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Needs for Socioeconomic Scenarios

IMPACTS, ADAPTATION, VULNERABILITY, AND IPCC WORKING GROUP 2

Christopher Field


Christopher Field, the leader of Working Group 2 (WG2) for the Fifth Assessment of the Intergovernmental Panel on Climate Change (IPCC), discussed scenarios in relation to this assessment. He said that instead of a list of possible impacts, the assessment needs to produce information about the possible future that will be useful for decisions. To achieve this goal, the assessment needs better integration of climate science and climate impacts in forms that help WG2 make good use of climate model outputs from Working Group 1 (WG1). The assessment also needs to put climate change in the context of other stresses within a consistent set of socioeconomic futures. He noted that there is some question about whether probabilities should be associated with the scenarios. What is important, he said, is to provide better treatment of extremes and disasters. Thus, the most important change in direction is probably to present issues in a way that provides a good foundation for decisions about risk, especially about low-probability, high-consequence events. The assessment also needs an expanded treatment of adaptation using a small enough set of scenarios to be useful. It also needs better integration of adaptation, mitigation, and development. Finally, the assessment is committed to the challenging task of developing a more comprehensive treatment of regional aspects of climate change. He identified two



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2 Needs for Socioeconomic Scenarios IMPACTS, ADAPTATION, VULNERABILITY, AND IPCC WORKING GROUP 2 Christopher Field Christopher Field, the leader of Working Group 2 (WG2) for the Fifth Assessment of the Intergovernmental Panel on Climate Change (IPCC), discussed scenarios in relation to this assessment. He said that instead of a list of possible impacts, the assessment needs to produce information about the possible future that will be useful for decisions. To achieve this goal, the assessment needs better integration of climate science and climate impacts in forms that help WG2 make good use of climate model outputs from Working Group 1 (WG1). The assessment also needs to put climate change in the context of other stresses within a consistent set of socioeconomic futures. He noted that there is some ques - tion about whether probabilities should be associated with the scenarios. What is important, he said, is to provide better treatment of extremes and disasters. Thus, the most important change in direction is probably to present issues in a way that provides a good foundation for decisions about risk, especially about low-probability, high-consequence events. The assessment also needs an expanded treatment of adaptation using a small enough set of scenarios to be useful. It also needs better integra - tion of adaptation, mitigation, and development. Finally, the assessment is committed to the challenging task of developing a more comprehen - sive treatment of regional aspects of climate change. He identified two 

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 DESCRIBING SOCIOECONOMIC FUTURES FOR CLIMATE CHANGE cross-cutting themes: (1) consistent evaluation of uncertainties and (2) better treatment of economic and noneconomic costs. He summarized by emphasizing that the IPCC Fifth Assessment needs to move from empha- sizing the point that climate change is real to providing information that stakeholders need. IPCC WORKING GROUP 3 PERSPECTIVES ON NEEDS FOR SOCIOECONOMIC SCENARIOS1 Ottmar Edenhofer Ottmar Edenhofer, chair of IPCC Working Group 3 (WG3), presented a WG3 perspective on the scenario process, including coordination issues. He noted that the current outline of the WG3 report frames the issue in terms of risk and then examines pathways for mitigation by sector, includ - ing a chapter on human settlements, infrastructure, and spatial planning. WG3 will look at a number of transformation pathways developed by the scientific community. It is intended that the pathways will be explicit about unintended side-effects, such as leakage from carbon storage proj - ects and effects of bioenergy development on food security, in order to show both the mitigation choices and their implications. Edenhofer said that, although the representative concentration pathways (RCPs) provide a minimum of consistency across the working groups, there is also a need for a realistic representation of the policy space that does not simply assume that all options are feasible. His understanding is that the RCPs will be analyzed by the climate community to yield patterns of climate change. He said that the socioeco- nomic variables coming from the IAM community need to be downscaled, and the assessment needs to explore the full range of transformation path- ways for each RCP. He suggested that it might be useful to develop what he called RSPs—representative socioeconomic pathways—which could be a basis for connection between the IAM and the IAV communities. He said that scenarios would need to identify demographic, economic, and other drivers and could serve as exogenous drivers for baseline conditions as well as for policy scenarios. He suggested that RSPs could be combined with policy scenarios, with each combination yielding an emissions trajec- tory. He also suggested that the process could also develop scenarios with “second-best” policies. 1 Edenhofer’s presentation is available at http://www7.nationalacademies.org/hdgc/ Mitigation_and_IPCC_WG_III_Presentation_by_Ottmar_Edenhofer.pdf [November 2010].

