Extending the Shared Socioeconomic Pathways for sub-national impacts,adaptation, and vulnerability studies

The exploration of alternative socioeconomic futures is an important aspect of understanding the potential consequences of climate change. While socioeconomic scenarios are common and, at times essential, tools for the impacts, adaptation and vulnerability and integrated assessment modeling research communities, their approaches to scenario development have historically been quite distinct. However, increasing convergence of impacts, adaptation and vulnerability and integrated assessment modeling research in terms of scales of analysis suggests there may be value in the development of a common framework for socioeconomic scenarios. The Shared Socioeconomic Pathways represents an opportunity for the development of such a common framework. However, the scales at which these global storylines have been developed are largely incommensurate with the sub-national scales at which impacts, adaptation and vulnerability and, increasingly, integrated assessment modeling studies are conducted. The objective of this study was to develop sub-national and sectoral extensions of the global SSP storylines in order to identify future socioeconomic challenges for adaptation for the U.S. Southeast. A set of nested qualitative socioeconomic storyline elements, integrated storylines, and accompanying quantitative indicators were developed through an application of the Factor–Actor–Sector framework. In addition to revealing challenges and opportunities associated with the use of the SSPs as a basis for more refined scenario development, this study generated sub-national storyline elements and storylines that can subsequently be used to explore the implications of alternative sub-national socioeconomic futures for the assessment of climate change impacts and adaptation.     

共享社会经济路径(SSPs)的应用与展望

共享社会经济路径(Shared Socioeconomic Pathways, SSPs)是新一代气候变化情景的重要组成部分。SSPs从提出至今已有10年的发展,对于推动气候变化预估与影响研究、支撑气候政策决策的作用逐渐凸显。文中基于179篇主题检索文献分析了SSPs发展和应用的进展,以及在当前气候变化研究中的应用特点。研究发现,次国家和部门层面的SSPs故事线拓展开始兴起,水资源、土地和健康是影响评估领域的关注焦点,方法学上强调模型间耦合与多模型比较。当前SSPs在中国的发展与应用集中于基本要素的预估及气候影响评估,路径对各省间及城乡间社会经济发展差异的刻画有待加强。基于情景发展和应用的现状,最后从加强与气候建模团队的合作、支持影响与脆弱性研究、拓展全球情景、加强模型间比较、提高决策支持力5个方面讨论了SSPs的未来研究展望。     

The marker quantification of the Shared Socioeconomic Pathway 2: A middle-of-the-road scenario for the 21st century

Studies of global environmental change make extensive use of scenarios to explore how the future can evolve under a consistent set of assumptions. The recently developed Shared Socioeconomic Pathways (SSPs) create a framework for the study of climate-related scenario outcomes. Their five narratives span a wide range of worlds that vary in their challenges for climate change mitigation and adaptation. Here we provide background on the quantification that has been selected to serve as the reference, or ‘marker’, implementation for SSP2. The SSP2 narrative describes a middle-of-the-road development in the mitigation and adaptation challenges space. We explain how the narrative has been translated into quantitative assumptions in the IIASA Integrated Assessment Modelling Framework. We show that our SSP2 marker implementation occupies a central position for key metrics along the mitigation and adaptation challenge dimensions. For many dimensions the SSP2 marker implementation also reflects an extension of the historical experience, particularly in terms of carbon and energy intensity improvements in its baseline. This leads to a steady emissions increase over the 21st century, with projected end-of-century warming nearing 4 °C relative to preindustrial levels. On the other hand, SSP2 also shows that global-mean temperature increase can be limited to below 2 °C, pending stringent climate policies throughout the world. The added value of the SSP2 marker implementation for the wider scientific community is that it can serve as a starting point to further explore integrated solutions for achieving multiple societal objectives in light of the climate adaptation and mitigation challenges that society could face over the 21st century.     

