Understanding Earth’s climate system is a key scientific challenge of the 21st century. It is a basis to climate change mitigation and adaptation and underpins, for example, the study of Earth surface dynamics, the evolution of life, and the sedimentary rock record. Earth’s climate is linked to the concentration of carbon dioxide (CO2) in the atmosphere and, thus, to the global carbon cycle. An important component of the carbon cycle is the chemical dissociation (weathering) of rocks near Earth’s surface. Where silicate minerals are exposed to the surface of the Earth by uplift and erosion, they weather and drive the precipitation of carbonate minerals. The carbonates lock up carbon in the rock record over hundreds of millions of years.
Rates of weathering reactions are controlled by the availability of weatherable bedrock. Uplifting mountain ranges expose >50% of the global rock mass. Therefore, they are hotspots for chemical weathering and could dramatically alter Earth’s climate. However, our understanding of the link between exposure of rock by erosion and their chemical weathering is limited by three main knowledge gaps (KG).
KG1: Existing datasets that link erosion and chemical weathering fluxes are characterized by a co-variation between erosion rate and climate. Thus, it remains difficult to unravel the relative importance on chemical weathering of climate and the exposure of fresh minerals.
KG2: Weathering rates and their effect on atmospheric CO2 depend strongly on mineralogy. Whereas silicate weathering with carbonic acid sequesters CO2, the oxidation of sulfides (such as pyrite) coupled to carbonate dissolution releases CO2 to the atmosphere. The effect of different lithologies on chemical weathering is poorly understood.
KG3: Weathering models are based on the continuous chemical alteration of bedrock and the formation of soils. However, as erosion rates increase, stochastic landslides dominate the exposure of rock and may strongly influence weathering fluxes. However, no models and very few data exist that explore chemical weathering of landslide deposits.
The proposed aim of WetSlide was to address KG3 with newly acquired data from New Zealand. However, a re-analysis of the literature and the covid pandemic led us to address KG1-3 (see below). This change affected the order of scientific investigations, but the dissemination, communication, mentoring, career development, and training goals were largely met as planned.
