Pearson and Palmer, 1999 (Seawater pH and atmospheric CO2)

Question 1

The carbon dioxide content of the atmosphere (partial pressure) affects the content of the … …, which in turn affects seawater …

Answer 1

surface ocean, pH

Question 2

The … isotope composition of contemporaneous planktonic … that calcified their … at different water depths can be used to reconstruct the …-… profile of ancient seawater.

Answer 2

boron, foraminifera, tests, pH-depth

Question 3

Construction of a pH profile for the middle … tropical … ocean shows that … … was probably similar to … concentrations or slightly ….

Answer 3

Eocene, Pacific, atmospheric pCO2, modern, higher

Question 4

Earth’s climate has … markedly in the last … million years from a peak of warmth in the early …. One hypothesis for why this may be is that…

Answer 4

cooled, 50, Eocene

concentrations of greenhouse gases, especially CO2, have declined in the atmosphere

Question 5

The middle-late Eocene is the period of greatest uncertainty in … …

Answer 5

CO2 concentrations

Question 6

The 𝛿^11B of … … may provide a direct measure of atmospheric pCO2 as it reflects the pH of the surface seawater in which the organisms …, which is closely dependent on …

Answer 6

foraminiferal calcite, calcified, pCO2

Question 7

The best estimate of pH gives an estimated pCO2 of … to …, only slightly higher than modern concentrations (in 1999 - current ppm of CO2 are actually around 407)

Answer 7

370, 400

Question 8

If this estimate of middle Eocene pCO2 is correct, it implies either that Earth’s climate is very … to small changes in pCO2, or that the global cooling since the Eocene was not…

Answer 8

sensitive,

driven by changes in pCO2

• but rather reflects reorganisation of ocean circulation resulting from tectonic opening and closing of oceanic gateways