SSP3: AIM implementation of Shared Socioeconomic Pathways

This study quantifies the Shared Socioeconomic Pathways (SSPs) using AIM/CGE (Asia-Pacific Integrated Assessment/Computable General Equilibrium). SSP3 (regional rivalry) forms the main focus of the study, which is supposed to face high challenges both in mitigation and adaptation. The AIM model has been selected as the model to quantify the SSP3 marker scenario, a representative case illustrating a particular narrative. Multiple parameter assumptions in AIM/CGE were differentiated across the SSPs for quantification. We confirm that SSP3 quantitative scenarios outcomes are consistent with its narrative. Moreover, four key features of SSP3 are observed. First, as SSP3 was originally designed to contain a high level of challenges to mitigation, mitigation costs in SSP3 were relatively high. This results from the combination of high greenhouse gas emissions in the baseline (no climate mitigation policy) scenario and low mitigative capacity. Second, the climate forcing level in 2100 for the baseline scenarios of SSP3 was similar to that of SSP2, whereas CO₂ emissions in SSP3 are higher than those in SSP2. This is mainly due to high aerosol emissions in SSP3. A third feature was the high air pollutant emissions associated with weak implementation of air quality legislation and a high level of coal dependency. Fourth, forest area steadily decreases with a large expansion of cropland and pasture land. These characteristics indicate at least four potential uses for SSP3. First, SSP3 is useful for both IAM and impact, adaptation, vulnerability (IAV) analyses to present the worst-case scenario. Second, by comparing SSP2 and SSP3, IAV analyses can clarify the influences of socioeconomic elements under similar climatic conditions. Third, the high air pollutant emissions would be of interest to atmospheric chemistry climate modelers. Finally, in addition to climate change studies, many other environmental studies could benefit from the meaningful insights available from the large-scale land use change resulting in SSP3.     

Energy,land-use and greenhouse gas emissions trajectories under a green growth paradigm

This paper describes the possible developments in global energy use and production, land use, emissions and climate changes following the SSP1 storyline, a development consistent with the green growth (or sustainable development) paradigm (a more inclusive development respecting environmental boundaries). The results are based on the implementation using the IMAGE 3.0 integrated assessment model and are compared with a) other IMAGE implementations of the SSPs (SSP2 and SSP3) and b) the SSP1 implementation of other integrated assessment models. The results show that a combination of resource efficiency, preferences for sustainable production methods and investment in human development could lead to a strong transition towards a more renewable energy supply, less land use and lower anthropogenic greenhouse gas emissions in 2100 than in 2010, even in the absence of explicit climate policies. At the same time, climate policy would still be needed to reduce emissions further, in order to reduce the projected increase of global mean temperature from 3 °C (SSP1 reference scenario) to 2 or 1.5 °C (in line with current policy targets). The SSP1 storyline could be a basis for further discussions on how climate policy can be combined with achieving other societal goals.     

The use of scenarios as the basis for combined assessment of climate change mitigation and adaptation

Scenarios are used to explore the consequences of different adaptation and mitigation strategies under uncertainty. In this paper, two scenarios are used to explore developments with (1) no mitigation leading to an increase of global mean temperature of 4 °C by 2100 and (2) an ambitious mitigation strategy leading to 2 °C increase by 2100. For the second scenario, uncertainties in the climate system imply that a global mean temperature increase of 3 °C or more cannot be ruled out. Our analysis shows that, in many cases, adaptation and mitigation are not trade-offs but supplements. For example, the number of people exposed to increased water resource stress due to climate change can be substantially reduced in the mitigation scenario, but adaptation will still be required for the remaining large numbers of people exposed to increased stress. Another example is sea level rise, for which, from a global and purely monetary perspective, adaptation (up to 2100) seems more effective than mitigation. From the perspective of poorer and small island countries, however, stringent mitigation is necessary to keep risks at manageable levels. For agriculture, only a scenario based on a combination of adaptation and mitigation is able to avoid serious climate change impacts.     

The impact of biofuel-induced food-price inflation on dietary energy demand and dietary greenhouse gas emissions

Dramatic increases in liquid biofuel production have led to concerns about associated impacts on food prices, with many modeling studies showing significant biofuel-related price inflation. In turn, by changing patterns of food demand, biofuel production may indirectly influence greenhouse gas emissions. We estimated changes to dietary energy (calorie) demand and greenhouse gas emissions embodied in average diets under different biofuel-related food-price scenarios for Brazil, China and the United States, using food-price projections and food-price elasticities. Average energy demand decreased in all countries, from about 40 kcal per person per day in Brazil under a moderate price inflation scenario – a reduction of 1% relative to the (2009) reference scenario – to nearly 300 per day in the United States with high price inflation – almost 8% of reference levels. However, emissions per calorie increased slightly in all three countries. In terms of total greenhouse gas emissions, the results are suggestive of overall reductions only in the United States, where average reductions ranged from about 40 to 110 kg of carbon dioxide equivalent emissions per person per year. In China, the direction of impact is unclear, but the net change is likely to be small. Brazilian results were sensitive to parameter values and the direction and magnitude of impact is therefore uncertain. Despite the uncertainty, even small changes (positive or negative) in individual dietary emissions can produce large changes at the population level, arguing for the inclusion of the dietary pathway in greenhouse gas accounting of liquid biofuels.     

