This paper quantifies the greenhouse gas mitigation potential, cost and feasibility of land-based climate measures such as forest protection, carbon sequestration through agriculture, bioenergy, reducing food waste and shifting to healthy sustainable diets. Across 250 countries and regions, the paper finds that cost-effective measures (defined as those costing up to $100/tCO2eq.) could mitigate 8–13.8 GtCO2eq yr−1 between 2020 and 2050. For context, emissions from Agriculture, Forestry and other Land Uses (AFOLU) were ~12 GtCO2eq yr−1 between 2007 and 2016.
The paper uses two different calculation methods (hence the range of results): first, a sectoral approach that aggregates the potential of 20 mitigation measures from individual studies; second, an integrated assessment model, which forecasts the emissions savings measures from different regions while taking into account the interactions and tradeoffs between them.
The figure below shows both the technical maximum emissions savings and the cost-effective mitigation available from the 20 measures in the sectoral approach. The largest cost-effective mitigation opportunities include reducing deforestation, afforestation and reforestation, biochar from crop residues, agroforestry, shifting to healthy diets, soil organic carbon in grasslands and croplands, and BECCS (bioenergy with carbon capture and storage). The authors note that BECCS can pose threats to food security and compete for land with other uses if not implemented carefully.
Note that healthy diets in this case are defined as keeping within 2250 calories per day, buying local food where available and “limiting meat-based protein consumption to 57 grams/ day”. The 57 grams/day figure comes from Project Drawdown, which suggests that it is red meat specifically that should be limited to 57 grams per day (as opposed to the daily protein content of the diet being limited to 57 g).
Image: Figure 3, Roe et al. Climate mitigation potentials for 20 land-based measures in 2020–2050, by region. Technical and cost-effective ($100/tCO2eq) mitigation potentials are provided for each measure using a sectoral approach.
Land-based climate mitigation measures have gained significant attention and importance in public and private sector climate policies. Building on previous studies, we refine and update the mitigation potentials for 20 land-based measures in >200 countries and five regions, comparing “bottom-up” sectoral estimates with integrated assessment models (IAMs). We also assess implementation feasibility at the country level. Cost-effective (available up to $100/tCO2eq) land-based mitigation is 8–13.8 GtCO2eq yr−1 between 2020 and 2050, with the bottom end of this range representing the IAM median and the upper end representing the sectoral estimate. The cost-effective sectoral estimate is about 40% of available technical potential and is in line with achieving a 1.5°C pathway in 2050. Compared to technical potentials, cost-effective estimates represent a more realistic and actionable target for policy. The cost-effective potential is approximately 50% from forests and other ecosystems, 35% from agriculture, and 15% from demand-side measures. The potential varies sixfold across the five regions assessed (0.75–4.8 GtCO2eq yr−1) and the top 15 countries account for about 60% of the global potential. Protection of forests and other ecosystems and demand-side measures present particularly high mitigation efficiency, high provision of co-benefits, and relatively lower costs. The feasibility assessment suggests that governance, economic investment, and socio-cultural conditions influence the likelihood that land-based mitigation potentials are realized. A substantial portion of potential (80%) is in developing countries and LDCs, where feasibility barriers are of greatest concern. Assisting countries to overcome barriers may result in significant quantities of near-term, low-cost mitigation while locally achieving important climate adaptation and development benefits. Opportunities among countries vary widely depending on types of land-based measures available, their potential co-benefits and risks, and their feasibility. Enhanced investments and country-specific plans that accommodate this complexity are urgently needed to realize the large global potential from improved land stewardship.
Roe, S., Streck, C., Beach, R., Busch, J., Chapman, M., Daioglou, V., Deppermann, A., Doelman, J., Emmet‐Booth, J., Engelmann, J. and Fricko, O., 2021. Land‐based measures to mitigate climate change: Potential and feasibility by country. Global Change Biology, Early View.