The Sun's Influence on Climate by Haigh Joanna D

Author:Haigh, Joanna D.
Language: eng
Format: epub
Publisher: Princeton University Press
Published: 2015-03-16T16:00:00+00:00

PALEOCLIMATE TEMPERATURE RECORDS

A record of the deuterium ratio, representing temperature, in an ice core retrieved from Vostok in East Antarctica is shown in Figure 6.1. The roughly 100,000-year periodicity of the transitions from glacial to warm epochs is clear and suggests a relationship with the variations in eccentricity of the Earth’s orbit around the Sun (see the discussion in Chapter 4), although this variation does not explain the steep transitions from cold to warm. Evidence of very long term temperature variations can also be obtained from ocean sediments. The skeletons of calciferous plankton make up a large proportion of the sediments at the bottom of the deep oceans, and the oxygen isotope ratio within these is determined by the temperature of the upper ocean at the time when the living plankton absorbed carbon dioxide. The sediment accumulates slowly, at a rate of perhaps 1 m every 40,000 years, so that changes over periods of less than about 1000 years are not detectable, but ice age cycles every 100,000 years are clearly portrayed.

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