Overcoming global inequality is critical for land-based mitigation in line with the Paris Agreement

In the period 2010–2019, global GHG emissions from the land sector (AFOLU) accounted for 13–21% of global total net anthropogenic GHG emissions, according to IPCC AR6 Working Group III. AFOLU emissions include CO₂ from land-use change and management and CH₄/N₂O from agriculture. In 2018, CO₂ from deforestation and other land conversions together with uptake from regrowth and re/afforestation accounted for 47% of global net AFOLU emissions; CH₄ from enteric fermentation was 25%, with smaller sources from managed soils (N₂O), rice cultivation (CH₄), manure management (CH₄, N₂O), and synthetic fertilizer application (N₂O). AFOLU’s share is typically higher in developing than in developed regions; in Africa, Latin America, and Southeast Asia, AFOLU GHG emissions are >50% of totals, versus ~7% in Europe and North America. In absolute terms, AFOLU GHG emissions in 2015 were ~5.92 Gt CO₂ in developing countries versus ~2.6 Gt CO₂ in industrialized countries, underscoring the importance of low- and middle-income countries in AFOLU mitigation consistent with the Paris Agreement. In 1.5 °C pathways, land-use transformation emissions are considerably lower in Africa and Asia compared to high-warming scenarios, and net CO₂ from land-use change and management in Africa and Latin America turns negative via re/afforestation. Mitigation pathways often assume globally coordinated GHG pricing across sectors including AFOLU, complemented by inclusive socio-economic development (e.g., convergence in demographics, lower food waste, healthy diets) and sustainable land-use practices (ecosystem protection, efficiency improvements). Yet, technological, institutional, and food security barriers risk a world of deepening inequality (SSP4) where effective AFOLU regulation and sustainable practices remain limited to high-income countries, while low- and middle-income regions experience higher population growth and persistent food insecurity, exacerbated by shocks like COVID-19 and geopolitical crises. Given the closing window for achieving 1.5 °C, the study asks how compatible AFOLU emissions are with Paris targets under deepening inequalities, and what mitigation options and co-benefits arise when expanding measures globally. The authors present model-based scenarios to quantify these dynamics.

The paper situates AFOLU within global mitigation citing IPCC AR6 WGIII assessments that AFOLU contributed 13–21% of net anthropogenic GHGs in 2010–2019. It reviews evidence that AFOLU’s relative share is higher in developing regions and that 1.5 °C pathways entail lower land-use conversion emissions and net negative CO₂ from land in Africa/Latin America via re/afforestation. It references prior scenario frameworks (SSPs, SDGs) and studies showing the role of global GHG pricing, sustainable development pathways (e.g., diet shifts, reduced waste), and sustainable land-use practices in enabling AFOLU mitigation. The authors highlight uncertainty and barriers (technological, institutional, food security) and recent shocks (COVID-19, geopolitical conflicts) that may widen inequalities, motivating analysis of inequality versus inclusive development scenarios within a consistent modeling framework.

