Final Report Summary - LUC4C (Land use change: assessing the net climate forcing, and options for climate change mitigation and adaptation)
Executive Summary:
1.1 Executive Summary
Climate change has long been known to affect the way humans use the land, for instance through affecting crop yields, the habitability of a region or hazards such as floods and storms. Likewise, land use is a strong global climate forcing agent. Land-based options to mitigate climate change are expected to deliver approximately a quarter of emissions reductions pledged by countries in their Nationally Determined Contributions (NDCs) under the Paris Climate Agreement, and are key to achieving a balance between anthropogenic emissions and removals in the second half of the 21st century. Land-based mitigation provides policy-makers with competing demands and trade-offs, but also possible co-benefits.
Land-based mitigation competes for land with food production, other ecosystem services & biodiversity. This competition can lead to increasing food prices as parts of existing agricultural land used to grow food is converted into bioenergy production. These price increase affect poor communities disproportionately. Land-based mitigation can also affect the ability of ecosystems to provide both the amount and the quality of ecosystem services, such as water provisioning, and can compete with the protection of biodiversity. It is, therefore, important to identify options that provide co-benefits, with possible measures including: Sustainable intensification through, for example, agroforestry and agropastoralism; Changing diets to reduce demand for land- and carbon-intensive products such as beef, through e.g. a tax or labelling; Restoring degraded forests to increase their carbon storage capacity and increase biodiversity; Using harvested wood products in buildings and other infrastructure to store carbon and reduce emissions from the production and transportation of cement.
In addition to greenhouse gas emissions and uptake, LULCC affects climate through biophysical effects such as the reflectance of sunlight from the Earth’s surface, cooling from evapotranspiration and forests absorbing wind energy. The net effects of these processes play out differently in different parts of the world, and the magnitude is uncertain. It is, however, possible to evaluate regional and local impacts. Currently, land-based climate mitigation policy does not consider biophysical effects, but the following options are noted: Robust scientific results are needed before biophysical effects to be included in global policy frameworks; A method for the evaluation of the regional impacts of land cover transitions exists and can inform regional and national mitigation efforts; Biophysical effects are stronger and more certain at local scales and so have the potential to be considered in local land use planning policy; Due to the geographical variability in biophysical effects, the location of carbon offsetting schemes can determine much of their effectiveness.
Time lags and multiple goals strongly limit the effectiveness of land-based mitigation, but there is potential for improvement and co-benefits can be achieved. Time lags in policy implementation and uptake strongly influence the effectiveness of land-based mitigation policy, but uptake has been shown to be slow even in the presence of incentives, due to various social factors. Developing policies that systematically cut across policy sectors would achieve co-benefits for multiple policy goals, including the potential for achieving mitigation-adaptation synergies.
A key challenge for policymaking is considering the mechanisms for achieving land use visions that connect environmental research to issues of sustainable development, local communities, cultural heritage, and human health. Land-based mitigation is not a ‘silver bullet’ to avoid climate change, but alongside drastic reductions in fossil fuel emissions, it can contribute to delivering the ‘balance of sources and sinks’ envisioned in the Paris Agreement, if the policy options available to support this objective are implemented.
Project Context and Objectives:
1.2 Project context and objectives
Context
Land-use and land-cover change is one of the key processes through which humans affect the functioning of the Earth system, contributing to both global environmental change and its impacts on human well-being. 40% of the land area is managed as croplands and pastures, and up to 80% of the land surface is impacted one way or the other by human activities.
Climate change has long been known to affect the way humans use the land, for instance through affecting crop yields, the habitability of a region or hazards such as floods and storms. Likewise, land use is a strong global climate forcing agent, through CO2 release following deforestation, or emissions of greenhouse gases such as N2O and CH4 related to land management. At the beginning of LUC4C less well understood were the regional climate change implications through changes in biophysical exchange processes related to land-use related land-cover changes.
In the wake of the Paris COP21 agreement, issues of land use are becoming central for achieving a <2°C warming world. What is currently a source of greenhouse gases will need to be rapidly transformed into a sink, and maintained that way. Land-based options to mitigate climate change are expected to deliver approximately a quarter of emissions reductions pledged by countries in their Nationally Determined Contributions (NDCs) under the Paris Climate Agreement. Whether – and how – this can be achieved while enhancing yields, providing areas for conservation and biodiversity, and enhancing other ecosystem services is under debate.
Objectives
The overall objectives of LUC4C were to advance our fundamental knowledge of the interactions between climate change and land-use change, and in doing so develop a framework for the synthesis of complex earth system science into guidelines that are of practical use for policy and societal stakeholders.
The LUC4C project therefore sought to
1. discern the key elements of land use that have the largest effect on climate, including their dependencies across time and space;
2. develop innovative methods to better quantify the dynamic interactions between land use and the climate system at different time and space scales;
3. deliver a portfolio of synthesis products and best practice guidelines for the identification of benefits or adverse effects of land-based mitigation options across different scenarios and where conflicts occur, the need for trade-offs.
Over the course of the project duration, LUC4C examined the societal and environmental drivers of land-use and land-cover change (LULCC) relevant to climate change, and assessed regional and global effects of different land-based mitigation policies and adaptation measures. The representation of LULCC in land surface and climate models was improved especially with respect to quantifying the effects of global vs. regional, and biophysical vs. biogeochemical ecosystem-atmosphere exchange. The work in LUC4C also aimed to provide progress in process understanding that will lead to a better assessment of LULCC-climate effects on multiple ecosystem services and to analyse these in relation to other societal needs that provide either a synergy or trade-off to land-based climate mitigation and adaptation.
The following points emerged as highly relevant to be addressed and some of the key project deliverables provided evidence on these issues:
• Competition of land-based climate change mitigation for land with food production, other ecosystem services and biodiversity;
• Biophysical effects of land-use change can be significant for regional surface climate and need to be accounted for in climate change assessments;
• Policy decision making needs to factor in time-lags in order to assess effectiveness;
• The effort of land-based mitigation efforts need also be viewed in terms of risks, especially related to fire;
• Model experiments and mode-data comparisons have identified a number of large uncertainties in the land-use/climate change interplay which need to be acknowledged for policy decision making.
These objectives were investigated in the project with a range of observation as well as modelling techniques. These aimed at identifying uncertainties related to measurements, scenarios and modelling. At the same time, observations were also used to inform model-based assessments.
LUC4C also aimed to reach out to policy makers via various avenues, such as via the production of policy briefs, stakeholder events, panel discussions, sessions at COPs and contribution to climate and biodiversity policy assessments.
Project Results:
NOTE: The complete section is contained in the attached pdf, since it contains Figures. The web-version contains only the text.
1.3 Main results
Today, nearly 80% of the land is impacted by human activities, approximately half of this area alone is used in form of cropland and pasture to provide food for the Earth’s population. In addition, human societies demand fibre, firewood, building materials and space for settlements, recreation, spirituality and conservation. Given the large pool of carbon in global vegetation and soils, and the large exchange fluxes of greenhouse gases CO2, N2O and CH4 between managed and natural ecosystems and the atmosphere, land use is also becoming increasingly central to fulfil yet another purpose: achieving a <2°C global warming in the wake of the Paris agreement. Land-based options to mitigate climate change are expected to deliver approximately a quarter of emissions reductions pledged by countries in their Nationally Determined Contributions (NDCs) under the Paris Climate Agreement, and are key to achieving the target of a balance between anthropogenic emissions and removals in the second half of the 21st century (Grassi et al., 2017).
Managed lands which now are a source of greenhouse gases will rapidly need to be transformed into a sink, and maintained that way, while at the same time fulfilling demands by society for a broad range of ecosystem services beyond cli3mate regulation. Since the land area is limited in its extent and suitability, the direct and indirect implications of carbon dioxide removal options, and options for reducing GHG emissions on land must, therefore, be comprehensively addressed to understand their role in achieving a much broader range of environmentally important objectives in addition to helping deliver climate goals (such as SDGs or Aichi targets). Yet despite of being closely interconnected, land-use challenges such as food, fibre and energy supply, conservation and biodiversity, carbon sequestration and greenhouse gas emissions, water and air quality are still often studied (and managed) separately, which is inappropriate and high-risk considering that land-use decisions made today will have effects over decades.
