
McKibben argues that climate change is different than any problem we have faced before, and that Obama's strategy of "working with Congress to pass something modest" simply will not work. Climate change defies conventional political paradigms:
The negotiation that really counts is not between Republicans and Democrats or industry and the greens, or even between the United States and China. The real bargaining is happening between human beings and physics and chemistry, and that’s a tough negotiation.
Mother Nature has drawn a line in the sand: 350 ppm is the highest acceptable concentration of carbon dioxide in the atmosphere. There is no negotiating. There is no compromise.
In order to meet this goal, we must demand more serious climate action from our legislators and our Commander in Chief (McKibben says, "The bill making its way through Congress explicitly aims for a world with 450 parts per million carbon."). If Obama is worried he will exhaust his political capital by throwing his weight behind stricter climate legislation while dealing with health care reform and the struggling economy, he must look no further than the 4594 events planned in 175 countries this Saturday. With such widespread support from the global community, how could he afford not to promote bold policies?
McKibben concludes his piece in the Globe with the following challenge to our President:
It would risk real political capital to push for change on the scale that the science demands. Since even a politician of his talents can’t amend the laws of nature, though, let’s hope that beginning today he’s willing to take some real risks.
Obama is scheduled to give a speech on "American leadership in clean energy" at MIT in the morning to promote the Senate climate bill. Let's listen carefully to what he says and decide if he lives up to McKibben's challenge or if he reverts back to conventional political practices.

One number will determine the fate of our planet. 350 parts per million is the atmospheric concentration of carbon dioxide above which the earth can no longer naturally sequester (absorb) the greenhouse gas and climate change occurs. 
