What's in the news?

An article regarding potentially ground-breaking changes in the understanding of how the East Antarctic ice sheet moves and expands appeared on the BBC News website last week (3^rd March). The news item draws from a paper by Robin et al. (2011) published in Science magazine a few weeks earlier.

The data collected by airborne radar showed the layering of ice, through the sheet to the bedrock. What this revealed was that liquid water – which had been known to exist under the ice sheet – was freezing in great amounts to the bottom of the East Antarctic ice sheet. Whilst this process was not fully understood before now, it was assumed that the freely moving water under the ice sheet, eventually fed back into the southern ocean. This previous focus for the processes involved with subglacial water is exemplified by a relatively recent paper by Wingham et al. (2006) which looks at periodic mass discharge of subglacial lakes as the primary outlet for basal water transfer. As one of the authors of the new paper stated for BBC News:

"...it was demonstrated this water could move, it could slosh around; but I think we still had this idea that it just spilled into the ocean... Well, now we can show these hydrologic systems are modifying the fundamental stratigraphy of the ice sheet.”

Evidently, the mass discharge of this subglacial water into the ocean proved to be incorrect, with the authors of the new paper noting that in some of the places they monitored; the newly formed layer accounted for over half of the entire ice column. With this new understanding of how the East Antarctic ice sheet behaves, it will be possible to revise estimates of how the glacial environment will respond to climate change. The paper states that at Dome A, this basal ice forms 24% of the ice sheet base. With the knowledge that in some areas basal ice formation accumulates at a faster rate than snow deposition, surely greater care will have to be taken in measuring glacial expansion.

This new discovery could also have impacts for paleoclimatic research using stable isotope analysis to date accumulated ice layers; which often require deep cores into the ice sheet. As the article states, the impacts are both good and bad. On the one hand, old ice could be pushed upwards by the new formation and make the archives of paleoclimatic data much more accessible. On the other hand, there may be noticeable damage inflicted to this old ice, including: “melting deformation and destruction of ice sheet records.”

This new information clearly has impacts for the way we understand Antarctic ice sheet dynamics; including both how the ice may have expanded in the past, but perhaps more importantly, how we understand and predict future changes. The size of both the Antarctic and Greenland ice sheets can’t be forgotten, as well as the potential effects either could have on global sea level rises. It is therefore important to fully understand the processes that underlay such large glacial environments.