Mass Balances of the Antarctic and Greenland Ice Sheets Monitored from Space

Abstract

Satellite data have revealed that the Greenland and Antarctic Ice Sheets are changing rapidly due to warming air and ocean temperatures. Crucially, Earth Observations can now be used to measure ice sheet mass balance at the continental scale, which can help reduce uncertainties in the ice sheets’ past, present, and future contributions to global mean sea level. The launch of satellite missions dedicated to the polar regions led to great progress towards a better assessment of the state of the ice sheets, which, in combination with ice sheet models, have furthered our understanding of the physical processes leading to changes in the ice sheets' properties. There is now a three-decade-long satellite record of Antarctica and Greenland mass changes, and new satellite missions are planned to both continue this record and further develop our observational capabilities, which is critical as the ice sheets remain the most uncertain component of future sea-level rise. In this paper, we review the mechanisms leading to ice sheets' mass changes and describe the state of the art of the satellite techniques used to monitor Greenland’s and Antarctica’s mass balance, providing an overview of the contributions of Earth Observations to our knowledge of these vast and remote regions.

Advances in monitoring glaciological processes in Kalallit Nunaat (Greenland) over the past decades

“…CryoSat, IceSat), satellite gravimetry (GRACE) or the input-output method [180][181][182]. Mass change on regional and ice-sheet wide scales can be quantified directly from gravimetry data, whereas with altimetry data it is necessary to make assumptions about ice/firn/snow density for the volume to mass conversion [181,183]. The input-output method on the other hand requires the estimation of SMB from RCMs, the measurement of ice discharge by determining ice flow and ice thickness at the grounding line [181,183].…”

“…Mass change on regional and ice-sheet wide scales can be quantified directly from gravimetry data, whereas with altimetry data it is necessary to make assumptions about ice/firn/snow density for the volume to mass conversion [181,183]. The input-output method on the other hand requires the estimation of SMB from RCMs, the measurement of ice discharge by determining ice flow and ice thickness at the grounding line [181,183]. Basal mass balance has only recently been included in mass balance estimates as it remains difficult to accurately quantify [183,184].…”

“…The input-output method on the other hand requires the estimation of SMB from RCMs, the measurement of ice discharge by determining ice flow and ice thickness at the grounding line [181,183]. Basal mass balance has only recently been included in mass balance estimates as it remains difficult to accurately quantify [183,184]. A comparison of outputs of the above methods has shown that they are generally in good accordance with each other, however discrepancies remain based on the respective strengths and weaknesses of each method [162].…”

Calculating exposure to extreme sea level risk will require high resolution ice sheet models

“…Quantifying the contribution of the Antarctic Ice Sheet (AIS) to global sea level rise over the coming centuries is crucial for policy makers and wider stakeholders due to the huge quantity of ice it contains [1] and the rapid acceleration of ice loss over the last few decades [e.g. 2,3]. In particular, the West Antarctic Ice Sheet (WAIS) alone contains enough ice to raise mean global sea level by up to 4 metres and it is the largest contributor of sea level rise from Antarctica, adding 6.5 mm to mean global sea level between 1992 and 2021 [3].…”

“…2,3]. In particular, the West Antarctic Ice Sheet (WAIS) alone contains enough ice to raise mean global sea level by up to 4 metres and it is the largest contributor of sea level rise from Antarctica, adding 6.5 mm to mean global sea level between 1992 and 2021 [3]. The biggest changes are found in the Amundsen Sea sector of WAIS, which contains two of the most rapidly thinning ice streams, Pine Island Glacier (PIG) and Thwaites Glacier (TG) [4].…”