Based on 40 months work in the LUC4C project, we highlight recent advances in our understanding of land-use change in the climate system, placed in context of the broader peer-reviewed literature, and identify emerging issues and challenges of land-use especially in view of supporting a <2oC warming world.
1.3.1. Competition of land-based climate change mitigation for land with food production, other ecosystem services and biodiversity
The land area required to achieve emission reductions from land-based mitigation consistent with most 2°C scenarios is substantially higher than the land area currently identified as in marginal agricultural use or recently abandoned from agricultural use (Humpenoder et al., 2014;Popp et al., 2014;Engstrom et al., 2016a). However, potential land allocation for climate change mitigation depends on other claims on the same lands, the degree of climate change, technological developments and dietary preferences (Humpenoder et al., 2015;Alexander et al., 2016a;Engstrom et al., 2016a). There is evidence to suggest that land-based mitigation already has increased food prices, and models predict further increases, due to the competition for land and the direct use of food crops as a bioenergy feedstock (Kreidenweis et al., 2016; see their Figure 2, next page). Land-based mitigation policies and strategies in one location affect land use elsewhere due to displacement; an example of indirect land-use change (iLUC)(Popp et al., 2014) which can be a major source of GHG emissions that are not always reported, particularly when the displacement happens in countries with limited reporting of GHG fluxes.
Terrestrial ecosystems provide a range of ecosystem services, but land-based mitigation may affect the ability of ecosystems to provide both the amount and the quality of some of these services. Intensification of agricultural land use could free up more land for climate mitigation, but will likely have adverse environmental impacts, such as the pollution of water resources by nitrogen detrimental, effects on air quality, or altered runoff and flood risks (Bonsch et al., 2016; Krause et al., 2017, see their Figures 2 and 4, next page). For instance, bioenergy production has a higher water demand than any other alternative energy source, and can compete with other water uses unless managed carefully (Bonsch et al., 2016;Krause et al., 2017).
Intensification of food production could lead to more land being available for other uses, but is associated with large nitrogen losses to the atmosphere and water pollution from fertilisers (Krause et al., 2017). Provisioning services (such as food and biomass production) and regulating services (such as carbon sequestration or flood protection) are currently often not compatible, but they could be with more integrated approaches to land management. Provisioning services are often more tangible and easier to exchange in the market than regulating services (Bayer et al., 2015), cultural services, or the protection of biodiversity (Eitelberg et al., 2017).
Land-based mitigation competes for land with biodiversity, but there is also potential for achieving co-benefits. Some land-based mitigation options are incompatible with biodiversity goals (Krause et al., 2017). Afforestation using monoculture plantations reduces species richness when introduced into (semi-)natural grasslands (Popp et al., 2014); a habitat that is prioritised for instance by EU policies on biodiversity. Evidence suggests that when faced with conflicting mitigation and biodiversity goals, biodiversity is typically given a lower priority, especially if the mitigation option is considered risk-free and economically feasible (Humpenoder et al., 2014;Alexander et al., 2015;Humpenoder et al., 2015;Eitelberg et al., 2016). Approaches that promote synergies, such as avoided deforestation, land sparing and sustainable farming practices in bioenergy production, and longer rotation-times and mixed-species forests in afforestation-reforestation, can avoid the loss of biodiversity from land-based mitigation. Systematic land-use planning would help to achieve land-based mitigation options that also limit trade-offs with biodiversity.
1.3.2 Biophysical effects of land-use change can be significant for regional surface climate and need to be accounted for in climate change assessments
Biophysical effects include the reflectance of sunlight from the Earth’s surface (albedo), cooling from evapotranspiration, and the surface roughness that affect the wind speed. Changes in vegetation cover alter the reflection of sunlight; crops and pastures tend to be more reflective (higher albedo) than darker forests (lower albedo), and this has a cooling effect. However, forests have higher evapotranspiration rates than crops and pastures, which cools the land surface as well as recycling water to fall as rain. Also, forests absorbance of wind energy has implications for local surface temperatures. LULCC affects climate therefore not only through greenhouse gas emissions and uptake, but also through biophysical effects, especially at the regional scale (Perugini et al., 2017; see their Figure 2, below; Quesada et al., 2017a; Quesada et al., 2017b). Larger scale LULCC can affect circulation patterns and have out of region impacts, however the scale at which this becomes important is uncertain (Quesada et al., 2017b).
The net effects of these processes play out differently in different parts of the world. Satellite observations show that large-scale regional deforestation has a predominantly warming effect in the tropics and parts of the temperate zone due to reduced evapotranspiration (Alkama and Cescatti, 2016). In the boreal zone, however, deforestation causes cooling due to increased reflection of sunlight linked with the effect of snow cover—although the agreement between measurements and models is less clear than in the tropics (Alkama and Cescatti, 2016; Perugini et al., 2017). Uncertainties remain regarding the magnitude of the effect, especially for seasonal variables (e.g. maximum summer temperatures) and for the effects on precipitation, but it is now well established that the regional biophysical effects of land-cover change are substantial (Alkama and Cescatti, 2016; Duveiller et al., 2016; Perugini et al., 2017;Quesada et al., 2017a; Quesada et al., 2017b). Furthermore, biophysical effects on local temperature are more rapid than warming arising from global atmospheric CO2 levels. Thus, mitigation actions taken at the regional level would benefit from considering the consequences of biophysical effects on local temperature as well as the impacts of GHG emissions. There are major benefits in doing so, especially in tropical regions, since accounting for the biophysical climate effects of LULCC can support both mitigation and adaptation objectives and thus make policy more effective. Future atmospheric CO2 increases will increase vegetation growth through a ‘fertilisation’ effect, and this will further enhance the biophysical cooling effects of forests. Thus, avoided deforestation as a land-based mitigation option benefits from positive effects on both the regional and global climate systems (Pugh et al., 2016b).
Current global policy frameworks do not consider biophysical effects, and hence opportunities exist for policy to realise co-benefits. Although local biophysical climate impacts from LULCC are large, they tend to be much smaller when aggregated globally; this has implications for global policy. The process of including land-based mitigation in the UNFCCC context has been a matter of long and complex negotiations. Hence, the relatively small and currently uncertain global biophysical effects make it difficult to justify efforts to include these effects in the complex negotiations of the UNFCCC process, at present. However, it is now possible to evaluate the regional biophysical impacts (changes in local temperature) of land cover transitions, following a tiered approach similar to that of the IPCC method to estimate the effects of GHG emissions. The method applies three levels of increasing complexity, from Tier 1 (i.e. default method and factors) to Tier 3 (i.e. country-specific methods and factors; see LUC4C deliverable report 7.2 and 7.4 and Figures from these deliverables, below and next page). The procedures proposed for each tier are transparent, taking into consideration the UNFCCC reporting principles and could inform mitigation efforts at regional or national scales to realise the co-benefits of accounting for biophysical effects.
1.3.3 Policy decision making needs to factor in time-lags in order to assess effectiveness
The relative contribution to climate mitigation of different land-based mitigation options changes through time (Pugh et al., 2015;Krause et al., 2016). Avoided deforestation provides immediate mitigation gains by reducing rapid carbon emissions that take place when forests are cut or burnt (as well as having co-benefits with multiple ecosystem services). Afforestation-reforestation can take up carbon immediately upon planting, but with varying, relatively small annual gains due to the slow rate of forest growth, and responding soil carbon pools, especially as forests approach maturity (Krause et al., 2016). Harvesting and replanting, with carbon storage in harvested wood products or use as bioenergy, can enable the same land to continue to contribute to mitigation, but care has to be taken to sustainably manage repeated harvesting in order not to deplete soil carbon stocks which seems to have a larger contribution that often anticipated. Large uncertainties in historic land-cover and land-use estimates make recommendations challenging (Arneth et al., 2017). Overall, bioenergy (especially lignocellulosic) is expected to contribute more to mitigation scenarios in the second half of the century, but this will depend on the availability of advanced negative emissions technologies (Popp et al., 2016).
