Quantifying the ozone and ultraviolet benefits already achieved by the Montreal Protocol

• Published in: Nature Communications
• Main Authors: Chipperfield, MP, Dhomse, SS, Feng, W, McKenzie, RL, Velders, GJM, Pyle, JA
• Format: Article in Journal/Newspaper
• Language: English
• Published: Nature Publishing Group 2015
• Subjects: Arctic; Antarctic; The Antarctic; Antarc*
• Online Access: https://eprints.whiterose.ac.uk/86454/; https://eprints.whiterose.ac.uk/86454/7/ncomms8233.pdf; https://doi.org/10.1038/ncomms8233

Chlorine- and bromine-containing ozone-depleting substances (ODSs) are controlled by the 1987 Montreal Protocol. In consequence, atmospheric equivalent chlorine peaked in 1993 and has been declining slowly since then. Consistent with this, models project a gradual increase in stratospheric ozone with the Antarctic ozone hole expected to disappear by ∼2050. However, we show that by 2013 the Montreal Protocol had already achieved significant benefits for the ozone layer. Using a 3D atmospheric chemistry transport model, we demonstrate that much larger ozone depletion than observed has been avoided by the protocol, with beneficial impacts on surface ultraviolet. A deep Arctic ozone hole, with column values <120 DU, would have occurred given meteorological conditions in 2011. The Antarctic ozone hole would have grown in size by 40% by 2013, with enhanced loss at subpolar latitudes. The decline over northern hemisphere middle latitudes would have continued, more than doubling to ∼15% by 2013.