Heterogeneity in ice sheets- vs. monsoon rainfall-induced silicate weathering from high to low latitudes

One of the most challenging problems in paleoclimate research is how orbital cyclicities forced Earth’s climate variations during the late Quaternary. To address this issue, we investigated the differences in silicate weathering, a sensitive climate indicator, at different latitudes on orbital timescales by examining geochemical and clay mineral data from the mid-latitude Sea of Okhotsk and integrating published weathering records from low to high latitudes. Results show that silicate weathering in the mid-latitude Sea of Okhotsk responded sensitively to both temperature and rainfall, indicating the combined influence of ice sheets and low-latitude monsoons. However, silicate weathering is more sensitive to temperature in high-latitude regions, and to rainfall in tropical areas. Therefore, ice sheets primarily control silicate weathering at high latitudes, whereas monsoon rainfall has greater influences in tropical areas. These findings seem to support the “Milankovitch–Kutzbach” hypothesis, which proposes that ice sheets and monsoons together control orbital-scale climate variations of Earth.