Land-based Climate Change Mitigation Research Articles

Additionality, baselines, and the proper accounting for land-based climate change mitigation efforts

Abstract Carbon storage and uptake on land is a critical part of climate change mitigation. Each year, up to 30% of anthropogenic emissions are neutralized by the ongoing background land sink. At the same time, greenhouse gas emissions from deforestation and forest degradation are major contributors to climate change. Protecting the background sink, avoiding additional emissions, and increasing removals are all key parts of a climate change mitigation portfolio. However, accurately measuring the true mitigation effects of a given intervention is challenging because of an inherent reliance on a counterfactual—an estimate of what would have happened in the absence of a given intervention. These counterfactuals are handled differently in carbon markets and in national greenhouse gas inventories, which can lead to confusion in accounting for progress on climate change mitigation. In this paper, we review how global carbon budgets, national greenhouse gas inventories, and carbon markets account for land-based carbon fluxes. We also examine the implications for additionality and identify some particularly challenging cases. Finally, we present recommendations moving forward and connect this work to broader challenges relevant to other carbon dioxide removal pathways.

The choice of land-based climate change mitigation measures influences future global biodiversity loss

Climate mitigation is reported to benefit biodiversity globally. However, the impacts of mitigation measures based on large-scale land-use modifications can be concentrated in the regions where they are introduced, resulting in regional mismatches between mitigation efforts and biodiversity benefits. Here, we evaluated the impacts of large-scale deployment of bioenergy with carbon capture and storage and afforestation to attain the climate stabilization target stated by the Paris Agreement on global and regional biodiversity by using an integrated model framework. Our results highlight that climate mitigation efforts can benefit global biodiversity regardless of large-scale implementation of land-based mitigation measures. However, the negative impacts of mitigation measures on biodiversity are concentrated in regions with a higher contribution to land-use change and carbon sequestration. The results imply the need to consider the unequal regional distribution of benefits from climate mitigation, as well as mitigation options that avoid regional biodiversity loss by minimizing land-use change.

Potential of land-based climate change mitigation strategies on abandoned cropland

Natural revegetation, afforestation, and lignocellulosic crops for bioenergy, possibly coupled with a developing technology like carbon capture and storage, are the most common land-based climate change mitigation options. However, they can compete for land and threaten food security or nature conservation. Using abandoned cropland for their deployment can minimize these risks, but associated potentials are unclear. Here, we compare alternative land-based mitigation options by integrating historical and future (up to 2050) abandoned cropland with site-specific biomass yields and life-cycle emissions. Considering natural revegetation in biodiversity priority areas and different measures in the remaining land can achieve a mitigation potential of 0.8–4.0 GtCO2-equivalents yr−1 (2–11% of 2021 global CO2 emissions). Afforestation generally provides larger climate benefits than bioenergy, but bioenergy with carbon capture and storage delivers the highest mitigation in most locations. Overall, these results offer refined estimates of mitigation potentials from abandoned cropland and highlight opportunities for context-specific mitigation measures.

How diet portfolio shifts combined with land-based climate change mitigation strategies could reduce climate burdens in Germany

Many studies have analysed the environmental impact of vegan, vegetarian, or reduced meat diets. To date, literature has not evaluated how diet shifts affect environmental impacts by utilising portfolios which reflect personal nutrition preferences. Further, changing diets could alter the available land for non-food uses. This paper defines novel diet portfolios to outline alternative diet transitions and choices within the population and finds their effect on greenhouse gas (GHG) emissions, primary energy use, and land use in Germany. The aim of this study is to capture how these diet shifts affect land availability and increase the options for land-based climate change mitigation strategies. To do so, a contextualisation is made to compare the use of freed-up land for afforestation or biomethane production (with and without carbon capture and storage). The investigated diet portfolios lead to a reduction of the investigated impacts (GHG emissions: 7–67%; energy use: 5–46%; land use: 6–64%). Additionally, afforestation of freed-up land from each diet portfolio leads to further emission removals of 4–37%. In comparison, using the land to produce energy crops for biomethane production could lead to 2–23% further CO2-eq emission reductions when replacing fossil methane. If biomethane production is paired with carbon capture and storage, emission abatement is increased to 3–34%. This research indicates various short-term pathways to reduce GHG emissions with portfolio diet shifts. Utilising freed-up land for climate change mitigation strategies could prove essential to meet climate targets, but trade-offs with, e.g. biodiversity and ecosystem services exist and should be considered.

