One year ago, amidst a swirl of pessimism, the UN negotiations on climate change kicked off in Cancun. Following the disappointment at Copenhagen, it seemed that the principles of international negotiation itself were on trial.

Expectations were low. But out of the acrimony arose a new consensus. For the first time, the world agreed to keep global warming to below two degrees.

This is significant. The world does not agree that often. We have but a few truly global agreements – and just one global organization. Next week, the United Nations will convene the next round of talks on a global climate treaty.

Unfortunately, for many countries times could not be harder. Europe faces a currency crisis of constitutional proportions. The United States is preoccupied with jobs and growth. The Middle East and North Africa are consumed by questions of political reform.

Last year, our focus was to keep the show on the road: as long as you are talking, there are options. But time is running out. As the International Energy Agency noted earlier this month, the window for meaningful action on climate change is now measured in years, not decades. The science tells us we must bring down global emissions by 2020 or face terrible consequences.

In Cancun, we began to put in place a global architecture to monitor emissions and support developing countries in tackling climate change. But a more fundamental question went unanswered. Where are the international talks heading?

Are we moving towards a legal agreement committing major emitters to binding emissions targets, or countries voluntarily pledging to take action?

My answer is simple: a global deal covering all major economies is an absolute necessity. This was important enough to both partners that it was in the Coalition Agreement. The UK remains a steadfast advocate of a legally binding agreement under the UN.

No major global problem – whether the arms race or trade conflicts – has ever been resolved by relying on the power of political promises.

Given the current climate, this is not going to happen immediately. Durban will not be our eureka moment. But we can provide a clear signal that it is our objective.

There is already a legally binding deal in place: the Kyoto Protocol. In 1997, 37 major economies – including Japan, Russia, Canada, Australia and the EU – formally committed to cutting emissions. The EU has already surpassed its Kyoto target.

The first Kyoto Protocol commitment period ends next year, and Japan, Russia and Canada have said they will not enter a second.

The EU, on the other hand, wants just that. But if the EU alone signs up – without comparable commitments from major emitters including the US, or major emerging economies such as China, Brazil and India – then we won’t have achieved much. The EU, responsible for just 12% of the world’s emissions, would be left sitting alone in a global framework – without the rest of the globe. That will not do.

We need major economies to commit now to a comprehensive legal framework, and to complete negotiations by 2015. That is not just what we want: it is what the vast majority of the developing world wants, especially vulnerable small islands and the poorest countries.

That is why, together with the rest of the EU, I have made it clear that I am keen to secure a second commitment period of Kyoto. But others must commit to the global legal framework the world needs. Ultimately, Durban is about the movement others make.

Kyoto provides the basis of the rules we need to manage a destabilizing climate. If we have learned anything from the financial crisis, it is that clear rules implemented properly can prevent the toxic buildup of risk. That is why Durban must not be the end of Kyoto. Rather, it must signal our re-commitment to a cause.

Rules work. A recent survey of large global firms found that 83% of business leaders think a multilateral agreement is needed to tackle climate change, but only 18% thought a deal was likely. Businesses want certainty; people want action. Only the politics lags behind.

A clear commitment to commit to a new agreement will provide that certainty. But we need immediate action too. The pledges currently on the table are not enough. In Durban, we should agree that we must close the gap. We can identify actions we can take now, and build momentum towards a major review of ambition. We can also build on the system we use to measure and verify emissions cuts.

We must do more on long-term financial support for developing countries, and establish the Green Fund. And we must continue the work already underway to reduce emissions from deforestation.

We must also show leadership. Next year I will be pressing for a more ambitious EU emissions target: a 30% reduction by 2020. That will help us raise our sights globally.

This will not be an easy path. But I believe it is the only feasible way of achieving our objectives. Milton Friedman once said ‘our basic function is to keep good ideas alive until the politically impossible becomes the politically inevitable’. That is a good description of the task that awaits in Durban.

Chris Huhne is the UK’s Minister for Energy and Climate Change.