Orbital forcings The ocean-atmosphere system: primary responses to orbital forcings ATMOSPHERE OCEAN temperature humidity CO 2 winds GLACIAL volume temperature CO 2 currents INTERGLACIAL

The oceanic d 18 O record: 80-90% RSL response; 10-20% temperature response?

SST changes from LGM to present in coastal waters of N. California (~100 km offshore?)

Radiolarian assemblages in core 1019 (989 m water depth) green line = GISP2  18 O record; black line=radiolarian record T1 YD

Primary productivity and zones of coastal upwelling image: terra.nasa.gov

Pelagic diatom assemblages of the N. Pacific (e.g. Okhotsk Sea cluster = one of three subarctic water masses, shown in black) from: Sancetta & Silvestri (1986) Paleoceanography 1, V V V RC10-216

“Okhotsk cluster” through time

RSL -temperature - salinity interactions in the Red Sea Low RSL = hypersaline Red Sea = no planktonic forams from: Rohling et al. (1998) Nature, 394,

A Heinrich layer (H-1) in a deep-sea core pelagic ooze ooze H - layer (ooze-filled burrows?)

Iceberg-rafted detritus (IRD) in H1

Heinrich events in the North Atlantic Ocean

Oceanographic effects of drifting icebergs >200 m drift cold fresh water nutrient- deficient nutrient-rich detritus

Heinrich (5-10 ka) events and Bond cycles (~1.5 ka) in VM23-81

N. Atlantic currents: iceberg-drift routes

The N. Atlantic ‘gate’ and the ‘binge- purge’ cycle of the Laurentide ice sheet Ocean ‘polar front’ cold warm

Dansgaard-Oeschger cycles and Heinrich events

Thermohaline circulation

Binge and purge: is there a Heinrich record in Antarctica? antiphasing?

Inferred Late Glacial and Holocene SST (Aegean Sea) from: Geraga et al., (2000), Palaeo 3, 156, 1-17 YD H1 SST C(org)%

Sapropel stratum in a core from the eastern Mediterranean (“sapro” = putrid - refers to high C org content); “pel” = mud

Episodes of sapropel formation in the last years in the eastern Mediterranean from: Kallel et al., (2000), Palaeo 3, 157, S1 S3 S4 S5 S6 S7 30°N

Laminated sapropel deposits from: Kemp et al., (1999), Nature, 398, 57-61

Sapropels: annually laminated diatom mats from: Kemp et al., (1999), Nature, 398, 57-61

Sapropel formation hypothesis after Kemp et al., (1999), Nature, 398, (see Sancetta (1999), Nature 398, for discussion) Greater freshwater runoff to eastern Mediterranean (heavy rainfall in Nile headwaters and in Med. Basin); leads to: Enhanced stratification of surface waters, produces ‘nutricline’ across surface halocline; leads to: Massive bloom of diatoms adapted to stratified waters (chiefly Rhizosolenia spp. and Hemiaulus hauckii). Winter mixing of water column causes mass sinking of diatom mats. Mixing brings nutrients to surface, promoting conventional near- surface winter blooms of mixed diatoms.

Freshwater sources in the Mediterranean base map from: Kallel et al., (2000), Palaeo 3, 157, 45-58

Sapropels and climate of the Nile basin S1a S1b “sapropelic” Eastern Mediterranean sedimentary record* Eastern Saharan sedimentary and archaeological record** * Geraga et al., (2000), Palaeo 3, 156, 1-17 ** Malville et al., (1998), Nature 392, arid wet arid ka BP

Location of core 74 KL in the Arabian Sea

74 KL:  18 O, dust deposition and CaCo 3 production Dust minimum

Sahara dust storm over adjacent Atlantic Ocean image: terra.nasa.gov

Dust accumulation and palaeoproductivity (core Meteor 12392: on continental rise offshore of Spanish Sahara)

Japan Sea dust record Dust source: Mongolia/N. China

Iron fertilization experiment: polar Southern Ocean (I) days from: Boyd et al., (2000), Nature 407,

Iron fertilization experiment: polar Southern Ocean (II)

Mechanisms of CO 2 drawdown

CO 2 drawdown (Vostok)

Iron fertilization experiment: polar Southern Ocean (III)

DMS makes clouds “brighter than white” from: Charlson et al., (1987) Nature 326,

Points to consider Ocean/atmosphere temperature - CO 2 - sea ice feedbacks. Continental climates and oceanic responses: dust exports and palaeoproductivity; monsoonal rains and sapropels; glacial surging and THC switching. Palaeoproductivity patterns: consider effects of currents, RSL and marine food chains.