Model and data: The study uses the global multi-regional MaGPIE 4.4.0 open-source land-use modeling framework to simulate spatially explicit AFOLU trajectories through the 21st century. MaGPIE integrates economic and biophysical components, taking regional economic conditions (demand for agricultural commodities, technological development, production costs) and biophysical constraints from LPJmL (0.5° resolution; crop yields, carbon densities, water availability). Due to computational constraints, 0.5° inputs are clustered: a two-stage approach first solves globally with 200 clusters across 12 economic regions to capture trade, then uses resulting trade balances to solve regions individually with a total of 2000 clusters, improving spatial granularity tenfold. Land types include cropland (food, feed, materials, biomass), pasture, timber plantations, forests (primary and secondary), other land (non-forest vegetation, abandoned agricultural land, deserts), and urban land (exogenous SSP-based). Land-use intensification and yield-increasing technological change are modeled endogenously via regional investment and interest rates. The land-use intensity factor τ reflects the degree of yield amplification from management and technology. Emissions accounting: Annual net CO₂ from land-use change and management is computed from vegetation carbon stock changes (including wood harvest and storage in products, carbon uptake in timber plantations), smoothed with a two-pass filter to address stock–flow variability while conserving integrals. CO₂/CH₄/N₂O from managed peatlands (drained/rewetted) use IPCC wetland emission factors. CH₄ sources include enteric fermentation, manure management, and rice cultivation (estimated from feed demand, manure, rice area). N₂O sources include agricultural soils (fertilizer application) and animal waste management based on nitrogen budgets for cropland, pasture, and livestock. In mitigation scenarios, AFOLU emissions are subject to pricing, which also activates technical non-CO₂ mitigation options (e.g., improved animal feed, anaerobic digesters, improved water management in rice, improved fertilizer application). Scenarios and assumptions: Regions are aggregated to five: OECD90+EU (high income), ASIA (India, China, other Asia), LAM (Latin America), SSA (Sub-Saharan Africa), ROW (MENA + Reforming countries). The study co-developed scenario narratives with stakeholders, resulting in two main scenarios and three decomposition scenarios: - Global-Inequality: AFOLU GHG pricing and sustainable land-use practices limited to high-income regions; low- and middle-income regions follow SSP4-like trajectories (higher population growth, persistent inequality), resource-intensive diets, higher food waste. - Global-Sustainability: Global AFOLU GHG pricing, sustainable land-use practices (biodiversity protection, environmental flow protection, nitrogen retention), and inclusive socio-economic development (SSP1-like; lower population growth, EAT-Lancet healthy diets, reduced food waste). Decomposition scenarios isolate drivers: Global-GHG Price (global AFOLU pricing under SSP4-like socio-economics), Global-EnvirProt (global sustainable land-use protections under SSP4-like socio-economics), Global-SustDemand (global inclusive socio-economic development: SSP1 + EAT-Lancet diet + lower food waste, with GHG pricing limited to OECD90+EU). Policy levers: AFOLU GHG pricing applied regionally per scenario; exogenous re/afforestation per NDC targets in all scenarios; endogenous re/afforestation incentivized where CO₂ is priced; biodiversity limit of 500 Mha for global afforestation in Global-Sustainability to avoid excessive land competition; second-generation bioenergy demand identical across scenarios. Climate impacts on yields, carbon densities, water availability, and labor productivity align with LPJmL under RCP1.9 consistent with 1.5 °C pathways. Indicators mapped to SDGs: AFOLU GHG emissions (SDG 13), CO₂ from land-use change and management, N₂O and CH₄ from agriculture, nitrogen fixation (proxy for nitrogen losses; SDG 15), agricultural water use (SDG 6), forest area without plantations (SDG 15), prevalence of underweight and obesity (SDGs 2 and 3).

- Under deepening inequalities (Global-Inequality), global net AFOLU GHG emissions remain positive throughout the century: ~8.4 Gt CO₂eq/yr in 2050 and ~5 Gt CO₂eq/yr in 2100, incompatible with 1.5 °C pathways. Global net CO₂ from land-use change and management is near zero mid-century due to offsets between re/afforestation in high-income regions and ongoing deforestation in Sub-Saharan Africa. Agricultural non-CO₂ emissions remain high, with 2050 agriculture emissions in Asia, Latin America, and SSA reaching ~2.4 Gt CO₂eq/yr (N₂O) and ~5.5 Gt CO₂eq/yr (CH₄). Agricultural water use is at or above 2020 levels globally by 2050, with Asia accounting for ~58% of global agricultural water use. Nitrogen fixation reaches ~137 Mt N/yr in 2050 (more than twice the planetary boundary of 62 Mt N/yr), ~60% from Asia and Latin America. Undernourishment stays above 600 million people, primarily in Asia and SSA; global obesity rises from 842 million (2020) to 1,537 million (2100). - Sustainable land-use practices alone (Global-EnvirProt) reduce pressures (notably primary forest loss and nitrogen fixation) but are insufficient to align AFOLU emissions with 1.5 °C: AFOLU emissions remain positive with ~6.7 Gt CO₂eq/yr in 2050 and ~3.1 Gt CO₂eq/yr in 2100; nitrogen fixation is 23% lower globally in 2050 versus Global-Inequality. - Global AFOLU GHG pricing (Global-GHG Price) has strong mitigation potential: the net AFOLU trajectory turns net-negative from ~2060; total AFOLU GHG is ~0.8 Gt CO₂eq/yr in 2050 and −2.2 Gt CO₂eq/yr in 2100. CO₂ effects include: (a) strong reduction of land-conversion emissions in SSA, LAM, and ASIA; (b) increased carbon sequestration with re/afforestation shifting from OECD90+EU to LAM; (c) reduced peatland CO₂ via rewetting. Net global carbon uptake reaches ~4.2 Gt CO₂eq/yr in 2050. Non-CO₂ emissions fall to ~1.8–1.9 Gt CO₂eq/yr (N₂O) and ~3.2 Gt CO₂eq/yr (CH₄) in 2050 (26% and 42% lower than Global-Inequality), but with trade-offs: higher agricultural water use and nitrogen fertilizer use, especially in Asia, and higher land-use intensification. - Global inclusive socio-economic development (Global-SustDemand) can achieve 1.5 °C-compatible AFOLU mitigation comparable to global pricing by 2050 through demand-side shifts (lower population growth, EAT-Lancet diet adoption, reduced food waste). 2050 emissions: N₂O ~1.2 Gt CO₂eq/yr and CH₄ ~2.2 Gt CO₂eq/yr (~50% reductions vs 2020). Net global carbon uptake ~3.5 Gt CO₂eq/yr in 2050. Co-benefits include reduced nitrogen fixation (−26%) and agricultural water use (−22%) versus Global-Inequality in 2050; prevalence of underweight and obesity is phased out by 2050 under healthy diets assumptions. - Integrating all levers (Global-Sustainability) maximizes mitigation and co-benefits: net AFOLU GHG turns net-negative by ~2035, reaching −4.1 Gt CO₂eq/yr in 2050 and −11.6 Gt CO₂eq/yr in 2100. CO₂-only net carbon uptake is ~5.7 Gt CO₂eq/yr in 2050; N₂O and CH₄ decline to ~0.7 and ~0.9 Gt CO₂eq/yr, respectively, by 2050. Nitrogen fixation and agricultural water use drop 41% and 29% globally by 2050 vs Global-Inequality. Undernutrition and obesity are eliminated by 2050 under the diet transition assumptions. - Forest outcomes: Net global forest cover (excluding plantations) increases by ~398 Mha (2020–2050) in Global-Sustainability and ~115 Mha in Global-Inequality. A global GHG price provides strong incentives for forest protection/restoration and shifts re/afforestation largely to Latin America where sequestration potential is higher; inclusive socio-economic development frees land for re/afforestation by lowering demand for crops and livestock. Overall, overcoming global inequality via inclusive socio-economic development is critical for achieving land-based mitigation consistent with the Paris Agreement; global AFOLU pricing can also achieve strong emissions reductions but with more trade-offs, while sustainable land-use protections alone are insufficient.

