Monday, June 30, 2014
Between 16 and 11 thousand years ago, the Fennoscandian Ice sheet, which once covered the greater
Scandinavia area, collapsed. When coastal ice sheets
disappear, they don’t just melt in place.
Rather, the outflow glaciers carry the ice to the sea, where it breaks
off and floats away as icebergs, faster than snow in the interior of the ice
sheets falls and gets compressed into new ice.
But the details of this process are not understood. As one of the more
serious potential consequences of global warming is the collapse of one or more
current ice sheets (which would result in several meters of sea level rise),
figuring out exactly how ice sheets collapse is kinda important.
Stokes et al. (2014) look at the rate of glacial retreat on the glaciers the carried Fennoscandian ice into the
Specifically, they looked at eight outflow glaciers in Northern
Norway. These outflow
glaciers (not fjords, because the ice is all gone) are all close together, so
experienced similar climactic conditions.
What the study found was that despite similar forcing, the glaciers
experienced very different responses, and all retreated at different speeds and
times. This shows that glacial dynamics cannot be predicted based on local
climactic conditions, without also accounting for local topography, bathymetry,
and ice flow.
The reason this is important is that many current glaciers in Greenland and the
Antarctic Peninsula are
retreating even faster than these glaciers did at the end of the last ice
age. And this paper shows that our
current predictive tools are inadequate to tell us how fast outflow glaciers
retreat, even when subjected to similar conditions. Individual glaciers, it
seems, all react in their own peculiar way.