Editing IPCC:AR6/WGI/Chapter-9 (section)

===== 9.6.3.2.3 Antarctic Ice Sheet =====

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For the Antarctic Ice Sheet (AIS), AR5 applied a temperature-based scaling approach for SMB and a quadratic function of time, calibrated to a multi-model assessment, for dynamic contributions. The SROCC used a new assessment based on the results of five process-based studies ( [[#9.4.2.5|Section 9.4.2.5]] ). For processes in whose projections we have at least ''medium confidence'' , the ''likely range'' projections for the AIS are based on: (i) the emulated ISMIP6 ensemble; and (ii) the LARMIP-2 ensemble, augmented with AR5 parametric Antarctic SMB model. The GMSL projections are produced with both distributions and combined in a ‘p-box’ ( [[#Kriegler--2005|Kriegler and Held, 2005]] ; [[#Le%20Cozannet--2017|Le Cozannet et al., 2017]] ), which represents the upper and lower bounds of the distribution ( [[#9.4.2.5|Section 9.4.2.5]] , Box 9.3 and Table 9.3). A ''likely'' range is then identified, spanning the lower of the two 17th percentile projections and the higher of the two 83rd percentile projections, <sup>[[#footnote-000|5]]</sup> with the median taken as the mean of the medians of the two projections. Since the ISMIP6 emulator does not account for temporal correlation, the AR5 parametric AIS model is substituted for the emulator in the p-box for rates of change. As AR5 projections are modestly lower than those from the ISMIP6 emulator, this substitution modestly broadens the ''likely'' range at the low end for projections of rate and changes beyond 2100. For projections beyond 2100 (when the ISMIP6 and LARMIP-2 simulations end), the AIS simulations are extrapolated using the same two approaches as the Greenland Ice Sheet (GrIS) projections ( [[#9.4.1.4|Section 9.4.1.4]] ). The ''likely'' ranges to 2100 are consistent with SROCC (Table 9.8).

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