Achieving the climate targets as agreed at the climate summit in Paris requires rapid decarbonization of all sectors. However, it is becoming increasingly unlikely that conventional climate change mitigation alone can stabilize atmospheric CO2 concentrations at a level compatible with the 1.5°C or even 2°C warming limit. Safe and scalable negative emission technologies (NETs), which actively remove CO2 from the atmosphere and ensure long-term carbon sequestration will be needed in addition to conventional climate change mitigation measures.

Multiple NETs have been proposed, including several land-based approaches capitalize on the ability to manage ecosystems for increased carbon sequestration and aim to strengthen the carbon sink on land. These include afforestation and reforestation and practices such as organic matter and biochar addition to increase soil carbon in agriculture. A potentially important but yet understudied NET is enhanced weathering of silicate minerals (ESW). When silicate minerals weather, CO2 is bound in aqueous form that eventually precipitates as carbonate, sequestering carbon for millennia. In nature, silicate rocks weather very slowly (geological time scale), among others because of the limited surface area of weatherable minerals. The idea behind ESW is to speed up this natural process by artificially increasing the weathering rate.

Organic matter addition, the use of biochar and ESW may be particularly interesting for farmers because of the expected co-benefits. These include increases in plant growth and crop yield, increased drought resistance and reduced greenhouse gas emissions.

We use manipulation experiments to quantify the carbon sequestration potential of land-based NETs as well as the side-effects such as plant growth and crop yield as well as nutrient and greenhouse gas fluxes.