GEOG 415 Advanced biogeography: Quaternary environments

1. GEOG 415Advanced biogeography:Quaternary environments Ian Hutchinson (RCB 7226) Office hours: Thursday 3:00-4:30 Office phone: 778.782.3232 email: ianh@sfu.ca

2. GEOG 415 - Housekeeping • Course email: geog415-all@sfu.ca • Lecture slides and all handouts will be posted on the course web site:www.sfu.ca/~ianh/geog415/ • Thumbnails of lecture slides (6/page) available from instructor • No text

3. GEOG 415 - Grades, etc. • Laboratory assignments: 30%(see schedule) • Term project: 30% • Final exam: 40%

4. Why study Quaternary environments? Reason #1 Modern landscapes, both physical and biotic (particularly at polar and north temperate latitudes), have been strongly influenced by Quaternary glaciations and associated environmental changes.

5. Why study Quaternary environments? Reason #2 Resource management decisions (e.g. groundwater utilization, peat extraction, placer mining, soil conservation, habitat management) may be considerably enhanced by an understanding of glaciology, Quaternary geology, and Quaternary palaeoclimates

6. Reason #3: the Quaternary is the period of hominid radiation Late Tertiary | Quaternary

7. Reason #4: The recent past may hold the key to the near future A) Is the current increase in global temperature merely a blip, within the domain of “natural variation”? B) Will global warming produce a super-interglacial? C) Will global warming shut down oceanic circulation, and initiate a new Ice Age?

8. Reason #4 (contd.) A) Domain of natural variation can be established by analysis of climatic and proxy environmental records for the late Quaternary; B) Previous “super interglacials” may be good analogues for current ‘global warming’; C) Phases of abrupt climate change in late Quaternary may provide clues to triggers forcing a switch to another climatic state.

9. Ice-Ages in geological history Permo- Carboniferous Quaternary Sturtian Varangian Gnejsö Ordovician 0 200 400 600 800 1000 million years BP

10. “Greenhouse””Icehouse” Strong circum-tropical current promotes efficient transfer of heat to polar areas Strong circum-polar currents inhibit transfer of heat to polar areas

11. Cenozoic climate decline Mean annual temperatures in NW Europe and NW North America (reconstructed from pollen) shown in red [based on Table 1.9 in Goudie (1992) “ Environmental Change”, Oxford. U.P.]

12. Tertiary cooling in sub-Antarctic waters: the drift to an icehouse world

13. What prompted Cenozoic climate decline and the onset of glaciation? Main factors: 1. Continental drift Isolation of Antarctica and initiation of sub-Antarctic oceanic circulation; ice-sheet formationIsolation of Arctic Ocean; sea-ice formation 2. OrogenesisIsolation of continental interiors, particularly of Central Asia, as a result of uplift of the Himalayas and Tibetan Plateau. High altitude areas = more snow cover = high albedo = regional cooling.

14. Palaeocene palaeogeography http://www.scotese.com/paleocen.htm

15. Oligocene palaeogeography http://www.scotese.com/oligocen.htm

16. Initiation of glaciation of Antarctica in the early Oligocene: the record from the Kerguelen Plateau Rapid northward movement of Australia after late Eocene Kerguelen Drake Passage (early Oligocene)

17. Uplift of the Tibetan Plateau Fig. 7.7 in Goudie (1992) “Environmental Change”

18. Tertiary cooling leads to Quaternary ice ages

19. Climatic decline in the Cenozoic

20. So if the Quaternary is defined as the most recent “Ice Age”, when did it begin? “perhaps the most stirring impression produced by recent great advances in the study of the Quaternary period is that the Quaternary itself is losing its classical identity” Flint, R.F. 1971. Glacial and Quaternary Geology, p. 2

21. Locating the Pliocene-Pleistocene boundary(Ma BP)

22. Quaternary time scale (ka BP)

23. Glaciations in the Alps:the Penck-Bruckner model (1909) “the great interglacial”

24. Quaternary temperature‘pulses’ interglacial glacial

25. Quaternary palaeothermometer: stable isotopes of oxygen Evaporation of a water molecule containing18O (‘heavy water’) requires ~12% more energy than one containing 16O. Condensation of ‘heavy water’ requires ~12% less energy.

