Bottom thickening of the EAIS
A study recently published in Science has prompted a radical rethink on how ice-sheets evolve and accumulate ice. The potential discovery of a new physical mechanism suggests that ice extensively melts and re-freezes at the base of the East Antarctic Ice Sheet, enough so to change the shape and elevation of the ice-surface.
Radar imagery obtained in 2008/9 (above) show large injections of ice, contributing as much as half of the total ice-volume. When meltwater accumulates at the base due to geothermal heating and pressure melting, it begins to flow to areas of less pressure and insulation, thus refreezing again on the underside of the ice-sheet.
Meltwater has been viewed primarily as a lubricant speeding ice-flow, however these new findings imply that water can also affect the overall topography of ice-sheets. Further study will be needed to fully understand its effects on ice-sheet dynamics across Antarctica and in the future, as well as searching for any analogues underneath the Greenland Ice Sheet.
Widespread Persistent Thickening of the East Antarctic Ice Sheet by Freezing from the Base [Bell, R., et al; Science]
Image: NASA Earth Observatory