COVER: Humanity’s actions have committed us to a warming climate and limited our options for mitigation. Although there is no turning back, some paths are still open to avoid catastrophic climate change and reduce its impacts. We must act now to drastically reduce greenhouse gas emissions and change our approaches to growing food, consuming products, and managing ecosystems to avoid a dire future. See page 1392.

Illustration: Myriam Wares

Our climate future

Time to act

CAROLINE ASH

The matter of a clean energy future

JAMES MORTON TURNER