Iterative risk management is a flexible and powerful approach for addressing the complex challenges of climate change.
Chapter 2 reviewed what is known about the risks posed by climate change, concluding that there is strong motivation for moving ahead with proactive response efforts. Yet as discussed in Chapter 3, the many complexities inherent to climate change make it difficult to define the specific actions that are needed in an effective long-term response strategy. This chapter introduces iterative risk management as an approach that lets decision makers begin to address climate change now, in a systematic way, while allowing response strategies to be adjusted and improved as new information and knowledge are gained. Iterative risk management is, in principle, a fairly simple and straightforward concept (see example in Box 4.1); however, the details of how it is actually applied in various real-world situations depend strongly on the context of that situation, including the specific problem being addressed, the stakeholders involved, the values and priorities of those stakeholders, and the decision-support tools and resources available. Thus, in this chapter we explore how iterative risk management may be used to address climate change in a general sense, but we do not attempt to offer a detailed formula for how to apply this framework in specific situations.
As noted in Chapter 2, the risks posed by climate change are diverse and in almost all cases are imperfectly understood. Risk management involves deciding what to do in light of this imperfect information. Of course, one option is always to do nothing. Most everyone ignores some risks in daily life, and the United States might chose to give little attention to the risks associated with climate change. In the committee’s view, however, such a path would not be prudent. Uncertainty is, after all, usually a two-edged sword: it is possible that future climate-related risks will be less serious than currently thought, but it is also possible that they will be even more serious. Even the most aggressive possible response could not remove all potential risks, since the
A Problem of Risk Management
The problem of managing climate-related risks shares important features with the problem faced by the captain of an ocean liner who had to pass through an iceberg-filled section of the ocean at night in the days before radar. The captain may have information about the location of some icebergs, but not all, and new ones can form at any time. The maneuverability and hull strength of the ocean liner—that is, its ability to avoid or survive a collision with an iceberg—may likewise be known in theory, but not tested in practice. Thus the risks are significant, but information is limited.
The captain could choose to go full-steam-ahead and hope that information becomes available in time to detect and avoid risks. Or the captain could consider alterative actions, such as taking a longer course through iceberg-free waters or fortifying the ship’s hull—but there may be substantial costs associated with such actions. In any of these cases, it would be prudent to post lookouts to learn as much as possible about the risks ahead, to constantly evaluate the ship’s environment and performance, and to be prepared to change course if needed, knowing that evasive maneuvers take time. In addition, it is essential to prepare for adverse outcomes that may occur, despite efforts to reduce their likelihood. The captain, in short, faces a problem of risk management.
America’s climate choices are not, of course, made by one “captain,” but by decision makers at all levels of society—from the President and Congress, to state and local leaders, to individual households and business owners. Nevertheless, the collective ship of state is best guided by coherent national strategies for assessing options and taking advantage of opportunities to reduce risk.
world is already committed to some degree of climate change as a result of GHG emissions to date.
Making America’s climate choices thus necessarily involves managing risks that may be quite substantial and that cannot be eliminated, yet are often difficult to assess precisely. Making choices under such conditions can seem very difficult in the abstract, yet most people make such decisions every day. For instance, people decide how fast to drive, knowing that driving faster saves time but also uses more gas, increases the chances of a speeding ticket, makes an accident more likely, and makes the consequences of an accident more severe. People invest in measures to prevent fires in their homes and businesses, and they take out insurance to deal with the consequences in case fires do occur. People who make financial investments usually diversify their portfolios to hedge against uncertain future market changes. At the national level, history contains countless examples of policy makers taking action to address serious but poorly defined risks that could be neither eliminated nor responsibly ignored. For instance, investments in deterrence during the Cold War were justified as reducing the
risk of a nuclear war, and investments in civil defense were justified as reducing the risks of catastrophic outcomes in case a war did occur.
In the case of climate change, appropriate strategies for reducing risks will change over time in light of new information, and so too will investments in different types of action. The committee suggests that some essential elements of a sound risk management strategy for responding to climate change include:
- Enacting policies and programs that reduce risk by limiting the causes of climate change and reducing vulnerability to its impacts;
- Investing in research and development efforts that increase knowledge and improve the number and effectiveness of response options;
- Developing institutions and processes that ensure pertinent information is collected and that link scientific and technical analysis with public deliberation and decision making; and
- Periodically evaluating how response efforts are progressing, and updating response goals and strategies in light of new information and understanding.1
To some extent, it is possible to make substitutions or trade-offs among investments in different elements of climate change response. For instance, substantially limiting the magnitude of climate change could make it less important to invest in adaptation efforts (recognizing that the outcomes of these different types of actions can occur over widely differing temporal and spatial scales, thus complicating direct trade-off relationships). In general, however, because the long-term benefits of investing in any particular response (e.g., R&D investments, emissions mitigation efforts, adaptation planning) are uncertain, a strategy of diversification across different types of responses will reduce risk more and be more robust than pursuing a single approach at the expense of all others.