Paradoxes of Aggravated Vulnerability, Marginalization, and Peril of Forest-Based Communities after Increasing Conservative Forest and Protected Areas in Nepal: A Policy Lesson on Land-Based Climate Change Mitigation

Many measures of international policies and support have dictated developing countries to upscale land areas of intact forestry, special biodiversity conservation site, and other wild reserves to half the land territory of the nation by 2050 for resulting environmental, and other benefits to global societies. The international initiations and work urged scholars to assess the potential impacts of the aggressive policy on forest-based communities and especially those living in institutionally and geo ecologically vulnerable areas. This study compiled the impacts of such international policy interventions on diverse affairs of the local community and national economies in Nepal and drew some conclusions on the well-being future of such forest-based communities. It explained that the international interventions in managing community-based resources induced serious disturbances in many local systems and resulted in vicious circles of emigration, income losses, social problems, psychological stresses, and food insecurities. The interventions have placed some communities and especially indigenous ethnic groups in the position either to be displaced from their ancestors’ homelands or suffer for generations. This study also explained some reinforcing phenomena that emerged from the external interventions which have placed situations of the resource impacting local communities adversely for years. It also investigated whether support of international agencies in policy formation and implementation for resource management safeguards the well-being of the resource-based communities. The agencies resulted in the best environmental and other benefits to foreign societies which have aggravated the misery of local communities, particularly the poor people, women, and indigenous ethnic communities. The adverse impacts on the local societies are not repercussions (accidentally or unknowingly happened). All these findings infer that the international policies of upscaling forests and wilderness areas or making conservation areas in half of their land territory, especially in developing societies for the global benefit, may place the lives of the forest-based communities in peril of suffering for generations or extirpating.

Land-based climate change mitigation measures can affect agricultural markets and food security.

Earlier studies have noted potential adverse impacts of land-related emissions mitigation strategies on food security, particularly due to food price increases-but without distinguishing these strategies' individual effects under different conditions. Using six global agroeconomic models, we show the extent to which three factors-non-CO2 emissions reduction, bioenergy production and afforestation-may change food security and agricultural market conditions under 2 °C climate-stabilization scenarios. Results show that afforestation (often simulated in the models by imposing carbon prices on land carbon stocks) could have a large impact on food security relative to non-CO2 emissions policies (generally implemented as emissions taxes). Respectively, these measures put an additional 41.9 million and 26.7 million people at risk of hunger in 2050 compared with the current trend scenario baseline. This highlights the need for better coordination in emissions reduction and agricultural market management policies as well as better representation of land use and associated greenhouse gas emissions in modelling.

Land-based climate change mitigation potentials within the agenda for sustainable development

Even though enormous expectations for greenhouse gas mitigation in the land use sector exist at the same time worries about potential implications for sustainable development have been raised as many Sustainable Development Goals (SDGs) are closely tied to developments in the sector. Here we assess the implications of achieving selected key SDG indicators for Zero Hunger, Clean Water and Sanitation, Responsible Consumption and Production, and Life on Land on the land-based climate change mitigation potential. We find that protecting highly biodiverse ecosystems has profound impacts on biomass potentials (−30% at >12 US dollar per gigajoule) while other SDGs mainly affect greenhouse gas abatement potentials. Achieving SDGs delivers synergies with greenhouse gas abatement and may even in the absence of additional mitigation policies allow to realize up to 25% of the expected greenhouse gas abatement from land use required to stay on track with the 1.5 °C target until 2050. Future land use mitigation policies should consider and take advantage of these synergies across SDGs.

