A comparison of statistical downscaling and climate change factor methods: impacts on low flows in the River Thames, United Kingdom

Strategic-scale assessments of climate change impacts are often undertaken using the change factor (CF) methodology whereby future changes in climate projected by General Circulation Models (GCMs) are applied to a baseline climatology. Alternatively, statistical downscaling (SD) methods apply climate variables from GCMs to statistical transfer functions to estimate point-scale meteorological series. This paper explores the relative merits of the CF and SD methods using a case study of low flows in the River Thames under baseline (1961–1990) and climate change conditions (centred on the 2020s, 2050s and 2080s). Archived model outputs for the UK Climate Impacts Programme (UKCIP02) scenarios are used to generate daily precipitation and potential evaporation (PE) for two climate change scenarios via the CF and SD methods. Both signal substantial reductions in summer precipitation accompanied by increased PE throughout the year, leading to reduced flows in the Thames in late summer and autumn. However, changes in flow associated with the SD scenarios are generally more conservative and complex than that arising from CFs. These departures are explained in terms of the different treatment of multidecadal natural variability, temporal structuring of daily climate variables and large-scale forcing of local precipitation and PE by the two downscaling methods.     

Assessing uncertainties in climate change impact analyses on the river flow regimes in the UK. Part 2: future climate

The first part of this paper demonstrated the existence of bias in GCM-derived precipitation series, downscaled using either a statistical technique (here the Statistical Downscaling Model) or dynamical method (here high resolution Regional Climate Model HadRM3) propagating to river flow estimated by a lumped hydrological model. This paper uses the same models and methods for a future time horizon (2080s) and analyses how significant these projected changes are compared to baseline natural variability in four British catchments. The UKCIP02 scenarios, which are widely used in the UK for climate change impact, are also considered. Results show that GCMs are the largest source of uncertainty in future flows. Uncertainties from downscaling techniques and emission scenarios are of similar magnitude, and generally smaller than GCM uncertainty. For catchments where hydrological modelling uncertainty is smaller than GCM variability for baseline flow, this uncertainty can be ignored for future projections, but might be significant otherwise. Predicted changes are not always significant compared to baseline variability, less than 50% of projections suggesting a significant change in monthly flow. Insignificant changes could occur due to climate variability alone and thus cannot be attributed to climate change, but are often ignored in climate change studies and could lead to misleading conclusions. Existing systematic bias in reproducing current climate does impact future projections and must, therefore, be considered when interpreting results. Changes in river flow variability, important for water management planning, can be easily assessed from simple resampling techniques applied to both baseline and future time horizons. Assessing future climate and its potential implication for river flows is a key challenge facing water resource planners. This two-part paper demonstrates that uncertainty due to hydrological and climate modelling must and can be accounted for to provide sound, scientifically-based advice to decision makers.     

Bridging the gap: empowering decision-making for adaptation through the UK Climate Impacts Programme

Abstract

The methods, tools and outputs of the UK Climate Impacts Programme (UKCIP) show how building adaptive capacity to climate change can be embedded within a wide range of organizations. UKCIP has been operating since 1997 to support decision-makers' assessments of their vulnerability to climate change so that they can plan how to adapt. Whilst stakeholder engagement is now generally regarded as vital to ensure that research meets the needs of decision-makers for information, this usually means that stakeholders are positioned in a ‘consultative’ role in research. In contrast, the UKCIP aims to bridge the gap between research and policy so that decision-makers take control to produce research in ways that are useful to them. The Programme has been flexible and was developed incrementally, with increased scientific understanding, taking advantage of collaborative funding and facilitating long-standing partnerships. Whilst the core framework of scenarios and tools has been developed centrally, most studies have been stakeholder-funded and led. The Programme's results suggest that if decision-makers are supported, capacity is built for assessments, and crucially, research outputs are directly applicable to their ongoing work and strategic planning. This capacity-building has worked across scales and sectors and is an effective route to mainstreaming climate change adaptation. The implication, therefore, is that more support should be given by funding agencies to develop institutional capacity to support adaptation to climate change in both the private and public sectors.     

Barriers perceived to engaging with climate change among the UK public and their policy implications

This paper reports on the barriers that members of the UK public perceive to engaging with climate change. It draws upon three mixed-method studies, with an emphasis on the qualitative data which offer an in-depth insight into how people make sense of climate change. The paper defines engagement as an individual's state, comprising three elements: cognitive, affective and behavioural. A number of common barriers emerge from the three studies, which operate broadly at ‘individual’ and ‘social’ levels. These major constraints to individual engagement with climate change have implications for achieving significant reductions in greenhouse gases in the UK. We argue that targeted and tailored information provision should be supported by wider structural change to enable citizens and communities to reduce their carbon dependency. Policy implications for effective engagement are discussed.     

