Just touching base with the polar opposite

The impacts of climate change in Antarctica is relatively neglected in today’s literature and mainstream media in comparison to the Arctic, but why? Is climate change negligible in Antarctica or is the mere scale of the continent mean and effects pass under the wayside.

In fact, the West Antarctic Peninsula is one of the fastest warming areas on the planet with only areas within the Arctic Circle experiencing more rapid heating. However, my earlier proposal in regards to scale is partly accurate. Due to the vastness of the continent the effects of climate change are largely heterogeneous with some areas experiencing the polar opposite to the Arctic, a gain in sea ice extent. If we think back to my previous post regarding the Arctic Meridional Overturning Circulation it was stated there that in fact a warming in the Arctic would lead to a warming in the South as CO2 forcing continued, therefore this wouldn’t come as a surprise. Yet it is not entirely representative. Figure 1 depicts the heating trends over Antarctica between 1981 and 2007, upon first glance it is undoubtedly clear that the majority of Antarctica is experiencing some sort of heating.

Figure 1: Representation of surface temperature change between 1981 and 2007. Credit: NASA 

Beyond regional climate shifts the Antarctica has the potential to influence global climate. Due to the massive ice sheet covering the landmass Antarctica operates as a major heat sink as well as displaying similar characteristics as the Arctic Sea Ice in regards to maintenance of ocean/atmosphere interaction and increasing salinity aiding in the formation of bottom water currents. It also has the potential to slow the thermohaline much like the Greenland Ice Sheet. The combination of a natural variability in the deep ocean adjacent to the ice sheet similar to El Nino/ La Nina but on a centennial scale; and warmer water causing direct melting of the ice sheet below the surface depositing large icebergs into the ocean (Bakker and Clarke, 2016). These combine to cause a large freshwater influx into the surrounding oceans and into the ocean currents, slowing the creation of bottom waters much like the Greenland Ice Sheet in my previous post. One crucial difference is that despite all of this, the influx of freshwater increases the formation of sea ice increasing the albedo of the area and beginning to neutralise the negative impacts on the bottom water. According the NSIDC, 2014 set a new record for maximum sea ice extent, before subsequently returning to average levels.

Figure 2: Satellite image depicting the summer Antarctic sea ice maximum, 2014. Credit: NASA

A subtle contributor to sea level rise?

Annually enough snow is deposited upon the ice sheet is equivalent to a 5mm rise in global sea level, this process is mirrored by the annual discharge of ice back into the ocean. Therefore, a slight imbalance in the inputs and outputs and it may be a major contributor to the rise in sea level experienced today, which currently stands at 1.5-2mm per year. However, the uncertainty is large as our current understanding of the processes in the Antarctic are severely limited.

Possible Weakening of the Ice Shelf?

Supraglacial lakes are revered for their influence on ice melting in Greenland. They are a literally and observable representation of the degree of melt occurring on the surface of the ice shelves, but beyond that they in fact can aid in the breaking up of the sheet. The supraglacial lakes can flow vertically down through the ice weakening its structure while at the same time lubricating the surface below allowing for large icebergs to break off more easily. A recent study found that during the summer months between 2000 and 2013, 8000 of these supra glacial lakes have formed on the Langhovde Glacier in East Antarctica, always thought to be the stable region. This is a concern as this is the first time such a phenomena has been observed on this part of the ice sheet, previously it has occurred in the warmer Antarctic Peninsula and is thought to of resulted in the shattering of the Larsen B ice shelf (2002).