thanks to the work of the London Stock Exchange, that market is now up and running, and almost a hundred companies have signed up.

But a Conservative Treasury can go even further. A recent survey by the Renewable Energy Association found that more than three quarters of Britain's green energy companies are now facing severe difficulties in accessing loans and investment. So in the coming months, we will be looking at how a Green Investment Bank can help kickstart our green recovery by providing green companies with the investment they need. This will help us deliver the green finance we need for new jobs in every region of the country.

The third role for a Conservative Treasury is being part of the answer to our environmental problems, instead of being treated as the problem. Take recycling, for example. Labour's approach has been to threaten families with bin taxes and taking away their bin collection. That hasn't worked: our recycling rates are still among the lowest in Europe. I've proposed a completely different approach, and you can see it in action in Conservative-run Windsor and Maidenhead, where we are paying the public to recycle. The result? Recycling rates have increased by 30 per cent, and the average family is on course to be £130 a year better off. In the years ahead, we want to encourage more councils to try this approach. But we can go further.

I believe that that the public is looking for a way to invest in the green recovery. So we will introduce new Green ISAs, a new tax-free savings product in which all the funds invested would help green our economy. This will not only unleash new sources of finance for green firms, but will give everyone a chance to be an investor in our low carbon future. That's the right way to green our economy and help families to save for the future.

Under a Conservative government, the Treasury will no longer be the cuckoo in the Whitehall nest when it comes to climate change. If I become Chancellor, the Treasury will become a green ally, not a foe.

George Osborne is Shadow Chancellor