The challenge of locating land-based climate change mitigation and adaptation politics within a social justice perspective: towards an idea of agrarian climate justice

The global land rush and mainstream climate change narratives have broadened the ranks of state and social actors concerned about land issues, while strengthening those opposed to social justice-oriented land policies. This emerging configuration of social forces makes the need for deep social reforms through redistribution, recognition, restitution, regeneration and resistance – book-ended by the twin principles of ‘maximum land size’ (‘size ceiling’) and a ‘guaranteed minimum land access’ (‘size floor’) – both more compelling and urgent, and, at the same time, more difficult than ever before. The five deep social reforms of socially just land policy are necessarily intertwined. But the global land rush amidst deepening climate change calls attention to the linkages, especially between the pursuit of agrarian justice on the one hand and climate justice on the other. Here, the relationship is not without contradictions, and warrants increased attention as both unit of analysis and object of political action. Understanding and deepening agrarian justice imperatives in climate politics, and understanding and deepening climate justice imperatives in agrarian politics, is needed more than ever in the ongoing pursuit of alternatives.

Large uncertainty in carbon uptake potential of land-based climate-change mitigation efforts.

Most climate mitigation scenarios involve negative emissions, especially those that aim to limit global temperature increase to 2°C or less. However, the carbon uptake potential in land-based climate change mitigation efforts is highly uncertain. Here, we address this uncertainty by using two land-based mitigation scenarios from two land-use models (IMAGE and MAgPIE) as input to four dynamic global vegetation models (DGVMs; LPJ-GUESS, ORCHIDEE, JULES, LPJmL). Each of the four combinations of land-use models and mitigation scenarios aimed for a cumulative carbon uptake of ~130 GtC by the end of the century, achieved either via the cultivation of bioenergy crops combined with carbon capture and storage (BECCS) or avoided deforestation and afforestation (ADAFF). Results suggest large uncertainty in simulated future land demand and carbon uptake rates, depending on the assumptions related to land use and land management in the models. Total cumulative carbon uptake in the DGVMs is highly variable across mitigation scenarios, ranging between 19 and 130 GtC by year 2099. Only one out of the 16 combinations of mitigation scenarios and DGVMs achieves an equivalent or higher carbon uptake than achieved in the land-use models. The large differences in carbon uptake between the DGVMs and their discrepancy against the carbon uptake in IMAGE and MAgPIE are mainly due to different model assumptions regarding bioenergy crop yields and due to the simulation of soil carbon response to land-use change. Differences between land-use models and DGVMs regarding forest biomass and the rate of forest regrowth also have an impact, albeit smaller, on the results. Given the low confidence in simulated carbon uptake for a given land-based mitigation scenario, and that negative emissions simulated by the DGVMs are typically lower than assumed in scenarios consistent with the 2°C target, relying on negative emissions to mitigate climate change is a highly uncertain strategy.

Carbon stock indicators: reductionist assessments and contentious policies on land use

ABSTRACTIndicators of carbon storage in forests and other land uses have gained much prominence to evaluate and endorse land-based climate change mitigation policies. The outcomes of such assessments can have direct livelihood implications for dwellers living at the forest–agriculture frontier, such as shifting cultivators or subsistence farmers. This contribution critically discusses the methodological relevance of carbon stock indicators to assess long-term emission dynamics of land uses, and furthermore addresses the ‘politics of measurement’ that can be involved in policy practice. From a complex socio-ecological systems perspective, the paper argues that carbon stock indicators provide necessary but not sufficient information to endorse land use policies with mitigation aims. While they may indicate one-off sequestration gains through vegetation and land-use change, they cannot account for permanent hidden emissions that emerge as part of the broader agrarian transitions that accompany land-use change. Over the long term, this may render related mitigation interventions ineffective, if not counterproductive. Furthermore, carbon stock estimates for future land-use scenarios sometimes draw on biased assumptions, or are constructed within histories of discrimination, through which they may further marginalize subaltern groups such as shifting cultivators. A paradigm shift is needed that includes more integrative assessment approaches.

