The latest assessment of Greenland and Antarctic ice sheets mass balance estimates losses have accelerated since the 1990s and account for a significant increase in the global mean sea level.
The results are based on the latest update from the Ice Sheet Mass Balance Inter-comparison Exercise (IMBIE) which compares and combines 50 independent estimates of ice sheet mass balance derived from satellite observations of temporal changes in ice sheet flow, in ice sheet volume, and in Earth's gravity field.
The study estimates that the ice sheets contributed 21.0±1.9 mm to global mean sea level between 1992-2020, with the rate of mass loss rising from 105 Gt yr−1 between 1992 and 1996 to 372 Gt yr−1 between 2016 and 2020.
Melting of the ice sheets has contributed to a 21 mm rise in global sea level since 1992, with losses from Greenland responsible for almost two-thirds (13.5 mm) of this rise. If the ice sheets continue to lose mass at this pace, the IPCC predicts that they will contribute between 148 and 272 mm to global mean sea level by the end of the century.
In Greenland, the rate of mass loss is 169±9 Gt yr−1 between 1992 and 2020, but there are large inter-annual variations in mass balance, with mass loss ranging from 86 Gt yr−1 in 2017 to 444 Gt yr−1in 2019 due to large variability in surface mass balance.
In Antarctica, ice losses continue to be dominated by mass loss from West Antarctica (82±9 Gt yr−1) and, to a lesser extent, from the Antarctic Peninsula (13±5 Gt yr−1). East Antarctica remains close to a state of balance, with a small gain of 3±15 Gt yr−1, but is the most uncertain component of Antarctica's mass balance.
The IMBIE project has taken advantage of several satellite missions including ESA’s CryoSat and the European Union’s Copernicus Sentinel-1. SrUsing these data, the study team are now able to chart polar ice sheet losses every year.
The assessment will now be updated annually to make sure that the scientific community has the very latest estimates of polar ice losses.
This work is an outcome of the Ice Sheet Mass Balance Inter-comparison Exercise (IMBIE) supported by the ESA EOEP-5 “EO Science for Society”, the ESA “Climate Change Initiative”, and the NASA Cryosphere Program.
The dataset is publicly available at https://doi.org/10.5285/77B64C55-7166-4A06-9DEF-2E400398E452.