Adaptation in an Uncertain World—Detection and Attribution of Climate Change Trends and Extreme Possibilities
Xiyue Li and Gary Yohe
This chapter offers results from an artificial simulation exercise that was designed to answer three fundamental questions that lie at the heart of anticipatory adaptation. First, how can confidence in projected vulnerabilities and impacts be greater than the confidence in attributing what has heretofore been observed? Second, are there characteristics of recent historical data series that do or do not portend our achieving high confidence in attribution to climate change in support of framing adaptation decisions in an uncertain future? And finally, what can analysis of confidence in attribution tell us about ranges of “not-implausible” extreme futures vis-à-vis projections based at least implicitly on an assumption that the climate system is static? An extension of the IPCC method of assessing our confidence in attribution to anthropogenic sources of detected warming presents an answer to the first question. It is also possible to identify characteristics that support an affirmative answer to the second. Finally, this chapter offer some insight into the significance of our attribution methodology in informing attempts to frame considerations of potential extremes and how to respond.
Pontus Lurcock and Fabio Florindo
Antarctic climate changes have been reconstructed from ice and sediment cores and numerical models (which also predict future changes). Major ice sheets first appeared 34 million years ago (Ma) and fluctuated throughout the Oligocene, with an overall cooling trend. Ice volume more than doubled at the Oligocene-Miocene boundary. Fluctuating Miocene temperatures peaked at 17–14 Ma, followed by dramatic cooling. Cooling continued through the Pliocene and Pleistocene, with another major glacial expansion at 3–2 Ma. Several interacting drivers control Antarctic climate. On timescales of 10,000–100,000 years, insolation varies with orbital cycles, causing periodic climate variations. Opening of Southern Ocean gateways produced a circumpolar current that thermally isolated Antarctica. Declining atmospheric CO2 triggered Cenozoic glaciation. Antarctic glaciations affect global climate by lowering sea level, intensifying atmospheric circulation, and increasing planetary albedo. Ice sheets interact with ocean water, forming water masses that play a key role in global ocean circulation.
Decision making under questions of deep uncertainty can be vague or specific, open-ended or fixed, easy or hard. This chapter very briefly addresses issues and approaches to decision making on adaptation to climate change. Depending on the research question, a complicated set of multiple approaches and tools may be needed. To highlight the types of approaches, this chapter discusses a variety of decision making tools and relates them to a particular problem: a homeowner choosing whether to do nothing, buy insurance, or elevate their home. The chapter culminates in a table summarizing the pros and cons of a variety of approaches.
Rob Wilby and Conor Murphy
Some of the most profound impacts of climate variability and change are expected in the water sector. These include more frequent, severe, and persistent droughts; more frequent, widespread, and extreme floods; more episodic and harmful water pollution episodes. Coping with more variable water supplies alongside rising demand will involve institutional reform, new infrastructure, adjustments to operations, and water demand management. A smarter, decision-led approach to deploying climate information in water management will also be required. This chapter begins with an overview of analytical frameworks for assessing and adapting water resource systems to uncertain climate threats and opportunities. It then gives examples of the diverse sources of information that are being accessed by some water managers to establish plausible ranges of climate change as a basis for decision-making. Examples from Denver, Colorado, and Dublin, Republic of Ireland show how narratives of future system changes and historical data can help test the efficacy of decisions under uncertainty. These two case studies demonstrate how early dialogue and information exchange among practitioners and scientists are fundamental to adaptation planning. In both places, unconventional sources of climate risk information were used to more rigorously stress test water management and planning assumptions. The preferred adaptation decision frameworks were dynamic, iterative, and open-ended. The chapter closes by acknowledging that further development of the decision-making approaches described herein may be needed to evaluate mixtures of adaptation options across multiple sectors.
Julie Rozenberg, Laura Bonzanigo, and Claire Nicolas
Increasing the amount of resilient infrastructure investments in developing countries is key to achieving development goals. Two issues need to be addressed to better support investment decisions. First, analysts need to better integrate the social, economic, and environmental dimensions of investment decisions in their quantitative analyses, given the intertwined objectives of climate change adaptation and poverty reduction. Second, analysts and practitioners need to recognize that the future state of those three dimensions is deeply uncertain and that new techniques need to be used that look for robust investments—performing well under multiple future conditions—rather than an optimal solution under a single prediction of the future. Doing so can be achieved by beginning important decision processes with an integrated model representing technical and socioeconomic factors, and exploring various interventions under many possible futures.
Indirect elicitation from ecological experts: From methods and software to habitat modelling and rock-wallabies
Claudia Tebaldi and Richard Smith
This article focuses on techniques for eliciting expert judgement about complex uncertainties, and more specifically the habitat of the Australian brush-tailed rock-wallaby. Modelling wildlife habitat requirements is important for mapping the distribution of the rock-wallaby, a threatened species, and therefore informing conservation and management. The Bayesian statistical modelling framework provides a useful ‘bridge’, from purely expert-defined models, to statistical models allowing survey data and expert knowledge to be ‘viewed as complementary, rather than alternative or competing, information sources’. The article describes the use of a rigorously designed and implemented expert elicitation for multiple experts, as well as a software tool for streamlining, automating and facilitating an indirect approach to elicitation. This approach makes it possible to infer the relationship between probability of occurrence and the environmental variables and demonstrates how expert knowledge can contribute to habitat modelling.