The mark of vegetation change on Earth\u2019s surface energy balance

Changing vegetation cover alters the radiative and non-radiative properties of the surface. The result of competing biophysical processes on Earth’s surface energy balance varies spatially and seasonally, and can lead to warming or cooling depending on the specific vegetation change and background climate. Here we provide the first data-driven assessment of the potential effect on the full surface energy balance of multiple vegetation transitions at global scale. For this purpose we developed a novel methodology that is optimized to disentangle the effect of mixed vegetation cover on the surface climate. We show that perturbations in the surface energy balance generated by vegetation change from 2000 to 2015 have led to an average increase of 0.23 ± 0.03 °C in local surface temperature where those vegetation changes occurred. Vegetation transitions behind this warming effect mainly relate to agricultural expansion in the tropics, where surface brightening and consequent reduction of net radiation does not counter-balance the increase in temperature associated with reduction in transpiration. This assessment will help the evaluation of land-based climate change mitigation plans.

Exploring SSP land-use dynamics using the IMAGE model: Regional and gridded scenarios of land-use change and land-based climate change mitigation

Abstract Projected increases in population, income and consumption rates are expected to lead to rising pressure on the land system. Ambitions to limit global warming to 2 °C or even 1.5 °C could also lead to additional pressures from land-based mitigation measures such as bioenergy production and afforestation. To investigate these dynamics, this paper describes five elaborations of the Shared Socio-economic Pathways (SSP) using the IMAGE 3.0 integrated assessment model framework to produce regional and gridded scenarios up to the year 2100. Additionally, land-based climate change mitigation is modelled aiming for long-term mitigation targets including 1.5 °C. Results show diverging global trends in agricultural land in the baseline scenarios ranging from an expansion of nearly 826 Mha in SSP3 to a decrease of more than 305 Mha in SSP1 for the period 2010–2050. Key drivers are population growth, changes in food consumption, and agricultural efficiency. The largest changes take place in Sub-Saharan Africa in SSP3 and SSP4, predominantly due to high population growth. With low increases in agricultural efficiency this leads to expansion of agricultural land and reduced food security. Land use also plays a crucial role in ambitious mitigation scenarios. First, agricultural emissions could form a substantial component of emissions that cannot be fully mitigated. Second, bioenergy and reforestation are crucial to create net negative emissions reducing emissions in SSP2 in 2050 by 8.7 Gt CO2/yr and 1.9 Gt CO2/yr, respectively (1.5 °C scenario compared to baseline). This is achieved by expansion of bioenergy area (516 Mha in 2050) and reforestation. Expansion of agriculture for food production is reduced due to REDD policy (290 Mha in 2050) affecting food security especially in Sub-Saharan Africa indicating an important trade-off of land-based mitigation. This set of SSP land-use scenarios provides a comprehensive quantification of interacting trends in the land system, both socio-economic and biophysical. By providing high resolution data, the scenario output can improve interactions between climate research and impact studies.

Impact of LULCC on the emission of BVOCs during the 21st century

Land-use and land-cover change (LULCC) is one of the key drivers of anthropogenic climate change. In addition to greenhouse gases such as CO2 or CH4, LULCC affects also the emission of other carbon trace gases such as biogenic volatile organic compounds (BVOCs). We investigate the impact of changing LULCC on the emission of isoprene and monoterpenes during the 21st century using seven different land-use projections, applying the dynamic vegetation modelling framework LPJ-GUESS. Climate change, and atmospheric CO2-concentration are based on the RCP2.6 scenario. The different LULCC-scenarios explore the impact of different land-based climate change mitigation strategies (such as afforestation and avoided deforestation, or bioenergy). We show that the increase of land area under crops or grassland would lead to a significant decrease of BVOC emissions, with a strong negative correlation between the fraction of managed global land area and the emission of isoprene and monoterpenes. But the choice of crops is important, especially for the bioenergy scenarios in which increasing fractional cover leads to decreasing BVOC emissions in our simulations; use of woody bioenergy crops can reverse this decrease. The strong impact of LULCC on the global and regional emission of BVOCs implies the need to include the impact of these changes in projections of atmospheric composition and air quality.

