The droughts that have parched big regions of the country are killing forests. In the arid Southwest, the body count is especially high. Besides trying to keep wildfires from burning up these desiccated forests, there’s not much anyone can do. In fact, scientists are only now figuring out how drought affects trees. Park Williams studies…

The last big ice age ended about 11,000 years ago, and not a moment too soon — it made a lot more of the world livable, at least for humans. But exactly what caused the big thaw isn’t clear, and new research suggests that a wobble in the Earth kicked off a complicated process that…

The National Academy of Engineering in Washington, D.C., once asked its members to pick the greatest engineering achievement ever. Their choice? The electrification of the country through what’s known as “the grid.” Ernest Moniz, director of the Energy Institute at MIT, says they were right on the money.