Portfolio screening to support the mainstreaming of adaptation to climate change into development assistance

The need to mainstream adaptation to climate change into development planning and ongoing sectoral decision-making is increasingly recognised, and several bilateral and multilateral development agencies are starting to take an interest. Over the past years at least six development agencies have screened their project portfolios, generally with two goals in mind: (1) to ascertain the extent to which existing development projects already consider climate risks or address vulnerability to climate variability and change, and (2) to identify opportunities for incorporating climate change explicitly into future projects. As each portfolio screening was conducted independently, the broader lessons emerging from the screenings have not been systematically analysed. In this paper we assess the screening activities to date, focusing on both the results and the methods applied. Based on this assessment we identify opportunities for development agencies to expand their current focus on the links between climate and development. Most agencies already consider climate change as a real but uncertain threat to future development, but they have given less thought to how different development patterns might affect vulnerability to climate change. The screenings undertaken have shown the need to take a comprehensive approach to adaptation and its integration into development planning and sectoral decision-making, and a number of policy initiatives have been taken to promote such integration. We provide some initial guidance as to how portfolio screening can be carried out in a way that would allow agencies to assess systematically the relevance of climate change to their ongoing and planned development projects.     

Scenarios that illuminate vulnerabilities and robust responses

Scenarios exist so that decision makers and those who provide them with information can make statements about the future that claim less confidence than do predictions, projections, and forecasts. Despite their prevalence, fundamental questions remain about how scenarios should best be developed and used. This paper proposes a particular conceptualization of scenarios that aims to address many of the challenges faced when using scenarios to inform contentious policy debates. The concept envisions scenarios as illuminating the vulnerabilities of proposed policies, that is, as concise summaries of the future states of the world in which a proposed policy would fail to meet its goals. Such scenarios emerge from a decision support process that begins with a proposed policy, seeks to understand the conditions under which it would fail, and then uses this information to identify and evaluate potential alternative policies that are robust over a wide range of future conditions. Statistical cluster analyses applied to databases of simulation model results can help identify scenarios as part of this process. Drawing on themes from the decision support literature, this paper first reviews difficulties faced when using scenarios to inform climate-related decisions, describes the proposed approach to address these challenges, illustrates the approach with applications for three different types of users, and concludes with some thoughts on implications for the provision of climate information and for future scenario processes.     

MODELLING CLIMATE CHANGE IMPACTS ON ECOSYSTEMS USING LINKED MODELS AND A GIS

Future climate change scenarios have been applied to a linked model at five UK sites. Results indicate a decrease in grassland productivity under a changed climate, resulting from lower soil water content, with possible large consequences to future UK water resource planning. The effect of running the grassland sub-model in isolation, compared with running it as part of a linked model showed that linked models should be used for climate change impacts studies. The location specific response to climate change was also highlighted. The model is mechanistic, consists of four sub-models (grassland, water balance, nitrate and evapotranspiration) and is spatially explicit.     

Global socio-economic and climate change mitigation scenarios through the lens of structural change

This paper analyses structural change in the economy as a key but largely unexplored aspect of global socio-economic and climate change mitigation scenarios. Structural change can actually drive energy and land use as much as economic growth and influence mitigation opportunities and barriers. Conversely, stringent climate policy is bound to induce specific structural and socio-economic transformations that are still insufficiently understood. We introduce Multi-Sectoral macroeconomic Integrated Assessment Models as tools to capture the key drivers of structural change and we conduct a multi-model study to assess main structural effects – changes of the sectoral composition and intensity of trade of global and regional economies – in a baseline and 2°C policy scenario by 2050. First, the range of baseline projections across models, for which we identify the main drivers, illustrates the uncertainty on future economic pathways – in emerging economies especially – and inform on plausible alternative futures with implications for energy use and emissions. Second, in all models, climate policy in the 2°C scenario imposes only a second-order impact on the economic structure at the macro-sectoral level – agriculture, manufacturing and services - compared to changes modelled in the baseline. However, this hides more radical changes for individual industries – within the energy sector especially. The study, which adopts a top-down framing of global structural change, represents a starting point to kick-start a conversation and propose a new research agenda seeking to improve understanding of the structural change effects in socio-economic and mitigation scenarios, and better inform policy assessments.     

