Remote Sensing under ice

SAR sensing using aircraft mounted radars flying 1,500′ above the ice can see nearly 10,000′ below the ice using special radar processing techniques.  The cross section through the ice during one flight has shown the unexpected existence of a lake well below the ice of Antarctica.  Organic contamination indicates the previous existence of plant life at these latitudes (with rolling hills and lakes).  This represents a substantial change in the temperature of the region from one which would support life to one which is now the harshest climate on Earth devoid of most species apart from a few species of acclimated penguins and birds who cling to an unusual lifestyle on the surface.

annotated-FL39-Jan09_335-341HGe4-300x225 Remote Sensing under iceWhat would cause such a dramatic change?