Washington, July 15 (IANS) Glaciers that lose their grounding on the seafloor and begin floating behave very erratically, producing larger icebergs than their grounded cousins, says a new study.
Fabian Walter and colleagues from Scripps Institute of Oceanography glaciologist have presented the first detailed observation of the transition from grounded to floating glaciers, says a report slated for publication in the journal Geophysical Research Letters.
Such a transition is currently taking place at Columbia Glacier, one of Alaska’s many tidewater glaciers.
Tidewater glaciers flow directly into the ocean, ending at a cliff in the sea, where icebergs are formed.
Previously, Alaskan tidewater glaciers were believed to be exclusively ‘grounded’ (resting on the ocean floor), and unable to float without disintegrating.
Photographers of the US Geological Survey (USGS) captured a dramatic submarine (undersea) calving event from the grounded terminus of Columbia Glacier June 17, 2005. Calving is the sudden release and breaking away of a mass of ice from a glacier.
The height of the ice cliff is approximately 70 meters (230 feet).
However, the Columbia Glacier unexpectedly developed a floating extension in 2007 that has endured far longer than researchers expected.
The research team believes that this floating section may have been caused by the speed at which the glacier is receding, says a Scripps statement.
Columbia is one of the fastest receding glaciers in the world, having retreated four km since 2004, and nearly 20 km since 1980.
‘We’re seeing more tidewater glaciers retreat. As they retreat, they thin and that increases the likelihood that they’ll afloat,’ Walter said.
The study, co-authored by USGS glaciologist and Scripps alumnus Shad O’Neel, is part of a larger effort to understand and include calving in large-scale glacier models, which are essential in producing accurate forecasts of sea-level rise.
