2. The Contribution of Alaska's Glaciers to Global Sea Level Rise
Keith Echelmeyer, William Harrison, Craig Lingle, Martin Truffer, Anthony Arendt, Virginia Valentine, Sandy Zirnheld University of Alaska Fairbanks

3. Outline Introduction Measuring volume changes Alaskan glacier changes
Future changes
Effects of glacier changes

4. Glaciers in the Arctic Total volume corresponds to ~8 m of sea level
Greenland 1,64 Mio km2
Canadian Arctic Mio km2
Alaska 0.09 Mio km2
Total volume corresponds to ~8 m of sea level

5. Mike Fleming, USGS

6. Measuring changes: The traditional method

7. Laser altimetry system

8. Calculating volume changes

9. about 100 glacier measured
(out of several thousand)

10. Regional volume change

11. Total volume change 3300 km3 since 1950s
enough to cover state of Alaska in 7 ft of water
(or Texas in 15 ft)

12. Contribution to Rising Sea Level
Time Period
Volume Change
(km3 WE/yr)
(mm/yr Sea Level EQ)
Early: 1950s to 1990s
-46  7
0.13  0.02
Recent: 1990s to 2001
-88  28
0.24  0.08

13. Assessing future changes
Use models to relate climate to current and past mass balance
Derive sensitivity factors for glaciers in different climate regimes (see Arendt et al poster)
These models only apply to current glacier geometry
Long term predictions need to take glacier dynamics into account

14. Complications
Glaciers with flow instabilities can show a variety of complex behavior:
Surging glaciers
Tidewater glaciers

15. 1965
1964
Austin Post, USGS

16. Surging glaciers Surge: no appreciable change in total mass
complete reversal of geometry
quasi periodic phenomenon
not (or weakly) related to climate

17. Tidewater glacier cycle: Glacier Bay
120 km

18. Tidewater glaciers Tidewater glacier cycle:
very rapid retreat (decades)
slow advance (centuries or more)
not directly related to climate

19. Effects of volume change
Sealevel rise: currently ~0.24 mm/a
Coastal currents

20. Alaska Coastal Current
Greenland 1,64 Mio km2
Canadian Arctic Mio km2
Alaska 0.09 Mio km2

21. Effects of volume change
Sealevel rise: currently ~0.24 mm/a
Coastal currents
Isostatic uplift

22. Larsen et al, 2003

23. Conclusions
Alaska provides the biggest current glacial contribution to sea level rise
Assessing the reactions to future climate change requires regional mass balance models
Glacier dynamics can pose significant challenges for such an assessment

24. Thank you

25. Glacier changes

26. Variations of the Earth’s surface temperature: past 1000 years.
(source: IPCC 2001)

27. 1895 ~1860 1790 Situk River ~1130 Yakutat Airport 5 miles
Hubbard
Glacier
1895
~1860
1790
Russell
Nunatak
Russell
Nunatak
Fiord
Fiord
Fiord
Fiord
Yakutat Bay
Situk River
~1130
Yakutat Airport
5 miles
Dennis Trabant, USGS

28. Grand Pacific Glacier
Glacier trim line (~1000 m asl)

29. Example of modern tidewater glacier retreat: Columbia Glacier