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The geologic record of climatic change
Author(s) -
Crowley Thomas J.
Publication year - 1983
Publication title -
reviews of geophysics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 8.087
H-Index - 156
eISSN - 1944-9208
pISSN - 8755-1209
DOI - 10.1029/rg021i004p00828
Subject(s) - paleoclimatology , climatology , geology , ice sheet , climate change , global cooling , glacial period , atmospheric circulation , global change , ocean current , geologic record , ice age , sea level , environmental science , oceanography , paleontology
This paper reviews the principal results from paleoclimate studies and includes background material slanted toward climate modelers. The inferred temperature history of the last 4.6 billion years indicates major changes in the components of the earth's climate system. A secular change in global insolation receipt is due to a 20–30% increase in solar luminosity since the formation of the earth. A CO 2 ‐H 2 O greenhouse effect may have offset the lower luminosity during early earth history. Inferred fluctuations of global temperature have occurred over a broad range of time scales. On time scales of 10 6 –10 8 years, paleogeographic factors (e.g., continental drift and sea level changes) have contributed significantly to temperature changes associated with transitions between nonglacial and glacial states. Preliminary modeling efforts indicate that additional factors (e.g., CO 2 , changes in atmospheric circulation) must also be considered in order to explain the origin of nonglacial climates. The origin of polar ice caps may result from ocean circulation changes that were caused by plate tectonic processes. Fluctuations of ice volume on a time scale of 10³–10 5 years correlate with insolation variations caused by orbital perturbations. Feedback interactions within the land‐sea‐air‐ice system (e.g., ocean circulation changes and bedrock dynamics) have been responsible for a significant modulation of the orbital signal. Ice ages may be due to orbitally induced temperature changes superimposed on a global cooling of terrestrial origin.