"Yesterday, for the first time in human history, concentrations of carbon dioxide, the primary global warming pollutant, hit 400 parts per million in our planet's atmosphere. This number is a reminder that for the last 150 years -- and especially over the last several decades -- we have been recklessly polluting the protective sheath of atmosphere that surrounds the Earth and protects the conditions that have fostered the flourishing of our civilization. We are altering the composition of our atmosphere at an unprecedented rate."

Scientists have reported that carbon dioxide has reached a daily level of 400 parts per million, which has been a "long-feared milestone." Ralph Keeling, director of the Scripps CO2 program told the New York Times: "...We are quickly losing the possibility of keeping the climate below ... possibly tolerable thresholds." 

"Already, deep fissures are emerging between, on one side, a base of ideological voters and lawmakers with strong ties to powerful tea-party groups and super PACs funded by the fossil-fuel industry who see climate change as a false threat concocted by liberals to justify greater government control; and on the other side, a quiet group of moderates, younger voters, and leading conservative intellectuals who fear that if Republicans continue to dismiss or deny climate change, the party will become irrelevant."