Complicated problems do not generally yield to simple solutions. And few are more complex than the question of how to confront the challenge posed by anthropogenic global warming.

The Paris climate accord, signed amid great fanfare on Saturday by the representatives of nearly 200 states, does not supply the final answer. What it does is to spread the responsibility for finding one beyond a small coterie of developed countries. This in itself is a historic achievement. But its success or failure ultimately hinges on how solemnly its many signatories are willing to accept this weighty charge.

The preparedness of the developing world to accept a share of the burden was always vital if any credible way forward on tackling climate change was possible. Past deals have mainly heaped the onus on those advanced economies that were responsible for much of the historic growth in emissions.