The study demonstrates that AFOLU mitigation consistent with 1.5 °C is unattainable in a world of deepening inequalities where pricing and sustainable practices are limited to high-income regions. Decomposition analyses show that both global AFOLU GHG pricing (supply-side) and inclusive socio-economic development (demand-side) can individually deliver stringent AFOLU emission reductions by mid-century, particularly in Asia, Latin America, and Sub-Saharan Africa. However, only inclusive socio-economic development yields broad co-benefits across SDGs (reductions in undernutrition, overnutrition, nitrogen pollution, and agricultural water use) and lowers pressure on land resources, while global pricing alone can increase water use, fertilizer demand, and intensification in some regions. Combining both approaches in Global-Sustainability achieves the strongest AFOLU mitigation (net-negative from ~2035) and maximizes co-benefits, reducing the mitigation burden on other sectors under economy-wide carbon budgets. The findings highlight the importance of globally coordinated policies that integrate climate action with SDG-aligned socio-economic transformations to unlock land-based mitigation potential and distribute actions toward regions with the largest marginal gains.

This work quantifies how global inequality shapes AFOLU mitigation prospects. If sustainable development remains limited to high-income regions, AFOLU emissions stay positive through 2100 and are incompatible with the Paris Agreement. Either global AFOLU GHG pricing or globally inclusive socio-economic development can, on their own, deliver stringent AFOLU emission reductions by 2050, but inclusive development uniquely secures major SDG co-benefits and reduces environmental pressures. Integrating global pricing, sustainable land-use protections, and inclusive socio-economic development yields the deepest AFOLU decarbonization and co-benefits, helping meet Paris targets while alleviating pressure on other sectors. Future research should (i) extend integrated assessments to include intersectoral feedbacks (energy, industry, transport, biomass markets), (ii) evaluate governance and finance mechanisms to enable inclusive development (e.g., international climate finance, development finance, carbon pricing revenue recycling), and (iii) refine regional scenario co-development beyond high-income stakeholder perspectives to better represent low- and middle-income contexts and constraints.

- Sectoral scope: The analysis is focused on the AFOLU sector and does not explicitly model interactions with other sectors (e.g., energy, industry) or full-economy feedbacks, which can influence biomass supply, land competition, and economy-wide mitigation costs. - Scenario assumptions: Inclusive socio-economic development assumes progress toward SDGs (healthy diets, reduced food waste, lower population growth via education and health), which require governance capacity and substantial investments that may not materialize uniformly. - Stakeholder representation: Scenario co-development primarily involved stakeholders based in Europe and other high-income regions, potentially biasing narratives and priorities. - Modeling constraints: Spatial aggregation via clustering and the two-stage solution approach, while improving tractability, still abstracts from local heterogeneity. Some land-use practice nuances (e.g., land-sparing vs land-sharing) are not fully represented. - Trade-offs and environmental limits: While pricing reduces emissions, it can increase agricultural water use and nitrogen inputs in some regions; these trade-offs depend on regional constraints and may be sensitive to parameter choices. - Climate forcing: Climate impact inputs are aligned with RCP1.9; alternative climate pathways could change yields, water availability, and carbon densities, affecting results.