The nitrogen-fixing legume kudzu (Pueraria montana) is a widespread invasive plant in the southeastern United States with physiological traits that may lead to important impacts on ecosystems and the atmosphere. Its spread has the potential to raise ozone levels in the region by increasing nitric oxide (NO) emissions from soils as a consequence of increasing nitrogen (N) inputs and cycling in soils. We studied the effects of kudzu invasions on soils and trace N gas emissions at three sites in Madison County, Georgia in 2007 and used the results to model the effects of kudzu invasion on regional air quality. We found that rates of net N mineralization increased by up to 1,000%, and net nitrification increased by up to 500% in invaded soils in Georgia. Nitric oxide emissions from invaded soils were more than 100% higher (2.81 vs. 1.24 ng NO-N cm−2 h−1). We used the GEOS-Chem chemical transport model to evaluate the potential impact of kudzu invasion on regional atmospheric chemistry and air quality. In an extreme scenario, extensive kudzu invasion leads directly to an increase in the number of high ozone events (above 70 ppb) of up to 7 days each summer in some areas, up from 10 to 20 days in a control scenario with no kudzu invasion. These results establish a quantitative link between a biological invasion and ozone formation and suggest that in this extreme scenario, kudzu invasion can overcome some of the air quality benefits of legislative control.
Many nations responded to the corona virus disease‐2019 (COVID‐19) pandemic by restricting travel and other activities during 2020, resulting in temporarily reduced emissions of CO2, other greenhouse gases and ozone and aerosol precursors. We present the initial results from a coordinated Intercomparison, CovidMIP, of Earth system model simulations which assess the impact on climate of these emissions reductions. 12 models performed multiple initial‐condition ensembles to produce over 300 simulations spanning both initial condition and model structural uncertainty. We find model consensus on reduced aerosol amounts (particularly over southern and eastern Asia) and associated increases in surface shortwave radiation levels. However, any impact on near‐surface temperature or rainfall during 2020–2024 is extremely small and is not detectable in this initial analysis. Regional analyses on a finer scale, and closer attention to extremes (especially linked to changes in atmospheric composition and air quality) are required to test the impact of COVID‐19‐related emission reductions on near‐term climate. ; C. D. Jones, P. Nabat, R. Séférian acknowledge support from the European Union's Horizon 2020 research and innovation program under grant agreement No 641816 (CRESCENDO). R. D. Lamboll, P. M. Forster, J. Rogelj, R. B. Skeie, P. Nolan, R. Séférian acknowledge support from the European Union's Horizon 2020 research and innovation program under grant agreement No 820829 (CONSTRAIN). E. Tourigny, T. Ilyina and H. Li acknowledge support from the European Union's Horizon 2020 research and innovation program under grant agreement No 821003 (4C). C. Timmreck is supported from the Deutsche Forschungsgemeinschaft DFG (FOR2820, TI 344/2–1). MPI‐ESM simulations were performed at the German Climate Computing Center (DKRZ). We acknowledge DKRZ colleague Martin Schupfner for cmorizing and publishing the MPI‐ESM model simulations. S. T. Rumbold was funded by the National Environmental Research Council (NERC) national capability grant for the UK Earth System Modeling project, grant NE/N017951/1. M. Wu, H. Wang and K. Calvin acknowledge support by the U.S. Department of Energy (DOE), Office of Science, Office of Biological and Environmental Research, Earth and Environmental System Modeling program as part of the Energy Exascale Earth System Model (E3SM) project. The Pacific Northwest National Laboratory (PNNL) is operated for DOE by Battelle Memorial Institute under contract DE‐AC05‐76RLO1830. N. Oshima, T. Koshiro, and M. Deushi were supported by the Japan Society for the Promotion of Science (grant numbers: JP18H03363, JP18H05292, JP19K12312, and JP20K04070), the Environment Research and Technology Development Fund (JPMEERF20202003 and JPMEERF20205001) of the Environmental Restoration and Conservation Agency of Japan, the Integrated Research Program for Advancing Climate Models (TOUGOU) grant number JPMXD0717935561 from the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan, and the Arctic Challenge for Sustainability II (ArCS II), Program Grant Number JPMXD1420318865. S.F. acknowledges funding for the Hans‐Ertel‐Center for Weather Research "Climate Monitoring and Diagnostic" (ID: BMVI/DWD 4818DWDP5A, https://www.herz.uni-bonn.de) and the Collaborative Research Center "Earth, evolution at the dry limit" (ID: DFG 68236062, https://sfb1211.uni-koeln.de). D. Olivié and J. Tjiputra acknowledge the Research Council of Norway funded projects INES (270061) and KeyClim (295046). Simulations of MIROC‐ES2L are supported by the TOUGOU project "Integrated Research Program for Advancing Climate Models" (grant number: JPMXD0717935715) of the Ministry of Education, Culture, Sports, Science, and Technology of Japan (MEXT). MIROC‐team acknowledges JAMSTEC for use of the Earth Simulator supercomputer. Simulations of UKESM1 and analysis of data were supported by the Joint UK BEIS/Defra Met Office Hadley Center Climate Program (GA01101). We gratefully acknowledge help from Martine Michou for setting up the model configuration used in this work and for processing of data from CNRM‐ESM2‐1. P. Nabat, C. Cassout and R. Séférian, thank the support of the team in charge of the CNRM‐CM climate model. Supercomputing time was provided by the Meteo‐France/DSI supercomputing center. Simulations of GISS‐E2‐1‐G were supported by NASA's Rapid Response and Novel Research in Earth Science program. Resources supporting this work were provided by the NASA High‐End Computing (HEC) Program through the NASA Center for Climate Simulation (NCCS) at Goddard Space Flight Center. We gratefully acknowledge Susanne Bauer, Gregory Faluvegi, Kenneth Lo, and Reto Ruedy for their assistance in preparing simulations and processing output. Y. Yang acknowledges the National Key Research and Development Program of China (Grant 2019YFA0606800 and 2020YFA0607803). S. Yang acknowledges support from the Danish National Center for Climate Research (Nationalt Center for Klimaforskning, NCKF). ; Peer Reviewed ; "Article signat per 49 autors/es: Chris D. Jones, Jonathan E. Hickman, Steven T. Rumbold, Jeremy Walton, Robin D. Lamboll , Ragnhild B. Skeie, Stephanie Fiedler, Piers M. Forster, Joeri Rogelj, Manabu Abe, Michael Botzet, Katherine Calvin, Christophe Cassou, Jason N.S. Cole, Paolo Davini, Makoto Deushi, Martin Dix, John C. Fyfe, Nathan P. Gillett, Tatiana Ilyina, Michio Kawamiya, Maxwell Kelley, Slava Kharin, Tsuyoshi Koshiro, Hongmei Li, Chloe Mackallah, Wolfgang A. Müller, Pierre Nabat, Twan van Noije, Paul Nolan, Rumi Ohgaito, Dirk Olivié, Naga Oshima, Jose Parodi, Thomas J. Reerink, Lili Ren, Anastasia Romanou, Roland Séférian, Yongming Tang, Claudia Timmreck , Jerry Tjiputra, Etienne Tourigny , Kostas Tsigaridis, Hailong Wang, Mingxuan Wu, Klaus Wyse,r Shuting Yang, Yang Yang, Tilo Ziehn" ; Postprint (published version)