26. 16O/18O ratios recorded in oceanic sediments Two sources of information: deep-sea cores or ice cores. Oceanic record primarily reflects changes in ice volume; ice-core record primarily reflects changes in temperature

27. Calcareous tests of planktonic foraminifera

28. d18O calculation (18O/ 16O) sample - (18O/ 16O) standard d18O = x 1000 (18O/ 16O) standard Results expressed as 0/00, ppt, or ‘per mil(le)’ Standards are: For forams: PDB (Pee Dee Formation belemnite from North Carolina); For water: SMOW (standard mean ocean water) = O0/00

29. Universality of the oceanic record(hence oxygen isotope stages)

30. The ice-core record ice crystals trapped air dust particles?

32. Spectralanalysisof Vostok d-18O time series Four superimposed pulses (105 ka, 41 ka, 23 ka, 19 ka), butwhat is the ‘pacemaker’?

33. Astronomical/celestial mechanics explanations:James Croll (1821-1890) • Scottishmechanic, hotelkeeper, life insurance salesman, janitor and scientist • Argued that greater orbital eccentricity led to colder winters and development of ice sheets in northern hemisphere

34. Orbital eccentricity(product of gravitational pull of other planets) aphelion perihelion

35. Croll’s model Ice Ages ~30% variation in solar radiation receipt between aphelion and perihelion at maximum eccentricity at 210 ka.

36. Milutin Milankovitch • Serbian physicist; elaborated Croll’s model of effects of periodic variations in Earth orbit: • 100 ka (eccentricity) • 41 ka (tilt) • 19-23 ka (precession)

37. Obliquity: axial tilt varies from 21.8° - 24.4° over 41 ka cycle as a result of rotational wobble strongly seasonal weakly seasonal

38. Precession of the equinoxes Precession results from changing position of North Pole. Pole position rotates because the Earth is not a perfect sphere; hence equinoxes change through year. At present northern hemisphere tilted toward sun ~ at aphelion.

39. Effects of astronomical forcings on summer solar radiation receipt at 65°N interglacials = warm northern summers? glacials = cool northern summers?

40. Synthesis of ocean-core evidence* late Pliocene (3.4 - 2.4 Ma): ice sheets in northern hemisphere small; extent controlled by small-scale quasi-periodic oscillations. early (Lower) Pleistocene (2.4 - 0.7 Ma): moderate amplitude climate changes controlled by 41 ka cycle of obliquity. late (Middle and Upper) Pleistocene (0.7 Ma - present): large amplitude climate changes controlled by 100 ka cycle of orbital eccentricity. * Ruddiman and Raymo 1988. Phil. Trans. Royal Soc., B318, 411-430

42. Solar activity and irradiance Image credit: NASA (Catania Astrophysical Laboratory)

43. Is global warming a product of increased solar activity? How do we track solar activity? 10-Be (“beryllium-10”) is a cosmogenic isotope that is produced when high-energy particles bombard Earth’s atmosphere. When the sun is “active” (during periods of increased sunspot activity) its magnetic field protects the Earth and little 10Be accumulates in ice and sediments. see:Benestad, R.E. (2002) “Solar Activity and Earth’s Climate”. Praxis

44. Solar activity and Earth’s climatic phases in the last 1150 yrs New Scientist, Nov. 12, 2003. Om Wm Sm Mm Dm MM “Medieval warm period” “ Little Ice Age”

45. Phases of solar activity in last millennium Approximate times of sunspot minima (Xm) AD 1000 - 1050Om =Oort minimum AD 1280 - 1340Wm =Wolf minimum AD 1420 - 1540Sm =Spörer minimumAD 1650 - 1710 Mm = Maunder minimumAD 1795 - 1825 Dm =Dalton minimum Approximate times of sunspot maxima (XM) AD 1100 -1230 MM = medieval maximum AD 1900 - 2000… (current maximum)

47. Future global temperature change scenarios (A, B, C) B 700 +5° 0° -5° CO2 (ppm) A 350 2000 2050 2100 C

50. Thermohaline circulation I = ‘The Great Salty”