The chemical weathering of silicate rocks in continents as an important sink of atmospheric CO₂ is of great significance for global environmental change. Rivers play a key role in earth surface processes and are regarded as the most important carrier of terrigenous materials into the sea. The chemical index of alteration (CIA) has been widely used as a proxy for chemical weathering in sediment source area. In this paper, the CIA values of suspended particulate matters from 44 rivers worldwide are recalculated. The CIA values vary significantly, with the highest average value occurring in African rivers and the lowest in North American rivers. The correlation analyses suggest that on a global scale the CIA is sensitive to land surface temperature, latitude at river mouth and soil depth in the drainage basins, but poorly correlated with drainage area, precipitation, average elevation and runoff. However, the CIA of the rivers draining east China are closely related to temperature, precipitation, latitude and runoff, primarily reflecting the dominant control of monsoon climate on chemical weathering in the catchments. It is therefore unrealistic to find a simple law of regulating chemical weathering in continents. The CIA actually reflects the integrated weathering history in the drainage basins and therefore, caution should be taken while using it as a direct and quantitative proxy for evaluating the intensity of instantaneous chemical weathering in continents.

Silicate weathering as an important negative feedback can regulate the Earth’s climate over time, but much debate concerns its response strength to each climatic factor and its evolution with land surface reorganisation. Such discrepancy arises from lacking weathering proxy validation and scarce quantitative paleo-constraints on individual forcing factors. Here we examine the catchment-scale link of silicate weathering intensity with various environmental parameters using a global compilation of modern sediment dataset (n = 3828). We show the primary control of temperature on silicate weathering given the monotonic increase of feldspar dissolution with it (0–30 °C), while controls of precipitation or topographic-lithological factors are regional and subordinate. We interpret the non-linear forcing of temperature on feldspar dissolution as depletion of more reactive plagioclase (relative to orthoclase) at higher temperature. Our results hint at stronger temperature-weathering feedback at lower surface temperature and support the hypothesis of increased land surface reactivity during the late Cenozoic cooling.