To what extent is climate change responsible for retreat of the Pine Island Glacier over the 20th century?

The relative contributions of anthropogenic climate change and internal variability in sea level rise from the Antarctic Ice Sheet are yet to be determined. This is primarily because of uncertainty arising from poorly constrained model parameters and chaotic forcing as well as a relatively short observation period. Using an established uncertainty quantification framework (known as calibrate-emulate-sample), we have quantified, for the first time, the role of anthropogenic climate change on retreat of a major Antarctic glacier. We find that anthropogenic trends in forcing, beginning in the 1960s, are only responsible for approximately 15% of the retreat of this glacier since its retreat began in the 1940s. Most of the retreat is attributable to the inertia associated with a slow retreat over the Holocene. We also find, however, that trends in forcing dominate retreat beyond the 21st century, with ice sheet retreat stabilized if anthropogenic trends plateau.