Environmental science: Agree on biodiversity metrics to track from space.

The authors reflect on the need for space agencies and ecologists to develop a global biodiversity monitoring strategy. They state that satellite remote sensing is essential for long-term global coverage and could quickly reveal where biodiversity losses can be reversed on a wide range of scales. They talk about the measurement of forest degradation from space and arguments on what constitutes degradation or the definition of forests, and consider how to improve interdisciplinary cooperation.