Leaves in tropical forests across South America to Southeast Asia are reaching temperatures so high that they could cease to perform photosynthesis, warns a new study.
The research shows that leaves start to lose their ability to photosynthesize when their temperature reaches around 46.7°C (116°F). This is a critical issue because leaves can become significantly hotter than the air temperature. The study combined temperature data from thermal satellite sensors on the International Space Station and ground-level observations from leaf-warming experiments.
While currently only 0.01% of leaves exceed the critical temperature, this percentage could rise due to global warming. Tropical forests cover about 12% of the Earth’s surface and harbor over half of the world’s species. They play a vital role in carbon absorption and climate regulation. The report suggests that these forests can handle around 4°C (7.2°F) of additional warming before reaching a tipping point where photosynthesis breaks down. If warming surpasses this level, up to 1.4% of leaves could exceed critical temperatures, potentially causing widespread leaf loss and tree mortality.
Although the numbers seem small, the implications are substantial, as photosynthesis is crucial for life and the climate system. The research highlights the risks posed by global warming to this essential process and the resilience of tropical forests. While some experts note the complexity of forest dynamics and uncertainties in the model, the study underscores the importance of monitoring these changes before they become widespread.