Paul Krugman: China, Coal, Climate

It’s easy to be cynical about summit meetings. Often they’re just photo ops, and the photos from the latest Asia-Pacific Economic Cooperation meeting, which had world leaders looking remarkably like the cast of “Star Trek,” were especially cringe-worthy. At best — almost always — they’re just occasions to formally announce agreements already worked out by lower-level officials.

Once in a while, however, something really important emerges. And this is one of those times: The agreement between China and the United States on carbon emissions is, in fact, a big deal.