Researchers have found that a sudden increase in ice loss has occurred in a region of Antarctica that was previously categorized as stable. The ice loss was so dramatic that it was able to influence changes in the Earth's gravity field.

Using ice sheet elevation measurements, the researchers, led by a team from the University of Bristol, observed that there were no signs of changes in the Southern Antarctic Peninsula before 2009. Around that year though, several glaciers measuring about 466 miles in length suddenly began shedding ice equivalent to around 55 trillion liters of water into the ocean each year, making the region the second biggest contributor to rising sea levels in Antarctica.

According to Dr. Bert Wouters, the study's lead, the glaciers have added almost 72 cubic miles of water to the ocean, an amount equivalent to the volume of nearly 350,000 Empire State Buildings.

Changes in the ice were detected by the European Space Agency's CryoSat-2 satellite. By examining five years of data, the researchers discovered that some of the glaciers are moving by up to 13 feet every year. The resulting change in the gravity as caused by the massive ice loss, on the other hand, was recorded by the Gravity Recovery and Climate Experiment satellite.

Dr. Wouters said the results surprised them. "It shows a very fast response of the ice sheet: in just a few years the dynamic regime completely shifted."

Guided by data from an Antarctic climate model, the researchers deduced that the sudden shift cannot be explained by mere changes in air temperature or amount of snowfall. Rather, they attributed the ice loss to oceans warming.

In the last two decades, ice shelves have already lost nearly a fifth of their thickness. As more and more of the ice are lost, the resisting force they provide glaciers are reduced. With glaciers grounded on bedrock below sea level, they will melt even more even if they retreat because warm water will follow them inland.

The researchers said that to specifically identify the root of the trigger for the sudden ice loss, more data will have to be collected. Crucial to the study is detailed knowledge on glacier flow speeds, ice sheet thickness, ocean floor topography and local ice shelf geometry.

Other authors for the study include: Jonathan Bamber, Michiel van den Broeke, Stefan Ligtenberg, Melchor van Wessem, Thomas Flament, Veit Helm, and Alba Martin-Español.