March 26, 2015

expert reaction to new research on Antarctic ice loss

A paper published in the journal Science has reported that the rate of loss of ice shelves, which hold back ice sheet flow, in the Antarctic has accelerated since 1994.

Prof. Andrew Shepherd, Director of the Centre for Polar Observation and Modelling at the University of Leeds, said:

“The floating ice shelves that fringe Antarctica are an incredibly important part of Earth’s climate system, because they help to stabilise the ice that is locked behind them. This new study shows that in many places there has been sustained ice shelf thinning as a result of increased ocean melting, with some Antarctic shelves losing a fifth of their ice in less than two decades.

“This is a real concern, because such high rates of thinning cannot be sustained for much longer, and because in the places where Antarctic ice shelves have already collapsed this has triggered rapid increases in the rate of ice loss from glaciers above ground, causing global sea levels to rise.”

Dr Colin Summerhayes, Emeritus Associate at the Scott Polar Research Institute, said:

“The new evidence for the melting of ice shelves adds weight to the argument that sea ice is growing around the continent at least in part in response to the addition of freshwater to the ocean surface there, which leads as well to increased stratification of the water column. The melting of the ice shelves owes a great deal to the ongoing advection of warm subsurface waters up onto the continental shelf beneath the shelves.”

Prof. Martin Siegert, Visiting Professor at the Bristol Glaciology Centre, said:

“Paolo et al. provide compelling evidence that ice shelf thinning in Antarctica is accelerating. The loss is mainly focused around the Amundsen Sea coast in West Antarctica, and confirms earlier work that this region of Antarctic is undergoing the first signs of a substantial change, potentially leading to significant (>1 m) sea level change.

“Changes to ice shelves elsewhere in Antarctica are less clear. However, several regions are known to be at or near a physical threshold of major change, meaning that even small losses to the ice shelf that acts to buttress the grounded ice could also result in major ice sheet loss. The notion of ice shelf stability over the period of the observations in some regions (Totten Glacier in East Antarctica; Institute Ice Stream in West Antarctica) should not be interpreted as meaning the ice sheet is not vulnerable to change in such places.”

Prof. David Vaughan, Director of Science at British Antarctic Survey (BAS), said,

“The paper from Paolo et al. is an excellent piece of work. Previous work led by BAS in 2010 showed the rates at which the various floating ice shelves around Antarctic were thinning, but this paper takes that work forward by showing how that thinning has changed over time. This new insight will allow us to improve our understanding of how the oceans around Antarctica are driving change in the ice sheet.”

“To begin to predict with confidence how ice sheets will change in future and contribute to global sea-level rise we need to understand exactly where and why they are changing at the moment. We already know that it is changes in the ocean which are driving changes in the floating ice shelves, and that those changes are in turn driving changes in grounded ice sheet. But these new results indicate that the pattern and rate of change in the floating ice is complex and changing from year-to-year. These satellite results are thus highlighting the areas that require detailed exploration and investigation. The NERC iSTAR programme has recently completed its second season of investigation into one of the key areas of change shown in this new study – Pine Island Glacier.”

“Most of the pattern of change, the strong loss around West Antarctica and the marginal gain around East Antarctica are what we expected, but the rate of ice loss (especially when considered in terms of the percentage of ice lost in the last two decades is dramatic. This research is a significant step towards improving our ability to predict the future of the Antarctic ice sheet and its contribution to global sea-level rise.”

‘Volume loss from Antarctic ice shelves is accelerating’ by Fernando S. Paolo et al. published in Science on Thursday 26^th March. 

Declared interests

None declared