A co-evolutionary approach to climate change impact assessment — Part II: A scenario-based case study in East Anglia (UK)

Policy makers are beginning to intensify their search for policies that assist society to adapt to the unfolding impacts of climate change at the local level. This paper forms the second part of two part a examination of the potential for using scenarios in adaptation and vulnerability assessment. Part I explained how climate change and socio-economic scenarios can be integrated to better understand the complex inter-relationships between a changing climate and a dynamically evolving social system. This second part describes how a broadly representative sample of public, private and voluntary organisations in the East Anglian region of the UK responded to the scenarios, and identifies future research priorities. The main findings are that integrated socio-economic and climate scenarios applied `bottom up’ to locally important stakeholders: (1) provide a sophisticated and dynamic mechanism to explore the potential feedbacks between natural and human systems; (2) offer a means to understand the vulnerability and adaptive capacity of different exposure units; (3) promote social learning by encouraging participants to assess the adequacy of their existing climate strategies for longer than their normal planning periods.     

The principal-agent problem and climate change adaptation on public lands

Climate change presents clear risks to natural resources, which carry potential economic costs. The limited nature of physical, financial, human and natural resources means that governments, as managers of natural resources, must make careful decisions regarding trade-offs and the potential future value of investments in climate change adaptation. This paper presents cost-benefit analysis of scenarios to characterise economic benefits of adaptation from the perspective of a public institution (the provincial government) and private agents (forest licensees). The example provided is the context of assisted migration strategies for regenerating forests that are currently being implemented in British Columbia to reduce future impacts of climate change on forests. The analysis revealed positive net present value of public investment in assisted migration across all scenarios under a range of conditions; however, private sector agents face disincentives to adopt these strategies. Uncertainty about how the costs, benefits and risks associated with climate change impacts will be distributed among public institutions and private actors influences incentives to adapt to climate change (the “principal-agent problem”) and further complicates adaptation. Absent development of risk-sharing mechanisms or re-alignment of incentives, uptake of assisted migration strategies by private agents is likely to be limited, creating longer-term risks for public institutions. Analyzing incentives and disincentives facing principals and agents using a well-known tool (cost-benefit analysis) can help decision-makers to identify and address underlying barriers to climate change adaptation in the context of public lands management.     

Key factors affecting the future provision of tree-based forest ecosystem goods and services

The continuous provisioning of forest ecosystem goods and services (EGS) is of considerable interest to society. To provide insights on how much EGS provision will change with a changing climate and which factors will influence this change the most, we simulated forest stands on six climatically different sites in Central Europe under several scenarios of species diversity, management, and climate change. We evaluated the influence of these factors on the provision of a range of tree-based EGS, represented by harvested basal area, total biomass, stand diversity, and productivity. The most influential factor was species diversity, with diverse forest stands showing a lower sensitivity to climate change than monocultures. Management mainly influenced biomass, with the most intensively managed stands retaining more of their original biomass than others. All three climate-change scenarios yielded very similar results. We showed that (1) only few factor combinations perform worse under climate-change conditions than others, (2) diversity aspects are important for adaptive management measures, but for some indicators, management may be more important than diversity, and (3) at locations subject to increasing drought, the future provision of EGS may decrease regardless of the factor combination. This quantitative evaluation of the influence of different factors on changes in the provision of forest EGS with climate change represents an important step towards the design of more focused adaptation strategies and highlights key factors that should be considered in simulation studies under climate change.     

Communicating uncertainty in the IPCC’s greenhouse gas emissions scenarios

The issue of climate change required the development of the Special Report on Emission Scenarios (SRES) by the IPCC. The complexity of the subject and the unique science-policy relation resulted in confusion and discussions appeared in popular media like The Economist. This paper reviews scenario literature and SRES, identifies the most vulnerable elements in the communication of SRES. In the communication of GHG emission scenarios through SRES, the weaknesses that have been identified by the authors of this paper are the normative character of climate change assessment, the plausibility of the scenarios, and the risk of simplification of complex messages. The causes of these communicative issues have been identified as the intrinsic difficulties of interdisciplinary science, the uniqueness of the science-policy relation, and the need for a high degree of transparency. This paper suggests improving future communication of complex messages from scientists to their audience by means of clear reasoning when communicating with non-scientists, explicitly normative emission scenarios, and increased stakeholder participation in scenario development. Based on a presentation at the “IIASA-YSSP uncertainty seminars,” 22 July 2004, and the discussions thereafter.     

