Proceedings from the National Academy of Sciences, 8 March 2022
Surface meltwater heats up as it passes down through cracks and fractures in the Greenland Ice Sheet – which means that some areas at the base of the ice sheet are melting up to 100 times faster than previously estimated. Falling meltwater carries an immense amount of kinetic energy. That energy causes water to warm as it pools beneath the ice sheet, which in turn increases the rate of melting at the bottom of the ice sheet (otherwise known as “basal melting”). The warm water trapped between the ground and the ice sheet also acts as a lubricant, allowing the ice sheet to slide more quickly toward the ocean. Models predicting global sea level rise do not include this effect of warm basal meltwater accelerating melting at the base of ice sheets, which suggest they may underestimate the rate of ice loss and contribution to rising sea levels. The Greenland Ice Sheet currently is the single largest contributor to global sea-level rise, and this ice loss mechanism would increase its overall melt rate by 8%. These findings support theoretical work done in a previous study published by Mankoff et al. in 2017; and if surface temperatures continue to rise, the generation of more meltwater on the Greenland Ice Sheet will continue to intensify this process of its basal melt, and accelerating its contribution to global sea-level rise. Developing a better understanding of this ice-loss mechanism is critical to anticipating the effects of future warming on the Greenland Ice Sheet, as well as potentially the much larger ice mass of Antarctica.