Time lags in policy implementation and uptake strongly influence the effectiveness of land-based mitigation policy (Rounsevell et al., 2014; Alexander et al., 2015; Brown et al., 2015; Brown et al., submitted, see their Figure 1, below). There are large uncertainties associated with the development and implementation of BECCS and other land-based mitigation options. Barriers arising from the rate of technological development and the considerable need for financial investment mean that the large-scale implementation of BECCS is not likely until around the middle of the 21st century, at the very earliest (Popp et al., 2016). Furthermore, farmers may be slow to begin growing bioenergy crops even with financial support. Such barriers could limit the success of bioenergy as a land-based mitigation option. This demonstrates the importance of immediate policy action and measures to support more rapid policy intervention and uptake.
Changing food consumption patterns (e.g. through low-meat diets, reducing over-eating and waste, and eating alternative protein sources) reduces the land area needed for food production providing opportunities for land-based mitigation (Alexander et al., 2017a;Alexander et al., 2017b). This also builds resilience to climate change, since the additional availability of land could offset the negative impact of climate change on crop yields and thus food production. These examples demonstrate potential opportunities, but there is little scientific evidence to support understanding of the full extent of mitigation-adaptation synergies (or trade-offs). Still, developing policies that systematically cut across policy sectors would achieve co-benefits for multiple policy goals. Co-benefits are not always realised, and a single sector focus can often cause unintended negative impacts on other sectors, e.g. by promoting land clearing for biofuels, which is associated with negative impacts on carbon stocks and flooding prevention. Well-grounded, land-based mitigation strategies can have positive social benefits, but conversely, land-based mitigation can have negative environmental and social impacts if poorly planned.
1.3.4 The effort of land-based mitigation efforts need also be viewed in terms of risks, especially related to fire
The success of afforestation-reforestation and avoided deforestation as mitigation options is subject to the changing risks from disturbances that affect forest permanence and depend on continued monitoring and management of forest stands over the long term. Temperature extremes and prolonged dry-spells increase fire risk, heat-waves and droughts will reduce the fitness of ecosystems, and a warmer climate could also lead to enhanced insect outbreaks. Such disturbances arising from climate extremes, wildfires, pests, and diseases affect afforestation-reforestation and avoided deforestation, but also yields of food and bioenergy crops (Bodin et al., 2016; Pugh et al., 2016a; Frieler et al., 2017). There is as yet no agreement on the main processes underlying heat-effects on yields, but irrigation was found to dampen the negative effects of high temperatures considerably (Schauberger et al., 2017). Fire is the sole episodic event that is included explicitly in current global scale ecosystem models (Hantson et al., 2016;Rabin et al., 2017), other causes of mortality are subsumed in a generic “background” disturbance. With warmer and drier temperatures fire risk is increasing but whether the enhanced fire risk also translates into larger burned area is debatable.. Studies showed that future burned area is reduced in (sub-)tropical semi-arid regions, where enhanced levels of CO2 foster shrub encroachment into C4 grass-dominated systems, while increasing human population density prevents fire spread globally. Across a range of RCPs and SSPs, Knorr et al (Knorr et al., 2016) demonstrated that uncertainties in future population growth combined with degree of urbanisation are of similar magnitude to uncertainties related to future climate change on burned area. Scenarios with moderate climate change combined with slow urbanisation at relatively large population growth resulted in a global decline of burned area – but not in an overall declining risk for humans per se since population increases in fire-prone regions (Knorr et al., 2016, see their Figure 3, below).
Better understanding disturbances and how to manage them in a changing climate would reduce uncertainty and therefore the risks associated with investment in mitigation options. Monitoring, Reporting, and Verification (MRV) of forest carbon and other land-based mitigation schemes need to be able to properly consider disturbances (and associated carbon losses) to provide confidence that land-based mitigation projects will meet their long-term objectives. This is, however, a sensitive issue within policy communities, since there is a common understanding that natural disturbances should not be accounted for by countries, since they are not anthropogenic. However, recent advances in satellites and modelling capabilities can support MRV, along with capacity-building in developing countries.
1.3.5 Model experiments and mode-data comparisons have identified a number of large uncertainties in the land-use/climate change interplay which need to be acknowledged for policy decision making
Quantitative assessment of model performance is crucial when using model output to support policy, and decision makers have accepted the inevitable uncertainty that comes with modelling environmental change. While progress has been made, systematic model evaluation that utilises all suitable streams of measurements or statistical information, and identification of uncertainties within and between models is still a critical challenge.The individual modelling tools used for understanding and projecting the broad implications of land-based mitigation (e.g. land-use models, dynamic global vegetation models, climate models, biodiversity models) all suffer from incomplete process-representations or uncertain parameterisations. Model-intercomparisons (Schmitz et al., 2014;Sitch et al., 2015;Lawrence et al., 2016) result in ensemble outputs that can help to assess how well models can reproduce historical variables and/or to derive a range of future changes. Whether or not agreement between models should be interpreted as a “robust” understanding of a system’s response is debatable and requires careful analysis and in-depth knowledge of the participating models, especially with respect to which processes are accounted for, and how these processes are included (Ahlstrom et al., 2015; Arneth et al., 2017, see their Figure 2, above).
In an analysis of future land-cover change, all kinds of existing future scenarios were compared (i.e. not specifying that the models should be run following a joint protocol) that were produced by a diverse set of global and European models (Alexander et al., 2016b; Prestele et al., 2016). Not surprisingly, large spread in future projections of main land-cover types were due to the different scenarios. However, the analysis identified also equally large uncertainty due to the modelling approach which highlight the needs to better understand the pros and cons of different land-use modelling paradigms and to ensure that models that seek to identify impacts incorporate a much broader range of future projections (and past hindcasts; (Bayer et al., 2017)) than available so far.
Formalised parameter uncertainty analysis has not yet been applied in many land-use change models. Recently, a statistical analyses of input parameter variability identified which of these affected outputs most strongly (in that study: related to meat consumption or yield improvement rates; (Engstrom et al., 2016b), and also investigated uncertainties in the parameters describing the scenario that was used to calculate land-use change (Engström et al., 2016). Using conditional probability ranges, broad overlap in the uncertainty distributions of future global total crop area was found for very different scenarios (SSP2,4,5), due to compensation effects that arose from changes in drivers. Future cropland area under SSP1 and 3 framework stood out (Engström et al., 2016) with assumptions (and uncertainties) in the SSP1 leading to notably declining crop area (associated with e.g. population decline and increasing yields; (Engström et al., 2016).
In summary, land-based mitigation is not a ‘silver bullet’ to avoid climate change, but alongside drastic reductions in fossil fuel emissions, it can contribute to delivering the ‘balance of sources and sinks’ in the Paris Agreement. Land-based mitigation is currently the only way to remove CO2 from the atmosphere at a scale that is potentially relevant to climate mitigation. The land sector will not be emissions-free, as emissions are necessarily associated with food production. Moreover, there is a real danger that land-based mitigation will compete with food production, the provision of other ecosystem services, and protection of biodiversity. Further analysis is required to understand fully the many trade-offs beyond climate mitigation that arise from land management and to identify policy options that support co-benefits. Land-based mitigation could potentially enable the land sector as a whole to approach a balance of sources and sinks, and, if barriers are overcome and sustainability ensured, it could further offset some of the more unavoidable emissions from fossil fuels.
Potential Impact:
NOTE: The complete section is contained in the attached pdf, since it contains Figures. The web-version contains only the text.
