Heat-wave-like conditions slow photosynthesis in young coast redwood needles

Science News reports that researchers tested needles from young coast redwoods in the lab at temperatures resembling recent heat waves. Photosynthesis rates roughly halved as temperatures rose from 30°C to 40°C, even with the samples submerged in water. Field measurements found needles up to 10°C hotter than the surrounding air. Researchers say drought combined with heat could make the slowdown more intense, but the threshold for irreversible damage remains unknown.