Uncertainties in the land-use flux resulting from land-use change reconstructions and gross land transitions

Abstract. Land-use and land-cover (LUC) changes are a key uncertainty when attributing changes in measured atmospheric CO2 concentration to its sinks and sources and must also be much better understood to determine the possibilities for land-based climate change mitigation, especially in the light of human demand on other land-based resources. On the spatial scale typically used in terrestrial ecosystem models (0.5 or 1°) changes in LUC over time periods of a few years or more can include bidirectional changes on the sub-grid level, such as the parallel expansion and abandonment of agricultural land (e.g. in shifting cultivation) or cropland–grassland conversion (and vice versa). These complex changes between classes within a grid cell have often been neglected in previous studies, and only net changes of land between natural vegetation cover, cropland and pastures accounted for, mainly because of a lack of reliable high-resolution historical information on gross land transitions, in combination with technical limitations within the models themselves. In the present study we applied a state-of-the-art dynamic global vegetation model with a detailed representation of croplands and carbon–nitrogen dynamics to quantify the uncertainty in terrestrial ecosystem carbon stocks and fluxes arising from the choice between net and gross representations of LUC. We used three frequently applied global, one recent global and one recent European LUC datasets, two of which resolve gross land transitions, either in Europe or in certain tropical regions. When considering only net changes, land-use-transition uncertainties (expressed as 1 standard deviation around decadal means of four models) in global carbon emissions from LUC (ELUC) are ±0.19, ±0.66 and ±0.47 Pg C a−1 in the 1980s, 1990s and 2000s, respectively, or between 14 and 39 % of mean ELUC. Carbon stocks at the end of the 20th century vary by ±11 Pg C for vegetation and ±37 Pg C for soil C due to the choice of LUC reconstruction, i.e. around 3 % of the respective C pools. Accounting for sub-grid (gross) land conversions significantly increased the effect of LUC on global and European carbon stocks and fluxes, most noticeably enhancing global cumulative ELUC by 33 Pg C (1750–2014) and entailing a significant reduction in carbon stored in vegetation, although the effect on soil C stocks was limited. Simulations demonstrated that assessments of historical carbon stocks and fluxes are highly uncertain due to the choice of LUC reconstruction and that the consideration of different contrasting LUC reconstructions is needed to account for this uncertainty. The analysis of gross, in addition to net, land-use changes showed that the full complexity of gross land-use changes is required in order to accurately predict the magnitude of LUC change emissions. This introduces technical challenges to process-based models and relies on extensive information regarding historical land-use transitions.

REDD+ and climate smart agriculture in landscapes: A case study in Vietnam using companion modelling

Finding land use strategies that merge land-based climate change mitigation measures and adaptation strategies is still an open issue in climate discourse. This article explores synergies and trade-offs between REDD+, a scheme that focuses mainly on mitigation through forest conservation, with “Climate Smart Agriculture”, an approach that emphasizes adaptive agriculture. We introduce a framework for ex-ante assessment of the impact of land management policies and interventions and for quantifying their impacts on land-based mitigation and adaptation goals. The framework includes a companion modelling (ComMod) process informed by interviews with policymakers, local experts and local farmers. The ComMod process consists of a Role-Playing Game with local farmers and an Agent Based Model. The game provided a participatory means to develop policy and climate change scenarios. These scenarios were then used as inputs to the Agent Based Model, a spatially explicit model to simulate landscape dynamics and the associated carbon emissions over decades. We applied the framework using as case study a community in central Vietnam, characterized by deforestation for subsistence agriculture and cultivation of acacias as a cash crop. The main findings show that the framework is useful in guiding consideration of local stakeholders' goals, needs and constraints. Additionally the framework provided beneficial information to policymakers, pointing to ways that policies might be re-designed to make them better tailored to local circumstances and therefore more effective in addressing synergistically climate change mitigation and adaptation objectives.

