Here's a small add. You say:

In 1972, all four lead authors believed a change of course was not only possible but likely. Today, only one remains a believer.

Donella Meadows, known as Dana, died about 10 years ago, but were she here I'm pretty sure she would still believe in her work.

One of the things she was doing then was tracking first frost and thaw dates at her New Hampshire farm -- and in something like 10 years, she'd seen noticeable shifts in how late the first frosts arrived and how early were the spring thaws.