From Top-Down to Bottom-Up Approaches to Risk Discovery: A Paradigm Shift in Climate Change Impacts and Adaptation Studies Related to the Water Sector (original) (raw)
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Advances in risk assessment for climate change adaptation policy
Philosophical Transactions of the Royal Society A, 2018
Climate change risk assessment involves formal analysis of the consequences, likelihoods and responses to the impacts of climate change and the options for addressing these under societal constraints. Conventional approaches to risk assessment are challenged by the significant temporal and spatial dynamics of climate change; by the amplification of risks through societal preferences and values; and through the interaction of multiple risk factors. This paper introduces the theme issue by reviewing the current practice and frontiers of climate change risk assessment, with specific emphasis on the development of adaptation policy that aims to manage those risks. These frontiers include integrated assessments, dealing with climate risks across borders and scales, addressing systemic risks, and innovative co-production methods to prioritize solutions to climate challenges with decision-makers. By reviewing recent developments in the use of large-scale risk assessment for adaptation policy-making, we suggest a forward-looking research agenda to meet ongoing strategic policy requirements in local, national and international contexts. This article is part of the theme issue ‘Advances in risk assessment for climate change adaptation policy’.
As part of the Mediterranean area, the Guadiana basin in Spain is particularly exposed to increasing water stress due to climate change. Future warmer and drier climate will have negative implications for the sustainability of water resources and irrigation agriculture, the main socioeconomic sector in the region. This paper illustrates a systematic analysis of climate change impacts and adaptation in the Guadiana basin based on a two-stage modeling approach. First, an integrated hydro-economic modeling framework was used to simulate the potential effects of regional climate change scenarios for the period 2000-2069. Second, a participatory multi-criteria technique, namely the Analytic Hierarchy Process (AHP), was applied to rank potential adaptation measures based on agreed criteria. Results show that, in the middle-long run and under severe climate change, reduced water availability, lower crop yields and increased irrigation demands might lead to water shortages, crop failure, and up to ten percent of income losses to irrigators. AHP results show how private farming adaptation measures, including improving irrigation efficiency and adjusting crop varieties, are preferred to public adaptation measures, such as building new dams. The integrated quantitative and qualitative methodology used in this research can be considered a socially-based valuable tool to support adaptation decision-making.
Trading-off tolerable risk with climate change adaptation costs in water supply systems
Water Resources Research, 2016
Choosing secure water resource management plans inevitably requires trade-offs between risks (for a variety of stakeholders), costs, and other impacts. We have previously argued that water resources planning should focus upon metrics of risk of water restrictions, accompanied by extensive simulation and scenario-based exploration of uncertainty. However, the results of optimization subject to risk constraints can be sensitive to the specification of tolerable risk, which may not be precisely or consistently defined by different stakeholders. In this paper, we recast the water resources planning problem as a multiobjective optimization problem to identify least cost schemes that satisfy a set of criteria for tolerable risk, where tolerable risk is defined in terms of the frequency of water use restrictions of different levels of severity. Our proposed method links a very large ensemble of climate model projections to a water resource system model and a multiobjective optimization algorithm to identify a Pareto optimal set of water resource management plans across a 25 years planning period. In a case study application to the London water supply system, we identify water resources management plans that, for a given financial cost, maximize performance with respect to one or more probabilistic criteria. This illustrates trade-offs between financial costs of plans and risk, and between risk criteria for four different severities of water use restrictions. Graphical representation of alternative sequences of investments in the Pareto set helps to identify water management options for which there is a robust case for including them in the plan. There has been extensive research to address the limitations of least cost planning approaches [e.g., Kasprzyk et al., 2013; Herman et al., 2014; Brown et al., 2015]. This has focused upon the role of uncertainty, in Key Points: Estimated the probability of water restrictions under nonstationary climate Identified water plans that meet tolerable risk criteria Demonstrated sensitivity of plans to risk criteria and model uncertainties
As part of the Mediterranean area, the Guadiana basin in Spain is particularly exposed to increasing water stress due to climate change. Future warmer and drier climate will have negative implications for the sustainability of water resources and irrigation agriculture, the main socio-economic sector in the region. This paper illustrates a systematic analysis of climate change impacts and adaptation in the Guadiana basin based on a two-stage modeling approach. First, an integrated hydro-economic modeling framework was used to simulate the potential effects of regional climate change scenarios for the period 2000-2069. Second, a participatory multi-criteria technique, namely the Analytic Hierarchy Process (AHP), was applied to rank potential adaptation measures based on agreed criteria. Results show that, in the middle-long run and under severe climate change, reduced water availability, lower crop yields and increased irrigation demands might lead to water shortages, crop failure, a...
