Many glaciers on the Southern Antarctic Peninsula (SAP) - a region previously thought to be stable compared to other glacier masses in Antarctica - became destabilized in 2009, and they have been melting at accelerating rates ever since, researchers say.

These glaciers, which rest on bedrock that dips below sea level toward the continent's interior, help to buttress inland ice shelves - but their structures are presumed to be unstable.

Now, Bert Wouters and colleagues have combined satellite altimetry and gravity observations to show how such land-based ice has thinned over the past 12 years or so in the region. The researchers' results suggest that ice shelves on the SAP have weakened significantly, causing marine-terminating glaciers to flow faster into the sea. Between 2002 and 2010, the mass balance of such glaciers remained around zero, according to Wouters and the other researchers.

But by about 2009, glaciers on the SAP had begun to lose mass at accelerating rates, they say. Since that year, the glaciers in the region have added 300 trillion liters of water to the ocean.

Today, these rapidly-melting glaciers pump out about 56 gigatons of water each year, constituting a major fraction of Antarctica's contribution to rising sea level. Based on their results, the researchers suggest that warming ocean currents are the likely culprit; changes in the wind circulation around Antarctica have increased the flow of warm subsurface waters from the deep ocean to the coastal zones, melting the ice shelves and glaciers from below.

Article #17: "Dynamic thinning of glaciers on the Southern Antarctic Peninsula," by B. Wouters; A. Martin-Espanol; J.L. Bamber at University of Bristol in Bristol, UK; V. Helm at Alfred-Wegener-Institut Helmholtz-Zentrum fur Polar- und Meeresforschung in Bremerhaven, Germany; T. Flament at Laboratoire d'Etudes en Geophysique et Oceanographie Spatiales in Toulouse, France; J.M. van Wessem; S.R.M. Ligtenberg; M.R. van den Broeke at Utrecht University in Utrecht, Netherlands.