Tropical forests may soon emit more carbon dioxide than they absorb.
Rising temperatures over the next few decades could cause Earth’s terrestrial ecosystems, including tropical forests, to turn from pure carbon sinks that remove carbon from the atmosphere to carbon sources that release it. How well an ecosystem can act as a carbon sink depends on temperature. This is because living things have an optimal temperature range at which they can function normally.
Katharyn Duffy of Northern Arizona University and her colleagues built a temperature response curve for plants, a model that predicts the response to temperature changes for all terrestrial vegetation on Earth. They built the model using data from FLUXNET, a global network of meteorological sensors that track carbon exchange in ecosystems.
In plants, an increase in temperature can lead to a decrease in the rate of photosynthesis. Given that plants also breathe, releasing carbon dioxide, ecosystems may gradually change from net stores of greenhouse gases to net sources of emissions. The team’s results show that the tipping point, when these terrestrial systems become carbon sources, could be reached in as little as 20 to 30 years.