A new study by 22 biologists and ecologists has found that environmental changes on our planet are reaching a point of no return that leads to mass extinctions and harms human welfare. The situation, said one scientist, “scares the hell out of me.” That would be James H. Brown, one of the authors of alarming paper published by Nature, talking to New York Times Green blogger Justin Gillis. Brown is not one of your everyday cranks predicting raptures and the end of days. He is a macroecologist at the University of New Mexico. And as The Atlantic's James Fallows, who...