Editorial — New York Times.

Yvo de Boer’s resignation on Thursday after nearly four tumultuous years as chief steward of the United Nations’ climate change negotiations has deepened a sense of pessimism about whether the world can ever get its act together on global warming. Mr. de Boer was plainly exhausted by endless bickering among nations and frustrated by the failure of December’s talks in Copenhagen to deliver the prize he had worked so hard for: a legally binding treaty committing nations to mandatory reductions in greenhouse gases.

His resignation comes at a fragile moment in the campaign to combat climate change. The Senate is stalemated over a climate change bill. The disclosure of apparently trivial errors in the U.N.’s 2007 climate report has given Senate critics fresh ammunition. And without Mr. de Boer, the slim chances of forging a binding agreement at the next round of talks in December in Cancún, Mexico, seem slimmer still.

Yet his departure is hardly the death knell for international negotiations. It is not proof that such talks are of no value or that the U.N. negotiating framework in place since 1992 should be abandoned. Even Copenhagen, messy as it was, brought rich and poor nations closer together than they had been. And more than 90 countries representing 83 percent of the world’s greenhouse gases promised, at least notionally, to reduce their emissions.

But his resignation does remind us that the U.N. process is tiring, cumbersome and slow. It reinforces the notion that some parallel negotiating track will be necessary if the world is to have any hope of achieving the reductions scientists believe are necessary to avert the worst consequences of climate change.

The Copenhagen pledges, even if all of them are met, will merely stabilize global emissions by 2020. What really matters is what happens after 2020, whether the world can achieve reductions of at least 50 percent by midcentury. That won’t happen without big cuts by big emitters like the United States, the European Union, China, India and Brazil.

Even before Copenhagen, global leaders were exploring parallel tracks. Former President George W. Bush brought together some of the big emitters, and President Obama has expanded on this idea with the Major Economies Forum on Energy and Climate, a group of 17 countries that plans to meet regularly. The Group of 20 has put climate change high on its agenda, and bilateral efforts — technology exchanges between China and the United States, for instance — are under discussion.

The underlying thought is that the ultimate goal is a safe planet, and that absent a top-down global treaty, that goal is probably best achieved by aggressive, bottom-up national strategies to reduce emissions. Not that these are a sure thing; the United States, embarrassingly, has no national strategy. Until it gets one, it can hardly lecture anyone else. Nor will the world stand a ghost of a chance of bringing emissions under control.