Several times in Earth's history, rapid global warming occurred, apparently spurred by amplifying feedbacks. In each case, more than half of plant and animal species became extinct. New species came into being over tens and hundreds of thousands of years. But these are time scales and generations that we cannot imagine.

The evidence for human-made climate change is overwhelming.

Imagine a giant asteroid on a direct collision course with Earth. That is the equivalent of what we face now with climate change, yet we dither.

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

We're running out of time.

The urgency derives from the nearness of climate tipping points.

I tend to be naive and gullible, I guess, but I try to believe that governments believe what they say.