Last Thursday, the atmospheric monitoring station on Mauna Loa recorded, for the first time, a daily average carbon dioxide level of over 400 parts per million. This grim milestone is a testament to our inadequate effort to halt the world’s rising greenhouse gas emissions.
A generation ago, scientists calculated that 350 ppm was the upper threshold for the planet to safely sustain human life. Glacier samples indicate that the 400 ppm level has not been…