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

The land sector plays a significant role in global greenhouse gas (GHG) emissions, contributing 13-21% of total net anthropogenic GHG emissions. A substantial portion of these emissions originates from low- and middle-income countries (LMICs). Transformative pathways towards meeting the Paris Agreement goals often assume globally implemented GHG emission pricing, inclusive socio-economic development, and sustainable land-use practices. However, achieving these changes faces significant barriers. This study addresses the crucial question of whether unequal development, where sustainable practices remain limited to high-income countries, will hinder global land-based mitigation efforts. The researchers hypothesize that overcoming global inequality is essential for achieving significant emission reductions in the AFOLU sector and maximizing co-benefits for other SDGs. The study's importance lies in quantifying the impact of unequal development on global AFOLU emissions and identifying pathways that promote both climate mitigation and broader sustainable development.

The literature review cites existing research highlighting the significant contribution of the AFOLU sector to global GHG emissions and the disproportionate impact on LMICs. It references IPCC reports emphasizing the need for global cooperation and sustainable land-use practices to meet climate targets. Studies on sustainable development pathways and their co-benefits with SDGs are also reviewed. The authors note existing uncertainties and gaps in GHG emission rates related to technological, institutional, and food security factors, potentially leading to deepening inequalities. Existing research on the impact of factors like education access on population growth and agricultural land use is also considered. The impact of global events such as the COVID-19 pandemic and the Ukraine conflict on SDG progress, particularly in LMICs, is also reviewed. A key gap identified is the lack of consistent modeling frameworks that analyze the compatibility of AFOLU emissions with the Paris Agreement objectives under scenarios of deepening global inequalities.

The study employs the global multi-regional MAGPIE 4.0 open-source land-use modeling framework to quantify two contrasting future scenarios for the AFOLU sector: Global-Inequality and Global-Sustainability. Global-Inequality assumes that sustainable development remains highly unequal, limited to high-income countries. Global-Sustainability incorporates global implementation of AFOLU GHG emission pricing, sustainable land-use practices, and inclusive socio-economic development. The model integrates socio-economic drivers (population, income, diets, food waste), environmental protection measures, and land-based mitigation strategies. The model's spatial resolution is enhanced using a two-staged approach, improving the accuracy of regional projections. The study uses regional data on biophysical conditions from the Lund-Potsdam-Jena managed land model (LPJmL), integrating factors such as carbon densities, agricultural productivity, and water availability. The model incorporates climate change impacts on crop yields, carbon densities, water availability, and labor productivity. The scenario narratives were co-developed through an iterative process involving scientists and land-use experts from diverse institutions. The model outputs are analyzed for various indicators, including AFOLU GHG emissions, agricultural water use, nitrogen fixation, and forest area change, and are linked to specific United Nations Sustainable Development Goals (SDGs).

The key findings reveal a stark contrast between the two scenarios. In the Global-Inequality scenario, global net AFOLU GHG emissions remain positive throughout the 21st century, significantly exceeding 1.5°C compatible projections. Emissions from agriculture in Asia, Latin America, and Sub-Saharan Africa remain high. Agricultural water use and nitrogen fixation exceed sustainable levels. The Global-Sustainability scenario, however, shows a drastic reduction in global AFOLU GHG emissions, turning net-negative by 2035. This is achieved through a combination of factors: lower population growth, healthier diets, reduced food waste, global GHG emission pricing, and sustainable land-use practices. Significant co-benefits are observed for several SDGs, including reduced malnutrition, obesity, improved water use, decreased nitrogen pollution, and increased forest cover. Decomposition of the drivers shows that both global GHG pricing and inclusive socio-economic development contribute significantly to emission reductions, but only the latter scenario maximizes co-benefits for various SDGs. Analysis of land-use changes highlights that global GHG pricing significantly reduces deforestation, while inclusive development reduces pressure on land resources and promotes reforestation. The results demonstrate that solely focusing on sustainable land-use practices in high-income countries is insufficient to meet global climate targets.

The findings demonstrate the crucial importance of addressing global inequalities to achieve ambitious land-based climate mitigation goals. The stark contrast between the Global-Inequality and Global-Sustainability scenarios emphasizes that effective climate action requires a holistic approach that addresses both environmental and socio-economic factors. The study highlights that while global GHG pricing can significantly reduce emissions, inclusive socio-economic development is crucial for maximizing co-benefits and ensuring a just transition. The integration of multiple SDG considerations into the modeling framework underscores the interconnectedness of climate change mitigation and broader sustainable development goals. The results strengthen the argument for increased investment in sustainable development initiatives in LMICs, emphasizing the need for international cooperation and financial support to bridge the investment gaps for achieving multiple SDGs.

This study convincingly demonstrates that overcoming global inequality is paramount for achieving land-based climate mitigation in line with the Paris Agreement. While both global GHG pricing and inclusive socio-economic development contribute to emission reductions, only the latter maximizes co-benefits with other SDGs, particularly in LMICs. Future research should explore the pathways for mobilizing financial resources and strengthening governance structures to facilitate inclusive sustainable development and address the identified investment gaps. The findings underscore the urgency for a coordinated global effort that integrates climate action and sustainable development to achieve a just and equitable future.

The study relies on model-based projections, which inherently involve uncertainties and simplifications. The model's assumptions regarding technological advancements, institutional changes, and future socio-economic trends might influence the results. The interactions between the AFOLU sector and other sectors, such as energy and food production, are not fully captured in this analysis. The scenario narratives are based on a co-development process involving a predominantly European and North American stakeholder group; this might affect the global representation of perspectives. Future research could refine the model to incorporate more detailed regional context and address these limitations.