1.4 Project impact and dissemination (max 10 pages) (including the socio-economic impact and the wider societal implications of the project so far) and the main dissemination activities and exploitation of results
Four main activities were pursued in LUC4C to disseminate project outcomes and to ensure impact at various levels:
• Policy outreach events
• Contribution to international assessments
• Education
• Scientific meetings and conferences
1.4.1 Policy outreach
LUC4C (co)organised two side events at the UNFCCC COP21 in Paris, which included “Synergies and Trade-Offs in Land-Based Climate Mitigation and Biodiversity”, which took place at the Rio Pavillon, and presented an analysis of the latest science on land-use change climate impacts (including biophysical effects) and mitigation potential (including trade-offs and socio-economic context), and the extent to which the land sector (e.g. Reduced Emissions from Deforestation and Degradation, bioenergy, agricultural sector) is included in national and international policy, including Intended Nationally Determined Contributions (INDCs). The event discussed the several disconnects between the production of scientific knowledge and the knowledge needs and uptake seen in current land-climate policy-making. This event was quite timely with respect to development of policy, and development of new science evidence related to effects of land-based mitigation scenarios within the IPCC scenario framework.
At COP21 (Dec. 2015), LUC4C participated also in the organisation of the side-event on ”Mmulti-level climate governance: an integrated analysis of national, regional and local policies”. In that event, the project coordination (Prof. Arneth) presented LUC4C research entitled: Using the natural capital and ecosystem services concept to assess synergies and trade-offs in land-based mitigation.
Likewise at the COP 13 of the CBD in Cancun (Dec. 2016) on” Climate, biodiversity and sustainable development – benefits from a new global land management strategy”. The primary goals of this science event were:
• to demonstrate current research progress in understanding the impact of the land system on both biodiversity and climate change, building on a broad range of innovative methods, using observations to enrich predictive modelling and scenarios,
• to gather the needs of policy makers and civil society in driving future research and assessment in this field.
Earlier, during the Brussels “Green Week” LUC4C participated in a Stand representing "Nature-Based Solutions for Biodiversity & Climate Change", which highlighted the work of 4 European Commission funded research projects that used Nature-Based Solutions (NBS) to address biodiversity and climate change for the benefit of human wellbeing.
Also in Brussels, LUC4C led a lunch-time debate “Land-based climate mitigation in a < 2 degree world: potentials and potential pit-falls”. The event was chaired by DG RTD and DG CLIMA and aimed to exchange knowledge on land-based climate change mitigation, supported by the latest EC-funded research, after the adoption of the Paris Agreement & in view of the IPCC report on limiting global warming to 1.5oC.
In association with the final science workshop of LUC4C, a stakeholder workshop was organised in Brussels in Septembe 2017 which focused on “The role of land use in achieving the <2oC Paris COP21 target: Key Messages on Policy Implications”, and was attended by a range of European policy stakeholders as well as a number of the scientists from the LUC4C project.
All of these siden-events and panel debates were well attended and the discussions fed back to the LUC4C work and its output materials (incl a nunber of policy briefs which can be downloaded from the project web-site, www.luc4c.eu). The final stakeholder day in particular was specifically designed such that the key outcomes of the processes to identify implications and options for policy (workshop and LUC4C expert judgement) were presented in the deliverable Recommendations to support best practice for climate mitigation and adaptation policy (D1.3). Key policy implications and options were identified as:
• Achieving sustainable intensification through, for example, agroforestry and agropastoralism;
• Changing diets to reduce demand for land- and carbon-intensive products such as beef, through e.g. a tax or labelling;
• Restoring degraded forests to increase their carbon storage capacity and increase biodiversity;
• Using harvested wood products in buildings and other infrastructure to store carbon and reduce emissions from the production and transportation of cement and iron;
• Robust scientific results are needed before biophysical effects are to be included in global policy frameworks;
• A method for the evaluation of the regional impacts of land cover transitions exists and can inform regional and national mitigation efforts;
• Biophysical effects are stronger and more certain at local scales and so, have the potential to be considered in local land use planning policy;
• Due to the geographical variability in biophysical effects, the location of carbon offsetting schemes can determine much of their effectiveness;
• Raising awareness in farmer communities, through measures such as knowledge hubs and advisory schemes, to enhance policy and technology uptake;
• Incentivizing adaptation measures in both the agricultural and forest sectors would build resilience to climate change and support land-based mitigation;
• Forward-looking policies to maintain carbon storage over longer time-frames, instead of short term carbon maximisation that negatively affects ecosystem functioning.
1.4.2. Contribution to assessments
Researchers in LUC4C have been involved in the IPCC assessments for many years. Importantly for the multi-disciplinary aspect of LUC4C results, scientist also became actively engaged in the ongoing assessments of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES). Prof. Rounsevell (LUC4C WP 1 lead) acted as co-chair of the IPBES Regional Assessment for Europe, Russia and Central Asia, which will be defended in the IPBES plenary in spring 2018. Prof. Arneth (LUC4C coordinator) is Coordinating Lead Author in the ongoing IPBES Global Assessment in the chapter on Future Scenarios of Nature, Nature’s Contribution to People and Good Quality of Life. She is also a CLA in the IPCC Special Report on Climate change and Land, which has just commenced.
Participation to these Assessments is important as ensures that results reported in the LUC4C published scientific literature contributes to inform the climate and environmental policy process. In that light, Prof. Arneth also participated a workshop (“Research on climate smart agriculture”) organised in February 2015 by DG AGRI discussing the research needs towards the development of a Climate Change and Agriculture research agenda to guide further activities under Horizon2020 in particular with regard to Societal Challenge 2 (Food Security, Sustainable Agriculture and Forestry, Marine, Maritime and Inland Water Research and the Bio-economy).
1.4.3 Education
Education of the next generation of environmental scientists is an important component of dissemination and impact. All LUC4C senior scientists contribute to teaching and supervision of students and young investigators. Specifically for LUC4C, a one-week winter school was organised for 25 international doctoral and post-doctoral researchers on “People, climate and the terrestrial biosphere” which aimed through lectures and practical work to give a broad overview of the role of the terrestrial biosphere in the Earth system, with a strong focus on anthropogenic land-use change and management and their implications. Lectures given during the course were filmed and are available via KIT on iTUNES U.
LUC4Kit includes the creation, development and delivery of an innovative, easy-to-use, pedagogical, fast and useful emulator tool (“LUC4Kit explorer”, available in 46.43.3.32/luc4c) to provide maps, time series, and custom global and regional averages of changes in carbon variables in response to pre-established and user’s land cover changes (LCC) scenario. The data provided for visualization (see Figure 1) is based on three sets of simulations performed with the dynamic global vegetation model LPJ-GUESS Carbon-Nitrogen version. The tool aims primarily at university students. A full documentation for pedagogical and policy-maker purposes will also be made available online (currently under development), it has been tested in a first course with ~15 M.Sc students during a lecture course in Karlsruhe, when the project responsible scientists (Benjamin Quesada and Almut Arneth) gave a practical course on carbon cycle and land-use. With the tool, users can specify own experiments, select output variables and safe output data (for later post-processing by different types of software).
1.4.4. Wider science dissemination
Scientist presented their work at numerous international conferences, both in form of oral presentations as well as posters. Conference sessions that were organised through LUC4C included, among others:
Global scenarios of land-use change and land-based mitigation, and their importance in the climate system at the Paris 2015 conference “Our common future under climate change” which was a large international meeting designed specifically to lead up to the COP 21 later that same year.
At the conference of the Future Earth Project iLEAPS, September 2017 in Oxford, LUC4C co-onvened the session “Land-use change in a warming worl: Interactions between climate and socio-ecological systems, and implications for land-based climate change mitigation”.
At the annual autumn meeting of the American Geophysical union, in 2016 in San Francisco, LUC4C co-convened a session on “Impacts of land use and land cover change in a changing climate, using modeling and measurements”.
