Preprints
https://doi.org/10.5194/acp-2020-1297
https://doi.org/10.5194/acp-2020-1297

  08 Jan 2021

08 Jan 2021

Review status: a revised version of this preprint was accepted for the journal ACP and is expected to appear here in due course.

An Arctic Ozone Hole in 2020 If Not For the Montreal Protocol

Catherine Wilka1, Susan Solomon1, Doug Kinnison2, and David Tarasick3 Catherine Wilka et al.
  • 1Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
  • 2Atmospheric Chemistry Division, National Center for Atmospheric Research, Boulder, CO, USA
  • 3Environment and Climate Change Canada, Toronto, ON, Canada

Abstract. Without the Montreal Protocol the already extreme Arctic ozone losses in boreal spring of 2020 would be expected to have produced an Antarctic-like ozone hole, with an area of total ozone below 220 DU of about 20 million km2. Record observed local lows of 0.1 ppmv at some altitudes in the lower stratosphere would have reached 0.01, again similar to the Antarctic. This provides an opportunity to test parameterizations of polar stratospheric cloud impacts on denitrification, and thereby to improve stratospheric models. Spring ozone depletion would have begun earlier and lasted longer without the Montreal Protocol, and by 2020 the year-round ozone depletion would have begun to dramatically diverge from the observed case. This study reinforces that the historically extreme 2020 Arctic ozone depletion is not cause for concern over the Montreal Protocol's effectiveness, but rather demonstrates that the Montreal Protocol indeed merits celebration for avoiding an Arctic ozone hole.

Catherine Wilka et al.

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2020-1297', Anonymous Referee #1, 08 Feb 2021
  • RC2: 'Comment on acp-2020-1297', Anonymous Referee #2, 12 Mar 2021
  • AC1: 'Comment on acp-2020-1297', Catherine Wilka, 23 Apr 2021

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2020-1297', Anonymous Referee #1, 08 Feb 2021
  • RC2: 'Comment on acp-2020-1297', Anonymous Referee #2, 12 Mar 2021
  • AC1: 'Comment on acp-2020-1297', Catherine Wilka, 23 Apr 2021

Catherine Wilka et al.

Catherine Wilka et al.

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Short summary
We use satellite and balloon measurements to evaluate modeled ozone loss seen in the unusually cold Arctic of 2020 in the real world, and compare to simulations of a World Avoided. We show that extensive denitrification in 2020 provides an important test case for stratospheric model process representations. If the Montreal Protocol had not banned ozone depleting substances, we show that an Arctic Ozone hole emerges for the first time in Spring 2020 that is comparable to those in the Antarctic.
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