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 NEEDS FOR SOCIOECONOMIC SCENARIOS ECOSYSTEM SERVICES Anthony Janetos Anthony Janetos spoke about the need for scenarios to consider eco - system services, which have not received much attention in past climate assessments, although he considered them important.2 He noted that the concept is anthropocentric: it includes only products of ecosystems that benefit humans, but that have no cost until there is a need to replace them. He said that the Millennium Ecosystem Assessment (MEA) was the most complete effort to develop this idea in the past decade. 3 An activity on the same scale as IPCC but not sponsored by governments, the MEA produced volumes on current conditions and trends and a volume on sce- narios for the future of ecosystem services that includes alternative policy choices. The report categorized services as supporting, provisioning (typi- cally services that are priced), and cultural (e.g., esthetic). He said that the assessment was not an exercise in justifying ecosystem preservation. It recognized that some past changes in ecosystems were of positive value to humans but considered that this value may degrade in the future in ways that are not well reflected in typical economic accounting. Janetos suggested that the IPCC should pay attention both to direct dependencies on ecosystems (e.g., for agriculture, fisheries, and water supplies) and to indirect dependencies (biological diversity, carbon sequestration). The latter is new territory for climate assessments. In addition, he said, the IPCC should capture differences in the demand for services (e.g., market versus subsistence demands, such as for fuelwood) and also address governance issues, such as the roles of resource man - agement agencies, the private sector, and household decisions, as well as differences in governance between developed and developing countries and changes in governance over time. Janetos said it will be important for the assessment not to try to monetize everything and also to use some natural units. He found the concept of the social cost of carbon problematic, noting that estimates are widely different because of the difficulties of monetizing all the ecosystem services. He said the community needs to find ways to merge economics- based and other forms of modeling. He also suggested that WG2 explore the relationships between the supply of services and the resilience of 2 The concept of ecosystem services was developed to provide a way to place value on the ways in which ecological systems improve human welfare that are not captured in com - mercial markets (see Costanza et al., 1997). 3 The MEA, which operated from 2001 to 2005, involved more than 1,360 experts world - wide in assessing the consequences of ecosystem change for human well-being. Information is available at http://www.maweb.org/en/index.aspx [November 2010].

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0 DESCRIBING SOCIOECONOMIC FUTURES FOR CLIMATE CHANGE societies. He said that the MEA did some of this, but the conclusions have not been very visible in policy discussions. In a comment at the end of the presentation, Granger Morgan expressed the view that ecosystem services should not be the sole fram- ing of ecological impacts. He noted that the U.S. Environmental Protec - tion Agency now analyzes ecosystem impacts only in terms of monetized ecosystem services and that it is important to monitor and report impacts in natural units as well. GLOBAL ENERGY ASSESSMENT4 Nebojsa Nakićenoić Nebojsa Nakićenović discussed scenarios as used in the Global Energy Assessment (GEA), a large nongovernmental analytical effort. 5 He said that the GEA may be one of the first assessments using an RSP approach. Its scenarios follow a simple logic based on indicators, such as universal access to energy by particular dates, and consider the effects of such variables. GEA produced three transformational scenarios describ - ing energy access and other variables. The scenarios are based on a single counterfactual reference scenario. The scenarios use a single set of popula- tion and economic growth projections, all gridded. They vary greatly, for example, in degree of urbanization and, partly because of that and other salient drivers, in fuel mix. All three scenarios lead to the similar climate outcome of stabilizing the future global mean temperature increase to 2˚ Celsius. This is achieved through different patterns of change in energy systems. All of the scenarios include significant development of carbon capture and storage and expansion of zero-carbon energy sources, includ- ing renewables and nuclear energy. The scenarios describe futures with a lot of efficiency and lifestyle changes. He concluded by saying that what are needed are analyses that show different socioeconomic futures that lead to both similar and different outcomes. 4Nakićenović’s presentation is available at http://www7.nationalacademies.org/ hdgc/Energy_Trends_and_Global_Energy_Assessment_Presentation_by_Nebojsa_ Nakicenovic.pdf [November 2010]. 5 The Global Energy Assessment, based at the International Institute for Applied Systems Analysis, is a multiyear international effort to provide national governments and intergov - ernmental organizations with “technical support for the implementation of commitments aimed at mitigating climate change and sustainable consumption of resources.” Information is available at http://www.iiasa.ac.at/Research/ENE/GEA/index.html [November 2010].

