Dr. Don PerovichJanuary 11, 2007

NOAA/NSTA Web SeminarThe Ocean’s Role in Weather and Climate

Its just a simple graph…

Past and future changes

Future: predictions for 2x CO2

• significant warming• most pronounced in the Arctic

Past: observed changes - 2005• 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 records Satellites Expeditions

Traditional knowledge

Charts Epic 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 changeB. Less sea iceC. 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 records Satellites Expeditions

Submarines Traditional knowledge

Drilling holes Epic 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 thicknessComparing 1958-1976 and the 1990’s

AB

C

DE

F

G

The Ice-Albedo Feedback: An Amplifier of Climate Change

The ice strikes back!

What is albedo?

1.

2.

3.

Albedo

incident sunlight

Albedo

Albedo =reflected sunlightincident sunlight

Albedo is fraction of sunlight reflected

What is the range of albedo?

Smallest? Largest?

- 0

-100 2

10

1 100

100100

0.5

Albedo is fraction of sunlight reflected

e

-1

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: interiorSpring Uniform appearance Snow-covered ice Large albedo (~ 0.8)

April 17

Ice albedo feedback: interiorSpring Uniform appearance Snow-covered ice Large albedo (~ 0.8)

Summer Variegated appearance More water Reduced albedo (~ 0.5)

Melting means lower albedo

August 8

Absorbedsunlight 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 AssociationGerry Wheeler, Executive Director

Frank Owens, Associate Executive Director Conferences and Programs

Al Byers, Assistant Executive Director e-Learning

LIVE INTERACTIVE LEARNING @ YOUR DESKTOP

NSTA Web SeminarsFlavio Mendez, Program Manager

Jeff Layman, Technical CoordinatorSusan Hurstcalderone, Volunteer Chat Moderator