Scientists believe open water in summer has become key to declining arctic ice

Sep 30, 2005

As researchers Wednesday announced the lowest amount of ice cover in more than a century in the Arctic, the fourth consecutive year of record and near-record lows, two polar scientists at the University of Washington's Applied Physics Laboratory say they believe a tipping point has been reached.

Too much open water in the summers -- not so much warmer air temperatures -- is now driving the amount of ice that is able to form each winter, hypothesize Ron Lindsay and Jinlun Zhang in a paper in press at the Journal of Climate.

Ice is like a shield over the ocean in summer with its hard bright surface reflecting much of the sun's energy back into space -- a quality researchers call high albedo. Open water, on the other hand, has a low albedo because it readily absorbs the sun's radiation instead of reflecting it.

An Arctic Ocean at the tipping point of having too much open water in summer will go into winter with less and less ice and with water too warm to develop an ice cover as thick as past ones, Lindsay says. The next summer, predictably, the ice is less extensive so there is even more open water to absorb the sun's heat.

Lindsay and Zhang believe the Arctic got into this situation of a "positive ice-albedo feedback" because:

 The ice was preconditioned by 50 years of gradually increasing fall, winter and spring air temperatures that caused newly formed ice to be less thick at the end of spring.

 There was a triggering event when wind patterns in the late 1980s and early 1990s temporarily shifted, flushing older, thicker ice out of the Arctic and down the east coast of Greenland, where it melted.

"The reduction in the thickness and extent of the ice continues unabated in spite of the fact the wind circulation patterns have returned to near normal conditions," Lindsay says.

"Only time will tell if we have really tipped the system into a new quasi-stable state in which very large extents of summer open water and winter first-year ice are the norm. The old regime may not be regained until there is a prolonged period of cooler temperatures in the Arctic."

Source: University of Washington

Explore further: ESA's planetary defence test set for 2020

Related Stories

Recommended for you

ESA's planetary defence test set for 2020

54 minutes ago

If an asteroid were spotted headed towards Earth, what could humanity do about it? ESA's latest mission is part of a larger international effort to find out.

Dusty substructure in a galaxy far far away

3 hours ago

Scientists at the Max Planck Institute for Astrophysics (MPA) have combined high-resolution images from the ALMA telescopes with a new scheme for undoing the distorting effects of a powerful gravitational ...

ALMA disentangles complex birth of giant stars

3 hours ago

A research group led by Aya Higuchi, a researcher at Ibaraki University, conducted observations of the massive-star forming region IRAS 16547-4247 with the Atacama Large Millimeter/submillimeter Array (ALMA). ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.