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 NEEDS FOR SOCIOECONOMIC SCENARIOS RELEVANCE OF THE NEW SCENARIO PROCESS Richard H. Moss Richard Moss gave an overview of the new scenario process devel - oped by three research communities—integrated assessment, climate change, and impacts-adaptation-vulnerability. He noted that a paper on the process, of which he is lead author, will appear in the February 11 issue of Nature (Moss et al., 2010). Moss said that previously scenarios were prepared and used sequentially, from driving forces to narratives that produced emissions scenarios, which led to estimates of radiative forc- ing, which were fed into climate models and then to models of impacts. Because all this work takes time, impact estimates in one assessment were based on climate models that were contemporary with a previous assessment. The IPCC decided in 2006 not to develop new emissions scenarios, thus prompting an interdisciplinary group of researchers to develop a new process to develop and apply consistent scenarios across the three distinct research communities. The new parallel process is intended to enhance coordination across these groups. Rather than starting with detailed socioeconomic scenarios, it starts with radiative forcing. A set of radiative forcing pathways was selected to map out a broad range of future climates. New climate and socioeconomic scenarios will be developed during the parallel phase of the new process. Some of the new socioeconomic scenarios will be directly related to the radiative forcing pathways (e.g., what socioeconomic paths lead to a particular pathway and level of forcing in 2100); some new socioeconomic scenario work will not be tied directly to the RCPs. Moss reviewed expectations for three sets of products: the RCPs, the climate scenarios, and the socioeconomic scenarios. The four current RCPs were generated from the available IAMs and are intended for use in climate models. They are defined in terms of radiative forcing in 2100. The RCPs differ in the forcings they show and in the trajectory of forc - ing. Two sets of climate model scenarios will be developed. In one set, extending to 2100 (or to 2300 in some cases), runs will be conducted at 1- or 2-degree geographic resolution. A second set of higher resolution (0.5 to 1 degree) will provide 2035 “decadal predictions” and will be run off a single scenario (RCP4.5), thus allowing larger model ensembles, higher resolution, and presumably better information on natural variability and extreme events. There are debates about whether decadal predictions are skillful and useful. Moss noted that the climate modeling community has been careful about prioritizing work to facilitate intercomparison of models and suggested that the same should be done with socioeconomic scenarios—the focus of this workshop. He noted that they are needed to

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 DESCRIBING SOCIOECONOMIC FUTURES FOR CLIMATE CHANGE provide the context for interpreting changes in climate and for exploring the different policies, technologies, and other conditions that could be consistent with different climate futures. He noted the need to be clear about what one needs to project, tying the scenarios to a particular pur- pose, and that the IPCC needs to identify a manageable number of key cases for use in its assessment. Moss concluded by expressing the excitement developing in this field and related it to integration across the communities. But he pointed out that progress will require resources. He said that user support is critical for further development of the scenarios, and there is a need to engage researchers in developing countries. DISCUSSION Several participants raised questions for discussion. One question was whether the IAM community is concerned about consistency in socio- economic assumptions across scenarios and whether good progress could be made with a short list of socioeconomic variables. It was noted that in IAV analysis, qualitative approaches are used more frequently than quan- titative ones. Following this idea, the question was raised as to whether it would be possible to have a small number of alternate visions of the societal future to work from and to relate to RCPs. Nakićenović pointed out that there are already a number of accounts of the socioeconomic future in the MEA and elsewhere, so it would be possible to link some of the downscaled socioeconomic scenarios to climate and to the RCPs. Gary Yohe noted that the scenarios developed for the last IPCC process are still potentially useful. Edenhofer suggested that the RCPs could be a focal point for consistency purposes and that RSPs could also be a focal point for consistency across IAV and mitigation analyses (for example, there could be pathways characterized by high urbanization or by high economic growth). Some participants emphasized the need to cluster the narratives to avoid a proliferation of too many scenarios. Many researchers think that the community should work with a small number of socioeconomic path- ways, but that developing these so that they are compatible with the large number of potential uses for IAV and mitigation analysis is an important challenge. Marc Levy proposed that RCP and RSP processes need not be similar. For RCPs, only the aggregate matters. Impacts, however, are highly varied regionally, which suggests that the process for producing socioeconomic pathways should not be modeled on the RCP process. He claimed that skill in projecting emissions was not necessarily correlated with skill in projecting socioeconomic conditions.

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 NEEDS FOR SOCIOECONOMIC SCENARIOS George Hurtt noted that coupled carbon-climate models need input data on spatially specific land use activities, as well as biophysical feed - backs from land use. He said that a new generation of fully coupled earth system models is now in development, with socioeconomic information included. He pointed out the need to relate this process to development of new socioeconomic scenarios in the new process. Gerald Nelson asked whether current models yield useful policy advice on key questions, such as whether soil carbon is included in an offset or compensation regime. There was some discussion as to whether probabilities will be asso- ciated with the scenarios, a subject of lively debate in the community. It may be that the probabilities of certain forcing pathways may be easier to estimate than the probabilities of socioeconomic futures.

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