Plants Release up to 30% More CO2 than Previously Thought

New research Finds Plants Release up to 30% More CO2 than Previously Thought

New research co-authored by a University of Canterbury scientist and academics from around the world, suggests that plant respiration is a larger source of carbon emissions than previously thought, and warns that as the world warms, this may reduce the ability of Earth’s land surface to absorb emissions due to fossil fuel burning.

The new findings, published in the journal Nature Communications this month and co-authored by Professor in Plant Physiological Ecology Matthew Turnbull, Head ofUC’s School of Biological Sciences, are based on the comprehensive GlobResp database, which comprises over 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 shows that plant respiration has been a potentially underestimated source of carbon dioxide release to the atmosphere. The study shows that across the world, carbon release by plant respiration may be around 30% higher than previously predicted. As mean global temperature increases, the researchers also estimate that respiration will increase significantly. Such increases may lower the future ability of global vegetation to offset carbon dioxide emissions caused by burning of fossil fuels.

People understand that plants take up carbon dioxide in photosynthesis, but less well known is that they also release it by respiration, Professor Turnbull says.

“In this international collaboration, including measurements in New Zealand forests, 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. This could have a major impact on the net amount of carbon dioxide that remains in the atmosphere, which we know is a major driver of the greenhouse effect.”

Plants both capture carbon dioxide and then release it by 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.

Lead author, Professor Chris Huntingford of the UK Centre for Ecology & Hydrology says, “For too long, plant respiration loses 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.”

This study has been the result of an especially close collaboration over several years between field scientists, those who build computer models of how the global land surface operates, and researchers assessing expected future climate change.

The study uses plant respiration data from over 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.

Paper details: Huntingford, C., Atkin, O.K., Martinez-de la Torre, A., Mercado, L.M., Heskel, M.A., Harper, A.B., Bloomfield, K.J., O’Sullivan, O.S., Reich, P.B., Wythers, K.R., Butler, E.E., Chen, M., Griffin, K.L., Meir, P., Tjoelker, M.G., Turnbull, M.H., Sitch, S., Wiltshire, A. and Malhi, Y. (2017) “Implications of improved representations of plant respiration in a changing climate.” Nature Communications. DOI: http://doi.org/10.1038/s41467-017-01774-z

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