The scientific excitement in comparing theory with data, and developing some understanding of global changes that are occurring, is what makes all the other stuff worth it.

The danger is that the compromises and special interests inherent in Kyoto-style targets and cap-and-trade will be accepted because of bureaucratic momentum.

I think we have a very brief window of opportunity to deal with climate change. No longer than a decade at most.

The question is not whether to close the parks, but how to accomplish this goal.

The fact is fossil fuel carbon will stay in the surface climate system for millennia.

The most difficult task, phase-out over the next 20-25 years of coal use that does not capture CO₂, is Herculean, yet feasible when compared with the efforts that went into World War II. The stakes, for all life on the planet, surpass those of any previous crisis. The greatest danger is continued ignorance and denial, which could make tragic consequences unavoidable.

We are on the precipice of climate system tipping points beyond which there is no redemption.