Harmonising climate change adaptation and mitigation: The case of tourist resorts in Fiji

Tourism in island states is vulnerable to climate change because it may result in detrimental changes in relation to extreme events, sea level rise, transport and communication interruption. This study analyses adaptation to climate change by tourist resorts in Fiji, as well as their potential to reduce climate change through reductions in carbon dioxide emissions. Interviews, site visitations, and an accommodation survey were undertaken. Many operators already prepare for climate-related events and therefore adapt to potential impacts resulting from climate change. Reducing emissions is not important to operators; however, decreasing energy costs for economic reasons is practised. Recommendations for further initiatives are made and synergies between the adaptation and mitigation approaches are explored.     

Pathways: An emerging concept for the theory and governance of low-carbon transitions

The concept of “pathways” has increasingly come to frame the challenge of transitioning to low-carbon societies. It also shows promise as a bridging concept, encouraging constructive dialogue among the diverse perspectives and constituencies evoking its use. However, its interpretations and attributes are rarely explicit and have yet to be subject to serious scrutiny. This raises important questions for both theory and governance as the way in which a problem is framed shapes how it is understood and addressed, structuring the possibilities considered and privileging certain responses. Therefore, this study explores the concept of pathways in the context of low-carbon transitions, exposing its conceptions, maturation, and implications. Based on a survey of the relevant climate change mitigation literature, this analysis uncovers three core conceptions of pathways in the context of low-carbon transitions: (1) biophysical, (2) techno-economic, and (3) socio-technical. Constituted by diverse perspectives and approaches, each of these three core conceptions emphasize different yet interconnected dimensions of the decarbonization challenge. This analysis also points to several key attributes and functions of the concept of pathways. Yet, while the concept may possess a variety of features that recommend its use as a critical problem frame for low-carbon transitions, it also raises issues that suggest a need for further reflexivity. If the concept is cast too strongly in terms of individual core conceptions, there may be a tendency to emphasize certain dynamics while paying somewhat less attention to others, inadvertently diminishing the complexity of the decarbonization challenge. Beyond this, there are other facets of the concept that have to date received more limited attention, including the implications of choices at critical junctures and the evolving character of social practices. So, there is room for the concept of pathways to engage more fully with the range of complexities embodied by low-carbon transitions.     

Exploring resource efficiency for energy,land and phosphorus use: Implications for resource scarcity and the global environment

In this paper, we present four model-based scenarios exploring the potential for resource efficiency for energy, land and phosphorus use, and implications for resource depletion, climate change and biodiversity. The scenarios explored include technological improvements as well as structural changes in production systems and lifestyle changes. Many of such changes have long lead times, requiring up front and timely investments in infrastructure, innovative incentive structures and education. For simulating the scenarios we applied the IMAGE modelling framework, with a time horizon until 2050.Our findings confirm a large potential for more efficient resource use: our (no new policies) baseline scenario shows a global increase, between 2010 and 2050, by 80% of primary energy use, 4% of arable land and 40% of phosphorus fertilisers. These numbers are reduced to +25% (primary energy), −9% (arable land) and +9% (phosphorus) in the global resource efficiency scenario. Baseline developments and resource efficiency opportunities vary strikingly among regions, resources and sectors. Phosphorus use, for example, is expected to increase most on croplands in developing countries, whereas the largest potential for phosphorus use efficiency lies in the livestock sector and urban sewage treatment in industrialised countries. Consequently, while resource efficiency resonates well as a general notion in policy thinking, concrete policies need to be region-specific, resource-specific and sector-specific.Efficiency efforts on one resource tend to contribute to efficient use of other resources and to benefit the environment. There are also trade-offs, however, and the synergies analysed do not make problem-specific policies redundant: in 2050, the global resource efficiency scenario presents higher phosphorus use and higher use of fossil fuels than in 2010; greenhouse gas emission targets are met by half; and biodiversity loss slows down but is not halted. Moreover, part of the efficiency gains in land and phosphorus use is sacrificed when this scenario is combined with ambitious climate policy, due to the substantial resource requirements for the deployment of bio-energy—albeit much less than in a scenario without more efficient resource use.     

