His call for US emissions to stabilize by 2025 marks a policy change, but is still behind other nations.
The president says the level will stabilize by that year, but he sets no cap.
Should the world put less focus on emissions caps and more on spurring clean technologies?
Tiny particles heat up the atmosphere faster than scientist once believed. The good news is this dust can be cleaned up fairly quickly.
By December 2009, binding greenhouse-gas emissions policies will be set for developing countries.
Rivers fed by melting glaciers across Latin America may soon dry up, forcing changes on the people who depend upon them.