Peter Challenor, Doug McNeall, and James Gattiker
This article examines the dynamics of the US economy over the last five decades using Bayesian analysis of dynamic stochastic general equilibrium (DSGE) models. It highlights an example application in what is commonly referred to as the new macroeconometrics, which combines macroeconomics with econometrics. The article describes a benchmark New Keynesian DSGE model that incorporates four types of agents: households that consume, save, and supply labour to a labour ‘packer’; a labour ‘packer’ that puts together the labour supplied by different households into an homogeneous labour unit; intermediate good producers, who produce goods using capital and aggregated labour; and a final good producer that mixes all the intermediate goods. It also considers the application of the model in policy analysis for public institutions such as central banks, along with private organizations and businesses. Finally, it discusses three avenues for further research in the estimation of DSGE models.
Colin Raymond, Dim Coumou, Tim Foreman, Andrew King, Kai Kornhuber, Corey Lesk, Camilo Mora, Sarah Perkins-Kirkpatrick, Simone Russo, and Sem Vijverberg
This chapter surveys how the state of knowledge about the physical processes that cause extreme heat and the societal factors that determine its impacts can be used to better predict these aspects of future climate change. Covering global projections; event attribution; atmospheric dynamics; regional and local effects; and impacts on health, agriculture, and the economy, this chapter aims to provide a guide to the rapidly growing body of literature on extreme heat and its impacts, as well as to highlight where there remain significant areas in need of further research.
Trends in Vulnerability to Climate-related Hazards in the Pacific: Research, Understanding and Implications
John Hay, Virginie Duvat, and Alexandre K. Magnan
The unique coping capacities and other attributes that Pacific island nations have been developing for centuries have sustained them in the face of an enormous range of local and global challenges. These include climate change-related hazards, and especially tropical cyclones and high-wave incidents that notably generate landslides and river and coastal flooding; droughts; heat waves; and ocean warming. Such hazards place resources, people, and assets at serious risk, as reflected by their vulnerability. However, measuring climate change vulnerability is problematic since climate hazards combine with anthropogenic and other physical drivers to influence the nature, levels, and variability of vulnerability. The few longitudinal studies that have been undertaken for the Pacific island countries show high and increasing vulnerabilities, despite considerable investment of money and other resources at community, island, sector, and national levels.Considering the elements of risk (hazard, exposure, vulnerability, and capacity to adapt), this chapter critically reviews the approaches used in the Pacific to assess vulnerability, analyzes recent changes in the vulnerability of island nations, and lays the foundation for some new thinking on island habitability and futures. It uses lessons learned, as well as success stories and success factors, to present priorities related to the assessment of climate change vulnerabilities, risks, and possible adaptation interventions in the Pacific islands region. These underpin a series of principles aimed at harmonizing understanding and action. Notably, the chapter concludes that transformational resilient development can provide a more effective response to increasingly unprecedented risks and higher vulnerabilities, for both high and low islands, including atolls.
This work reports on the main physical processes that arise in the environment of the megacity from the “urban metabolism”—the complex interactions of the climate with the activities performed in the city and its built structure and texture—as well as on associated large-scale processes that generate hazards for the megacity’s inhabitants. It is estimated that in a few decades most of the world’s population will live in urban centers. Both the growth of megacities and climate change will increase the vulnerability of huge sectors of the population to climatic consequences of the urban metabolism. These include urban heat islands, pollution, and extreme weather events such as heat waves and floods. Developing policies to mitigate these threats will require integrating scientific knowledge with management skills, communication among cities about effective approaches, and taking into account residents’ needs for health and the capacity to live safely.
Peter Berry, Anna Yusa, and Livia Bizikova
Climate change is likely to increase drought globally and regionally, including within Canada, by the end of the century. In recent years, drought has affected communities across Canada and can have significant impacts on individuals. Health risks relate to the exacerbation of food and waterborne diseases, inadequate nutrition, impacts on air quality, vector-borne diseases, illnesses related to the exposure of toxins, mental health effects, and impacts from injuries (e.g., traffic accidents, spinal cord injuries). In Canada, the impacts of drought on human health and well-being are not well understood and monitoring and surveillance of such impacts is limited. In addition, important factors that make people and communities vulnerable to health impacts of drought require more investigation. These factors may differ significantly among the populations (e.g., rural vs urban) and regions (prairies, coastal, and northern). Vulnerability to drought health impacts in Canada due to climate change may be affected by: (1) changes in exposure as droughts increase or combine with other extreme events (wildfires, heat waves) to harm health; (2) changes in adaptive capacity due to impacts on, for example, health services from increasing extreme weather events; and (3) changes in susceptibility related to demographic (e.g., aging, chronic diseases) and socioeconomic trends. Effective measures to increase the resiliency of Canadians to drought health impacts require proactive adaptation efforts that increase knowledge of factors that make people and their communities vulnerable to this hazard, information as to how droughts might increase in the future, and integration of this information into future policies and programs. This paper identifies a set of indicators that may be used to gauge vulnerability to the impacts of drought on health in the context of climate change in Canada to inform adaptation actions.