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

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

Antarctic Peninsula melt - Mean annual air temp

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

Faraday/Vernadsky mean annual temperature Source: BAS

Faraday/Vernadsky – seasonal trends Source: BAS

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

Source: Andy Smith …quantitative – Rothera ramp

Antarctica Peninsula - orientation

Annual PDDs

Antarctic Peninsula melt - Station trends

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) (r 2 = 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) (r 2 = 0.79).

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

Antarctic Peninsula melt - Mass balance and runoff

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 Runoff was calculated. At present it is ( ) mm a -1 of sea level rise with the likelihood that with continued warming it will perhaps treble within 50 years. Increasing uncertainty

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

Sheldon Glacier

Analysis of glacier-front changes Extract from table showing mean change per year observed in 5-year intervals

Change in glacier length

Complete population

Latitude Sectors

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

Tracking features in radar (SAR) images SAR1SAR2 measurement = (glacier flow) & (orbit offset) random error systematic error +35 days

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

Tracking features in radar (SAR) images 0 md scenes km glaciers 9 summers

Change in flow speed 1993 to 2003 Change in flow speed % that accelerated +7.8 %60% %65% %65% %67% % (± 0.5 to 0.7%) 75% (by > 5%)

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

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

Conclusions 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%, ): at least 0.06 mm /yr Total: 0.19 mm /yr Alaska melt (Arendt et al. 2002): 0.14 mm/yr

Conclusions