Elevated CO2 negates O3 impacts on terrestrial carbon and nitrogen cycles

Authors: XIA, LONGLONG - Karlsruhe Institute Of Technology; LAM, SHU KEE - University Of Melbourne; KIESE, RALF - Karlsruhe Institute Of Technology; CHEN, DELI - University Of Melbourne; LUO, YIQI - Northern Arizona University; VAN GROENIGEN, KEES JAN - University Of Exeter; Ainsworth, Elizabeth - Lisa; CHEN, JI - Aarhus University; LIU, SHUWEI - Nanjing Agricultural University; MA, LEI - Karlsruhe Institute Of Technology; ZHU, YUHAO - Karlsruhe Institute Of Technology; BUTTERBACH-BAHL, KLAUS - Karlsruhe Institute Of Technology

Submitted to: One Earth
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/17/2021
Publication Date: 12/17/2021
Citation: Xia, L., Lam, S., Kiese, R., Chen, D., Luo, Y., van Groenigen, K., Ainsworth, E.A., Chen, J., Liu, S., Ma, L., Zhu, Y., Butterbach-Bahl, K. 2021. Elevated CO2 negates O3 impacts on terrestrial carbon and nitrogen cycles. One Earth. 4(12):1752-1763. https://doi.org/10.1016/j.oneear.2021.11.009.
DOI: https://doi.org/10.1016/j.oneear.2021.11.009

Interpretive Summary: Concentrations of carbon dioxide and ozone have dramatically risen in the lower atmosphere since the industrial revolution. The atmospheric gases have opposing effects of plants, with ozone reducing photosynthesis and carbon dioxide stimulating photosynthesis. This meta-anlysis investigated the combined effects of rising atmospheric carbon dioxide and ozone on terrestrial carbon and nitrogen pools and fluxes using results of 810 studies and over 9000 observations. While elevated ozone decreased plant productivity along with plant and soil carbon and nitrogen pools, elevated carbon dioxide offset those changes on ecosystem carbon and nitrogen cycling. This study highlights the importance of exploring the interactive effects of multiple global change drivers, to better understand how changes in global atmospheric composition will affect C and N cycles of global terrestrial ecosystems.

Technical Abstract: Increasing tropospheric concentrations of ozone (e[O3]) and carbon dioxide (e[CO2]) profoundly perturb terrestrial ecosystem functions through carbon and nitrogen cycles, affecting beneficial services such as their capacity to combat climate change and provide food. However, the interactive effects of e[O3] and e[CO2] on these functions and services remain unclear. Here, we synthesize the results of 810 studies (9,109 observations), spanning boreal to tropical regions around the world, and show that e[O3] significantly decreases global net primary productivity and food production as well as the capacity of ecosystems to store carbon and nitrogen, which are stimulated by e[CO2]. More importantly, simultaneous increases in [CO2] and [O3] negate or even overcompensate the negative effects of e[O3] on ecosystem functions and carbon and nitrogen cycles. Therefore, the negative effects of e[O3] on terrestrial ecosystems would be overestimated if e[CO2] impacts are not considered, stressing the need for evaluating terrestrial carbon and nitrogen feedbacks to concurrent changes in global atmospheric composition.