On ice streams

This amazing image is doing the rounds just now -- it's on the BBC web site today.  It looks as if it is a product of one of the computer simulations of ice movement, but it isn't -- this one is based on real surface velocity data, assembled by many different satellites and processed into a complete "image" for Antarctica.

Note that over the thickest parts of the East Antarctic Ice Sheet there is very little ice movement -- ice velocities are generally less than 5m per year.  But out towards the coasts, the ice evacuation speeds are greater -- between 10m and 100m per year.  Then we come to the ice streams, which show up spectacularly as dark blue and purple, sometimes flowing at velocities far in excess of 1 km per year and carrying vast volumes of glacier ice towards the Ronne, Ross and Amery Ice Shelves.

If you had looked down on the Scandinavian / British Ice Sheet around 450,000 years ago, and done similar measurements, you would have seen something similar with respect to the Irish Sea Glacier.......