Bottom-up estimate of the carbon dioxide removal potential of land-based mitigation technologies using a coupled ESM/ land-use change model framework

Carbon dioxide removal (CDR) strategies are critical for climate stabilisation under the Paris Agreement. All current IPCC scenarios that achieve the Paris Agreement’s objectives rely on CDR, and implementing CDR explicit representations into Earth System Models will allow the production of more realistic future scenario projections for CMIP7 and beyond. Here we present results from the LANDMARC project which aims to explore the efficiency of carbon dioxide removal as well as risks associated with land-based mitigation technologies (LMTs). We employ a coupled modeling system consisting of the EC-Earth3-CC Earth System Model with the LPJ-GUESS dynamic global vegetation model, and the LandSHIFT-G land-use model, and simulate five different LMTs, specifically i) fixing carbon in vegetation and soils by afforestation/ reforestation; increasing soil carbon by ii) no/reduced tillage agriculture and iii) combining the substitution of fossil fuels with biofuels and medium to long-term storage of carbon by iv) bioenergy and carbon capture and storage (BECCS) and biochar as well as v) reducing deforestation through agro-forestry and agro-pastoral practices. Based on two different portfolios, assuming an either moderate or high ambition to employ LMTs, we estimate the potential carbon removal through LMTs, and their impact on the average and variability in climate. We find that implementing LMTs has the potential to achieve net-negative emissions before the end of the century, and to reduce the atmospheric CO₂ concentration by 47 - 62 ppm depending on the LMT portfolio investigated. The carbon removal is simulated to dampen the global increase in temperature by roughly 0.4°C by the end of the century. While this reduction alone is insufficient to meet the Paris Agreement goals, it highlights the need to invest significantly in both CDR and emissions reductions, which serve as complementary means for achieving climate stabilisation alongside sustainable development goals.