Recent decades of climate and cryospheric change on the Antarctic Peninsula

1. Recent decades of climate and cryospheric change on the Antarctic Peninsula David G. Vaughan British Antarctic Survey

2. Climate Warming - Antarctica Source: Vaughan et al. Climatic Change, 2002

3. Antarctic Peninsula melt - Mean annual air temp

4. Part 1 - More melt… Vaughan, D.G., 2006: Recent trends in melting conditions on the Antarctic Peninsula and their implications for ice-sheet mass balance. Arctic, Antarctic and Alpine Research, 38(1), pp. 147-152.

5. Faraday/Vernadsky mean annual temperature Source: BAS

6. Faraday/Vernadsky – seasonal trends Source: BAS

7. Antarctic Peninsula Fossil Bluff 1985/86 Fossil Bluff 1996/97 Source: DGV

8. …quantitative – Rothera ramp Source: Andy Smith

9. Antarctica Peninsula - orientation

10. Annual PDDs

11. Antarctic Peninsula melt - Station trends

12. Parameterisation of ann. temp vs. PDDs Figure 3. Correlation of mean annual air temperature to positive degree-days for all Antarctic Peninsula station data. East coast sites are represented by open circles and have a best fit regression line (solid) of, Φ = 1089 e (0.261 T / ˚C) (r2 = 0.84). West coast sites are represented by black triangles and have a best-fit regression line (dashed) of, Φ = 358 e (0.251 T / ˚C) (r2 = 0.79).

13. Melt-day distribution 1950 2000 2050 Figure 4. Distribution of annual positive degree-days calculated for a. 1950 (i.e. 2000 – 2.5˚C), b. 2000 and c. 2050 (i.e. 2000 – 2.5˚C).

14. Antarctic Peninsula melt - Mass balance and runoff

15. Conclusions • Long-term meteorological station data show increased duration of melt conditions across the Antarctic Peninsula over the past 50 years • Parameterization of the number of PDDs as a function of mean annual temperature allows mapping of change • Increasing surface ablation was estimated and shown to be likely to have doubled between 1950 and 2000, and given continued summer warming could double or treble by 2050. • Runoff was calculated. At present it is (0.008 - 0.055) mm a-1 of sea level rise with the likelihood that with continued warming it will perhaps treble within 50 years. Increasing uncertainty

16. Part 2 - Shortening glaciers… Cook, A., A.J. Fox, D.G. Vaughan, and J.G. Ferrigno, 2005: Retreating glacier-fronts on the Antarctic Peninsula over the last 50 years. Science, 22, pp. 541-544.

18. Sheldon Glacier 1957 1969 1998 1986 2001

19. Analysis of glacier-front changes 1970- 1974 1975- 1979 1980- 1984 1985- 1989 1990- 1994 1995- 1999 Extract from table showing mean change per year observed in 5-year intervals

20. Change in glacier length

21. Complete population

22. Latitude Sectors

23. Part 3 - Faster glaciers… H. Pritchard and D.G. Vaughan, in prep.

24. measurement = (glacier flow) & (orbit offset) random error systematic error Tracking features in radar (SAR) images SAR1 +35 days SAR2

25. Tracking error: the case for azimuth-direction data 1) Range direction 2) range Azimuth direction azimuth 1 5

26. 0 md-1 4 0 15 30 Tracking features in radar (SAR) images • 150 scenes • 70 000 km2 • 337 glaciers • 9 summers

27. Change in flow speed 1993 to 2003

28. +8% 64°S +14% 10 % 0 +14% +13% +13% 68°S Retreat rate Cook et al. (2005)

29. Conclusions • Significant, widespread speed-up • Appears driven by retreat • Response to strong regional warming

30. Antarctic Peninsula contribution to sea level: • AP runoff: up to 0.06 mm /yr • Shelf collapse (Rignot et al. 2004): 0.07 mm /yr • AP flow imbalance (12%, 1993-2003):at least0.06 mm /yr • Total:0.19 mm /yr Conclusions Alaska melt(Arendt et al. 2002):0.14 mm/yr

31. Conclusions