The sensitivity of stratospheric ozone changes through the 21st century to N2O and CH4
1National Institute of Water and Atmospheric Research, Christchurch, New Zealand
2Department of Chemistry, University of Canterbury, New Zealand
3Bodeker Scientific, Alexandra, New Zealand
4Physical-Meteorological Observatory Davos/World Radiation Center, Davos, Switzerland
5Institute for Atmospheric and Climate Science ETH, Zurich, Switzerland
Abstract. Through the 21st century, anthropogenic emissions of the greenhouse gases N2O and CH4 are projected to increase, thus increasing their atmospheric concentrations. Consequently, reactive nitrogen species produced from N2O and reactive hydrogen species produced from CH4 are expected to play an increasingly important role in determining stratospheric ozone concentrations. Eight chemistry-climate model simulations were performed to assess the sensitivity of stratospheric ozone to different emissions scenarios for N2O and CH4. Increases in reactive nitrogen-mediated ozone loss resulting from increasing N2O concentrations lead to a decrease in global-mean total column ozone. Increasing CH4 concentrations increase the rate of reactive hydrogen-mediated ozone loss in the upper stratosphere. Overall however, increasing CH4 concentrations lead to an increase in global-mean total column ozone. Stratospheric column ozone over the 21st century exhibits a near-linear response to changes in N2O and CH4 surface concentrations, which provides a simple parameterization for the ozone response to changes in these gases.