1. A Tale of Two Isotopes:
δ18O and δ13C

2. δ18O in benthic foram tests:
temperature effect: δ18O decreases by 1‰ for every 4.2oC increase in T
ice volume effect: δ18O in the deep ocean increases as ice sheets grow
δ13C in benthic foram tests:
nutrient effect: δ13C decreases as nutrient concentration increases
deep water formation effect: δ13C in the deep ocean increases as NADW formation decreases

6. Major features of climate record over last 5 Ma
gradual cooling
over past ~3 Ma,
with onset of
NH glaciations
switch from 41 ky
cycle to 100 ky
extreme amplitude
glacial/interglacial
transition
ODP Site 849 – eastern eq. Pac., 3839 m depth

7. Northeast Atlantic, 2179 m depth