A massive iceberg twice the size of Manhattan has broken off of
a glacier in Greenland, according to NASA satellite imagery, in
what could be the latest indication of global warming. The
images released Wednesday show the massive chunk of ice breaking
off of the Petermann Glacier on the northwestern coast of
Greenland. The glacier produced a similar ice island twice as
large in 2010. NASA said the crack in the glacier had been
visible since 2001, and that its polar-orbiting Aqua satellite
had observed the break on July 16-17. Oceanographer Andreas
Muenchow of the University of Delaware said that while the
icebergs seem large, most of the glacial melting takes place 600
meters (1,800 feet) below the surface, where the glacier meets
bedrock and the ocean water is much warmer than at the surface.
"The dominant mass loss is via ocean melting from below. This
dominant process is not visible, it is not possible to capture
it with eye-catching images," he wrote on his blog at
icyseas.org. "Furthermore, and this appe