What makes a tree a tree?

Large crack in East African Rift is evidence of continent splitting in two

Will the world ever be ready for solar geoengineering?

The first time Frank Keutsch heard about solar geoengineering, he thought the idea was terrifying. To the Harvard University atmospheric chemist, schemes such as spraying millions of tons of sulfate particles into the sky to reflect the sun’s rays and cool the planet seemed perilous. Not only might the strategies disrupt the atmosphere in unexpected ways, but they might also dramatically alter the weather and harm the lives of Earth’s inhabitants.

Listening for illegal logging chainsaws using TensorFlow

Our team has built the world’s first scalable, real-time detection and alert system for logging and environmental conservation in the rainforest. Building hardware that will survive in the rainforest is challenging, but we’re using what’s already there: the trees. We’ve hidden modified smartphones powered with solar panels—called “Guardian” devices—in trees in threatened areas, and continuously monitor the sounds of the forest, sending all audio up to our cloud-based servers over the standard, local cell-phone network.