2. Late Quaternary environments of the dry tropics and subtropics Ô North Africa Ô Arabia - India Ô Australia Ô South Africa Ô South America

3. Saharan dust In the journal of his voyage aboard HMS Beagle in 1833, Darwin commented on the “atmospheric dust” off the Cape Verde Islands, “dirtying everything on board”. In 1844 Ehrenberg was surprised to find that the valves of freshwater diatoms comprised a substantial component of Darwin’s dust samples. Recent samples (e.g. those collected in 1982 aboard the French research vessel Le Chinon) demonstrate that about 50% these diatoms belong to planktonic taxa such as Aulacoseira.. The remainder are freshwater benthics. Where do they come from?

4. Saharan dust storm over adjacent Atlantic Ocean and ODP core site image: terra.nasa.gov ODP658C Arrows indicate dominant winter wind direction HMS Beagle

5. ODP658C core log deMenocal et al., (2000) Quaternary Science Rev., 19, 347-361

6. Dust sources: dried beds of early-mid Holocene Saharan lakes Relict shorelines (in background), L. Asal, Djibouti (PAGES News) Yardangs in lake sediments, C. Sahara

7. Summer monsoon climates of N.Africa and the Near East SE Trades SW Monsoon <100 mm >1000 mm May 01- Sept 31

8. Four N. African palaeosites 1. Sebhka Mellala 3. Oyo (West Nubia) 5. Fayum 2. Lake Chad 4. Lake Abhé 1 2 3 5 4

9. Palaeo-lake deposits, Sebhka Mellala, Algeria 8.2 cal ka cold snap

10. Lake Chad: recent hydrological changes http://edcwww.cr.usgs.gov/earthshots/slow/LakeChad/LakeChad 1963 1997 50 km

11. Lake Mega- Chad 1100 ft (300m) shoreline dates to ~20-30 ka BP. L. Mega-Chad covered ~600 000 km 2 and was ~200 m deep Bougdouma Kajemarum

12. Palaeo-lake deposits, Bougdouma, Niger

13. Late Holocene climate change, Kajemarum Oasis, NE Nigeria from: Holmes et al., (1998) J. Paleolimnology, 20, 369-380 deep fresh shallow saline

14. West Nubian sites

15. West Nubian palaeo- lake Hoelzmann et al. (2001) Palaeo 3 169, 193-217.

16. Pollen evidence from: Roberts, N. (1996) “The Holocene”, 2° ed.

17. Lake Ahbé, Ethiopia ~4200 cal yr BP

18. Variations in Nile discharge The Nilometer at Roda (A.D.641 - present) Said (1993) “The River Nile: Geology, Hydrology and Utilization” Pergamon Press

19. Nile flow (9000 - 300 BC)

20. Lake Moeris (Fayum depression) 9 8 7 6 5 4 3 2 1 0 ka BP +25 0 -25 -50 Elevation (m, asl) Birket Qarun ??

21. The end of the humid period and the demise of the Egyptian Old Kingdom (2180 BC; ~4200 cal yr BP) Lo, the desert claims the land Towns are ravaged, Upper Egypt became a wasteland Lo, everyone's hair [has fallen out] Lo, great and small say, "I wish I were dead" Lo, children of nobles are dashed against walls Infants are put on high ground Food is lacking Wearers of fine linen are beaten with [sticks] Ladies suffer like maidservants Lo, those who were entombed are cast on high grounds Men stir up strife unopposed Groaning is throughout the land, mingled with laments See now the land deprived of kingship What the pyramid hid is empty [The] People are diminished. (Egyptian sage, Ipuwer)

22. S.W. Egypt* * Malville et al., (1998), Nature 392, 488-491; ** (discharge units are billion cumecs/yr) arid wet arid 11 10 9 8 7 6 5 4 3 2 1 0 ka BP Oyo, Sudan L. Fayum L. Ahbé, ≥200 ≤100 low dust influxhigh dust influx ODP685C Lake Chad S. Mellala high drylow inter. Nubia Nile R.**

23. Vegetation of north and central Africa: 8000 ka BP pink = desert; pale yellow = grass savanna http://www.uni-mannheim.de/phygeo/8000BP.htm

24. Rock art, Tassilli and Ennedi massifs, central and eastern Sahara a and c: http://ennedi.free.fr/ b c a a= mouflon; b, c = giraffes

28. Sites in Arabia and Pakistan Yemen Oman Thar desert 74KL

29. 74 KL:  18 O, dust deposition and CaCo 3 production Dust minimum 7850 8850

30. Holocene climate change in Arabia 11 10 9 8 7 6 5 4 3 2 1 0 ka BP Rock hyrax (Procavia capensis) middens agriculture Archaeological record abandoned villages http://www.usgs.gov/public/press/ public_affairs/press_releases/pr1482.html Data from: increasing aridity and/or overgrazing 5.2 2.5 wet hyperarid YEMEN OMAN Calcite deposition rate in Hoti Cave (Neff et al., (2001) Nature, 411, 290-292. mm/yr 1 0 74 KL dust minimum

31. Indian subcontinent: Thar desert

32. Thar desert paleolake record

33. Changing palaeo- climates in southern Africa: the Mega- Kalahari

34. Dune- activity phases, southern Africa from: O’Connor and Thomas (1999) Quaternary Research, 52, 44-55.

35. Monsoon palaeoclimate sites, NW Australia 1 2 1. Gregory Lakes 2. Fitzroy R. basin NE Trades (Nov. -April)

36. Late Pleistocene pluvial phases in NW Australia from: Bowler et al., (2001) Quaternary International, 83-85, 63-80.

37. Post- glacial monsoon initiation from: Wrywoll and Miller (2001) Quaternary International, 83-85, 119-128.

38. Selected palaeoclimate sites, Atacama desert and neighbouring areas 0° 30°S 1 2 3 1. Salar de Atacama, Chile 2. Lake Titicaca, Bolivia 3. Galapagos archipelago Moche culture area

39. Late Quaternary wet phases, Salar de Atacama from: Bobst et al., (2001) Palaeo 3, 173, 21-42.

40. Late Holocene climatic variation, Bolivian altiplano from: Abbot et al., (1997) Quaternary Research, 47, 169-180 Moche culture

41. A 6000-yr record of El Niño activity from the Galapagos Islands Bainbridge Crater Lake

42. Millenial-scale variablity of El Niño events in the Galapagos Islands Data: Riedinger et al., (2002) J. Paleolimnology 27, 1-7. 435 events in last 6000 years Bainbridge Crater Lake During moderate El Niño events the surface waters of this hypersaline lake become relatively fresh and carbonates are precipitated; during severe events there is erosion of the crater walls into the lake. Laminae in the organic-rich salts that have collected on the lake bed record these events