BY CHILLYMANJARO July 18, 2012
Another spectacular event on Greenland this year is second big calving of Petermann Glacier, following retreats of the Jakobshavn Glacier and lowest reflectivity of the Greenland ice sheet on record. This calving was expected to happen, as the rift in the glacier has been there for year. The break-off point has been visible for at least 8 years in MODIS imagery propagating at speeds of 1 km/year towards Nares Strait. The fracture also extended further across the floating ice sheet from the northern towards its southern side.
The large iceberg breaking from the Petermann Glacier serves as a reminder that ice sheets are dynamic. A glacier is like a relatively slow-moving river of ice. When a glacier flows into the ocean, as the Petermann Glacier does, ice breaks or calves from the end, creating new icebergs. So, calving is a natural process. How frequently icebergs calve from a glacier depends on how fast the glacier grows because of new snow, how fast it flows into the ocean, and how fast it melts.