The temperature control on the intensity of silicate weathering

Chemical weathering of silicate minerals plays a vital role in maintaining the long-term habitability of Earth’s climate over geological timescales via a negative feedback mechanism. But much debate concerns the response strength of silicate weathering 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 for calculation of weathering intensity proxies, including chemical index of alteration (CIA) and weathering index of Parker (WIP).

We show the primary control of temperature on silicate weathering given the monotonic increase of feldspar dissolution (constrained by CIA) with it at 0-30 ^oC, while controls of precipitation or topographic-lithological factors are regional and subordinate¹. We interpret the non-linear forcing of temperature on feldspar dissolution as depletion of more reactive plagioclase (relative to orthoclase) at higher temperature. Accordingly, the surface temperature decrease could be accompanied with a higher proportion of more reactive plagioclase available for weathering, supporting the hypothesis that land surface reactivity has increased during the late Cenozoic cooling². We also propose a first-order quantitative relationship between surface temperature, feldspar dissolution and CO₂ consumption that will be of great potential for deep-time temperature reconstruction and carbon cycle modeling.

References

1. Deng, K., Yang, S. & Guo, Y. (2022) Nat Commun 13, 1781.

2. Caves Rugenstein, J.K., Ibarra, D.E. & von Blanckenburg, F. (2019) Nature 571, 99–102.