1. Using a climate change story to
teach about large lake processes
Jay Austin
Associate Professor
Large Lakes Observatory /Department of Physics
University of Minnesota Duluth
Teaching Climate Change:
Lessons from the Past
20 June, 2012

3. The Past and Present
• The Past: What sorts of records allow
us to reliably look into the past?
• The Present: How do we understand how
Lake Superior is changing right now?

6. Sault Ste. Marie, 1906-2006
(“the past”)

7. SSM, July-September avg.

8. SSM, July-September avg.

9. Global AT average

10. Global AT average

11. Comparing SSM to globe

12. Comparing SSM to globe
~0.1C/yr

13. Regional Air Temperature
Anomaly
~0.06C/yr

14. NOAA’s NDBC buoys
(“The Present”)
• Three buoys in Lake
Superior
• 1979-Present
• April-November
• AT,WT, WS/WD
• (also buoys in other
lakes)

15. 45006
* 45001
* 45004
* 45006

16. NDBC 45001 (Central)
Water Temperature, July-Sep
~0.1C/yr

17. NDBC 45001 (Central)
Water Temperature
(Max.
Temperatures)
~0.12C/yr

18. Lakes around the world

19. Freshwater Density

20. Summer stratification
Warm water overlies cooler
water- surface layer can be
relatively thin (~10-30m)

21. Winter Stratification
Cool water overlies warmer water-
surface layer very deep- often
comprises entire water column

23. Start of Stratified season

24. Central Buoy WT, 2006
Max temp., mid August
Fall Cooling
Rapid warming
Buoy recovered
Slow warming
Summer Overturn

25. Two extremes-
1996 (cold) and 1998 (warm)
1998
1996

26. Ice Cover in Decline

28. Magnuson et al. 2000
Formation dates
Breakup dates

29. Magnuson et al., 2000

30. Howk 2008

31. Summer Overturn date depends
on last winter’s ice cover

32. Summer Water Temperature
depends on last winter’s ice cover
(1998)

33. Length of season
10d later/century
12d earlier/century
22d longer/century

34. Acknowledgements!