Future tropospheric ozone simulated with a climate-chemistry-biosphere model

A climate-chemistry model and a biogenic emission model are used to investigate the relative impact of anthropogenic and biogenic emissions of ozone precursors and global warming on the evolution of ozone in 2100. A warmer and wetter climate leads to enhanced ozone photochemical destruction in the lower troposphere, a more intense Brewer-Dobson circulation in the stratosphere and a lightning NO_x emission increased from 5 to 7.5 Tg(N)/yr. Over Europe and the eastern US climate change locally causes surface ozone to increase because of enhanced PAN thermal decomposition and more stagnant meteorological conditions. The global and annual mean OH concentration remains quite stable and the methane lifetime is unchanged in the future. Increased biogenic emissions contribute by 30-50% to surface ozone summer formation in northern continental regions. The feedback of climate change and of biogenic emissions increases the 2000 to 2100 tropospheric ozone radiative forcing by 12%, up to a global mean value of 0.58 Wm^-2.