Rates of forcing vs. response:
Rates of forcing vs. response
Slide26:
Zachos et al., 2001
Benthic foram d18O tracks deep ocean T and ice volume….
Uses “global” benthic foram d18O data set from >40 odp sites
Total Dd18O since 65 Ma = 5.4o/oo (if T alone = 22°C)
Dd18O from 51Ma to 34 Ma = 3o/oo (T drop of up to 12°C through 34 Ma) then a precipitous 1o/oo increase in d18O at 34 Ma that is about 60 to 90% ice build-up with the remainder a further decrease in bottom water T.
This event appears to correspond to the sudden buildup of a permanent Antarctic ice sheet……probably temperate in nature. The trigger appears to have been the opening of the Tasman/Antarctic gateway.
Antarctica glaciated @ ~50% modern ice volume until 26 Ma
“Warmer” from 26 Ma until about 15 Ma when “cooling” and Antarctic ice growth began again. Trigger? Not obvious….perhaps pCO2?
General cooling through Mio/Plio boundary, when West Antarctic ice growth was inferred – triggered by Panama seaway closure?
“Subtle warming” at about 3.2 Ma in the Pliocene, then continued cooling and d18O increase associated with growth of the northern hemisphere ice sheets.
Slide28:
Soft collision of India w/ S. Tibet----- Hard collision of India w/ Eurasia----- Opening of Antarctic gateways------ Closure of SE Asia deep passage----- Closure of Panama deep passage----- Africa moving northward ---------
Slide32:
(2001)
Slide34:
Naish et al., 2001
Slide35:
Naish et al., 2001
Slide36:
Pearson and Palmer, 2000