Reports from Breakout Groups
The participants divided into three breakout groups on the first day and two groups on the second day. The following summaries were presented by rapporteurs drawn from among the participants in each breakout group.
IMPACT, ADAPTATION, AND VULNERABILITY SCENARIOS FOR 2020-2050
Kristie Ebi, Rapporteur
Kristie Ebi identified five major themes that arose in the discussion:
Climate is unlikely to be a major driver in most regions and sectors in this time period, so it is not possible to distinguish meaningfully among scenarios. It will be important to focus on extreme events and other particular events that might be important, making narratives consistent with actual development pathways—for example, it might be useful to talk in terms of the Millennium Development Goals, which she noted are likely to be unmet in any event. Ebi suggested that nonclimate events will be more important than climate in the short term.
The number of driving forces is too large to consider in a narrative. Thus, scenarios should focus on a few key drivers, such as governance and institutions, access to public-sector services,
ecosystem services, urbanization, and globalization and trade, and they should take a livelihoods approach to development pathways in certain regions and sectors.
There is a need for a few narratives as a framework onto which additional narratives can be added for particular sectors and regions. It is possible to analyze regions and sectors individually only for low degrees of climate change.
There is a need for baseline and policy narratives: no-regrets options, options with regrets, and overshoot situations.
There is a need to identify desired end points for this time frame (i.e., where societies would like to be) and develop scenarios by working backward from those states.
One group member added the need to distinguish global from local scenarios.
IMPACT, ADAPTATION, AND VULNERABILITY ISSUES TO 2100
Ferenc Toth, Rapporteur
Ferenc Toth identified the following themes from the discussion:
It is important in this time frame to examine factors with large inertia, which change mainly in the long term, such as education levels, income distributions, urbanization, resource availability, and expertise. There is a need to encourage research on linkages involving factors about which less is known. It is important to define the core elements of scenarios and add other elements later.
A large number of factors could be included in scenarios. Key foci should be on the driving forces that make a large difference and on combinations of driving forces that would create results that would be difficult to cope with. Many of these relate to the Millennium Development Goals, which could serve as an initial list of forces to consider. Toth noted that, in some cases, efforts to achieve these goals would increase vulnerability (e.g., increased access to constrained drinking water supplies). Many key drivers of impact, adaptation, and vulnerability (IAV) cannot be examined well with current models. Toth noted that the IAV assessments in the Fourth Assessment of the Intergovernmental Panel on Climate Change (IPCC) were not linked to reasonable socioeconomic scenarios.
The group raised several concerns with existing scenarios: the lack of a baseline on which to superimpose impacts, the need to incorporate interannual variability in IAV analyses, the difficulty of
assessing the effects of climate extremes on socioeconomic extremes (e.g., a drought during an economic recession), the need to develop multiple-stress scenarios and consider response options for them, and the frequent focus on climate with an implicit assumption of no change in other important drivers of well-being.
The group discussed the question of the function of scenarios, considering that there are many stakeholders who would like analyses that are relevant to their different goals and policy concerns. It identified a need to work backward from impacts, for example, from future impacts that would be considered acceptable.
Members questioned whether the community is organized to do all of what is needed, suggesting that an expert workshop or other tools could be considered to address this issue.
SCENARIOS FOR MITIGATION TO 2100
Michael Mastrandrea, Rapporteur
Michael Mastrandrea identified the following issues that were raised in the discussion:
The most important factors to include in scenarios include the Kaya identity elements (population, income, energy intensity, and emissions intensity), technology availability and accessibility, governance structure (including capacity and barriers), and policy targets. Analyses of technology need to address both technical feasibility and willingness to use technologies, for example, in view of their risks. Other factors to address are changes in urban structure and patterns of consumerism that affect the carbon impact of income.
