"For the first time in human history, the concentration of carbon dioxide in the atmosphere has reached 400 parts per million (ppm). The arrival at this threshold represents a powerful symbol of the growing human influence on the Earth's climate."

We've passed a "line in the sand" on climate science-- the concentration of carbon dioxide in our atmosphere has reached 400 parts per million. Where is the action? Is the obstructionist anti-science science committee in congress dooming us with irreversible climate change? Cenk Uygur and Ana Kasparian discuss.