An Estimation of the Future Development of the Ozone Layer by a Coupled Chemistry-Climate Model

The future development of stratospheric ozone layer is estimated using an atmospheric general circulation model that includes a fully interactive chemistry module (coupled chemistry-climate model). Four transient integrations of 65 years (1986 to 2050) have been performed for this estimation. Each of four integrations considered the projected future variations of ozone-depleting substances (ODSs), CH₄ and N₂O mixing ratio at the earth's surface. In addition to that, one integration considered the projected increase of CO₂ concentration in the atmosphere and the corresponding variation of sea surface temperature (SST), but others did consider only either forcing or did not consider both. The resulted long-term trend of ozone in the Antarctic region is not greatly influenced by carbon dioxide increase and SST variation but seems to be mainly regulated by simulated chlorine-loading in the lower stratosphere. The minimum of springtime Antarctic column ozone (~ 140 Dobson Unit(DU)) takes place in around 2000, and the column ozone recovers above 220 DU after 2040. In the Arctic region, large ozone depletion such as that causing the Antarctic ozone-hole (e.g. less than 200 DU) does not occur in any of four integrations.