Leveraging ecosystems responses to enhanced rock weathering in mitigation scenarios

Abstract

Abstract Carbon dioxide removal (CDR) is deemed necessary to attain the Paris Agreement's climate objectives. While bioenergy with carbon capture and storage (BECCS) has generated substantial attention, sustainability concerns have led to increased examination of alternative strategies, including enhanced rock weathering (EW). We analyse the role of EW under cost-effective mitigation pathways, by including the CDR potential of basalt applications from silicate weathering and enhanced ecosystem growth and carbon storage in response to phosphorus released by basalt. Using an integrated carbon cycle, climate and energy system model, we show that applying basalt to forests could triple the level of carbon sequestration induced by EW compared to an application restricted to croplands. EW reduces the costs of achieving the Paris Agreement targets, and alleviates the pressure on food prices by reducing the willingness to pay for bioenergy; however, it does not significantly reduce the use of BECCS, which remains a major cost-effective mitigation option. Further understanding requires improved knowledge of weathering rates through field testing.