Everyone worries about sea level rise – presumably, because that puts the evil day further into the future.
I am more worried by rapid loss of Habitat for human existence.
Image credit:Jason Roberts, BBC-Cracked surface: The largest ice cap in the Eurasian Arctic - Austfonna in Svalbard -
19 February, 2015
The Austfonna ice cap is located in northeastern Svalbard within the arctic circle north of Scandinavia. "Roughly 28% of the ice cap bed lies below sea level and over 200 km of its southern and eastern margin terminates in the ocean [Dowdeswell, 1986; Dowdeswell et al., 2008], with parts resting on a retrograde slope."
This glacier appears to have come ungrounded, flowing out to sea at a rapid pace and draining ice from the ice cap in the process. The ice cap is now thinning by an average of 25 meters per year.
The waters of the Arctic Ocean have warmed at a rapid pace relative to the rest of the world over recent years, and 2012 in particular was a year of exceptional melting and warmth in the arctic due to some extreme storms. The sudden movement in this glacier suggests that this pulse of heat has helped destabilize glaciers in the surrounding territory and it is happening at an exceptionally rapid pace.
To date, the observed dynamical imbalance has propagated 50 km inland to within 8 km of the ice cap summit, producing widespread ice loss to the ocean. Currently, the glacier terminus rests on a broadly undulating bed; however, farther inland the bed deepens, providing the potential for future instability if further ungrounding occurs [Schoof, 2007]. The imbalance could have been triggered by a number of processes, including an internally generated surge, increased meltwater availability at the bed [Dunse et al., 2014], or enhanced ocean- or atmosphere-driven melting at the terminus; indeed, a combination of factors may have contributed [Nick et al., 2009; Jenkins, 2011]. Across Austfonna, however, there is a coherent pattern of ice margin thinning at all marine-based sectors, which is not apparent at land-terminating basins (Figure 1). This may suggest either a common ocean forcing or the influence of bed conditions specific to marine settings. Additional evidence of anomalously warm waters offshore [Polyakov et al., 2005, 2013] and insignificantly increased atmospheric melting in recent years leads us to favor the former mechanism, rather than one linked to increased melt water delivery to the bed, although a definitive link would require dynamical modeling and measurements at the calving front. Until then, it is unclear whether the moderate rates of thinning of other marine ice sectors are a prelude to similar widespread mass loss in these areas, or whether the large dynamical imbalance at basin 3 will be sustained over time. Nonetheless, the behavior recorded here demonstrates that slow-flowing ice caps can enter states of significant imbalance over very short timescales and highlights their capacity for increased ice loss in the future.
This video is from Chasing Ice where Adam LeWinter and Director Jeff Orlowski filmed a historic breakup at the Ilulissat Glacier in Western Greenland. Though not Austfonna, we get the idea of what is happening to our glaciers worldwide.