HONG KONG — Focusing on climate change, the most recent Group of Eight meeting, chaired by Germany and attended by five of the world's biggest developing countries, marked a significant step forward in a battle for nothing less than the survival of humanity on this planet.

For one thing, the European Union, Canada and Japan agreed to halve greenhouse gas emissions by 2050, compared to that of various baseline years. This compares with the Kyoto Protocol target of reducing emissions by 5 percent from 1990 levels by 2012.

Although the United States — the world's largest emitter of greenhouse gases — did not commit itself to this target, it did agree to "seriously consider" it, as did Russia. This is a step forward, as U.S. President George W. Bush previously had been implacably opposed to any emission reduction targets.