Decision Frameworks for Addressing Climate Change
Historically, humans have responded to changing environments by a process of muddling through; that is, by taking an ad hoc approach to decision making as choices arise.2 In the modern era, techniques and approaches have been developed that allow decision makers to think through complex issues systematically. One prominent approach is the precautionary principle,3 which emphasizes avoidance of potentially serious or irreversible environmental harm, even when scientific uncertainties may be substantial. At the other extreme is what might be called “staying the course,” or not taking any action until the need for action is fully established and the consequences of any action are fully understood. Another common approach is cost-benefit analysis
and other related instruments that attempt to weigh the potential outcomes of taking (or not taking) action using a common metric, usually dollars discounted to present values.
All of these approaches present serious drawbacks in the context of climate change. In muddling through, for instance, decisions are generally driven by immediate events and the lessons learned from one’s most recent experiences. Such an approach makes it difficult to thoughtfully consider long-term consequences of climate-related decisions. For instance, with regard to the prospect of irreversible or “tipping point” impacts, it will be too late to change course if one waits until such impacts have begun to unfold.
Analyses based on the precautionary principle or staying the course both reflect a substantial aversion to risk. In the case of the precautionary principle, the goal is to minimize risks of future adverse consequences of climate change with little regard for present costs. In the case of staying the course, the goal is to minimize the risks of incurring costs from responding to climate change with little regard for the risks of climate change. These approaches do not provide a way to decide among competing goals (e.g., minimizing risks of climate change impacts versus minimizing risks to economic growth) or to deal systematically with uncertainty.4
Cost-benefit analysis has been applied in many evaluations of climate change policy5 and can provide some useful insights in some contexts. But using cost-benefit analyses as a primary basis for making climate choices is problematic for a number of reasons. Many of the costs of climate change impacts are difficult or impossible to quantify.6 The sheer diversity and extent of potential costs and benefits of climate change make it very difficult to aggregate costs. Estimates can vary widely, depending on normative judgments about risk aversion and about how to account for equity concerns across generations, social groups, and regions of the world.7 Estimating the costs of actions to address climate change, while seemingly a more tractable task, is also problematic—for instance, because the costs of emission reductions over the coming decades depend critically on the pace of technological change.8
An iterative risk management approach9 for making climate change-related decisions overcomes many of these limitations. This approach can draw upon multiple forms of input—including analyses used under precautionary principle and cost-benefit frame-works—but it is not limited to single criterion (such as risk avoidance or economic efficiency) for making choices. Iterative risk management is a system for assessing risks, identifying options that are robust across a range of possible futures, and assessing and revising those choices as new information emerges. In cases where uncertainties are substantial or risks cannot be reliably quantified, one can pursue multiple, comple-
mentary actions—sometimes called a “portfolio approach” or “hedging strategy.” And ideally, this approach includes mechanisms for integrating scientific and technical analysis with broad-based deliberations among the stakeholders most affected by any given decision (see Box 4.2 on analytic deliberation processes).
NRC, Informing Effective Decisions emphasizes some key features of an iterative risk management process:
- It is not a single set of judgments at some point in time, but rather a process of ongoing assessment, action, reassessment, and response—which in the case of many climate-related decisions may persist for decades or longer.
- Eliminating all potential risks is impossible, as even the best possible decision will entail some residual risk. Determining which risks are acceptable or unacceptable is an integral part of the process of risk management. Different stakeholders will inevitably hold different views.
- For addressing a problem as complex as climate change, risk management should be implemented through a process of “adaptive governance” that involves assuring adequate coordination among the institutions and actors involved in responding to climate change, sharing information with decision makers across different levels and sectors, ensuring that decisions are regularly reviewed and adjusted in light of new information, and designing policies that can adapt but that are also durable over time. These concepts are illustrated in Figure 4.1 and discussed further in Chapter 5.