List of Websites:
www.luc4c.eu
1.1 Executive Summary
Climate change has long been known to affect the way humans use the land, for instance through affecting crop yields, the habitability of a region or hazards such as floods and storms. Likewise, land use is a strong global climate forcing agent. Land-based options to mitigate climate change are expected to deliver approximately a quarter of emissions reductions pledged by countries in their Nationally Determined Contributions (NDCs) under the Paris Climate Agreement, and are key to achieving a balance between anthropogenic emissions and removals in the second half of the 21st century. Land-based mitigation provides policy-makers with competing demands and trade-offs, but also possible co-benefits.
Land-based mitigation competes for land with food production, other ecosystem services & biodiversity. This competition can lead to increasing food prices as parts of existing agricultural land used to grow food is converted into bioenergy production. These price increase affect poor communities disproportionately. Land-based mitigation can also affect the ability of ecosystems to provide both the amount and the quality of ecosystem services, such as water provisioning, and can compete with the protection of biodiversity. It is, therefore, important to identify options that provide co-benefits, with possible measures including: Sustainable intensification through, for example, agroforestry and agropastoralism; Changing diets to reduce demand for land- and carbon-intensive products such as beef, through e.g. a tax or labelling; Restoring degraded forests to increase their carbon storage capacity and increase biodiversity; Using harvested wood products in buildings and other infrastructure to store carbon and reduce emissions from the production and transportation of cement.
In addition to greenhouse gas emissions and uptake, LULCC affects climate through biophysical effects such as the reflectance of sunlight from the Earth’s surface, cooling from evapotranspiration and forests absorbing wind energy. The net effects of these processes play out differently in different parts of the world, and the magnitude is uncertain. It is, however, possible to evaluate regional and local impacts. Currently, land-based climate mitigation policy does not consider biophysical effects, but the following options are noted: Robust scientific results are needed before biophysical effects to be included in global policy frameworks; A method for the evaluation of the regional impacts of land cover transitions exists and can inform regional and national mitigation efforts; Biophysical effects are stronger and more certain at local scales and so have the potential to be considered in local land use planning policy; Due to the geographical variability in biophysical effects, the location of carbon offsetting schemes can determine much of their effectiveness.
Time lags and multiple goals strongly limit the effectiveness of land-based mitigation, but there is potential for improvement and co-benefits can be achieved. Time lags in policy implementation and uptake strongly influence the effectiveness of land-based mitigation policy, but uptake has been shown to be slow even in the presence of incentives, due to various social factors. Developing policies that systematically cut across policy sectors would achieve co-benefits for multiple policy goals, including the potential for achieving mitigation-adaptation synergies.
A key challenge for policymaking is considering the mechanisms for achieving land use visions that connect environmental research to issues of sustainable development, local communities, cultural heritage, and human health. Land-based mitigation is not a ‘silver bullet’ to avoid climate change, but alongside drastic reductions in fossil fuel emissions, it can contribute to delivering the ‘balance of sources and sinks’ envisioned in the Paris Agreement, if the policy options available to support this objective are implemented.
Project Context and Objectives:
1.2 Project context and objectives
Context
Land-use and land-cover change is one of the key processes through which humans affect the functioning of the Earth system, contributing to both global environmental change and its impacts on human well-being. 40% of the land area is managed as croplands and pastures, and up to 80% of the land surface is impacted one way or the other by human activities.
Climate change has long been known to affect the way humans use the land, for instance through affecting crop yields, the habitability of a region or hazards such as floods and storms. Likewise, land use is a strong global climate forcing agent, through CO2 release following deforestation, or emissions of greenhouse gases such as N2O and CH4 related to land management. At the beginning of LUC4C less well understood were the regional climate change implications through changes in biophysical exchange processes related to land-use related land-cover changes.
In the wake of the Paris COP21 agreement, issues of land use are becoming central for achieving a <2°C warming world. What is currently a source of greenhouse gases will need to be rapidly transformed into a sink, and maintained that way. Land-based options to mitigate climate change are expected to deliver approximately a quarter of emissions reductions pledged by countries in their Nationally Determined Contributions (NDCs) under the Paris Climate Agreement. Whether – and how – this can be achieved while enhancing yields, providing areas for conservation and biodiversity, and enhancing other ecosystem services is under debate.
Objectives
The overall objectives of LUC4C were to advance our fundamental knowledge of the interactions between climate change and land-use change, and in doing so develop a framework for the synthesis of complex earth system science into guidelines that are of practical use for policy and societal stakeholders.
The LUC4C project therefore sought to
1. discern the key elements of land use that have the largest effect on climate, including their dependencies across time and space;
2. develop innovative methods to better quantify the dynamic interactions between land use and the climate system at different time and space scales;
3. deliver a portfolio of synthesis products and best practice guidelines for the identification of benefits or adverse effects of land-based mitigation options across different scenarios and where conflicts occur, the need for trade-offs.
Over the course of the project duration, LUC4C examined the societal and environmental drivers of land-use and land-cover change (LULCC) relevant to climate change, and assessed regional and global effects of different land-based mitigation policies and adaptation measures. The representation of LULCC in land surface and climate models was improved especially with respect to quantifying the effects of global vs. regional, and biophysical vs. biogeochemical ecosystem-atmosphere exchange. The work in LUC4C also aimed to provide progress in process understanding that will lead to a better assessment of LULCC-climate effects on multiple ecosystem services and to analyse these in relation to other societal needs that provide either a synergy or trade-off to land-based climate mitigation and adaptation.
The following points emerged as highly relevant to be addressed and some of the key project deliverables provided evidence on these issues:
• Competition of land-based climate change mitigation for land with food production, other ecosystem services and biodiversity;
• Biophysical effects of land-use change can be significant for regional surface climate and need to be accounted for in climate change assessments;
• Policy decision making needs to factor in time-lags in order to assess effectiveness;
• The effort of land-based mitigation efforts need also be viewed in terms of risks, especially related to fire;
• Model experiments and mode-data comparisons have identified a number of large uncertainties in the land-use/climate change interplay which need to be acknowledged for policy decision making.
These objectives were investigated in the project with a range of observation as well as modelling techniques. These aimed at identifying uncertainties related to measurements, scenarios and modelling. At the same time, observations were also used to inform model-based assessments.
LUC4C also aimed to reach out to policy makers via various avenues, such as via the production of policy briefs, stakeholder events, panel discussions, sessions at COPs and contribution to climate and biodiversity policy assessments.
Project Results:
NOTE: The complete section is contained in the attached pdf, since it contains Figures. The web-version contains only the text.
1.3 Main results
Today, nearly 80% of the land is impacted by human activities, approximately half of this area alone is used in form of cropland and pasture to provide food for the Earth’s population. In addition, human societies demand fibre, firewood, building materials and space for settlements, recreation, spirituality and conservation. Given the large pool of carbon in global vegetation and soils, and the large exchange fluxes of greenhouse gases CO2, N2O and CH4 between managed and natural ecosystems and the atmosphere, land use is also becoming increasingly central to fulfil yet another purpose: achieving a <2°C global warming in the wake of the Paris agreement. Land-based options to mitigate climate change are expected to deliver approximately a quarter of emissions reductions pledged by countries in their Nationally Determined Contributions (NDCs) under the Paris Climate Agreement, and are key to achieving the target of a balance between anthropogenic emissions and removals in the second half of the 21st century (Grassi et al., 2017).
Managed lands which now are a source of greenhouse gases will rapidly need to be transformed into a sink, and maintained that way, while at the same time fulfilling demands by society for a broad range of ecosystem services beyond cli3mate regulation. Since the land area is limited in its extent and suitability, the direct and indirect implications of carbon dioxide removal options, and options for reducing GHG emissions on land must, therefore, be comprehensively addressed to understand their role in achieving a much broader range of environmentally important objectives in addition to helping deliver climate goals (such as SDGs or Aichi targets). Yet despite of being closely interconnected, land-use challenges such as food, fibre and energy supply, conservation and biodiversity, carbon sequestration and greenhouse gas emissions, water and air quality are still often studied (and managed) separately, which is inappropriate and high-risk considering that land-use decisions made today will have effects over decades.
