Earth’s climate history
Jan 22, 2016
Earth’s climate history
Cenozoic cooling
CaCO3 is taken up by marine organisms
CoccolithophoridForaminifer
... as is SiO2
Diatom (SiO2) (50microns)Radiolarian (SiO2) (50 microns)
Carbon reservoirs today
Destination of atmospheric CO2
Inorganic carbon cycle
Carbon ends up here
Volcanic eruptions main source of CO2
BLAG model – spreading rates sometimes fast, sometimes slow
Pre-Quaternary atmospheric CO2 levels cannot yet be directly determined.
Can be modeled from the carbon isotope record?BLAG (Berner, Lasaga, Garrels) Model
Steady-State Flux Balance EquationFwc +Fmc + Fwg = Fbc + Fbgw: weatheringm: metamorphismb: burialc: carbonateg: organic
Ocean andatmosphere
C
CarbonateC Organic
C5000
1250
2.9
Fwc Fwg
FbgFbcFmc Fmg
Climate through Earth history
Cenozoic cooling
Spreading rates have decreased over last 65 million years
Silicate rock weathering
Weathering rates increase over Cenozoic
• Does the amount of high elevation terrain result in unusual physical weathering?
• Most likely given 10 fold increase of sediment to the Indian Ocean– Steep terrain along
southern Himalayan margin
– Presence of powerful South Asian monsoon
Tibetan plateau
Changes in amount of uplift of continental rockcould regulate amount of weathering
“Upliftweatheringhypothesis”
Uplift mainlywhen continentscollide
Climate through Earth history