palaeo-atmospheric composition

Question 1

Name three proxies that can be used to reconstruct palaeo carbon dioxide levels in the atmosphere

Answer 1

Air measured in the ice core records, boron isotopes, stomatal density on the leaves of plants can all be used to provide a measurement of past carbon dioxide levels.

Question 2

Carbon dioxide enters a leaf through its stomata. Is the density of stomata high or low during periods of increased carbon dioxide?

Answer 2

With increasing levels of carbon dioxide, the density of stomata on leaves reduces.

Question 3

When do records suggest that the first ice formed on Antarctica?

Answer 3

Glaciation of the Antarctic continent first occurred at the Eocene-Oligocene boundary (approximately 34 million years ago).

Question 4

What are benthic oxygen isotopes used as a proxy to measure?

Answer 4

Benthic oxygen isotopes are a combined measure of bottom water temperature and global ice volume.

Question 5

Is the glaciation of Antarctica associated with increasing or decreasing levels of atmospheric carbon dioxide?

Answer 5

The increase in ice on Antarctica during the Eocene-Oligocene boundary was associated with a significant decline in atmospheric carbon dioxide.

Question 6

Which warm period in Earth history has been targeted in order to understand what the world might look like under current climate warming scenarios?

Answer 6

The mid or Late Pliocene warm period is the most recent time in Earth history where mean global temperatures were warmer, providing an example of what models estimate could be the Earth of the late 21st Century.