The discussion noted several links of mitigation and adaptation with each other and with other issues (e.g., land use change, food security, water resources). For example, information needs and decisions often occur at different scales for adaptation and for mitigation. Regional issues in adaptation and mitigation priorities interact, so that analyses of only one of these get different answers from what would come from addressing both in an integrated way. A world pursuing both adaptation and mitigation can run into constraints. For example, adaptation can drive energy demand (e.g., for space cooling in hot climates, for moving water in droughts) and thus interfere with mitigation efforts. Both water and land use constraints need to be embedded in scenarios that integrate adaptation, mitigation, vulnerability, and impacts.
Major challenges in developing scenarios include (a) the need to make global models provide local information, which raises issues about downscaling and nesting models; (b) the need to include income heterogeneity and address equity issues; (c) framing uncertainties (e.g., about technological change, consumer preferences, capacity for and implementation of governance of technology and policy, co-benefits and trade-offs); and (d) the need to consider surprises and disruptive events that may affect capacity to mitigate or to adapt.
Other issues were also raised in the discussion. One participant commented on the need to consider agriculture in mitigation analysis, saying that it is much cheaper to mitigate with changes in agricultural practices than with carbon capture and storage. Another commented that very little is known about the ultimate effects of carbon capture and storage. One participant noted that changing dietary preferences might have significant impacts on land use and greenhouse gas emissions. Another observed that macroeconomic data might lead to misunderstandings because of failure to include income gaps and generational changes in lifestyles, both of which are very important in China. Another comment concerned the different users of scenarios: different decision makers have different needs concerning adaptation and mitigation, and different information is needed in different levels and sectors. Moreover, in a society dependent on local resources, information may have to be downscaled to local ecological regions, which is different from other kinds of downscaling.
POSSIBLE PRODUCTS FOR THE FIFTH ASSESSMENT REPORT AND IMPLICATIONS FOR WORKING GROUPS 2 AND 3
Elmar Kriegler, Rapporteur
Based on the breakout group discussion, Elmar Kriegler suggested that the Fifth Assessment Report could include different levels of radiative forcing (e.g., in 2100) and the outcomes of the climate models associated with these levels, including air pollution outcomes. The report could also include representative socioeconomic pathways (RSPs) with socioeconomic data. For a given RSP and a given forcing target, it would be possible to estimate costs for mitigation and adaptation. Additional information from WG2 and WG3 would be needed to address policy options. Kriegler presented a matrix that could be filled by research. RSPs would represent adaptive capacity and mitigative capacity on two axes. Some socioeconomic variables, such as gross domestic product, affect both; some may affect only one (for example, income distribution may
affect only adaptation). The effort to develop RSPs might begin with a very few variables (e.g., population and income), adding more variables after discussion (urbanization, income distribution, etc.). John Weyant said it would not be appropriate to compare cost estimates, but that it would be useful if one could compare marginal physical impacts with marginal mitigation costs (though not in a cost-benefit mode, in which physical impacts would be monetized). Steven Rose suggested that the term “RSP” may be confusing to people who might think they are representative of the range of what is possible. He suggested the term CSP, for “common socioeconomic pathways,” which would indicate only that these pathways are used in common by many analyses.
WHAT THE IAV AND IAM COMMUNITIES MIGHT GET FROM EACH OTHER
Linda Mearns, Rapporteur
Prior to this discussion, Thomas Wilbanks had proposed a different frame. He said that the IAV community is not looking to the integrated assessment models (IAM) community to provide socioeconomic scenarios but would prefer to develop the scenarios together, because the communities may have different ideas about what scenarios should look like.
Linda Mearns reported that, in the breakout discussion, some participants expressed the desire for IAMs to provide regional economic insights to establish differential adaptive capacities, input on willingness to maintain adaptation infrastructures, explorations of how land use change constrains socioeconomic change, estimates of the effects of different energy mixes on the multiple stressors for a region, analyses of national security issues, and insights on “trigger points” (e.g., when do food prices get high enough to cause enough hunger to lead to political destabilization?). It was suggested that different IAMs might be able to provide information to different sectors.
Mearns reported that the discussion also identified some research opportunities: coupling demography into IAMs, analyzing two-way interactions involving land use and land cover change, and determining allowable emissions for protecting oceans from acidity.