On Monday, the administration of President Barack Obama was to release a plan to curb greenhouse-gas emissions from U.S. power plants by almost a third over the next 15 years.
On its own, the rule will not be nearly enough to save the world from global warming.
The U.S. is responsible for about a seventh of the world's emissions, calculations based on World Resources Institute data show. And of that fraction, carbon-spewing power plants account for less than half. Developing countries such as China and India are expected to produce most of the growth in emissions for the rest of the century.