New evidence suggests that we have already passed a dangerous threshold for the amount of carbon dioxide in the atmosphere and that the time for taking strong action is slipping away.

As debate begins on Capitol Hill, the prospects for passing a climate change bill this year are dimming. Increasingly, it appears as though any new law will await a new Congress and a new president.

Quietly and somewhat surprisingly, green groups are cropping up throughout China and are starting to have an impact. In the first in a series on Chinese environmentalists, journalist Christina Larson visits with Zhao Zhong, who is leading the fight to save the Yellow River.