PARIS — I had low expectations for the U.N. climate meeting here and it met all of them — beautifully. I say that without cynicism.

Any global conference that includes so many countries can’t be expected to agree on much more than the lowest common denominator. But the fact that the lowest common denominator is now so high — a willingness by 188 countries to offer plans to steadily and verifiably reduce their carbon emissions — means we still have a chance to meet what scientists say is our key challenge: to avoid the worst impacts of global warming that we cannot possibly manage and to manage those impacts that we can no longer avoid. That is a big, big deal.

Many leaders had a hand in it, but it would not have happened without the diplomacy of President Obama and John Kerry.

Hat’s off, because this keeps alive the hope of capping the earth’s warming to 2 degrees Celsius, or 3.6 Fahrenheit, above the level that existed at the dawn of the Industrial Revolution — the rough redline scientists have drawn beyond which “global weirding” will set in and the weather will most likely get really weird and unstable. We’re already almost halfway to passing that redline.