Based on 40 months work in the LUC4C project, we highlight recent advances in our understanding of land-use change in the climate system, placed in context of the broader peer-reviewed literature, and identify emerging issues and challenges of land-use especially in view of supporting a <2oC warming world.
1.3.1. Competition of land-based climate change mitigation for land with food production, other ecosystem services and biodiversity
The land area required to achieve emission reductions from land-based mitigation consistent with most 2°C scenarios is substantially higher than the land area currently identified as in marginal agricultural use or recently abandoned from agricultural use (Humpenoder et al., 2014;Popp et al., 2014;Engstrom et al., 2016a). However, potential land allocation for climate change mitigation depends on other claims on the same lands, the degree of climate change, technological developments and dietary preferences (Humpenoder et al., 2015;Alexander et al., 2016a;Engstrom et al., 2016a). There is evidence to suggest that land-based mitigation already has increased food prices, and models predict further increases, due to the competition for land and the direct use of food crops as a bioenergy feedstock (Kreidenweis et al., 2016; see their Figure 2, next page). Land-based mitigation policies and strategies in one location affect land use elsewhere due to displacement; an example of indirect land-use change (iLUC)(Popp et al., 2014) which can be a major source of GHG emissions that are not always reported, particularly when the displacement happens in countries with limited reporting of GHG fluxes.
Terrestrial ecosystems provide a range of ecosystem services, but land-based mitigation may affect the ability of ecosystems to provide both the amount and the quality of some of these services. Intensification of agricultural land use could free up more land for climate mitigation, but will likely have adverse environmental impacts, such as the pollution of water resources by nitrogen detrimental, effects on air quality, or altered runoff and flood risks (Bonsch et al., 2016; Krause et al., 2017, see their Figures 2 and 4, next page). For instance, bioenergy production has a higher water demand than any other alternative energy source, and can compete with other water uses unless managed carefully (Bonsch et al., 2016;Krause et al., 2017).
Intensification of food production could lead to more land being available for other uses, but is associated with large nitrogen losses to the atmosphere and water pollution from fertilisers (Krause et al., 2017). Provisioning services (such as food and biomass production) and regulating services (such as carbon sequestration or flood protection) are currently often not compatible, but they could be with more integrated approaches to land management. Provisioning services are often more tangible and easier to exchange in the market than regulating services (Bayer et al., 2015), cultural services, or the protection of biodiversity (Eitelberg et al., 2017).
Land-based mitigation competes for land with biodiversity, but there is also potential for achieving co-benefits. Some land-based mitigation options are incompatible with biodiversity goals (Krause et al., 2017). Afforestation using monoculture plantations reduces species richness when introduced into (semi-)natural grasslands (Popp et al., 2014); a habitat that is prioritised for instance by EU policies on biodiversity. Evidence suggests that when faced with conflicting mitigation and biodiversity goals, biodiversity is typically given a lower priority, especially if the mitigation option is considered risk-free and economically feasible (Humpenoder et al., 2014;Alexander et al., 2015;Humpenoder et al., 2015;Eitelberg et al., 2016). Approaches that promote synergies, such as avoided deforestation, land sparing and sustainable farming practices in bioenergy production, and longer rotation-times and mixed-species forests in afforestation-reforestation, can avoid the loss of biodiversity from land-based mitigation. Systematic land-use planning would help to achieve land-based mitigation options that also limit trade-offs with biodiversity.
1.3.2 Biophysical effects of land-use change can be significant for regional surface climate and need to be accounted for in climate change assessments
Biophysical effects include the reflectance of sunlight from the Earth’s surface (albedo), cooling from evapotranspiration, and the surface roughness that affect the wind speed. Changes in vegetation cover alter the reflection of sunlight; crops and pastures tend to be more reflective (higher albedo) than darker forests (lower albedo), and this has a cooling effect. However, forests have higher evapotranspiration rates than crops and pastures, which cools the land surface as well as recycling water to fall as rain. Also, forests absorbance of wind energy has implications for local surface temperatures. LULCC affects climate therefore not only through greenhouse gas emissions and uptake, but also through biophysical effects, especially at the regional scale (Perugini et al., 2017; see their Figure 2, below; Quesada et al., 2017a; Quesada et al., 2017b). Larger scale LULCC can affect circulation patterns and have out of region impacts, however the scale at which this becomes important is uncertain (Quesada et al., 2017b).
The net effects of these processes play out differently in different parts of the world. Satellite observations show that large-scale regional deforestation has a predominantly warming effect in the tropics and parts of the temperate zone due to reduced evapotranspiration (Alkama and Cescatti, 2016). In the boreal zone, however, deforestation causes cooling due to increased reflection of sunlight linked with the effect of snow cover—although the agreement between measurements and models is less clear than in the tropics (Alkama and Cescatti, 2016; Perugini et al., 2017). Uncertainties remain regarding the magnitude of the effect, especially for seasonal variables (e.g. maximum summer temperatures) and for the effects on precipitation, but it is now well established that the regional biophysical effects of land-cover change are substantial (Alkama and Cescatti, 2016; Duveiller et al., 2016; Perugini et al., 2017;Quesada et al., 2017a; Quesada et al., 2017b). Furthermore, biophysical effects on local temperature are more rapid than warming arising from global atmospheric CO2 levels. Thus, mitigation actions taken at the regional level would benefit from considering the consequences of biophysical effects on local temperature as well as the impacts of GHG emissions. There are major benefits in doing so, especially in tropical regions, since accounting for the biophysical climate effects of LULCC can support both mitigation and adaptation objectives and thus make policy more effective. Future atmospheric CO2 increases will increase vegetation growth through a ‘fertilisation’ effect, and this will further enhance the biophysical cooling effects of forests. Thus, avoided deforestation as a land-based mitigation option benefits from positive effects on both the regional and global climate systems (Pugh et al., 2016b).
Current global policy frameworks do not consider biophysical effects, and hence opportunities exist for policy to realise co-benefits. Although local biophysical climate impacts from LULCC are large, they tend to be much smaller when aggregated globally; this has implications for global policy. The process of including land-based mitigation in the UNFCCC context has been a matter of long and complex negotiations. Hence, the relatively small and currently uncertain global biophysical effects make it difficult to justify efforts to include these effects in the complex negotiations of the UNFCCC process, at present. However, it is now possible to evaluate the regional biophysical impacts (changes in local temperature) of land cover transitions, following a tiered approach similar to that of the IPCC method to estimate the effects of GHG emissions. The method applies three levels of increasing complexity, from Tier 1 (i.e. default method and factors) to Tier 3 (i.e. country-specific methods and factors; see LUC4C deliverable report 7.2 and 7.4 and Figures from these deliverables, below and next page). The procedures proposed for each tier are transparent, taking into consideration the UNFCCC reporting principles and could inform mitigation efforts at regional or national scales to realise the co-benefits of accounting for biophysical effects.
1.3.3 Policy decision making needs to factor in time-lags in order to assess effectiveness
The relative contribution to climate mitigation of different land-based mitigation options changes through time (Pugh et al., 2015;Krause et al., 2016). Avoided deforestation provides immediate mitigation gains by reducing rapid carbon emissions that take place when forests are cut or burnt (as well as having co-benefits with multiple ecosystem services). Afforestation-reforestation can take up carbon immediately upon planting, but with varying, relatively small annual gains due to the slow rate of forest growth, and responding soil carbon pools, especially as forests approach maturity (Krause et al., 2016). Harvesting and replanting, with carbon storage in harvested wood products or use as bioenergy, can enable the same land to continue to contribute to mitigation, but care has to be taken to sustainably manage repeated harvesting in order not to deplete soil carbon stocks which seems to have a larger contribution that often anticipated. Large uncertainties in historic land-cover and land-use estimates make recommendations challenging (Arneth et al., 2017). Overall, bioenergy (especially lignocellulosic) is expected to contribute more to mitigation scenarios in the second half of the century, but this will depend on the availability of advanced negative emissions technologies (Popp et al., 2016).
