1. Arctic Climate Change John C. Fyfe Canadian Centre for Climate Modelling and Analysis

3. Questions 1.What is the scientific basis for Arctic amplification? 2.Is there a human influence on Arctic climate change? 3.How accurate are model projections of Arctic climate change?

4. Graversen et al. [2008] Temperature anomaly (°C) Year Arctic Winter temperatures over land Northern Hemisphere

5. Yang, Fyfe and Flato [2010] °C per decade (vertically weighted) Annual trends 1991 to 2000 Linked to heat transport

6. Annual trends 1991 to 2000 Linked to heat transport °C per decade (vertically weighted) Latitude Level (hPa) Yang, Fyfe and Flato [2010]

7. Screen and Simmonds [2010] Level (hPa) Total trends Linked to sea ice Winter temperature trends: 1989 to 2008

8. Summer moisture trends: 1989 to 2008 Total trends Linked to sea ice Level (hPa) Screen and Simmonds [2010]

9. Sigmond and Fyfe [2010] The Antarctic paradox: it’s sea ice is increasing The ozone hole is linked to less, not more, sea ice! Model sea ice change: 1979-2005

10. Gillett et al. [2008] A human influence on Arctic warming Temperature anomaly (°C) Year OBS ALL NAT

11. A human influence on Arctic moistening Min et al. [2008] OBSANT ALLNAT

12. Arctic surface temperature projections IPCC AR4 WG1 Report [2007]

13. Arctic sea ice extent projections Boé and Hall [2009]

14. Bitz, Fyfe and Flato [2002] April sea ice thickness (meters) From observed winds From model winds

15. Contaminant pathways Macdonald, Harner and Fyfe [2005]

16. A typical global climate model grid IPCC AR4 WG1 Report [2007]

17. @Konrad Steffen Jakobshavn Glacier Holland et al. [2008] Acceleration triggered by the arrival of warm ocean waters

18. Main messages 1.While our understanding of Arctic climate change is advancing some significant challenges remain 2.While climate models for the Arctic are continuing to improve some important shortcomings remain

19. Arctic Climate Change John C. Fyfe Canadian Centre for Climate Modelling and Analysis