Every spring, chlorophyll returns to center stage. Tiny green molecules fill leaves and needles, capturing sunlight and powering photosynthesis—the remarkable process that feeds nearly all life on Earth. Without chlorophyll, there would be no forests, no abundant oxygen, and no thriving ecosystems. But chlorophyll may be doing something else that is less obvious. The living green it creates appears to benefit us, too. Scientists have long known that forests improve our physic