2. Arctic Climate Change: Where Reality Exceeds Expectations Mark C. Serreze National Snow and Ice Data Center (NSIDC) Cooperative Institute for Research in Environmental Sciences at the University of Colorado at Boulder Special Thanks: Julienne Stroeve, Andy Barrett, Ted Scambos, Drew Slater, Dave Lawrence, Tingjun Zhang

3. July, 1982: Global Warming? Bah!! Ellesmere Island, near Lake Hazen

4. Peering into the future ….

5. IPCC 2007 Arctic Amplification

6. Loss of Near-Surface Permafrost Lawrence and Slater, 2005

7. Left: changes in multi-model mean freshwater budget terms for the Arctic Ocean with respect to 1950-1980 means: positive anomalies indicate an increasing source (or decreasing sink) of freshwater for the Arctic Ocean Holland et al. 2007; Serreze et al. 2006 Acceleration of the Freshwater Cycle

8. Arctic sea ice is disappearing Stroeve et al. 2008

9. Observed rate of loss is faster than expected Adapted from Stroeve et al., 2007

10. The Northwest Passage: open by late August 2007 G. Spreen, L. Kaleschke, and G. Heygster/IUP Universitat Bremen, AMSR data from National Snow and Ice Data Center (left); unknown (upper right); Dave Kavanagh (middle right); D. Thoreson (lower right) Manhattan 1968 Gjoa 1903 Cloud Nine 2007

11. Impacts on Polar Bears

12. Model-Projected Arctic Amplification Mark Serreze, Andy Barrett, Marika Holland Model projection of 2-meter temperature anomalies by month and year for 70–90 degrees North latitude, compared to 1979–2007 means (CCSM3) Latitude by height dependence of zonally averaged October–March temperature anomalies for 2050– 2059, compared to 1979–2007 means (CCSM3)

13. Arctic amplification has emerged Temperature anomalies, 2003–2007 minus 1979–2007 NCEP/NCAR, Climate Diagnostics Center October

14. Observed Autumn Temperature Trends, 1960-2007 GISS Analysis

15. W. Abdalati Greenland’s Changing Mass Budget

16. Surface Melt and the “Zwally Effect” K. Steffen, M. Tedesco

17. Greenland’s Largest Glacier: Acceleration and Retreat Ian Howat, Ian Joughin, Ted Scambos

18. Warming Permafrost Russian Permafrost Temperature -4 -3 -2 0 1 2 3 4 19501955196019651970197519801985199019952000 Year Temperature Departure (°C) 0.2 m; Trend = +0.78°C/decade 0.4 m; Trend = +0.79°C/decade 0.8 m; Trend = +0.65°C/decade 1.6 m; Trend = +0.55°C/decade 3.2 m; Trend = +0.66°C/decade Alaska: 4 to 6°C increase in 20th Century, 2 to 3°C in the last 30 years Siberia: >3°C increase from mid-1950s to 1990 Canadian Arctic: 1 to 3°C increase in past several decades Tibetan Plateau: up to 1.0°C increase since 1970s IPCC 2007

19. Infrastructure Impacts Chersky, Russia Qinghai-Xizang Highway bridge collapse Alaska Thermokarst in Yakutsk, Russia (Skiklomanov, 2005).

20. Methane Release from Arctic Lakes Burning methane over a thermokarst lake in Siberia (K. Walter) Methane bubbles trapped in lake ice Lakes boiling with methane in the Arctic

21. Talik Formation Active layer Permafrost Seasonally frozen layer Permafrost Talik (layer of unfrozen ground)

22. Chandler River, 50 miles S. of Umiat: Sturm, Racine and Tape: Fifty Years of Change in Arctic Alaskan Shrub Abundance 1949 Changes in Shrub Abundance: Chandler River, AK

23. 2001

24. Concluding Comments  Even our earliest climate models projected that effects of greenhouse gas loading would be seen first in the Arctic.  Even eight years ago, attribution of observed changes was uncertain.  Despite strong imprints of natural variability, a role of greenhouse greenhouse gas loading now seems clear  A number of key changes are exceeding expectations from climate models. Could we lose the summer sea ice cover by 2030?  Much remains to be understood—the idea of “tipping points” has emerged as a key issue.  Not everything is rapidly changing (hydrologic cycle).