West Antarctic Ice Sheet warming raises sea level fears

So thankfully the world didn't come to a dramatic end this week as the Mayan's had (possibly) predicted all those years ago. What is not such great news is that a new article published online a few days ago, just to lighten up our Christmases, has shone a great deal of attention to Antarctic warming and global sea level rise.

The Bromwich et al. (2012) study in Nature Geoscience attempted to iron out uncertainties over the magnitude, seasonality and extent of warming that is widely assumed to have been occurring in the West Antarctic region since the 1950s. The problem was that temperature records relied on observations from the Bryd Station, found in the centre of the West Antarctic Ice Sheet, which were incomplete. The new research used computer modelling and analysis of the atmosphere to fill in these gaps.

Figure 1. Antarctica  

It has been found that the region is warming twice as fast as was previously thought. The report noted a ‘linear increase in annual temperature between 1958 and 2010 by 2.4 ± 1.2 °C’, which makes it one of the most rapidly warming regions of the world (Bromwich et al. 2012). Interestingly, and what is of great importance, is that summer temperatures were found to be increasing. This has implications for surface melting of the ice sheet. It has previously been suggested that warm ocean currents were the main contributor of ice loss in the West Antarctic (Pritchard et al. 2012). Thus basal, rather than surface melting, was thought to be key. Now, one can only speculate that surface melting will play a greater role to accelerate ice sheet loss.

I feel that the implications this could have on global sea level are enormous. There is obviously the direct impact of increased meltwater making a greater contribution to sea level rise. However, there is also the indirect effect that this melt could have which would be similar to the collapse of the Larsen B ice shelf in 2002. If the ice shelves were to collapse natural ice flow which is normally restrained, in glaciers for example, would be released into the ocean (Bromwich 2012).

This is one of the reasons the region has had so much attention - if all of the West Antarctic Ice Sheet were to melt sea level would rise by over 3 metres (BBC 2009)! While this may make recent changes appear miniscule in comparison, this should not be a reason to give up home in the battle against sea level rise. Instead, it should feed greater impetus for the war on anthropogenic climate change so that these drastic conditions are not realised.

References

BBC (2009) ‘Ice sheet melt threat reassessed’ (WWW), London: BBC News (http://news.bbc.co.uk/1/hi/sci/tech/8050094.stm; 26 December 2012).

Bromwich, D. (2012) ‘‘Study shows rapid warming on the West Antarctic Ice Sheet’ (WWW), Ohio: The Ohio State University Research News (http://researchnews.osu.edu/archive/byrdwarm.htm; 26 December 2012).

Bromwich, D.H., J.P. Nicolas, A.J. Monaghan, M.A. Lazzara, L.M. Keller, G.A. Weidner and A.B. Wilson (2012) ‘Central West Antarctica among the most rapidly warming regions on Earth’ (WWW), Nature Geoscience (http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1671.html; 26 December 2012).

Pritchard, H.D., S.R.M. Ligtenberg, H.A. Fricker, D.G. Vaughan, M.R. van den Broeke and L. Padman (2012) ‘Antarctic ice-sheet loss driven by basal melting of ice shelves’, Nature, 485, 7395, 502-5.