Earth ID: 3592

Fall Arctic Sea Ice Thickness Declining Rapidly

Visualizations by Lori Perkins Released on April 5, 2009

Using five years of data from NASA's Ice, Cloud and land Elevation Satellite (ICESat), a team of NASA and university scientists made the first basin-wide estimate of the thickness and volume of the Arctic Ocean ice cover between 2003 and 2008. The scientists found that younger, thinner ice has replaced older, thicker ice as the dominant type over the past five years. Until recently, the majority of Arctic ice survived at least one summer and often several. That balance has now flipped. Seasonal ice, or ice that melts and re-freezes every year, now comprises about 70 percent of the Arctic sea ice in wintertime, up from 40 to 50 percent in the 1980s and 1990s. Thicker ice - surviving two or more years - now comprises just 10 percent of ice cover, down from 30 to 40 percent in years past.Sea ice thickness has been hard to measure directly so scientists have typically used estimates of ice age to approximate thickness. With ICESat, NASA scientists were for the first time able to monitor the ice thickness and volume changes over the entire Arctic Ocean. The Arctic ice cap grows each winter as the sun sets for several months and intense cold sets in. The total volume of winter Arctic ice is equal to the volume of fresh water in Lake Superior and Lake Michigan combined. Some of that ice is naturally pushed out of the Arctic by winds, while much of it melts in place.

But not all of the ice in the Arctic melts each summer, and the thicker, older ice that survives one or more summers is more likely to persist through the next summer. This older, thicker ice is declining thinner ice that is more vulnerable to summer melt. Seasonal sea ice usually reaches about 2 meters (6 feet) in thickness, while ice that has lasted through more than one summer averages 3 meters (9 feet), though it can grow much thicker in some locations near the coast. From 2003 to 2008, multi-year ice has thinned by an average of 60 centimeters (2 feet). The total ice volume in winter has decreased by 6,300 cubic kilometers, or 40 percent. The maximum extent of multi-year ice is now one-third of what it was in the 1990s.

This sequence shows Arctic sea ice thickness derived from fall campaigns from the ICESat satellite. While the sea ice extent might look similar from year to year this thickness data shows dramatic thinning especially near the North Pole (shown in dark blue). This image was generated with data acquired between Oct 4 - Oct 19, 2008.

Arctic Sea Ice Thickness from Oct 2 - Nov 5, 2007

Areas with thickness less then 1 meter are shown in dark blue and areas of 4 or more meters are shown in white. Notice the large dark blue area north of Siberia that almost extends to the North Pole.

Arctic Sea Ice Thickness from Oct 25 - Nov 27, 2006. Areas with thickness less then 1 meter are shown in dark blue and areas of 4 or more meters are shown in white.

Oct 21 - Nov 24, 2005

Notice the dark blue area above Siberia is a larger area then in previous years and the white region is smaller then in previous years.

Visualization Credits

Lori Perkins (NASA/GSFC): Lead Animator
Horace Mitchell (NASA/GSFC): Animator
Jay Zwally (NASA/GSFC): Scientist
Thorsten Markus (NASA/GSFC): Scientist
Donghui Yi (SGT): Scientist

Please give credit for this item to:
NASA/Goddard Space Flight Center Scientific Visualization Studio The Next Generation Blue Marble data is courtesy of Reto Stockli (NASA/GSFC).

Science Paper:
Zwally, H. J., D. H. Yi, et al. 2008. ICESat Measurements of Sea Ice Freeboard and Estimates of Sea Ice Thickness in the Weddell Sea. Journal of Geophysical Research-Oceans 113(C2). http://adsabs.harvard.edu/abs/2007AGUFM.C11B0421Z

Short URL to share this page:
https://svs.gsfc.nasa.gov/3592

Mission:
Ice, Cloud, and land Elevation Satellite (ICESat)

Data Used: