An analysis of temperature trends conducive to chemical loss of ozone in the Arctic stratosphere: are the coldest Arctic winters getting colder?

Abstract:

Chemical loss of ozone in the Arctic stratosphere is governed by the abundance of halogens as well as temperature, with greater loss occurring during winters with cold conditions favorable to the formation of polar stratospheric clouds (PSCs). In this presentation, we examine the temporal evolution of the PSC formation potential (PFP) within the Arctic stratosphere, based upon using data from four international meteorological centers. We show that data from all four centers exhibit a positive, statistically significant rise in the local maxima of PFP (PFP^LM) over the past four decades. Next, we show that output from numerous General Circulation Models (GCMs) archived for the Coupled Model Intercomparison Project Phase 6 (CMIP6) project also exhibit positive trends in PFP^LM over 1950 to 2100, with the largest values occurring towards the end of this century. We examine GCM output from the various Shared Socioeconomic Pathway (SSP) scenarios from the CMIP6 GCMs to suggest that stratospheric cooling caused by human release of greenhouse gases (GHGs) likely drives the rise in PFP^LM within these models. As a result, we suggest that extremely cold conditions in the Arctic stratosphere during winter of 2019-2020, which led to extensive regions of low total column ozone, may have been caused in part by elevated levels of anthropogenic GHGs.