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Plant Respiration of CO2 Underestimated by up to 30%

Plant respiration is a larger source of carbon emissions than previously thought, with a study published in Nature Communications warning that the ability of the Earth’s land surface to absorb emissions due to fossil fuel combustion may reduce as the world warms.

The new findings are based on the GlobResp database, which comprises more than 10,000 measurements of carbon dioxide plant respiration from many plant species and from across the globe. Merging these data with existing computer models of global land carbon cycling revealed that plant respiration has been an underestimated source of carbon dioxide release to the atmosphere.

Study co-author Prof Matthew Turnbull of The University of Canterbury says that while people understand that plants take up carbon dioxide during photosynthesis, less well-known is that plants also release it through respiration. Changes to either of these processes in response to climate change have profound implications for how much ecosystems soak up carbon dioxide emissions from burning fossil fuels.

“We find that respiration losses of carbon dioxide by plant respiration is 30% higher than previous estimates, and is expected to increase more than expected under global warming,” Turnbull says. “This could have a major impact on the net amount of carbon dioxide that remains in the atmosphere.”

Lead author Prof Chris Huntingford of the UK Centre for Ecology & Hydrology says: “For too long, plant respiration losses of carbon dioxide to the atmosphere have been the Cinderella of ecosystem computer modelling, with carbon dioxide gains via photosynthesis stealing the attention. Here we address that, using extensive measurements of respiration to guide computer-based calculations of how carbon cycles through trees and plants.”

The study used plant respiration data from more than 100 remote sites around the world, from hot deserts in Australia to the deciduous and boreal forests of North America and Europe, the Arctic tundra in Alaska and the tropical forests of South America, Asia, Africa and northern Australia.