Nature Communications, 9 May 2022
More than 40% of the Petermann ice shelf has disappeared over the past decade. Rising global temperatures increase the flow of warm water against the bottom of floating ice shelves, accelerating melt and rendering them more vulnerable to collapse. Ice shelves serve as gatekeepers; they restrain the flow of larger glaciers and ice sheets into the ocean. Petermann is one of Greenland’s last remaining ice shelves. Its loss would destabilize large regions of the Greenland Ice Sheet, resulting in sustained ice sheet loss and accelerated sea level rise on a global scale. Rapidly curbing emissions to keep within the 1.5°C limit of the Paris Agreement could however prevent this, by allowing thicker layers of sea ice to accumulate and re-stabilize the ice shelf. Under such low emissions pathways, without substantial overshoot of 1.5°C, the Petermann ice shelf could potentially regrow. Otherwise, it is committed to irreversible collapse. Limiting global emissions provides the only viable escape route from committing to decades and centuries of increased sea level rise from Greenland. These findings underscore how exceedingly difficult it is for ice shelves and glaciers to withstand and recover should current extremes of climate warming continue.