Carbon dioxide removal and net zero emissions in Africa: an integrated assessment modelling based on three different land-based negative emission solutions

As the remaining carbon budget for limiting warming to 1.5 degrees C rapidly diminishes, it is clear that, besides decarbonization, the world will need to remove 100-1000 GtCO2 from the atmosphere by the end of the century. Yet, Africa, where many carbon removal schemes are planned, remains a 'blindspot' in existing studies. There is limited understanding of the trade-offs and synergies associated with carbon removal within Africa's energy-land-water system. To address this research gap, we model a stylized net-zero emissions (NZEs) in Africa by 2050, with focus on three land-based biological carbon removal approaches: afforestation/reforestation (AR), bioenergy with carbon capture and storage (BECCS), and biochar. We find that by 2050, the total gross carbon removal is projected to reach 1.2 GtCO2 yr-1 when all three carbon removal approaches are available, and 0.5 GtCO2 yr-1 when Africa relies solely on AR. Pursuing NZE with only AR or AR alongside biochar in Africa would be the most expensive mitigation option but they lead to the lowest residual fossil fuel and industry CO2 emissions. An NZE by 2050 in Africa could reduce cropland by 30%-40% from 2020 to 2050, depending on the carbon dioxide removal deployment strategy adopted. Southern Africa would be particularly affected, facing significant challenges in balancing food security with climate goals. The highest increase in staple food prices will occur under AR only, while the availability of AR-BECCS-biochar produces the lowest rise in staple food prices. Our findings highlight the need for balanced and region-specific carbon dioxide removal strategies to ensure climate and other sustainability goals are met.