As difficult as it is to eliminate the risk of nuclear warfare, it requires fewer changes to the global economy than does averting or reversing climate change.

Trying to conserve a privileged global position makes change traumatic for the US.

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.

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.

To survive, humans need food, water, and air. Yet biodiversity, the Earth's bodies of water, and the planet's atmosphere are all under threat.

If nuclear warfare is believed to be somewhat controlled, then climate change is now the greatest threat.

Technology is a many-headed monster and perhaps it would be better to regress to a safer past and avoid technological change; it is tempting to think like that.