Trees and clean energy [are] the long-run solution but we have no time to wait for the long run. We need a short-run solution now, and one that encourages and facilitates the transition to the long-run solution.

Geoengineering means changing the Earth's fundamental large-scale processes.

While denial leads to certainty, it is only the certainty of death. This is true for individuals and also for civilizations.

We have used the majority of our carbon budget and we are already at dangerous levels of CO2 concentrations, about 400 parts per million. The levels were 250 before industrialization. So the problem is what we have done already and, therefore, what must be undone.

We know little of the consequences of the geoengineering process, such as spraying particles into the atmosphere that shade the planet from the sun's rays and could decrease its temperature. But this process is how dinosaurs disappeared from the Earth about 60 million years ago, by particles spewed by a volcano or a giant meteorite impact, and our species could follow suit.

The first reaction to trauma is denial, then comes anger and finally, acceptance. I think the US is still between denial and anger, and I hope we will reach acceptance because almost perversely, right now, only the US has the technology that is needed for global economic change.

We have to remove the CO2 that the industrial economy has already emitted, which otherwise will remain in the atmosphere for hundreds of years and alter the Earth's climate irreversibly. It is possible to do this.