Dr. Don Perovich January 11, 2007 NOAA/NSTA Web Seminar The Ocean’s Role in Weather and Climate

Its just a simple graph…

Past and future changes Future: predictions for 2x CO 2 significant warming most pronounced in the Arctic Past: observed changes widespread warming most pronounced in the Arctic Arctic is the “canary in a coal mine.” Temperature change in degrees Celsius

The Arctic Sea Ice Cover From the Living Earth Frozen ocean Floating, moving ice Meters thick Highly reflecting An indicator and an amplifier

How can you measure area of ice? Ship recordsSatellitesExpeditions Traditional knowledge ChartsEpic sagas

Satellites! Visible, infrared, and microwave imagers Day, night, all weather, since 1970’s 7.5 million square kilometers About size of continental US Area covered by sea ice

Has sea ice extent changed? A.No change B.Less sea ice C.More sea ice

Sea ice extent Complicated story

Sea ice extent Make it simple

Sea ice extent Sea ice extent is shrinking Large interannual variability Downward trend Rate of decline: ~ 6.5 % per decade

Changes in sea ice extent Reduction from 1982 to 2005

How does this loss compare to U.S.? A C D B

Comparable change to U.S. 22 states – almost entire US east of the Mississippi C

How can you measure ice thickness? Electromagnetic sensors Ship recordsSatellitesExpeditions SubmarinesTraditional knowledge Drilling holesEpic sagas

Changes in ice thickness - submarines Submarine-based upward looking sonar

Sea ice thickness: then and now Sea ice is thinning … everywhere Average decrease was 40% From 3 m to under 2 m Changes in summer thickness Comparing and the 1990’s A B C D E F G

The Ice-Albedo Feedback: An Amplifier of Climate Change The ice strikes back!

What is albedo?

Albedo incident sunlight

Albedo Albedo = reflected sunlight incident sunlight Albedo is fraction of sunlight reflected

What is the range of albedo? Smallest? Largest? -   Albedo is fraction of sunlight reflected e

What is the range of albedo? Smallest?Largest? = 0= 1

Ice albedo feedback:Ice albedo feedback: ice edge retreat

Ice albedo feedback:Ice albedo feedback: ice edge retreat Largest albedo to smallest Ocean

April 17 Ice albedo feedback: interior Spring  Uniform appearance  Snow-covered ice  Large albedo (~ 0.8)

April 17 Ice albedo feedback: interior Spring  Uniform appearance  Snow-covered ice  Large albedo (~ 0.8) Summer  Variegated appearance  More water  Reduced albedo (~ 0.5) Melting means lower albedo August 8

Absorbed sunlight Lower albedo Melting + ++ An amplifier of climate change

One sick canary Rapid change and tipping points

International Polar Year Take the pulse of the poles. Biggest effort in 50 years Arctic observing network Life in extreme environments Antarctic ice sheets Education and outreach A “beehive” of activity

IPY Symposium: Impact of Polar Climate Change on Living Systems IPY Symposium: The Fragile Ice IPY Symposium: Polar Climates, How Are They Changing? NSTA National Conference on Science Education St. Louis, MO March 29 – April 1, 2007

National Science Teachers Association Gerry Wheeler, Executive Director Frank Owens, Associate Executive Director Conferences and Programs Al Byers, Assistant Executive Director e-Learning LIVE INTERACTIVE YOUR DESKTOP NSTA Web Seminars Flavio Mendez, Program Manager Jeff Layman, Technical Coordinator Susan Hurstcalderone, Volunteer Chat Moderator