Trading more food: Implications for land use,greenhouse gas emissions,and the food system

The volume of agricultural trade increased by more than ten times throughout the past six decades and is likely to continue with high rates in the future. Thereby, it largely affects environment and climate. We analyse future trade scenarios covering the period of 2005–2045 by evaluating economic and environmental effects using the global land-use model MAgPIE (“Model of Agricultural Production and its Impact on the Environment”). This is the first trade study using spatially explicit mapping of land use patterns and greenhouse gas emissions. We focus on three scenarios: the reference scenario fixes current trade patterns, the policy scenario follows a historically derived liberalisation pathway, and the liberalisation scenario assumes a path, which ends with full trade liberalisation in 2045.Further trade liberalisation leads to lower global costs of food. Regions with comparative advantages like Latin America for cereals and oil crops and China for livestock products will export more. In contrast, regions like the Middle East, North Africa, and South Asia face the highest increases of imports. Deforestation, mainly in Latin America, leads to significant amounts of additional carbon emissions due to trade liberalisation. Non-CO₂ emissions will mostly shift to China due to comparative advantages in livestock production and rising livestock demand in the region. Overall, further trade liberalisation leads to higher economic benefits at the expense of environment and climate, if no other regulations are put in place.     

Recent climatic change,greenhouse gas emissions and future climate: The implications for India

Summary In this paper, we discuss past climatic trends over India, greenhouse gas emissions due to energy consumption, forest and land-use changes, climate change scenarios for the year 2050, potential consequences for agriculture and cyclone activity and the possibility that India might limit the increasing trend in its emissions.India's mean surface air temperature has increased significantly by about 0.4°C over the past ccntury. Neither monsoon nor annual rainfall shows any significant trend. On average, there has been a rise in sea levels around India over recent decades, though considerable uncertainties exist in the accuracy and interpretation of the available data.Carbon emissions from the energy sector amount to 71 MT a year, equivalent to all other sectors combined. From land-use data, a marginal net sequestration of 5.25 million tonnes of carbon occurred during 1986. Following the IPCC guidelines, methane emissions from rice and livestock are estimated at 17.4 and 12.8 Tg/year, respectively.According to recent climate model projections, India may experience a further rise in temperature of 1 °C by the year 2050, about four times the rate of warming experienced over the past 100 years. A modest increase in precipitation amounts might occur. Cereals production is estimated to decrease and the nutrition security of the population-rich but land-hungry region of India might be hampered. An increase in local tropical cyclone activity may occur over thc next century, posing added problems as large areas in the coastal regions have a dense population.About 70% of the electricity generation in India is from coal-based power stations. Altering this dependence significantly to reduce emissions would imply a substantial change in the present energy policy of India. There is great potential for improving energy efficiency and conservation. The adoption of cleaner coal-technologies should be considered, as must the development of renewable, non-conventional energy sources. In all cases, serious institulional barriers and resource limitations need to be addressed. The scope for carbon sequestration is limiled by land availabilily and other factors. It is argued that any response to global warming must be located firmly in the framework of sustainable development.With 5 Figures     

Fossil-fueled development (SSP5): An energy and resource intensive scenario for the 21st century

This paper presents a set of energy and resource intensive scenarios based on the concept of Shared Socio-Economic Pathways (SSPs). The scenario family is characterized by rapid and fossil-fueled development with high socio-economic challenges to mitigation and low socio-economic challenges to adaptation (SSP5). A special focus is placed on the SSP5 marker scenario developed by the REMIND-MAgPIE integrated assessment modeling framework. The SSP5 baseline scenarios exhibit very high levels of fossil fuel use, up to a doubling of global food demand, and up to a tripling of energy demand and greenhouse gas emissions over the course of the century, marking the upper end of the scenario literature in several dimensions. These scenarios are currently the only SSP scenarios that result in a radiative forcing pathway as high as the highest Representative Concentration Pathway (RCP8.5). This paper further investigates the direct impact of mitigation policies on the SSP5 energy, land and emissions dynamics confirming high socio-economic challenges to mitigation in SSP5. Nonetheless, mitigation policies reaching climate forcing levels as low as in the lowest Representative Concentration Pathway (RCP2.6) are accessible in SSP5. The SSP5 scenarios presented in this paper aim to provide useful reference points for future climate change, climate impact, adaption and mitigation analysis, and broader questions of sustainable development.     

