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Grassland plants show surprising appetite for carbon dioxide

Results from a long-running field experiment suggest that a major group of plants could thrive as the level of carbon dioxide in the atmosphere increases. 

Grasslands in warm and dry climates could grow faster as carbon dioxide levels rise, according to data from a long-term ecological field experiment in Minnesota. The finding, which runs counter to long-established ideas about how plants will respond to the greenhouse gas, suggests that grasslands could provide a buffer against climate change.

The research, published on 19 April in Science, "Plant responses to CO2 are a question of time" delves into a longstanding question about how Earth’s two major groups of plants will respond to the growing level of CO2 in the atmosphere. The biggest group, known as C3 plants, comprise 97% of all plant species. These species make energy through photosynthesis, using sunlight to synthesize sugars from CO2 and water. In theory, giving these plants extra CO2 would rev up their energy production.

The other group of plants — so-called C4 species — use a two-step process to boost their internal CO2 levels before photosynthesis takes place, making energy production more efficient. For decades, scientists have thought that C4 plants would not benefit from additional CO2 in the atmosphere because they are already turbo-charged. But the Science paper suggests that the opposite might be true.