Pearson and Palmer, 2000 (Atmospheric CO2 conc over past 60my)

Question 1

Atmospheric CO2 concentrations in the early … era (about 60 million years ago) are widely believed to have been … than at present, although there is disagreement regarding the exact levels, the timing of the … and the … that are most important for the control of CO2 concentrations over geological timescales

Answer 1

Cenozoic, higher, decline, mechanisms

Question 2

This study used the same boron-isotope ratios of ancient planktonic … shells to estimate the pH of …-… sea water throughout the past 60 my, used to reconstruct atmospheric CO2 concentrations.

Answer 2

foraminifera, surface-layer

Question 3

It estimates CO2 concentrations of more than … for the late … and earliest … periods (from about 60 to 52 Myr ago) and an erratic decline between 55 and … Myr ago`

Answer 3

2000ppm, Palaeocene, Eocene, 40

Question 4

This decline may have been caused by reduced CO2 … from ocean …, … and metamorphic belts and increased carbon ….

Answer 4

outgassing, ridges, volcanoes, burial

Question 5

Since the early … (about 24 Myr ago), atmospheric CO2 concentrations appear to have remained below … ppm and were more … than before, although … intervals of CO2 reduction may have occurred during periods of rapid cooling approximately 15 and 3 Myr ago.

Answer 5

Miocene, 500, stable, transient

Question 6

Rise in atmospheric CO2 concentration –> more CO2 … in … … –> reduction in …

Answer 6

dissolved, surface ocean, pH

Question 7

To arrive at pH estimates that most closely reflect atmospheric pCO2 it is necessary to measure the boron isotopes of carbonates that were precipitated far from … influences and sources of …

Answer 7

coastal, upwelling

Question 8

In this study, ocean … over time was also estimated (alongside pH) to help estimate atmospheric pCO2 over time

Answer 8

alkalinity

Question 9

Since the earliest Miocene the carbon system seems to have been much more … and … to the present, despite continuing climate cooling. This suggests other factors, such as … activity, were also important in determining global climate change

Answer 9

constant, comparable, tectonic