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Title: Global chemical erosion over the last 250 my: Variations due to changes in paleogeography, paleoclimate, and paleogeology

Abstract

The authors utilize predictions of runoff from two series of GENESIS (version 1.02) climate model experiments to calculate chemical erosion rates for 12 time slices that span the Mesozoic and Cenozoic. A set of control experiments where geography is altered according to published paleogeographic reconstructions and atmospheric pCO{sub 2} is held fixed at the present-day value was designed to elucidate climate sensitivity to geography alone. A second series of experiments, where the (elevated) atmospheric CO{sub 2} level for each time slice was adapted from Berner (1991), was executed to determine the additional climate sensitivity to this parameter. By holding other climate forcing factors (for example, vegetation) constant throughout the sequence of experiments the authors evaluate the effects of systematic/coherent paleogeographic changes on runoff and temperature, and thus on global rates of chemical weathering. By using empirical relationships between runoff and bicarbonate fluxes for different rock types and maps of paleogeology they calculate global bicarbonate fluxes, taking into account spatial variations in lithology and hydrology. They find that spatial variations in lithology account for little variation in the total or silicate chemical erosion rates. Calculations suggest a weaker-than-expected CO{sub 2}-climate weathering feedback. The reasonable atmospheric pCO{sub 2} variations specified for themore » climate-model simulations do not lead to climatic effects that support large changes in the chemical erosion rate, compared to those generated by changing paleogeography. In general, however, they find that silicate weathering rates are similar to outgassing rates of volcanic and methamorphic CO{sub 2}.« less

Authors:
; ; ;
Publication Date:
Research Org.:
Univ. of Wisconsin, Madison, WI (US)
OSTI Identifier:
20006253
Resource Type:
Journal Article
Journal Name:
American Journal of Science
Additional Journal Information:
Journal Volume: 299; Journal Issue: 7-9; Other Information: PBD: 1999; Journal ID: ISSN 0002-9599
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; 58 GEOSCIENCES; CLIMATE MODELS; RUNOFF; EROSION; WEATHERING; ATMOSPHERIC CHEMISTRY; CARBON DIOXIDE; GLOBAL ASPECTS; PALEOCLIMATOLOGY; ACID CARBONATES; LITHOLOGY

Citation Formats

Gibbs, M T, Bluth, G J.S., Fawcett, P J, and Kump, L R. Global chemical erosion over the last 250 my: Variations due to changes in paleogeography, paleoclimate, and paleogeology. United States: N. p., 1999. Web. doi:10.2475/ajs.299.7-9.611.
Gibbs, M T, Bluth, G J.S., Fawcett, P J, & Kump, L R. Global chemical erosion over the last 250 my: Variations due to changes in paleogeography, paleoclimate, and paleogeology. United States. https://doi.org/10.2475/ajs.299.7-9.611
Gibbs, M T, Bluth, G J.S., Fawcett, P J, and Kump, L R. Thu . "Global chemical erosion over the last 250 my: Variations due to changes in paleogeography, paleoclimate, and paleogeology". United States. https://doi.org/10.2475/ajs.299.7-9.611.
@article{osti_20006253,
title = {Global chemical erosion over the last 250 my: Variations due to changes in paleogeography, paleoclimate, and paleogeology},
author = {Gibbs, M T and Bluth, G J.S. and Fawcett, P J and Kump, L R},
abstractNote = {The authors utilize predictions of runoff from two series of GENESIS (version 1.02) climate model experiments to calculate chemical erosion rates for 12 time slices that span the Mesozoic and Cenozoic. A set of control experiments where geography is altered according to published paleogeographic reconstructions and atmospheric pCO{sub 2} is held fixed at the present-day value was designed to elucidate climate sensitivity to geography alone. A second series of experiments, where the (elevated) atmospheric CO{sub 2} level for each time slice was adapted from Berner (1991), was executed to determine the additional climate sensitivity to this parameter. By holding other climate forcing factors (for example, vegetation) constant throughout the sequence of experiments the authors evaluate the effects of systematic/coherent paleogeographic changes on runoff and temperature, and thus on global rates of chemical weathering. By using empirical relationships between runoff and bicarbonate fluxes for different rock types and maps of paleogeology they calculate global bicarbonate fluxes, taking into account spatial variations in lithology and hydrology. They find that spatial variations in lithology account for little variation in the total or silicate chemical erosion rates. Calculations suggest a weaker-than-expected CO{sub 2}-climate weathering feedback. The reasonable atmospheric pCO{sub 2} variations specified for the climate-model simulations do not lead to climatic effects that support large changes in the chemical erosion rate, compared to those generated by changing paleogeography. In general, however, they find that silicate weathering rates are similar to outgassing rates of volcanic and methamorphic CO{sub 2}.},
doi = {10.2475/ajs.299.7-9.611},
url = {https://www.osti.gov/biblio/20006253}, journal = {American Journal of Science},
issn = {0002-9599},
number = 7-9,
volume = 299,
place = {United States},
year = {1999},
month = {7}
}