The special climate change fund: origins and prioritisation assessment

The Special Climate Change (SCC) fund was established by the Marrakesh Accords under the United Nations Framework Convention on Climate Change. This fund will finance climate change activities in the areas of: adaptation, technology transfer, certain specific sectors, and activities to assist oil-exporting countries diversify their economies. These activities are to be complementary to those funded by the Global Environment Facility and by bilateral and multilateral funding. This paper describes the origins of the SCC fund and proposes a framework for the prioritisation of its activities. The fund has a complicated history that is intrinsically linked to numerous Convention issues, which explains the range of activities included in it. The framework proposed is based on certain principles: sound scientific knowledge, the ultimate objective of the Convention, “common but differentiated responsibilities and respective capabilities” and the status of the climate negotiations. This appraisal suggests that the fund should prioritise adaptation, followed by mitigation and finally economic diversification.     

The emissions gap between the Copenhagen pledges and the 2 °C climate goal: Options for closing and risks that could widen the gap

As part of the Copenhagen Accord, Annex I Parties (industrialised countries) and non-Annex I Parties (developing countries) have submitted reduction proposals (pledges) and mitigation actions to the UNFCCC secretariat. Our calculations show that if the current reduction offers of Annex I and non-Annex I countries are fully implemented, global greenhouse gas emissions could amount to 48.6-49.7 GtCO₂eq by 2020. Recent literature suggests that the emission level should be between 42 and 46 GtCO₂eq by 2020 to maintain a “medium” chance (50-66%) of meeting the 2 °C target. The emission gap is therefore 2.6-7.7 GtCO₂eq. We have identified a combined set of options, which could result in an additional 2.8 GtCO₂eq emission reduction. This would lead to an emission level just within the range needed. The options include reducing deforestation and emissions from bunker fuels, excluding emissions allowance increases from land use and forestry rules, and taking into account the national climate plans of China and India. However, there are also important risks that could widen the emissions gap, like lower reductions from countries with only a conditional pledge and the use of Kyoto and/or trading of new surplus emission allowances.     

The climatic impacts of land surface change and carbon management, and the implications for climate-change mitigation policy

Strategies to mitigate anthropogenic climate change recognize that carbon sequestration in the terrestrial biosphere can reduce the build-up of carbon dioxide in the Earth’s atmosphere. However, climate mitigation policies do not generally incorporate the effects of these changes in the land surface on the surface albedo, the fluxes of sensible and latent heat to the atmosphere, and the distribution of energy within the climate system. Changes in these components of the surface energy budget can affect the local, regional, and global climate. Given the goal of mitigating climate change, it is important to consider all of the effects of changes in terrestrial vegetation and to work toward a better understanding of the full climate system. Acknowledging the importance of land surface change as a component of climate change makes it more challenging to create a system of credits and debits wherein emission or sequestration of carbon in the biosphere is equated with emission of carbon from fossil fuels. Recognition of the complexity of human-caused changes in climate does not, however, weaken the importance of actions that would seek to minimize our disturbance of the Earth’s environmental system and that would reduce societal and ecological vulnerability to environmental change and variability.     

Creating usable science: Opportunities and constraints for climate knowledge use and their implications for science policy

In the past several decades, decision makers in the United States have increasingly called upon publicly funded science to provide “usable” information for policy making, whether in the case of acid rain, famine prevention or climate change policy. As demands for usability become more prevalent for publicly accountable scientific programs, there is a need to better understand opportunities and constraints to science use in order to inform policy design and implementation. Motivated by recent critique of the decision support function of the US Global Change Research Program, this paper seeks to address this issue by specifically examining the production and use of climate science. It reviews empirical evidence from the rich scholarship focused on climate science use, particularly seasonal climate forecasts, to identify factors that constrain or foster usability. It finds, first, that climate science usability is a function both of the context of potential use and of the process of scientific knowledge production itself. Second, nearly every case of successful use of climate knowledge involved some kind of iteration between knowledge producers and users. The paper argues that, rather than an automatic outcome of the call for the production of usable science, iterativity is the result of the action of specific actors and organizations who ‘own’ the task of building the conditions and mechanisms fostering its creation. Several different types of institutional arrangements can accomplish this task, depending on the needs and resources available. While not all of the factors that enhance usability of science for decision making are within the realm of the scientific enterprise itself, many do offer opportunities for improvement. Science policy mechanisms such as the level of flexibility afforded to research projects and the metrics used to evaluate the outcomes of research investment can be critical to providing the necessary foundation for iterativity and production of usable science to occur.