Geological perspective on climate change
- Pennsylvania State Univ., University Park, PA (United States). Dept of Geosciences
Current estimates of fossil fuel reserves approach 6x the current atmospheric CO[sub 2] content; model calculations have shown that much of this carbon will remain in the atmosphere for several millennia. The potential increase in atmospheric CO[sub 2] over the next few centuries dwarfs natural fluctuations on Milankovitch time scales. Indeed, one must turn far into the geological past to find an analogy for the climate system under such remarkably different atmospheric and climatic states. As a result, perhaps, of the growing need to understand future climates, paleoclimate research activity has intensified. The focus of much of this research has been on the unusually warm periods of the Eocene and Cretaceous. Atmospheric general circulation models have been used to study the adjustment of the climate system to changes in the geographical distribution of the continents. Such efforts generally show that the achievement of significantly enhanced global temperatures requires increases in the atmospheric content of greenhouse gases. The question then arises as to whether these modifications of atmospheric composition are consistent with the geologic record and its interpretation based on global geochemical cycles. Several approaches have been advanced to address this question. The dependence upon CO[sub 2] concentration of the isotope discrimination during photosynthesis means that the carbon isotopic composition of organic and carbonate carbon, as it is preserved in coeval sedimentary rocks, is a potential CO[sub 2] paleobarometer. Similarly, the isotopic composition of paleosols can be used to infer ancient atmospheric carbon contents. Finally, models of the global carbon cycle, especially when coupled with climate models, demonstrate that long-term climate change is intimately interwoven with the factors that affect the carbon cycle, including the geographical distribution of weathering lithologies, and intensity of tectonism.
- OSTI ID:
- 5975493
- Report Number(s):
- CONF-921058-; CODEN: GAAPBC
- Journal Information:
- Geological Society of America, Abstracts with Programs; (United States), Vol. 24:7; Conference: 1992 annual meeting of the Geological Society of America (GSA), Cincinnati, OH (United States), 26-29 Oct 1992; ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CARBON CYCLE
CORRELATIONS
PALEOCLIMATOLOGY
ATMOSPHERIC CHEMISTRY
CARBON DIOXIDE
CARBONATE ROCKS
CLIMATE MODELS
CLIMATIC CHANGE
FOSSIL FUELS
GENERAL CIRCULATION MODELS
GEOLOGY
ISOTOPE RATIO
LITHOLOGY
PLATE TECTONICS
RESEARCH PROGRAMS
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
CHEMISTRY
ENERGY SOURCES
FUELS
MATHEMATICAL MODELS
OXIDES
OXYGEN COMPOUNDS
PALEONTOLOGY
PETROLOGY
ROCKS
SEDIMENTARY ROCKS
TECTONICS
580000* - Geosciences