Investigating afforestation and bioenergy CCS as climate change mitigation strategies

The land-use sector can contribute to climate change mitigation not only by reducing greenhouse gas (GHG) emissions, but also by increasing carbon uptake from the atmosphere and thereby creating negative CO2 emissions. In this paper, we investigate two land-based climate change mitigation strategies for carbon removal: (1) afforestation and (2) bioenergy in combination with carbon capture and storage technology (bioenergy CCS). In our approach, a global tax on GHG emissions aimed at ambitious climate change mitigation incentivizes land-based mitigation by penalizing positive and rewarding negative CO2 emissions from the land-use system. We analyze afforestation and bioenergy CCS as standalone and combined mitigation strategies. We find that afforestation is a cost-efficient strategy for carbon removal at relatively low carbon prices, while bioenergy CCS becomes competitive only at higher prices. According to our results, cumulative carbon removal due to afforestation and bioenergy CCS is similar at the end of 21st century (600–700 GtCO2), while land-demand for afforestation is much higher compared to bioenergy CCS. In the combined setting, we identify competition for land, but the impact on the mitigation potential (1000 GtCO2) is partially alleviated by productivity increases in the agricultural sector. Moreover, our results indicate that early-century afforestation presumably will not negatively impact carbon removal due to bioenergy CCS in the second half of the 21st century. A sensitivity analysis shows that land-based mitigation is very sensitive to different levels of GHG taxes. Besides that, the mitigation potential of bioenergy CCS highly depends on the development of future bioenergy yields and the availability of geological carbon storage, while for afforestation projects the length of the crediting period is crucial.

CDM Forestry and the Ultimate Objective of the Climate Convention

In its Article 2, the U.N. Framework Convention on Climate Change policymakers gave themselves a long-term dynamic mandate under uncertainty. Taking the example of forestry activities in developing countries, the present article discusses whether land-based climate change mitigation measures in the context of compensation mechanisms for human-induced greenhouse gas emissions are covered under the UNFCCC's ultimate objective. Both the problem of climate change and human intervention act over long, yet finite timeframes. The article argues for taking a dynamic 100-year timeframe as reference for present-day activities. It concludes that increasing biotic carbon storage is legitimate for measures that contribute to biodiversity conservation, as long as it does not serve as a pretext for neglecting technological change. Among all forestry options, the list of priorities should be avoiding deforestation and devegetation, sustainable forest management, and afforestation. The problem of saturation can be encountered by the combination of forestry with the increased use of wood products and bioenergy. Concluding, the article gathers criteria for forest climate activities in the post-2012 regime.

Foreign Aid, Institutions, and Governance in Sub‐Saharan Africa

Introduction More than a decade ago, the World Bank argued that “underlying the litany of Africa’s development problems is a crisis of governance.” Poor quality institutions, weak rule of law, an absence of accountability, tight controls over information, and high levels of corruption still characterize many African states today. Aid levels have been reduced in many parts of Africa during the past decade. Yet in many of the countries with poor governance records, aid continues to contribute a very high percentage of government budgets. This article explores the institutional impact of these high levels of aid and the way that large amounts of aid are delivered. There are many reasons why governance is poor in much of sub-Saharan Africa. Colonialism did little to develop strong, indigenously rooted institutions that could tackle the development demands of modern states. Economic crisis and unsustainable debt, civil wars, and political instability have all taken their toll over the past 2 decades and more. It is difficult to separate the impact of these problems from the possible impact of foreign aid, which is often high in countries that suffer from precisely these problems. Theory provides conflicting guidance here. On the one hand, aid can release governments from binding revenue constraints, enabling them to strengthen domestic institutions and pay higher salaries to civil servants. Aid can provide training and technical assistance to build legal systems and accounting offices. In many countries, aid personnel (sometimes expatriate) manage important government programs, and the infusion of resources and technical assistance can give an important boost to the efficiency and effectiveness of governance, if only in a partial sense. Yet despite these likely benefits, it is also possible that, continued over