65Ma of climate change: biogeography of the Cenozoic era

1. 65Ma of climate change: biogeography of the Cenozoic era Mean annual temperatures in NW Europe and NW North America (reconstructed from pollen data) shown in red

2. Cenozoic climate change: the record from sub-Antarctic waters thermal maximum

3. Pal(a)eocene biogeography Start: http://www.scotese.com/paleocen.htm

4. Northern hemisphere biogeography in the early Cenozoic (Paleocene/Early Eocene thermal maximum @ 55My BP) • Arctic Ocean fresh (floating mats of Azolla algae); • CO2 ~2000 ppm (cf. 380 ppm @ PD) • Arctic MAT increased from ~18°C (Paleocene) to ~23°C (cf. -20°C @ PD) • Early mammals (ancestors of all major groups) likely originated in Asia in late Paleocene and apparently migrated across the northern continents at or about the time of the thermal maximum. Sources: Bowen, G.M. et al. 2002. Mammalian Dispersal at the Paleocene/Eocene Boundary. Science295: 2062 - 2065. Sluijs, A. et al., 2006. Subtropical Arctic Ocean temperatures during the Palaeocene/Eocene thermal maximum. Nature, 441: 610-613.

5. Early Tertiary coal deposits, Axel Heiberg Island(stumps are dawn redwood: Metasequoia)

6. Plant macrofossils from early Tertiary coalbeds, Axel Heiberg Island

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

8. Major Eocene-Oligocene fossil flora sites in the PNW Eugene John Day N.M.

9. Eo-Oligocene biogeography of the Pacific NW • John Day Fossil Beds National Monument, Oregon • Current vegetation: sagebrush “high desert”; mean ann. ppt ~200 mm.

10. John Day chrono-stratigraphy

11. Deciduous riparian forest (alder- elm-hickory-walnut), east-central Oregon(Whitecap Knoll beds; late Eocene)

12. Eocene-Oligocene fossil beds near Eugene, Oregon Warm temperate forest (alder-oak-sycamore-sweet clover [Meliosma], dawn redwood [Metasequoia] Source: Retallack, G.J. et al., 2004.Eocene-Oligocene extinction and paleoclimatic change near Eugene, Oregon. Geological Society of America Bulletin, 116, 817-839.

13. Mid-Cenozoic paleoclimate;west-central Oregon Eugene @ PD: MAT ~11°C; P ~1300 mm Source: Retallack, G.J. et al., 2004.

14. Cenozoic climatic decline and the onset of glaciation

15. 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.

16. Holocene The Quaternary: endpoint of Tertiary cooling 10 ka Pleistocene Tertiary Quaternary 1.67 Ma Pliocene Colder - Warmer

17. When did the first cold phase occur? IRD = iceberg-rafted detritus Colder - Warmer IRD

18. Vegetation of Late Pliocene Holland Local extinctions after the first cold phase cold ~ 2.4 Ma = beginning of Quaternary?

19. Ice and Change:Quaternary Biogeography Nature of the evidence Chronology Fluctuating climates Glacial phases Interglacial phases

20. Iceworld: Wisconsinan glaciation storm paths

21. Glacial - interglacial seesaw: e.g. 9 glacial phases in last 0.7 Ma?

22. Assemblage Palaeotemperatures (50 - 20 ka BP) in Britain derived from beetle assemblages l Polar lll Cold continental ll Oceanic Polar l Species ranges

23. Pollen analysis:identification based on shape and ornamentation of grain

24. Pollen “rain” Lakes Bogs

25. Pollen analysis results:% pollen and pollen influx

26. The last interglacial - glacial cycle slow cooling quickwarming quickwarming ~ 100 ka Glacial / periglacial areas

27. European vegetation distribution: 13 ka BP (= late glacial)

28. Full-glacial vegetation of eastern North America Laurentide Ice Sheet

29. Bio-indicators of lowered sea level in late Quaternarymammoth teeth freshwater peat oolites(= lake deposits)all continental shelves exposed in glacial phases

30. Exposed continental shelves = land bridges

31. Trans-Beringia mammal migrations during the Quaternary Beaver Lynx Snow & mountain sheep Moose Elk Bears Wolverine Wolf Arctic fox Arctic hare Bison Mountain goat Coyote Kit fox Camels Horse (and humans)

32. Beringia: Arctic fish refuge? refuge? refuge?

33. Multiple trans-Beringian migrations: the Bison case Bison priscus Bison bison Bison antiquus

34. Quaternary fluctuations in precipitation in the western US “Provo” relict shoreline, Lake Bonneville http://wwwpaztcn.wr.usgs.gov/rsch_highlight/articles/200409.html

35. Lake levelsin US Southwest; full - late glacial phase = “pluvial”

36. Elevation - vegetation relations, Grand Canyon area:full-glacial was cooler and wetter

37. Douglas-fir: a refuge relict in the Mexican Sierras? pine - fir forest Glacial Interglacial

38. Glacial -interglacial migrations(e.g. Holocene) Interglacial range Glacial refuge

39. Refuges and migrations: individualistic patterns

40. Refuges and migrations: aquatic biota

41. Postglacial migration paths: aquatic biota Glacial refuges

42. Ranges and refuges: the tropical biotas

43. Inferred glacial refuges in tropical areas:an extreme view

44. Climatic deterioration during interglacialphases ?

45. Climatic optima in early interglacial time: the driving forces

46. Evidence for the Holocene hypsithermal The early part of the Holocene is generally considered to have been a “climatic optimum” with higher temperatures (and lower rainfall?) than at present. Can you find evidence of this in the pollen records from the Pacific Northwest?

47. Elsewhere, the ‘hypsithermal’ may have been wetter: (e.g. the central Sahara) Eroded lake beds, Taouendi Rock art, Tassili Massif

48. Pollen evidence (after Ritchie)