In 2002, using data collected during the three-day grounding of all aircraft in the U.S. after 9/11, scientists discovered that contrails—the wispy white streaks that trail jets—were narrowing the natural day-night temperature cycle in well-trafficked areas. Now a NASA study indicates that warmed-up nights are outpacing cooled-down days. In the U.S., for example, detailed atmospheric modeling suggests that contrails could account for a climate-warming trend—just under 0.3
Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.