Similar principles have been recommended and illustrated by other high-level advisory groups worldwide, including, for instance, the IPCC, the United Nations Development Programme, the World Bank, the Australian Greenhouse Office, and the UK Climate Impacts Programme.10 Closer to home, a number of NRC and other reports have pointed to the planning efforts being carried out by New York City as a good example of a climate change response strategy that embodies many key elements of iterative risk management.11
These efforts—which are set forth in PlaNYC, the city’s sustainability and growth management initiative—include for instance:
- ambitious goals for limiting greenhouse gas (GHG) emissions, and a series of policies and programs to accomplish those goals (for instance, by reducing energy consumption by the city’s municipal buildings and operations);
- the creation of a New York City Panel of Climate Change—consisting of climate change scientists and representatives from legal, insurance, and risk-management firms—tasked with providing information about key climate
The idea of linking science and decision making is explored in a growing body of research literature.a One specific approach suggested in this literature is “analytic deliberation”, an iterative process in which interested parties initially define objectives and select options to consider, work with experts to generate and interpret relevant new information, and use that information to revise objectives and make choices.b
When addressing a problem such as climate change, analytic deliberation processes are particularly valuable because stakeholder discussions help to inform decision makers and the scientific community about local conditions—which is critical because many actions to limit emissions or adapt to climate change must be tailored to local conditions in order to be successful. It also helps to ensure that the scientific community is aware of public concerns and can thus direct research attention to those concerns. Finally, it helps ensure two-way dialogue between scientific experts and the public, which is a more effective communications strategy than a one-way flow of information from scientists to the public. To be successful, however, these deliberative processes require recognizing and overcoming many common obstacles to effective communication. Several NRC and other studies offer guidance on addressing such communication challenges.c
One example of this type of engagement process can be found in the NOAA Regional Integrated Sciences and Assessments (RISA) Program,d which supports teams at universities and regional centers to conduct research related to climate impacts (e.g., on fisheries, water, wildfire management, agriculture, tourism and recreation, public health, coastal management, infrastructure)—with the goal of helping to inform the decisions of regional-level planners and managers. RISA projects typically involve an array of stakeholders in framing problems for research, and they emphasize collaboration among scientists and decision makers. Although still a relatively new effort, the RISA programs are important test beds for learning how to apply principles of stakeholder engagement for informing decisions about adapting to climate change.
a See, for instance, D. H. Guston, “Boundary organizations in environmental policy and science: An introduction” (Science, Technology, and Human Values26:399-408, 2001); D. W. Cash, W. C. Clark, F. Alcock, N. M. Dickson, N. Eckley, D. H. Guston, J. Jäger, and. R. B. Mitchell, “Knowledge systems for sustainable development” (Proceedings of the National Academy of Sciences100:8086-8091, 2003); NRC, Public Participation in Environmental Assessment and Decision Making (Washington, D.C.: National Academies Press, 2008); NRC, Informing Effective Decisions.
b See also NRC, Understanding Risk: Informing Decisions in a Democratic Society, eds. P. C. Stern and H. Fineberg (Washington, D.C.: National Academy Press, 1996); NRC, Public Participation; O. Renn, Risk Governance: Towards an Integrative Approach (Geneva, Switzerland: International Risk Governance Council, 2005).
c NRC, Understanding Risk, Public Participation, Informing Decisions, Advancing the Science, and Informing Effective Decisions; EPA, Improved Science-Based Environmental Stakeholder Processes: A Commentary by the EPA Science Advisory Board, EPA-SAB-EC-COM-01-006 (Washington, D.C.: U.S. Environmental Protection Agency, 2001).
FIGURE 4.1 Illustration of the steps in an iterative risk management approach for addressing climate change. SOURCE: Adapted from R. I. Willows and R. K. Connell, Climate Adaptation: Risk, Uncertainty, and Decision Making, UKCIP Technical Report (Oxford, UK: UK Climate Impacts Programme, 2003).
hazards for the city and the surrounding region, likelihoods of their occurrence, and potential implications for critical infrastructure;
- a Climate Change Adaptation Task Force, consisting of over 40 public and private sector stakeholders, that developed a coordinated adaptation plan for the city; and
- a Policy Working Group that identified codes, rules, and regulations governing city infrastructure that may need to be changed or created to help the city cope with climate change.
These activities explicitly call for iterative processes in which goals and strategies are regularly monitored and reassessed, to determine whether intended objectives are being met, to discern any unforeseen consequences, and to allow for periodic corrections. NRC, Adapting to the Impacts and Informing Effective Decisions contain more details about these New York City activities, and other case studies illustrating how iterative risk management principles are being implemented in both the public and private sectors.
