Trees keep our planet cool and breathable. They make the rain and sustain biodiversity. They are essential for nature and for us. And yet, we are cutting and burning them at such a rate that many forests are fast approaching tipping points beyond which they will simply shrivel and die. But there is still time, and there is still hope. If we had a trillion more trees, the damage could be undone. So should we get planting? Not so fast. Fred Pearce argues in this inspiring new book that we can have our forests back, but mass planting should be a last resort. Instead, we should mostly stand back, make room and let nature -- and those who dwell in the forests -- do the rest.