Mechanisms of gas-driven mineral weathering in a changing climate

Introduction

Chemical reactions in the unsaturated zone in Earth's shallow subsurface, where pores are filled with a mixture of fluid and gas, support life on our planet and have a profound influence on the global carbon cycle and climate.

Importance of Gas-Driven Mineral Weathering

Gas-driven mineral weathering reactions not only provide nutrients essential to life but serve to regulate atmospheric CO2 concentrations and climate. These reactions are facilitated in the unsaturated zone where reactive gases like CO2 and O2 are readily transported.

Climate Change and Its Effects

Earth's climate has experienced major fluctuations over its history and is currently changing rapidly due to human activities. Climate change impacts the size and water content of the unsaturated zone, and therefore the rates of mineral weathering.

Challenges in Prediction

At present, the prediction of the impacts of changes in water saturation, CO2 concentration, and temperature on mineral weathering rates is hindered by an incomplete understanding of the controls on mineral weathering in the unsaturated zone.

Project Overview: DryCO2

DryCO2 will elucidate the physical and chemical controls on gas-driven mineral weathering in the unsaturated zone to:

1. Evaluate climate evolution over Earth's history.
2. Optimize engineered CO2 removal for climate change mitigation.
3. Forecast the impact of future anthropogenic climate change on the mineral weathering reactions that store CO2 and release nutrients.

Methodology

DryCO2 will comprise five work packages and combines:

• Experimental studies at multiple scales in the laboratory and field.
• Analysis of key field samples.
• Multi-scale reactive transport modelling.

This multi-scale, multi-tool approach will allow DryCO2 to quantify the effects of CO2 concentration and changes in water availability on mineral weathering reactions from the mineral surface to the global scale in a comprehensive fashion.