Water resources, climate change and human vulnerability
… Congress, Cairns, Australia 13-17 July …, 2009
It is well recognised today that climate change is affecting the Earth's physical and biological systems, and is expected to do so on forthcoming decadal to century timescales. A need exists for useable predictions of the impacts associated with such climate change, and the likely societal responses to these. This must also be seen in the context of other drivers of global change, and be presented at suitable spatial and temporal scales, to enable prioritisation of adaptation measures which are feasible in the most vulnerable communities, countries and regions.
Bridging the gap: linking climate-impacts research with adaptation planning and management
Climatic Change, 2010
A critical challenge in supporting climate change adaptation is improving the linkage between climate-impacts and vulnerability research and public and private planning and management decisions. We highlight the need for bottom-up/ top-down vulnerability assessment, bringing together bottom-up knowledge of existing vulnerabilities with top-down climate-impact projections, as a transparent basis for informing decisions intended to reduce vulnerability. This approach can be used to evaluate the likelihood of crossing identified thresholds of exposure, and to evaluate alternative adaptation strategies based on their ability to reduce sensitivity to projected changes in exposure and their robustness across uncertainty in future outcomes. By identifying thresholds for which adaptive capacity is limited in particular systems, adaptation and mitigation become complements where the magnitudes of climate change at which such thresholds cluster can help to define mitigation targets.
A risk management approach to climate change adaptation
This paper addresses ways in which climate information can be used to manage climate change risks. The aim is to maximise decision-making on adaptation by managing uncertainty. Many governments, including those of New Zealand and Australia, have endorsed risk management as the principal method for assessing adaptation options for climate change. The methods they recommend are developed from the standard approach to climate impact assessment, which is largely predictive in nature. While useful, this approach can be integrated with others. Incorporating predictive and diagnostic approaches, the use of planning horizons linked to types of adaptation and likelihoods expressed as the probability of exceeding a given level of outcome are proposed as methods to improve decision-making. Using the likelihood of exceeding given levels of warming as a proxy for local risks, adaptation and mitigation can be weighted (i.e., hedged) as risk management strategies at the national scale. Adaptation can be defined as the principal strategy for managing unavoidable climate change to 2030, after which hedging between adaptation and mitigation increases in relevance. A whole of climate approach needs to be taken at the local level because it is the scale at which impacts occur and where most adaptation will take place. This involves linking current climate and adaptive responses with future projections, and addressing short- and long-term fluctuations in natural climate variability and the consequences thereof. Planned adaptations may need to account for potential abrupt climate changes. A case study example for Victoria, Australia, shows that a recent step change in regional climate to warmer and drier conditions is larger than the worst-case model-based projections for 2030-2050. This has altered the current baseline and makes information about how climate is changing more important than the model-based projections. Projected changes in extremes over time using the changing baseline have been shown to be useful for planned, incremental adaptation. For anticipatory adaptation over the longer term, balancing the costs of adapting and the penalties of not adapting across a range of possible outcomes, ‘climate proof’ and ‘win-win’ options may be identified. For adaptations contingent on particular outcomes, some of which may involve system failure, a portfolio of actions and the ability to respond quickly to changing circumstances may be more robust than adapting to a ‘most likely’ outcome.
A review of climate risk information for adaptation and development planning
International Journal of Climatology, 2009
Although the use of climate scenarios for impact assessment has grown steadily since the 1990s, uptake of such information for adaptation is lagging by nearly a decade in terms of scientific output. Nonetheless, integration of climate risk information in development planning is now a priority for donor agencies because of the need to prepare for climate change impacts across different sectors and countries. This urgency stems from concerns that progress made against Millennium Development Goals (MDGs) could be threatened by anthropogenic climate change beyond 2015. Up to this time the human signal, though detectable and growing, will be a relatively small component of climate variability and change. This implies the need for a twin-track approach: on the one hand, vulnerability assessments of social and economic strategies for coping with present climate extremes and variability, and, on the other hand, development of climate forecast tools and scenarios to evaluate sector-specific, incremental changes in risk over the next few decades. This review starts by describing the climate outlook for the next couple of decades and the implications for adaptation assessments. We then review ways in which climate risk information is already being used in adaptation assessments and evaluate the strengths and weaknesses of three groups of techniques. Next we identify knowledge gaps and opportunities for improving the production and uptake of climate risk information for the 2020s. We assert that climate change scenarios can meet some, but not all, of the needs of adaptation planning. Even then, the choice of scenario technique must be matched to the intended application, taking into account local constraints of time, resources, human capacity and supporting infrastructure. We also show that much greater attention should be given to improving and critiquing models used for climate impact assessment, as standard practice. Finally, we highlight the over-arching need for the scientific community to provide more information and guidance on adapting to the risks of climate variability and change over nearer time horizons (i.e. the 2020s). Although the focus of the review is on information provision and uptake in developing regions, it is clear that many developed countries are facing the same challenges.