Influence of terrestrial weathering on ocean acidification and the next glacial inception

Abstract

[1] Ocean uptake of anthropogenic CO 2 causes a decline in seawater pH, a process known as ocean acidification, which may adversely affect marine organisms. We investigate whether continental weathering can mitigate future ocean acidification by sequestering atmospheric CO 2 . We conducted simulations under a suite of carbon emission scenarios with different weathering parameterizations. The short-term impact of a strong weathering feedback was only notable for large emissions with slow injection. This mitigation by enhanced weathering, however, is an order of magnitude smaller than the expected maximum pH decline based on the default parameterizations. Thus on short timescales, weathering has little effect on future atmospheric CO 2 and ocean acidification, regardless of the assumed weathering feedback strength. But on longer timescales and for large emissions, different weathering parameterizations introduce large uncertainties regarding the time when pCO 2 will return to climatically relevant levels of, say, 400 matm in the future. Citation: Uchikawa, J., and R. E. Zeebe (2008), Influence of terrestrial weathering on ocean acidification and the next glacial inception, Geophys. Res. Lett., 35, L23608,

Geoengineering potential of artificially enhanced silicate weathering of olivine

“…Our results expand previous studies on the impact of natural weathering in the future (19)(20)(21). Olivine (Mg 2 SiO 4 ) is a well-studied mineral with known dissolution kinetics (22) and has been suggested to be useful for CDR geoengineering (18).…”

Long-term legacy of massive carbon input to the Earth system: Anthropocene versus Eocene

“…After 50 kyr, atmospheric CO 2 has dropped below approximately 500 μatm (airborne fraction less than 14%). This number is somewhat sensitive to the choice of parameter values used in the weathering parametrization [75]. However, the LOSCAR model's standard configuration uses a relatively weak weathering feedback.…”

LOSCAR: Long-term Ocean-atmosphere-Sediment CArbon cycle Reservoir Model v2.0.4

“…We have previously published several applications of LOSCAR dealing, for instance, with future projections of ocean chemistry and weathering, pCO 2 sensitivity to carbon cycle perturbations throughout the Cenozoic, and carbon/calcium cycling during the Paleocene-Eocene Thermal Maximum (PETM) Zachos et al, 2008;Zeebe et al, 2009;Uchikawa and Zeebe, 2008;Stuecker and Zeebe, 2010;Uchikawa and Zeebe, 2010;Komar and Zeebe, 2011;Zeebe and Ridgwell, 2011;Zeebe, 2012). The subject of the present contribution is the detailed description of the model including numerical architecture, processes and parameterizations, tuning, and examples of input and output.…”

“…c Walker and Kasting (1992). d Uchikawa and Zeebe (2008). e Rain of refractory, non-CaCO 3 material to sediments.…”

“…The default values for n cc and n si adopted in LOSCAR were chosen so as to represent conservative values, resulting in a weak default weathering feedback at the lower end of the spectrum (see Fig. 1 in Uchikawa and Zeebe, 2008). The user is welcome to change and vary these parameters values (cf.…”