Time lags in policy implementation and uptake strongly influence the effectiveness of land-based mitigation policy (Rounsevell et al., 2014; Alexander et al., 2015; Brown et al., 2015; Brown et al., submitted, see their Figure 1, below). There are large uncertainties associated with the development and implementation of BECCS and other land-based mitigation options. Barriers arising from the rate of technological development and the considerable need for financial investment mean that the large-scale implementation of BECCS is not likely until around the middle of the 21st century, at the very earliest (Popp et al., 2016). Furthermore, farmers may be slow to begin growing bioenergy crops even with financial support. Such barriers could limit the success of bioenergy as a land-based mitigation option. This demonstrates the importance of immediate policy action and measures to support more rapid policy intervention and uptake.
Changing food consumption patterns (e.g. through low-meat diets, reducing over-eating and waste, and eating alternative protein sources) reduces the land area needed for food production providing opportunities for land-based mitigation (Alexander et al., 2017a;Alexander et al., 2017b). This also builds resilience to climate change, since the additional availability of land could offset the negative impact of climate change on crop yields and thus food production. These examples demonstrate potential opportunities, but there is little scientific evidence to support understanding of the full extent of mitigation-adaptation synergies (or trade-offs). Still, developing policies that systematically cut across policy sectors would achieve co-benefits for multiple policy goals. Co-benefits are not always realised, and a single sector focus can often cause unintended negative impacts on other sectors, e.g. by promoting land clearing for biofuels, which is associated with negative impacts on carbon stocks and flooding prevention. Well-grounded, land-based mitigation strategies can have positive social benefits, but conversely, land-based mitigation can have negative environmental and social impacts if poorly planned.
1.3.4 The effort of land-based mitigation efforts need also be viewed in terms of risks, especially related to fire
The success of afforestation-reforestation and avoided deforestation as mitigation options is subject to the changing risks from disturbances that affect forest permanence and depend on continued monitoring and management of forest stands over the long term. Temperature extremes and prolonged dry-spells increase fire risk, heat-waves and droughts will reduce the fitness of ecosystems, and a warmer climate could also lead to enhanced insect outbreaks. Such disturbances arising from climate extremes, wildfires, pests, and diseases affect afforestation-reforestation and avoided deforestation, but also yields of food and bioenergy crops (Bodin et al., 2016; Pugh et al., 2016a; Frieler et al., 2017). There is as yet no agreement on the main processes underlying heat-effects on yields, but irrigation was found to dampen the negative effects of high temperatures considerably (Schauberger et al., 2017). Fire is the sole episodic event that is included explicitly in current global scale ecosystem models (Hantson et al., 2016;Rabin et al., 2017), other causes of mortality are subsumed in a generic “background” disturbance. With warmer and drier temperatures fire risk is increasing but whether the enhanced fire risk also translates into larger burned area is debatable.. Studies showed that future burned area is reduced in (sub-)tropical semi-arid regions, where enhanced levels of CO2 foster shrub encroachment into C4 grass-dominated systems, while increasing human population density prevents fire spread globally. Across a range of RCPs and SSPs, Knorr et al (Knorr et al., 2016) demonstrated that uncertainties in future population growth combined with degree of urbanisation are of similar magnitude to uncertainties related to future climate change on burned area. Scenarios with moderate climate change combined with slow urbanisation at relatively large population growth resulted in a global decline of burned area – but not in an overall declining risk for humans per se since population increases in fire-prone regions (Knorr et al., 2016, see their Figure 3, below).
Better understanding disturbances and how to manage them in a changing climate would reduce uncertainty and therefore the risks associated with investment in mitigation options. Monitoring, Reporting, and Verification (MRV) of forest carbon and other land-based mitigation schemes need to be able to properly consider disturbances (and associated carbon losses) to provide confidence that land-based mitigation projects will meet their long-term objectives. This is, however, a sensitive issue within policy communities, since there is a common understanding that natural disturbances should not be accounted for by countries, since they are not anthropogenic. However, recent advances in satellites and modelling capabilities can support MRV, along with capacity-building in developing countries.
1.3.5 Model experiments and mode-data comparisons have identified a number of large uncertainties in the land-use/climate change interplay which need to be acknowledged for policy decision making
Quantitative assessment of model performance is crucial when using model output to support policy, and decision makers have accepted the inevitable uncertainty that comes with modelling environmental change. While progress has been made, systematic model evaluation that utilises all suitable streams of measurements or statistical information, and identification of uncertainties within and between models is still a critical challenge.The individual modelling tools used for understanding and projecting the broad implications of land-based mitigation (e.g. land-use models, dynamic global vegetation models, climate models, biodiversity models) all suffer from incomplete process-representations or uncertain parameterisations. Model-intercomparisons (Schmitz et al., 2014;Sitch et al., 2015;Lawrence et al., 2016) result in ensemble outputs that can help to assess how well models can reproduce historical variables and/or to derive a range of future changes. Whether or not agreement between models should be interpreted as a “robust” understanding of a system’s response is debatable and requires careful analysis and in-depth knowledge of the participating models, especially with respect to which processes are accounted for, and how these processes are included (Ahlstrom et al., 2015; Arneth et al., 2017, see their Figure 2, above).
In an analysis of future land-cover change, all kinds of existing future scenarios were compared (i.e. not specifying that the models should be run following a joint protocol) that were produced by a diverse set of global and European models (Alexander et al., 2016b; Prestele et al., 2016). Not surprisingly, large spread in future projections of main land-cover types were due to the different scenarios. However, the analysis identified also equally large uncertainty due to the modelling approach which highlight the needs to better understand the pros and cons of different land-use modelling paradigms and to ensure that models that seek to identify impacts incorporate a much broader range of future projections (and past hindcasts; (Bayer et al., 2017)) than available so far.
Formalised parameter uncertainty analysis has not yet been applied in many land-use change models. Recently, a statistical analyses of input parameter variability identified which of these affected outputs most strongly (in that study: related to meat consumption or yield improvement rates; (Engstrom et al., 2016b), and also investigated uncertainties in the parameters describing the scenario that was used to calculate land-use change (Engström et al., 2016). Using conditional probability ranges, broad overlap in the uncertainty distributions of future global total crop area was found for very different scenarios (SSP2,4,5), due to compensation effects that arose from changes in drivers. Future cropland area under SSP1 and 3 framework stood out (Engström et al., 2016) with assumptions (and uncertainties) in the SSP1 leading to notably declining crop area (associated with e.g. population decline and increasing yields; (Engström et al., 2016).
In summary, land-based mitigation is not a ‘silver bullet’ to avoid climate change, but alongside drastic reductions in fossil fuel emissions, it can contribute to delivering the ‘balance of sources and sinks’ in the Paris Agreement. Land-based mitigation is currently the only way to remove CO2 from the atmosphere at a scale that is potentially relevant to climate mitigation. The land sector will not be emissions-free, as emissions are necessarily associated with food production. Moreover, there is a real danger that land-based mitigation will compete with food production, the provision of other ecosystem services, and protection of biodiversity. Further analysis is required to understand fully the many trade-offs beyond climate mitigation that arise from land management and to identify policy options that support co-benefits. Land-based mitigation could potentially enable the land sector as a whole to approach a balance of sources and sinks, and, if barriers are overcome and sustainability ensured, it could further offset some of the more unavoidable emissions from fossil fuels.
Potential Impact:
NOTE: The complete section is contained in the attached pdf, since it contains Figures. The web-version contains only the text.