This section explores some of the criteria that would be most critical for climate-related decision making in the context of an iterative risk management framework.
Risk reduction potential. A key benefit desired for any action taken to respond to climate change is the potential to actually reduce climate-related risks, by either reducing the likelihood of adverse events (i.e., limiting climate change) or reducing vulnerability to such events (i.e., adapting to climate change) or ideally both. Although risk reduction potential is often difficult to quantify, it can provide a basis for choosing between different options under consideration. As an example, to respond to sea level rise, a community may face a choice between building sea walls to protect buildings and infrastructure or moving those assets to higher ground. The latter option would be more expensive and disruptive in most situations, but it could protect against a broader range of outcomes.
In certain cases, response options can reduce some risks while increasing others, thus requiring trade-offs among risks. For example, promoting more widespread use of air-conditioning to adapt to higher summer temperatures will undermine efforts to limit climate change, to the extent that the additional electricity required is generated by sources that emit GHGs. In other cases, an option may offer complementary risk reduction benefits. For example, improvements in the energy efficiency of buildings and their cooling systems can both constrain the growth of GHG emissions and reduce the threat that heat waves pose to vulnerable populations.
Some actions—such as those involving investment in new technologies, infrastructure, and workforce capacity—may offer little or no direct risk reduction potential themselves but can open the door to future options that may significantly reduce risk. For example, investing in development of a “smart grid” would provide flexibility for integrating distributed renewable electricity generation, and investing in the training of scientists and engineers can improve scientific understanding and the likelihood of significant technological breakthroughs over time.12 Other options, in contrast, may foreclose future risk-reducing possibilities. For example, continuing to build new coal-fired power plants will lock in further dependence on GHG-intensive energy sources (unless commercial-scale carbon capture and storage soon become widely implemented).
The field of risk analysis, which has a large research literature,13 offers general guidance on the process of estimating risk reduction potential. For the issue of climate change in particular, the many uncertainties and personal judgments that are inevi-
tably involved in weighing different types of risks have led some analysts to develop methods that synthesize the judgments of many experts.14
Feasibility and effectiveness. The potential for any given climate change response action to reduce risk must be measured against the feasibility (which may encompass technical, economic, and political feasibility) and the likely effectiveness of that action. A good deal is known, for example, about the feasibility and effectiveness of certain renewable energy technologies (e.g., wind), while relatively little is known about the feasibility of others (e.g., tidal).15 Where an option promises substantial risk reduction but has high costs and is of unproven effectiveness, the best response may be investment in further study or pilot testing to reduce unknowns surrounding its application.
Questions about feasibility and effectiveness also apply to policy tools. Insights about the effectiveness of different policy approaches can be gained from the research literature and also from the diverse experience of state and local governments, efforts in other nations, and U.S. federal programs in analogous contexts. For instance, to learn about the effectiveness of cap-and-trade programs, one can look to the experiences of the Regional Greenhouse Gas Initiative of the northeastern states, of the European Union’s emission trading system, and of the acid rain cap-and-trade program under Title IV of the Clean Air Act.16
Cost and cost-effectiveness. In a world of finite resources, cost and cost-effectiveness are important criteria for helping policy makers decide among different response options. Cost-effectiveness analysis assumes a similar level of risk reduction among options—if two options have similar risk reduction potential and likely effectiveness, a decision maker would choose the option with lower costs. In contrast, cost-benefit analysis is typically used to determine an optimal risk reduction strategy that balances costs and social benefits. As discussed earlier, however, cost-benefit and cost-effectiveness analysis have some important limitations when it comes to analyzing climate choices.
The cost of some options may be so disproportionate to risk reduction potential as to be clearly unreasonable: for instance, certain actions may threaten widespread business closures or other economic impacts that render the option unwise or politically impractical. (For this reason, cost considerations could be viewed as one aspect of the “feasibility” criterion discussed above.) In contrast, some options may be warranted by the positive economic returns or ancillary benefits they offer, even without consideration of climate-related benefits—including, for example, programs to encourage energy efficiency that yield a positive net economic benefit.17
Ancillary costs and benefits. Some options designed to reduce climate-related risks may have negative impacts on national interests in other areas, such as ecosystem services, human health, and national security. Examples include nuclear proliferation risks associated with increased reliance on nuclear power, and risks to ecological systems and food security stemming from increased assignment of agricultural land to biofuels production.
