The role of land weathering in carbon consumption and its impact on global carbon cycling since the Last Interglacial period

Atmospheric CO2 variations across glacial-interglacial cycles are tightly linked to oceanic and terrestrial carbon reservoirs, but the contribution of weathering remains poorly constrained. Using a new PCM-weathering model (Past terrestrial Carbon storage Model coupling weathering sub-model), we reconstructed global silicate and carbonate weathering fluxes over the past 120,000 years. Silicate weathering was higher during interglacials (~ 125–163 Tg C/yr) and lower at glacials (~ 119–122 Tg C/yr), tracking atmospheric CO2. In contrast, carbonate weathering increased during glacials (~ 303–320 Tg C/yr) due to expanded land exposure resulting from glacial sea-level fall and declined at interglacials (~ 168–265 Tg C/yr). On glacial-interglacial timescales, total carbon consumption by silicate and carbonate weathering far exceeded changes in oceanic and terrestrial organic carbon pools. These results highlight a dynamic, compensatory balance between silicate and carbonate weathering in modulating Quaternary carbon fluxes.