Angela Merkel has good reason to be pleased with the outcome of the meeting of the Group of Eight leading countries she chaired this week. Her reputation as an effective conciliator and a determined negotiator has gained in lustre. Under her guidance, the G8 summit marks a turning point on tackling climate change. Whether George W. Bush meant what he signed is unclear. But this meeting marks the end of the beginning of the global debate. The US is now at last engaged.

The communiqué’s salient point is that the G8 agreed to begin talks this year on a successor to the Kyoto treaty, due to expire in 2012. Any such successor will be negotiated under the auspices of the United Nations. It will also surely have objectives for emissions of greenhouse gases, along with measures to achieve them. In both respects this marks a transformation for US policy.