Half a century ago a group of more than 2,000 scientists signed a warning of environmental crisis and nuclear war. Named after the French town where it was compiled, the “Menton Message” turned out to be somewhat hyperbolic in its environmental predictions, and did not account for some of humankind’s remarkable developmental progress over the following decades. However, some of its concerns certainly remain prescient today. And so another, smaller, group of scientists convened, on the 50-year...