Ice is melting at the ends of the world
June 28th, 2010In Antarctica, a robot submarine sent beneath the Pine Island glacier’s floating ice sheet has shown that the glacier has become unpinned from an undersea ridge and that warm water is now circulating under the ice, causing the glacier to melt even faster in an accelerating feedback loop.
The study, Observations beneath Pine Island Glacier in West Antarctica and implications for its retreat, is published in Nature Geoscience.
The 400 meter- high ridge has previously been anchoring the glacier and preventing warm seawater from reaching the ice, melting it from underneath. A modeling study published in January suggested that once the glacier retreated behind the ridge, the glacier would not be able to recover.
Pine Island glacier is one of a handful in West Antarctica which together are estimated to be responsible for about 10% of global sea-level rise.
At the other end of the world, scientists are predicting that September 2010 will see yet another “critical minimum” for Arctic sea ice.
One forecast, contained in the September Sea Ice Outlook: June Report, was developed by the team from Klima Campus of the University of Hamburg. It estimates a September minimum of 4.7 million square kilometers. Another estimate produced by AWI researchers is a bit higher – 5.2 million km². Neither of the two research groups anticipates that the record minimum of 4.3 million km² in 2007 will be reached. But scientists caution that the decisive factors for the situation in late summer, such as the ice thickness in the central Arctic and further development of the weather in summer, are not yet known.
What is known is that Arctic sea ice volume is falling off a cliff.
Continuously updated Arctic Sea Ice Volume Anomaly from PIOMAS. Daily Sea Ice volume anomalies for each day are computed relative to the 1979 to 2009 average for that day. The trend for the 1979- present period is shown in blue. Shaded areas show one and two standard deviations from the trend. Click on image for a larger version of the figure