Direct effect of ice sheets on terrestrial bicarbonate, sulphate and base cation fluxes during the last glacial cycle: minimal impact on atmospheric CO2 concentrations
journal contribution
posted on 2008-05-06, 16:14authored byMartyn Tranter, P. Huybrechts, G. Munhoven, M.J. Sharp, G.H. Brown, I.W. Jones, A.J. Hodson, Richard HodgkinsRichard Hodgkins
Chemical erosion in glacial environments is normally a consequence of chemical weathering reactions dominated by
sulphide oxidation linked to carbonate dissolution and the carbonation of carbonates and silicates. Solute fluxes from small
valley glaciers are usually a linear function of discharge. Representative glacial solute concentrations can be derived from the
linear association of solute flux with discharge. These representative glacial concentrations of the major ions are f25% of
those in global river water. A 3-D thermomechanically coupled model of the growth and decay of the Northern Hemisphere ice
sheets was used to simulate glacial runoff at 100-year time steps during the last glacial cycle (130 ka to the present). The
glacially derived fluxes of major cations, anions and Si over the glaciation were estimated from the product of the glacial runoff
and the representative glacial concentration. A second estimate was obtained from the product of the glacial runoff and a realistic
upper limit for glacial solute concentrations derived from theoretical considerations. The fluxes over the last glacial cycle are
usually less than a few percent of current riverine solute fluxes to the oceans. The glacial fluxes were used to provide input to an
oceanic carbon cycling model that also calculates changes in atmospheric CO2. The potential change in atmospheric CO2
concentrations over the last glacial cycle that arise from perturbations in glacial solute fluxes are insignificant, being < 1 ppm.
History
School
Social Sciences
Department
Geography and Environment
Citation
TRANTER, M. ... et al, 2002. Direct effect of ice sheets on terrestrial bicarbonate, sulphate and base cation fluxes during the last glacial cycle: minimal impact on atmospheric CO2 concentrations. Chemical Geology, 190, pp. 33-44