Yvo de Boer, executive secretary of the United Nations Framework Convention on Climate Change (UNFCCC), steps down, effective July 1.
Some specialists are calling for an overhaul of the UN global warming process, which yielded only modest progress in Copenhagen.
The US, China, India, South Africa, and Brazil agreed to a voluntary climate pact. President Obama acknowledged that 'we have much further to go.' The deal did not produce commitments on emissions reductions.
Ten Northeast states already have their own greenhouse-gas emissions regime. It's one model for the federal plan.
A recession may be a cruel remedy for environmental degradation. But some experts say the earth welcomes the breathing room.
But how much will they cost Americans, particularly during a recession?
His call for US emissions to stabilize by 2025 marks a policy change, but is still behind other nations.