Precipitation extremes in a karst region: a case study in the Guizhou province, southwest China

The topography of hilly landscapes modifies crop environment changing the fluxes of water and energy, increasing risk in these vulnerable agriculture systems, which could become more accentuated under climate change (drought, increased variability of rainfall). In order to quantify how wheat production in hilly terrain will be affected by future climate, a newly developed and calibrated micro-meteorological model for hilly terrain was linked to a crop growth simulation model to analyse impact scenarios for different European regions. Distributions of yield and growing length of rainfed winter wheat and durum wheat were generated as probabilistic indices from baseline and low (B2) and high (A2) emission climate scenarios provided from the Hadley Centre Regional Climate Model (HadRM3). We used site-specific terrain parameters for two sample catchments in Europe, ranging from humid temperate (southeast UK) to semi-arid Mediterranean (southern Italy). Results for baseline scenario show that UK winter wheat is mainly affected by annual differences in precipitation and yield distributions do not change with terrain, whilst in the southern Mediterranean climate yield variability is significantly related to a slope × elevation index. For future climate, our simulations confirm earlier predictions of yield increase in the UK, even under the high emission scenario. In the southern Mediterranean, yield reduction is significantly related to slope × elevation index increasing crop failure in drier elevated spots but not in wet years under baseline weather. In scenarios for the future, the likelihood of crop failure rises sharply to more than 60%, and even in wet years, yields are likely to decrease in elevated spots.     

Identifying climate services needs for national planning: insights from Malawi

The importance of climate services, i.e. providing targeted, tailored, and timely weather and climate information, has gained momentum, but requires improved understanding of user needs. This article identifies the opportunities and barriers to the use of climate services for planning in Malawi, to identify the types of information that can better inform future adaptation decisions in sub-Saharan Africa. From policy analysis, stakeholder interviews, and a national workshop utilizing serious games, it is determined that only 5–10 day and seasonal forecasts are currently being used in government decision making. Impediments to greater integration of climate services include spatial and temporal scale, accessibility, timing, credibility and the mismatch in timeframes between planning cycles (1–5 years) and climate projections (over 20 years). Information that could more usefully inform planning decisions includes rainfall distribution within a season, forecasts with 2–3 week lead times, likely timing and location of extreme events in the short term (1–5 years), and projections (e.g. rainfall and temperature change) in the medium term (6–20 years). Development of a national set of scenarios would also make climate information more accessible to decision makers, and capacity building around such scenarios would enable its improved use in short- to medium-term planning. Improved climate science and its integration with impact models offer exciting opportunities for integrated climate-resilient planning across sub-Saharan Africa. Accrual of positive impacts requires enhanced national capacity to interpret climate information and implement communication strategies across sectors.

Policy relevance

For climate services to achieve their goal of improving adaptation decision making, it is necessary to understand the decision making process and how and when various types of weather and climate information can be incorporated. Through a case study of public sector planning in Malawi, this article highlights relevant planning and policy-making processes. The current use of weather and climate information and needs, over various timescales – sub-annual to short term (1–5 years) to medium term (6–20 years) – is outlined. If climate scientists working with boundary organizations are able to address these issues in a more targeted, sector-facing manner they will improve the uptake of climate services and the likelihood of climate-resilient decisions across sub-Saharan Africa.     

An iconic approach for representing climate change

International and national greenhouse gas emissions reduction goals implicitly rely in part on individuals undertaking voluntary emissions reductions through lifestyle decisions. Whilst there is widespread public recognition of climate change as an issue, there are many barriers – cognitive, psychological and social – preventing individuals from enacting lifestyle decarbonisation. More effective climate change communication approaches are needed which allow individuals to engage meaningfully with climate change, thus opening new prospects for lifestyle decarbonisation. This study presents an iconic approach to engagement, tested in the UK context, which allows individuals to approach climate change through their own personal values and experiences. The iconic approach harnesses the emotive and visual power of climate icons with a rigorous scientific analysis of climate impacts under a different climate future. Although some climate icons already exist – for example the Thermohaline Circulation shutdown – these ‘expert-led’ icons fail to effectively engage ‘non-experts’. We demonstrate that the non-expert-led iconic approach helps overcome some of the cognitive and affective barriers that impede action towards lifestyle decarbonisation.     

Climate change impacts and adaptation of commercial marine fisheries in Australia: a review of the science

Commercial marine fishing contributes significantly to the Australian economy, and has great importance for coastal communities. However, climate change presents significant challenges for Australia’s fishing industries, now and into the future. With greater use of targeted information, the fishing industry will be better placed to minimise the negative impacts and take advantage of opportunities associated with the effects of climate change. The future of the fishing industry—specifically wild capture fisheries—will depend on its ability and capacity to apply appropriate adaptation strategies for its viability and sustainability in the long-term. Knowledge regarding expected long-term changes in species distributions, improved weather and seasonal climate forecasts and their influence on target species, and better understanding of species tolerances, can inform adaptation responses. This paper provides a review of recent advances in research addressing Australia’s priorities in relation to commercial marine fisheries’ responses to current and anticipated future climate change impacts, and considers barriers and adaptation options for fisheries management over the near-term planning horizon of 5–7 years.     

