TO UNLOCK THE secrets of the atmosphere, first, travel away from cities, forests, cars and people, to somewhere the air blows clean. Say, the top of a Hawaiian volcano. Bring two round glass flasks, volleyball-sized but with the air vacuumed out, wrapped in surgical tape for safety. Point the glass nozzle jutting from each toward that fresh air. Now hold your breath and walk at least ten feet into the wind. Open the valve, let the air rush in and, well after the hissing has stopped, close it back up.
“Then you can breathe once you’ve done all that,” says Tim Lueker, a scientist with the Scripps Institution of Oceanography. “Now you have an air sample, and I’m still amazed that it works.”
Charles David Keeling established this method in…