Current policies and historical trends constrain future mass loss from the Greenland Ice Sheet

Greenland ice loss is projected to be a significant contributor to global sea-level rise. However, this contribution is estimated to range from 11–174 cm by 2300 (Fox-Kemper et al. 2021), owing to unknown warming trajectories and unconstrained ice-sheet simulations. Here, we show that if all submitted and announced emissions-reduction targets over the next few decades are met (the “Optimistic” pathway), Greenland's sea-level contribution is projected to be 16–33 cm (17–83% likely range) by 2300. This contribution would approximately double to 32–59 cm if existing climate actions based on current policies continue (the “Current policy actions” pathway). Our results are based on a statistical emulator that is trained on a large ensemble of Greenland ice-sheet simulations, then forced with warming scenarios guided by global climate policy actions, and finally constrained via a history-calibration method. On a millennial timescale (i.e., by the year 3000), our calibrated emulator indicates that if global temperature continues to rise until 2300 instead of peaking in 2050, Greenland’s contribution to sea-level rise will increase by an additional 135%.