资源环境科技发展态势分析平台

We evaluate total-column ozone trends using a piecewise linear regression approach and maximizing usage of five gridded total-column ozone datasets. The new approach yields more consistent estimates of observed ozone loss during 1979-2000, when halocarbon concentrations were increasing, and consequently, using CMIP6 simulations, an increased Effective Radiative Forcing estimate of ozone-depleting substances with a substantially reduced uncertainty range versus an earlier evaluation. At more than 84% confidence it is now larger than zero and compares more favorably with three previous evaluations. We furthermore find significant positive post-1997 global- and Southern-Hemisphere mean trends, respectively, in these five datasets. For the extrapolar region (S-N) and for the Northern Hemisphere, the assessment whether there is a positive trend is inconclusive and depends on which observational dataset is included in the calculation.