New lessons for technology policy and climate change: investment for innovation

The direction of UK energy policy requires a renewed impetus if the goal of climate change stabilization is to be met. Cost is not the main issue: a transformation to a low-carbon energy system may be no more expensive than meeting future energy demands with fossil fuels. Institutional barriers are preventing the large-scale adoption of the necessary technologies. New institutions to promote low-carbon technologies have not yet led to investment on the necessary scale. Further changes to the operation of the UK electricity markets to create a ‘level playing field’ for small-scale and intermittent generation are necessary. UK policy can contribute to international agreements following on from the Kyoto Accord, which also need to address the institutional barriers to energy technology development and transfer.     

A method for incorporating climate variability in climate change impact assessments: Sensitivity of river flows in the Eden catchment to precipitation scenarios

Interest in the impacts of climate change is ever increasing. This is particularly true of the water sector where understanding potential changes in the occurrence of both floods and droughts is important for strategic planning. Climate variability has been shown to have a significant impact on UK climate and accounting for this in future climate change projections is essential to fully anticipate potential future impacts. In this paper a new resampling methodology is developed which includes the variability of both baseline and future precipitation. The resampling methodology is applied to 13 CMIP3 climate models for the 2080s, resulting in an ensemble of monthly precipitation change factors. The change factors are applied to the Eden catchment in eastern Scotland with analysis undertaken for the sensitivity of future river flows to the changes in precipitation. Climate variability is shown to influence the magnitude and direction of change of both precipitation and in turn river flow, which are not apparent without the use of the resampling methodology. The transformation of precipitation changes to river flow changes display a degree of non-linearity due to the catchment’s role in buffering the response. The resampling methodology developed in this paper provides a new technique for creating climate change scenarios which incorporate the important issue of climate variability.     

Divergent trends in ecosystem services under different climate-management futures in a fire-prone forest landscape

While ecosystem services and climate change are often examined independently, quantitative assessments integrating these fields are needed to inform future land management decisions. Using climate-informed state-and-transition simulations, we examined projected trends and tradeoffs for a suite of ecosystem services under four climate change scenarios and two management scenarios (active management emphasizing fuel treatments and no management other than fire suppression) in a fire-prone landscape of dry and moist mixed-conifer forests in central Oregon, USA. Focal ecosystem services included fire potential (regulating service), timber volume (provisioning service), and potential wildlife habitat (supporting service). Projections without climate change suggested active management in dry mixed-conifer forests would create more open forest structures, reduce crown fire potential, and maintain timber stocks, while in moist mixed-conifer forests, active management would reduce crown fire potential but at the expense of timber stocks. When climate change was considered, however, trends in most ecosystem services changed substantially, with large increases in wildfire area predominating broad-scale trends in outputs, regardless of management approach (e.g., strong declines in timber stocks and habitat for closed-forest wildlife species). Active management still had an influence under a changing climate, but as a moderator of the strong climate-driven trends rather than being a principal driver of ecosystem service outputs. These results suggest projections of future ecosystem services that do not consider climate change may result in unrealistic expectations of benefits.     

A co-evolutionary approach to climate change impact assessment: Part I. Integrating socio-economic and climate change scenarios

Climate change policies currently pay disproportionately greater attention to the mitigation of climate change through emission reductions strategies than to adaptation measures. Realising that the world is already committed to some global warming, policy makers are beginning to turn their attention to the challenge of preparing society to adapt to the unfolding impacts at the local level. This two-part article presents an integrated, or `co-evolutionary', approach to using scenarios in adaptation and vulnerability assessment. Part I explains how climate and social scenarios can be integrated to better understand the inter-relationships between a changing climate and the dynamic evolution of social, economic and political systems. The integrated scenarios are then calibrated so that they can be applied `bottom up’ to local stakeholders in vulnerable sectors of the economy. Part I concludes that a co-evolutionary approach (1) produces a more sophisticated and dynamic account of the potential feedbacks between natural and human systems; (2) suggests that sustainability indicators are both a potentially valuable input to and an output of integrated scenario formulation and application. Part II describes how a broadly representative sample of public, private and voluntary organisations in the East Anglian region of the UK responded to the scenarios, and identifies future research priorities.