Reacción a "Antarctica loses 12,800 km² of coastline over 30 years"

This comprehensive study, conducted from 1992 to the present, regards the boundary between continental ice and the ocean —the Grounding Line (GL)— as a sensitive indicator of the stability and mass balance of Antarctic glaciers. By integrating satellite data —specifically differential synthetic aperture radar interferometry (DInSAR — from a range of sources, the authors have been able to produce a map of GL variations over the past three decades. The results show that most (77%) of the coastline has not experienced any GL migration. However, certain sectors are highly vulnerable to the loss of large expanses of ice. These areas are located in West Antarctica, the Antarctic Peninsula and parts of East Antarctica, where the total loss of continental ice is estimated at 12,820 km².

In the study, and taking into account the effects of multiple tidal cycles, the transition between continental ice and floating ice is considered more appropriately represented as an interface or transition zone —the Ice Grounding Zone (IGZ)— which encompasses the GL. The size of the IGZ is related to ice melt, which is lower where the IGZ is narrower. Glacier retreat may be associated either with further development of the ice shelf or, conversely, with its regression. The authors emphasise the complexity of the interacting factors involved in this relationship. One of the most significant is the intrusion of warm waters from the Circumpolar Deep Water (CDW) mass, which leads to more rapid ice melt within the IGZ. This oceanic influence on glacier retreat is strongly conditioned by the morphology and bathymetry of the continental shelf. However, in parts of East Antarctica, glacier retreat appears to be linked to other, as yet unidentified factors rather than to CDW.

The authors conclude that, in light of their findings, inferring GL positions and their changes from altimetric data is not as robust as previously thought. Moreover, GL migration and the mass balance of the ice sheet are closely interrelated, with sectors showing GL retreat also exhibiting a deficit in glacial mass.

The observations and conclusions drawn from this continent-wide study provide an important benchmark for the development of future models of ice-sheet formation and loss based on the IGZ, and more broadly for modelling the evolution of Antarctic glacier masses.