It is not nice to say "I told you so," but this time has to be an exception. In late February I wrote an article in this column which I called "U.S. climate change strategy should include summit with China", predicting that the United States would seek a one-to-one deal on climate change with China this year.

It has just been revealed by Suzanne Goldenburg, U.S. environmental correspondent of the Guardian, that a memorandum of understanding on exactly such a deal already exists. That is very good news.

John Holdren, now President Obama's chief scientific adviser, told me last year that he had been talking to the Chinese leadership and assured me that they were ready for a deal on climate, but he said nothing about a bilateral deal between the United States and China. Nevertheless, that was obviously what was needed: there is no other point of departure that could get the world to the finish line on time.

The finish line is a global deal on cutting emissions fast enough to avoid runaway warming, and the deadline is this December, when it is supposed to be wrapped up and signed in Copenhagen. But there are 117 countries taking part in the negotiations, and there is not a chance in a thousand that they can all arrive at the finish line together and on time without some template for an agreement. The real purpose of a bilateral U.S.-Chinese climate deal is to provide that template.

The deal would be very useful just on its own: together, the two countries account for forty percent of the world's greenhouse gas emissions.

But if the U.S.-Chinese agreement can become the model, with other rich countries accepting the same terms as the United States and other rapidly developing countries making the same commitments as China, we might actually end up in December with a global deal worth having.

Work on the bilateral deal began in the dying days of the Bush administration, with the initiative on the Chinese side coming from Xie Zhenhua, vice-chairman of the National Development and Reform Commission. On the American side the driving forces were John Holdren and Bill Chandler, director of the energy and climate programme at the Carnegie Endowment for International Peace.

It is not a done deal yet, but Chandler predicts it will happen by autumn, and that it will be "serious" and "substantive".

The draft agreement, drawn up by Holdren and Chandler late last year, has three main points: the U.S. and China will use existing technologies to cut carbon emissions by 20 percent by 2010; they will cooperate on new technologies including carbon capture and storage and better fuel efficiency in vehicles; and they will both join the global agreement in Copenhagen in December.

This U.S.-Chinese draft has not been signed, but Xie has agreed to it.

A deal like this will not end the climate crisis, even if all the other big emitters accept similar terms. Past emissions have already committed us to so much warming that there will be famines, waves of refugees and wars in some of the worst-hit regions no matter what we do now.

Nevertheless, the kind of treaty that the U.S.-Chinese deal might lead to in Copenhagen in December is worth having, because if we move fast enough there is still time to preserve most of the world we know in a more or less recognizable form.

Twenty percent across-the-board cuts in emissions by 2010, or even by 2012 or 2013, would be an excellent start. And in the meantime, Obama has just cut a deal with the automobile industry on fuel efficiency that will make a real difference to American emissions.

With the highest rate of car ownership in the world (five cars for every six people) and the world's worst fuel efficiency, U.S. cars emit much more carbon dioxide per year than all the cars in Japan, China, India, Russia, France, Italy, Germany, Britain, and Canada put together.

The target first set by Governor Arnold Schwarzenegger in California, an average of 6.62 litres per 100 kilometres for all cars and light trucks by 2016, has now been adopted by President Obama for the whole country. That will eventually cut U.S. vehicle emissions by 40 percent (current average mileage in the U.S. vehicle fleet is only 11 litres/100 km.) It also means that U.S. oil imports may fall by up to half over the next ten years.

By the time the United States reaches its 6.62 litres/100 km in 2016, most other countries in the world will have moved on to an average of 5.23 litres/100 km or better. (China's current requirement is 5.47 litres/100 km, and the European Union's target is 5 litres/100 km by 2012.)

Having left everything so late, the U.S. will be playing catch-up for a long time—but at least it is back in the game. And China is finally talking about cutting its emissions, too.

"There are these two countries that the world blames for doing nothing, and they have a better story to tell," said Terry Tamminen, Governor Schwarzenegger's environmental adviser, who was at the talks in China. Things are moving in the right direction at last.

Gwynne Dyer's latest book, Climate Wars, was published recently in Canada by Random House.