Abstract
Abstract. The Antarctic surface mass balance (SMB) has global climatic impacts through its effects on global sea-level rise. The forced increase in Antarctic SMB over the second half of the 20th century was argued to stem from multiple forcing agents, including ozone and ozone-depleting substances (ODSs). Here we use ensembles of fixed-forcing model simulations to quantify and contrast the contributions of stratospheric ozone, tropospheric ozone and ODSs to increases in the Antarctic SMB. We show that ODSs and stratospheric ozone make comparable contributions and together account for 44 % of the increase in the annual mean Antarctic SMB over the second half of the 20th century. In contrast, tropospheric ozone has an insignificant impact on the SMB increase. A large portion of the annual mean SMB increase occurs during austral summer, when stratospheric ozone is found to account for 63 % of the increase. Furthermore, we demonstrate that stratospheric ozone increases the SMB by enhancing the meridional mean and eddy flows towards the continent, thus converging more water vapor over the Antarctic.
Highlights
Being the largest freshwater reservoir on Earth, the Antarctic ice sheet is potentially the largest contributor to future global sea-level rise (IPCC, 2013; Fretwell et al, 2013)
Validating the results of Previdi and Polvani (2017) with a different model, we find that the increased emissions of ozone-depleting substances (ODSs) account for 20 % (38.4 Gt yr−1) of the annual mean surface mass balance (SMB) increase; stratospheric ozone depletion accounts for 24.2 % (46.4 Gt yr−1) of the annual mean SMB increase
Two recent studies have suggested that increasing ozonedepleting substances (ODSs) and the accompanying loss of stratospheric ozone have caused a substantial fraction of the increase in Antarctic surface mass balance over the second half of the 20th century
Summary
Being the largest freshwater reservoir on Earth, the Antarctic ice sheet is potentially the largest contributor to future global sea-level rise (IPCC, 2013; Fretwell et al, 2013). By 2100, the projected loss of Antarctic land–ice due to dynamical processes (i.e., the flow of the ice sheet) will increase sea level by up to 185 mm (IPCC, 2013; Golledge, 2020). Only the dynamical mass loss due to the acceleration of outlet glaciers has been documented (Rignot et al, 2004; Shepherd et al, 2012; Velicogna et al, 2014; Wouters et al, 2015; Rignot et al, 2019); the Antarctic SMB has exhibited insignificant trends (Monaghan et al, 2006a,b; Lenaerts et al, 2012) and has yet to mitigate sea-level rise. Two recent studies have argued for the importance of increases in the emissions of ozone-depleting substances (ODSs)
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