This is a sweeping global pact but an agreement made in China and the United States.
Without concord between Beijing and Washington, the world could not have struck a comprehensive deal to tackle global warming.
![A slogan, "FOR THE PLANET", is projected on the Eiffel Tower as part of the UN Climate Conference in Paris.](http://web.archive.org./web/20170823153050im_/https://www.fairfaxstatic.com.au/content/dam/images/g/l/m/5/r/y/image.related.articleLeadwide.620x349.glmfo3.png/1450056169330.jpg)
As if to illustrate the point, by climatic coincidence the air quality in Beijing has been bad enough in recent weeks to prompt a red alert from local authorities.
China's determination to clean up its act and see the Paris talks succeed makes for a stunning turnaround from the obstinate attitude Beijing took to Copenhagen six years ago.
![United Nations climate change chief Christiana Figueres, left, UN Secretary-General Ban Ki-moon, French Foreign Affairs ...](http://web.archive.org./web/20170823153050im_/https://www.fairfaxstatic.com.au/content/dam/images/g/l/m/8/h/7/image.related.articleLeadwide.620x349.glmfo3.png/1496409045989.jpg)
Back then, with Kevin Rudd in back rooms and complaining about "ratf---ers", China's premier refused to even talk with a new-in-the-job Barack Obama.
However, the success in Paris at the weekend was a consequence of direct diplomacy between China and the US for well over a year, and a determination from the leaders of both countries to see a deal done.
Such was the confidence, the leaders did not even need to physically be there at the end.
This marks an important moment: recognition that economic development depends on a healthy planet, and also the setting of a precedent for resolving complex, common challenges.
Getting the rest of the world together was crucially important, but for all the activist attention on tiny island nations and their "coalition of high ambition" to stop sinking beneath the waves, the powerhouse nations always have the most influence.
These negotiations have been an exercise in realpolitik far more than environmental idealism, and because of that, the outcome will not satisfy everyone.
Expect truck-sized holes to be identified over coming weeks in the freshly signed commitments, and more loud debate between green zealots and climate change deniers alike.
However, for all the frustration, setbacks and delays encountered in what has been decades of environmental diplomacy since the greenhouse effect became a public concern, undoubted progress is worth celebrating.