The problem of climate change is almost universally understood and acknowledged. This is in itself an achievement. Now is the moment to get serious about the solution.

Such a solution has to be global. It must include America and China. It has to be radical. It must put the world on a path away from carbon dependence to a new, green economy.

The report I published last week is based on the work of experts from around the world. It warns of the danger of a chasm between the calls for radical action from scientists, environmental groups and people rightly alarmed at the effect of greenhouse gas emissions on the planet, and the anxiety of decision makers in politics and business, who share the aims of radical action but worry whether it is realistic.

In the long term everyone accepts that the needs of the economy and the environment are in partnership. In the short term there is tension. And we live in the short term. The report tries to bridge this chasm.

There is a blunt reality that we need to acknowledge amid all the talk of targets, goals and obligations: the climate demands a radical change in the nature of the world economy, moving from growth built on carbon dependence to environmentally sustainable development.

We need to be clear about the size of the task. America’s emissions are still growing. So are those in Japan. In Europe they are static.

China and India are, rightly, industrialising and moving hundreds of millions of poor people from subsistence agriculture to the modern economy.

We are talking of a global 2050 target of at least a 50% cut in emissions. This is decades away and decades beyond the political life of any government. The key challenge is to describe a realistic path to it. That implies shorter-term goals, but these are immensely demanding, asking developed economies to move from growth in emissions to significant cuts within 10-15 years.

Europe has bold 2020 targets and it will take bold action to achieve them. The recent Warner-Lieberman bill before the US Senate implied 5% cuts in emissions by 2020. That would be a big step but it falls short of the cuts necessary for world emissions to peak in 2020.

China has set a target of a 20% cut in energy intensity by 2010, a huge step forward. This is again immensely demanding but, even if met, will not cut overall emissions, given China’s need for growth. India also wants to grow.

The challenge is truly profound. It is as technically and scientifically complex, as politically sensitive and as institutionally fraught as any the international community has had to deal with since the postwar Bretton Woods economic settlement.

And, above all, our knowledge is constantly evolving. Though we talk as if the science were certain, the precise details are often open to debate.

Therefore this report proposes an approach to the United Nations negotiation in Copenhagen at the end of next year that does not attempt to resolve all issues up to 2050 or even 2030 or 2020. Instead it should begin a process that will then undergo revision as our knowledge improves and the facts become clearer.

What we need are practical, realistic steps to set the world economy on a new path.

What might the framework look like and what leadership do we need from the Hokkaido summit next month? First we must set a clear direction in Copenhagen through a realistic target for emissions cuts and get the action under way. And Copenhagen is the beginning, not the end of a process.

The G8 and the Major Economies Meeting must give a lead by agreeing this target.

The countries attending these two summits represent three-quarters of the global emissions. A steer from them is an essential precondition to a deal. It doesn’t supplant the UN process at Copenhagen but supports it.

They can also help find the answers to questions that will be stumbling blocks to serious negotiation. The G8 should agree a plan through to next year to get this work done. Then the Copenhagen negotiation has a chance of success.

There are also facts whose significance gets lost. For example, energy efficiency would provide about one-quarter of the gains necessary.

The vast majority of new power stations in China and India will be coal-fired. So developing carbon capture and storage technology is not optional; it is of the essence.

Without at least some countries engaging in a substantial renaissance of nuclear power, it is hard to see how any global deal could work.

For developing countries to grow, they will need funds and technology; otherwise they will not be able to reduce emissions within the necessary time.

Deforestation amounts to about 15-20% of the emissions problem.

Certain key sectors such as cement, steel and, of course, power account for a huge percentage – almost half of all emissions.

Airline and shipping emissions, though only 5% today, are a fast-growing part of the problem.

Finally, some good news. It is clear the deal can be done. Indeed, long term, there will be benefits not just to the environment but to the economy. In the short term, we need to get it right.

It is time to take this issue from a campaign to a practical plan of action. And the time to do it is now.

Tony Blair is leading the Breaking the Climate Deadlock initiative to promote a new global deal on climate change. The full report is available at www.tonyblairoffice.org

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