Other policies designed to limit or adapt to climate change may have significant ancillary benefits. For example, increasing energy efficiency to limit GHG emissions can also reduce emissions of conventional pollutants,18 and reducing GHG emissions from the transportation sector could potentially reduce petroleum consumption and thus the nation’s vulnerability to high oil prices and oil-supply disruptions.19 Encouraging carbon sequestration through soil and forest management practices (e.g., minimum tillage practices, reducing timber harvesting, improving manure management, reducing livestock herd size) may also offer the benefits of helping to control nutrient runoff, soil erosion, and habitat loss.20 It is wise to consider potential co-benefits of this kind when choosing among alternative possible strategies for reducing climate risks.
Equity and fairness. Equity and fairness concerns are important criteria for evaluating any public policy option. International debates have focused on how to fairly allocate the burdens of addressing climate change between developed and developing countries. Intergenerational justice debates center around defining the present genera-tion’s obligations to help ensure the well-being of future generations. Domestic policy debates have focused on how policies for reducing GHG emissions may alleviate or exacerbate burdens among different parts of society (e.g., on low-income households or on geographical regions that are heavily dependent on fossil fuel-based industries) and on the socioeconomic distributional impacts of actions taken to adapt to climate change.
Consider, for example, the case of lower-income households, which consume less energy per capita and thus contribute proportionately less to GHG emissions relative to more affluent households. Energy purchases are a larger fraction of their total consumption, and therefore they are more affected by changes in energy prices.21 Limited discretionary income may also preclude lower-income households from participating in energy efficiency initiatives that would reduce their energy costs over the longer term. At the same time, lower-income households may suffer disproportionately from the impacts of climate change.22 Some ways in which policy design can help address such concerns are discussed in Chapter 5.
International considerations. America’s climate choices affect and are affected by the global dimensions of climate change. U.S. emissions reductions alone will not be adequate to avert dangerous climate change risks; rather, our emission reductions must be accompanied by comparable actions from all other major emitters. U.S. climate policies can potentially have a major effect on the actions other countries take, and this potential represents another important criterion for evaluating domestic response options. In general, domestic policies that help leverage broader international-scale efforts (for example, cooperative research and development programs in clean energy technology) can be expected to reduce overall climate risk more than policies that affect U.S. emissions alone. Similarly, in comparing the advantages and disadvantages of different policy options for reducing U.S. GHG emissions (e.g., cap-and-trade programs, carbon taxes, regulatory approaches), each should be considered in the context of how they link domestic policies to global efforts.
Robustness. Given the uncertainties inherent in predicting future climate change and its impacts, as well as the difficulty of predicting technological, social, and economic developments, there is a great strategic advantage in pursuing response options that can perform well under a wide range of possible futures. For instance, sound risk management in the agricultural sector may include investing in the development of crop varieties that are resilient to a wide range of temperature and precipitation conditions. As another example, market-based regimes offer an advantage over industry-specific performance standards because the former approach has a higher likelihood of continued effectiveness under varying future economic or technological conditions.23
When the likelihood of different future outcomes is not well known, pursuing multiple options (i.e., a portfolio approach) and other “hedging” strategies can help ensure a robust response. For example, it would be prudent to invest in multiple new energy technologies to meet future needs because the ultimate success of any one new technology is always uncertain. As another example, it is prudent to design the infrastructure for transportation, water, and utilities to withstand a range of weather extremes including intense rainfall, flooding, and drought scenarios. Ensuring robustness may also include strengthening general adaptive capacity through early warning systems and disaster response preparations.
The degree to which any particular policy option meets the different criteria listed above depends not only on the type of policy but also its scope and stringency. For example, an overly weak auto fuel efficiency standard may be cheap and politically feasible but not very effective in reducing climate-related risks, whereas an overly tough standard may promise high levels of risk reduction but be very expensive, pose significant equity concerns, and be difficult to implement successfully.
Ultimately, any choice involves weighing multiple criteria. Decision makers will differ in their judgments about which criteria are most important and in their methods for dealing with uncertainties. Even when it is possible to characterize how different response actions rank under the different criteria, this information may not necessarily point to a preferred action or strategy. Rather, this information provides a basis on which decision makers can make reasoned judgments and engage in informed debates. The decision sciences offer a variety of methods for helping decision makers evaluate and make trade-offs among options,24 but even these methods do not obviate the need for deliberation and judgment.
In the committee’s judgment, iterative risk management—which emphasizes taking action now, but in doing so, being ready to learn from experience and adjust these efforts later on—offers the most useful approach for guiding America’s climate choices. The successful application of this approach requires broad-based continuous learning by the scientific community together with decision makers in the government, the private sector, and the general public.