1.4 Project impact and dissemination (max 10 pages) (including the socio-economic impact and the wider societal implications of the project so far) and the main dissemination activities and exploitation of results
Four main activities were pursued in LUC4C to disseminate project outcomes and to ensure impact at various levels:
• Policy outreach events
• Contribution to international assessments
• Education
• Scientific meetings and conferences
1.4.1 Policy outreach
LUC4C (co)organised two side events at the UNFCCC COP21 in Paris, which included “Synergies and Trade-Offs in Land-Based Climate Mitigation and Biodiversity”, which took place at the Rio Pavillon, and presented an analysis of the latest science on land-use change climate impacts (including biophysical effects) and mitigation potential (including trade-offs and socio-economic context), and the extent to which the land sector (e.g. Reduced Emissions from Deforestation and Degradation, bioenergy, agricultural sector) is included in national and international policy, including Intended Nationally Determined Contributions (INDCs). The event discussed the several disconnects between the production of scientific knowledge and the knowledge needs and uptake seen in current land-climate policy-making. This event was quite timely with respect to development of policy, and development of new science evidence related to effects of land-based mitigation scenarios within the IPCC scenario framework.
At COP21 (Dec. 2015), LUC4C participated also in the organisation of the side-event on ”Mmulti-level climate governance: an integrated analysis of national, regional and local policies”. In that event, the project coordination (Prof. Arneth) presented LUC4C research entitled: Using the natural capital and ecosystem services concept to assess synergies and trade-offs in land-based mitigation.
Likewise at the COP 13 of the CBD in Cancun (Dec. 2016) on” Climate, biodiversity and sustainable development – benefits from a new global land management strategy”. The primary goals of this science event were:
• to demonstrate current research progress in understanding the impact of the land system on both biodiversity and climate change, building on a broad range of innovative methods, using observations to enrich predictive modelling and scenarios,
• to gather the needs of policy makers and civil society in driving future research and assessment in this field.
Earlier, during the Brussels “Green Week” LUC4C participated in a Stand representing "Nature-Based Solutions for Biodiversity & Climate Change", which highlighted the work of 4 European Commission funded research projects that used Nature-Based Solutions (NBS) to address biodiversity and climate change for the benefit of human wellbeing.
Also in Brussels, LUC4C led a lunch-time debate “Land-based climate mitigation in a < 2 degree world: potentials and potential pit-falls”. The event was chaired by DG RTD and DG CLIMA and aimed to exchange knowledge on land-based climate change mitigation, supported by the latest EC-funded research, after the adoption of the Paris Agreement & in view of the IPCC report on limiting global warming to 1.5oC.
In association with the final science workshop of LUC4C, a stakeholder workshop was organised in Brussels in Septembe 2017 which focused on “The role of land use in achieving the <2oC Paris COP21 target: Key Messages on Policy Implications”, and was attended by a range of European policy stakeholders as well as a number of the scientists from the LUC4C project.
All of these siden-events and panel debates were well attended and the discussions fed back to the LUC4C work and its output materials (incl a nunber of policy briefs which can be downloaded from the project web-site, www.luc4c.eu). The final stakeholder day in particular was specifically designed such that the key outcomes of the processes to identify implications and options for policy (workshop and LUC4C expert judgement) were presented in the deliverable Recommendations to support best practice for climate mitigation and adaptation policy (D1.3). Key policy implications and options were identified as:
• Achieving sustainable intensification through, for example, agroforestry and agropastoralism;
• Changing diets to reduce demand for land- and carbon-intensive products such as beef, through e.g. a tax or labelling;
• Restoring degraded forests to increase their carbon storage capacity and increase biodiversity;
• Using harvested wood products in buildings and other infrastructure to store carbon and reduce emissions from the production and transportation of cement and iron;
• Robust scientific results are needed before biophysical effects are to be included in global policy frameworks;
• A method for the evaluation of the regional impacts of land cover transitions exists and can inform regional and national mitigation efforts;
• Biophysical effects are stronger and more certain at local scales and so, have the potential to be considered in local land use planning policy;
• Due to the geographical variability in biophysical effects, the location of carbon offsetting schemes can determine much of their effectiveness;
• Raising awareness in farmer communities, through measures such as knowledge hubs and advisory schemes, to enhance policy and technology uptake;
• Incentivizing adaptation measures in both the agricultural and forest sectors would build resilience to climate change and support land-based mitigation;
• Forward-looking policies to maintain carbon storage over longer time-frames, instead of short term carbon maximisation that negatively affects ecosystem functioning.
1.4.2. Contribution to assessments
Researchers in LUC4C have been involved in the IPCC assessments for many years. Importantly for the multi-disciplinary aspect of LUC4C results, scientist also became actively engaged in the ongoing assessments of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES). Prof. Rounsevell (LUC4C WP 1 lead) acted as co-chair of the IPBES Regional Assessment for Europe, Russia and Central Asia, which will be defended in the IPBES plenary in spring 2018. Prof. Arneth (LUC4C coordinator) is Coordinating Lead Author in the ongoing IPBES Global Assessment in the chapter on Future Scenarios of Nature, Nature’s Contribution to People and Good Quality of Life. She is also a CLA in the IPCC Special Report on Climate change and Land, which has just commenced.
Participation to these Assessments is important as ensures that results reported in the LUC4C published scientific literature contributes to inform the climate and environmental policy process. In that light, Prof. Arneth also participated a workshop (“Research on climate smart agriculture”) organised in February 2015 by DG AGRI discussing the research needs towards the development of a Climate Change and Agriculture research agenda to guide further activities under Horizon2020 in particular with regard to Societal Challenge 2 (Food Security, Sustainable Agriculture and Forestry, Marine, Maritime and Inland Water Research and the Bio-economy).
1.4.3 Education
Education of the next generation of environmental scientists is an important component of dissemination and impact. All LUC4C senior scientists contribute to teaching and supervision of students and young investigators. Specifically for LUC4C, a one-week winter school was organised for 25 international doctoral and post-doctoral researchers on “People, climate and the terrestrial biosphere” which aimed through lectures and practical work to give a broad overview of the role of the terrestrial biosphere in the Earth system, with a strong focus on anthropogenic land-use change and management and their implications. Lectures given during the course were filmed and are available via KIT on iTUNES U.
LUC4Kit includes the creation, development and delivery of an innovative, easy-to-use, pedagogical, fast and useful emulator tool (“LUC4Kit explorer”, available in 46.43.3.32/luc4c) to provide maps, time series, and custom global and regional averages of changes in carbon variables in response to pre-established and user’s land cover changes (LCC) scenario. The data provided for visualization (see Figure 1) is based on three sets of simulations performed with the dynamic global vegetation model LPJ-GUESS Carbon-Nitrogen version. The tool aims primarily at university students. A full documentation for pedagogical and policy-maker purposes will also be made available online (currently under development), it has been tested in a first course with ~15 M.Sc students during a lecture course in Karlsruhe, when the project responsible scientists (Benjamin Quesada and Almut Arneth) gave a practical course on carbon cycle and land-use. With the tool, users can specify own experiments, select output variables and safe output data (for later post-processing by different types of software).
1.4.4. Wider science dissemination
Scientist presented their work at numerous international conferences, both in form of oral presentations as well as posters. Conference sessions that were organised through LUC4C included, among others:
Global scenarios of land-use change and land-based mitigation, and their importance in the climate system at the Paris 2015 conference “Our common future under climate change” which was a large international meeting designed specifically to lead up to the COP 21 later that same year.
At the conference of the Future Earth Project iLEAPS, September 2017 in Oxford, LUC4C co-onvened the session “Land-use change in a warming worl: Interactions between climate and socio-ecological systems, and implications for land-based climate change mitigation”.
At the annual autumn meeting of the American Geophysical union, in 2016 in San Francisco, LUC4C co-convened a session on “Impacts of land use and land cover change in a changing climate, using modeling and measurements”.
List of Websites:
www.luc4c.eu
