High-latitude climate trends
what is d18O composition of benthic foraminifera samples a proxy of?
deepwater temperature, ice volume changes
what do the records of calcite mass accumulation rate suggest about the changes occurring/how many steps they occurred in
it suggests that they occurred in 2 steps
in what direction is the temperature and pressure gradient in the Pacific? (high temp --> low temp)
west--> east
Is there a clear, specific cause for global cooling?
No, there are various factors at play
Where glacial/interglacial events common in the last 4 Myr?
YES!
what did the d18O record indicate about the pliocene?
at high latitudes, pliocene temps were warmer than those of interglacial periods of the past million years.
Which monsoon systems impacted the subtropical sampling data?
African and Asian
what is the source of thermocline waters?
surface waters subducted at mid latitudes
How would you describe the transition from Pliocene (warm) - Pleistocene (cold)?
Gradual, slow, not so fast.
What was considered to be a major driving force for glacial/interglacial events before late Pleistocene?
Changes in Earth's tilt ---> variations in solar heating in different latitudinal regions.
did d18O composition increase or decrease from more ancient to more recent times?
increase
The second step of subtropical reorganization was during a time of high-latitude climate stability. How do we know?
how is el nino related to walker circulation?
What happens when deepwater formation regions at high-latitudes cool + deep water temperature & stratification increase + thermocline shoals?
Tropical-subtropical upwelling regions cool (positive feedback)
δ 18O suggests what about climate sensitivity in high latitudes?
It increased
what was some other evidence of northern hemisphere high-latitude climate reorganization? where in the figure(s) was this shown?
sudden increase in north pacific surface water stratification (fig 2c)
reduction in northern hemisphere ventilated thermohaline overturn rates
Which changes in CaCO3 were associated with changes in seasonality?
drop in accumulation rate.
Were pliocene warm period tropical waters warmer than today?
Yes.
If significant NHG occurs at the same time of cooling of subtropical regions, what does that suggests?
There is a link between high-latitude and subtropical climates (changes in one region e.g., deep water formation, thermocline, upwelling, etc.)
During what period did climate sensitivity in high latitudes reach its peak?
is higher glacier calving indicative of polar ice melt or ice formation?
ice formation in this case! can't calve glaciers if here are no glaciers
We know why CaCO3-MAR increase may be influenced by shoaling of the thermocline, but how can it be influenced by increase in windstress curl?
Windstress curl drives upwelling, which brings nutritious cold water up into the photic zone for coccolithophores to exploit.
which tropical climate transition did the development of walker circulation correspond with? when was it?
2nd! Between 2 and 1.5 mya.
What were the proposed factors that caused the global cooling in the Pleistocene and approximately for how long?
Gradual changes (~4-1.5 Myr) in greenhouse gas composition, basin geometry, and land-surface conditions
According to this paper, wat was the tipping point for obliquity-induced greenhouse-icehouse transition in the Pliocene? Despite solar forcing being present in the warm period, it didn't cause the same cooling effect.
Shoaling of the thermocline