Swirls along an Ice Highway

Swirls along an ice highway in the sea water off the east coast of Greenland, observed by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite on October 17, 2012.    NASA image courtesy Jeff Schmaltz, LANCE MODIS Rapid Response Team at NASA GSFC.

Larger image

Thin, free-drifting ice moves very easily with winds and currents.

In fact, this ice moved discernibly between October 16 and October 17.

Each year, Arctic sea ice grows through the winter, reaching its maximum extent around March. It then melts through the summer, reaching its minimum in September. By October, Arctic waters start freezing again. However, the ice in the image above is more likely a remnant of old ice that migrated down to the coast of Greenland. Sea water is unlikely to start freezing this far south in October.

Along Greenland’s east coast, the Fram Strait serves as an expressway for sea ice moving out of the Arctic Ocean. The movement of ice through the strait used to be offset by the growth of ice in the Beaufort Gyre. Until the late 1990s, ice would persist in the gyre for years, growing thicker and more resistant to melt. Since the start of the twenty-first century, however, ice has been less likely to survive its trip through the southern part of the Beaufort Gyre. As a result, less Arctic sea ice has been able to pile up and form multi-year ice.

With less thick ice there is less Arctic sea ice volume, something the researchers at the Polar Science Center at the University of Washington have modeled from 1979 to 2012.

Arctic sea ice volumeGraph by Jesse Allen based on modeled ice volume data from the Polar Science Center, University of Washington. Caption by Michon Scott with information from Ted Scambos, National Snow and Ice Data Center.

Read more earthobservatory