1. Outline Background, climatology & variability Role of snow in the global climate system Indicators of climate change Future projections & implications of global change

2. Background, climatology & variability

3. Distinct properties of snow High albedo (α = 0.45 to 0.95) Low thermal conductivity High emissivity (ε = 0.82 to 0.99) Translucent Limited by 0 o C (low energy status) Reservoir for water Porous Mobile surface Varies greatly in space & time

4. Surface radiation budget over snow Q * = net radiation K↓ = incoming shortwave radiation L↓ = incoming longwave radiation L↑ = σT 4 = outgoing longwave radiation (maximum of 316 W m -2 ) Q * = K ↓ (1- α) + L ↓ + σT 4

5. Snow and global change science Stephen Déry, ENSC 425/625 - 7 November 2006

6. Surface energy budget over snow Q * = net energy Q H = sensible heat flux Q E = latent heat flux (sublimation) = L s E Q G = ground heat flux Q M = snowmelt ΔQ S = change in heat storage Q * = Q H + Q E + Q G + Q M + ΔQ S

7. Hydrological Cycle Surface water budget:  S = P – E – R

8. 20 th Century Climatology Observed GFDL Ref: Masuda

9. Current snow coverage 6 November 2006

10. Departure from average 6 November 2006

11. Seasonal climatology

12. Observed & GFDL Northern Hemisphere Snow Extent (x10 6 km 2 ), 1973-2000 SeasonOBSGFDLMAERMSE Winter44422.40.55 Spring30354.81.00 Summer642.30.51 Fall19201.70.40 Annual25 0.90.22

13. Mean annual maximum monthly snow mass (kg m -2 ) in Canada, 1980-1997 (Brown et al. 2003)

14. Current Snow Depth (7 Nov. 2006)

15. Northern Hemisphere Variability

16. North American Variability

17. Eurasian Variability

18. Monthly Eurasian normalized snow cover extent anomalies

19. Interannual variability Source: Karl et al. (1993).

20. Role of snow in the global climate system

21. Annual cycle of daily discharge in Skeena River (1955-2004) freshet

22. Variation of peak discharge with latitude for 42 Hudson Bay rivers Source: Déry et al. (2005), J. Climate.

23. Contribution of snow to river runoff Source: Barnett et al. (2005).

24. Teleconnections Definition: Atmospheric interactions between widely separated regions that have been identified through statistical correlations (in space and time). For example, the El Niño teleconnection with the Southwest United States involves large-scale changes in climatic conditions that are linked to increased winter rainfall.

29. Correlation coefficient between annual Eurasian snow extent anomalies & discharge anomalies the following year in 64 rivers of northern Canada Source: Déry et al. (2005), JGR.

30. Indicators of global change Snow depth, swe, density, albedo & temperature (heat content) Duration of snow cover & growing season Snowmelt/spring freshet date Soil moisture

31. Snow depth Source: Curtis et al. (1998), Int. J. Climatology

33. Trend (%) in April lst swe, 1950- 1997 Source: Mote et al. (2005), BAMS

34. Albedo Source: Stone et al. (2002), JGR.

35. Trend (days/year) in snow cover duration, 1972-2000

36. Snowmelt Date Source: Stone et al. (2002), JGR.

37. Trend in centre of volume in river discharge across western N. America Source: Stewart et al. (2005), J. Climate.

38. Changes in annual cycle of pentad discharge for the Skeena River Source: Déry et al. (2006), in preparation.

39. Trends in river runoff & air temperature in Skeena River Basin

40. Trends in river runoff & precipitation in Skeena River Basin

41. Future projections & implications of global change

42. Components of the climate system

43. 21 st century global climate model simulations of surface air temperature IPCC 3 rd Assessment

44. 21st century global climate model simulations of precipitation

45. IPCC 4 th Assessment Runs

46. Trends in Northern Hemisphere snow cover extent Source: Déry et al. (2006), JGR.

47. Projected change in seasonal snow cover frequency based on GFDL CM2 simulations (21 st - 20 th century) Projected change in frequency -0

48. Trends in Northern Hemisphere snow mass

49. Projected change in seasonal snow water equivalent (swe) based on GFDL CM2 simulations (21 st - 20 th century) Projected change in swe (mm)

51. Implications of global change Increase in planetary albedo (positive feedback on global warming) Decreasing water resources, including soil moisture Longer growing season Impacts on recreational activities Ecological implications

52. Further reading:

53. Online resources: Canadian Cryospheric Information Network: http://www.ccin.ca/ http://www.ccin.ca/ National Snow and Ice Data Center: http://nsidc.org/http://nsidc.org/ National Operational Hydrologic Remote Sensing Center: http://www.nohrsc.nws.gov/http://www.nohrsc.nws.gov/ BC Ministry of Environment: http://www.gov.bc.ca/env/ http://www.gov.bc.ca/env/ Rutgers Global Snow Lab: http://climate.rutgers.edu/snowcover/ http://climate.rutgers.edu/snowcover/

55. Thank You!! http://web.unbc.ca/~sdery/