Obama science adviser suggests geoengineering to combat climate change.
Since 1970s, loose association of conservation-minded urban areas has grown up worldwide.
Organic waste becomes salable compost – and millions in carbon credits.
Secretary of State Hillary Clinton wrapped up her trip to Japan, South Korea, Indonesia, and China on Sunday. Her aim was to reenergize key ties to the region.
Readers write about a cap-and-trade policy for CO2 emissions, why the West shouldn't lecture China about greenhouse-gases, the need for Afghanistan's neighbors to help contain the volatile country, and mandatory service in the US.