1. Arctic Sea Ice in 2008: Standing on the Threshold
Mark Serreze, Walt Meier, Julienne Stroeve, Ted Scambos, Stephanie Renfrow National Snow and Ice Data Center (NSIDC) Cooperative Institute for Research in Environmental Sciences at the University of Colorado at Boulder

2. September 2007: A New Record Minimum
Stroeve et al. 2008

3. Observed Rate of Ice Loss Exceeds Expectations
Updated from Stroeve et al., 2007

4. Standing on the Threshold?
Has the sea ice cover been preconditioned to such
a degree through thinning that a strong “kick” from natural
variability can initiate a rapid slide towards ice-free
conditions in summer?
Has the kick already occurred?
Was the kick the “perfect storm” associated with the
record 2007 minimum?
All eyes were on 2008.

5. Even More Young, Thin Ice than in Spring 2007
NIC Analysis of Multiyear
Ice Fraction
Estimated Ice Age from
Tracking Algorithm
National Ice Center (left), J. Maslanik (right)

6. Ice Extent through June 3: On Track

7. July: Falling Off the Pace
By early July, it was clear that we had fallen “off the pace” of 2007.
Atmospheric circulation patterns were not as favorable
as in 2007.
Setting a new record minimum started to seem less likely.

8. No “Perfect Storm” as Seen in 2007
SLP, July 2008
SLP, July 2007
NSIDC and NOAA Climate Diagnostics Center

9. August: Stirring the Pot
By early August, the rate of ice loss usually starts to
slow – this was seen even in 2007.
In 2008, ice extent continued downward at a brisk pace.
A change in atmospheric circulation “stirred the pot.”
We started to run out of ice thickness.

10. The Plot Thickens August 26: Ice extent falls to second
lowest in satellite record
(left), University of Bremen (right)

11. Amundsen’s NW Passage opens
And Thickens
Amundsen’s NW Passage opens
Remarkable ice losses in
Chukchi and East Siberian seas
J. Stroeve, W. Meier (NSIDC) and University of Bremen

12. 2008 Falls Just Short Sept 14, 2008: 4.51 million sq. km
Left: From Serreze et al. (2008); Right: Updated from Stroeve et al. (2007) 12

13. Parting Thoughts Was 2007 the kick? We’ll see.
NSIDC will be giving the blow-by-blow account of 2009.
Ice-free summers by 2030? Perhaps even earlier?
We need to be ready

14. Thank You 14