Observing the disintegration of the Thwaites B30 Iceberg with CryoSat-2 and Satellite Imagery

Icebergs account for half of all ice loss from Antarctica and, once released, present a hazard to maritime operations. Their melting leads to a redistribution of cold fresh water around the Southern Ocean which, in turn, influences water circulation, promotes sea ice formation, and fosters primary production.

To quantify the total volume loss of icebergs both changes in area and in thickness have to be considered. In this study, we combine CryoSat-2 satellite altimetry with MODIS and Sentinel-1 satellite imagery to track changes in the area, freeboard, thickness, and volume of the B30 tabular iceberg between 2012 and 2018. Since it calved the iceberg’s area has decreased from 1500 +/- 60 to 426 +/- 27 km^2 , its mean freeboard has fallen from 49.0 +/- 4.6 to 38.8 +/- 2.2 m, and its mean thickness has reduced from 315 ± 36 to 198 ± 14 m. The combined loss amounts to an 80 +/- 16 % reduction in volume, two thirds (69 ± 14 %) of which is due to fragmentation and the remainder (31 ± 11 %) is due to basal melting.

The quantification of fresh water released from icebergs will help both the risk assessment of maritime operators and the improvement of ocean models by including a realistic – spatially and temporally variable - fresh water flux from iceberg melting in the Southern Ocean. Icebergs can also be used to study the reaction of glacial ice to warming environmental conditions, which they experience when they drift. These conditions might also become present at the ice shelf front in the future and therefore iceberg studies can inform the prediction of ice shelf response to warmer conditions.