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While it is generally asserted that those countries who have contributed least to anthropogenic climate change are most vulnerable to its adverse impacts some recently developed indices of vulnerability to climate change come to a different conclusion. Confirmation or rejection of this assertion is complicated by the lack of an agreed metric for measuring countries’ vulnerability to climate change and by conflicting interpretations of vulnerability. This paper presents a comprehensive semi-quantitative analysis of the disparity between countries’ responsibility for climate change, their capability to act and assist, and their vulnerability to climate change for four climate-sensitive sectors based on a broad range of disaggregated vulnerability indicators. This analysis finds a double inequity between responsibility and capability on the one hand and the vulnerability of food security, human health, and coastal populations on the other. This double inequity is robust across alternative indicator choices and interpretations of vulnerability. The main cause for the higher vulnerability of poor nations who have generally contributed little to climate change is their lower adaptive capacity. In addition, the biophysical sensitivity and socio-economic exposure of poor nations to climate impacts on food security and human health generally exceeds that of wealthier nations. No definite statement can be made on the inequity associated with climate impacts on water supply due to large uncertainties about future changes in regional water availability and to conflicting indicators of current water scarcity. The robust double inequity between responsibility and vulnerability for most climate-sensitive sectors strengthens the moral case for financial and technical assistance from those countries most responsible for climate change to those countries most vulnerable to its adverse impacts. However, the complex and geographically heterogeneous patterns of vulnerability factors for different climate-sensitive sectors suggest that the allocation of international adaptation funds to developing countries should be guided by sector-specific or hazard-specific criteria despite repeated requests from participants in international climate negotiations to develop a generic index of countries’ vulnerability to climate change.

Integrated assessment models (IAMs) of climate change combine dynamic descriptions of the energy-economy system, the climate system, and climate impacts to support the formulation of global, and possibly regional, climate policy. Originally they have been designed to inform mitigation policy but some of them are now applied in the context of adaptation policy as well. This article reviews the modeling of climate impacts and adaptation in global IAMs, including both models with an economic focus and models with a science focus. Key advances in the representation of climate impacts in IAMs during the last decade include improved consideration of differences in impacts across regions, the development of nonmonetary reduced-form climate impact models, and coupling of global IAMs with regional and sectoral impact models to assess climate change together with other sustainability issues. Further advances include a stronger focus on probabilistic analysis and attempt at considering large-scale climate instabilities. Adaptation has received only limited attention in global IAMs so far, mostly due to the mismatch in spatial scales at which mitigation and adaptation decisions are generally made. Some recent IAMs attempt to identify optimal levels of adaptation in climate-sensitive sectors or do include adaptation to climate change explicitly as a decision variable. The main reason for the consideration of adaptation in global welfare-maximizing IAMs is to assess the sensitivity of mitigation targets to different assumptions about the magnitude and effectiveness of adaptation. IAMs with geographically explicit impact models may also provide information that is useful for adaptation planning. Copyright © 2010 John Wiley & Sons, Ltd. For further resources related to this article, please visit the WIREs website

The IPCC Fourth Assessment Report (AR4) published in 2007 presents the most complete and authoritative assessment of the status of scientific knowledge on all aspects of climate change. This paper presents an updated assessment of the risks from anthropogenic climate change, based on a comprehensive review of the pertinent scientific literature published since finalisation of the AR4. Many risks are now assessed as stronger than in the AR4, including the risk of large sea-level rise already in the current century, the amplification of global warming due to biological and geological carbon-cycle feedbacks, a large magnitude of “committed warming” currently concealed by a strong aerosol mask, substantial increases in climate variability and extreme weather events, and the risks to marine ecosystems from climate change and ocean acidification. Some topics remain the subject of intense scientific debate, such as past and future changes in tropical cyclone activity and the risk of large-scale Amazon forest dieback. The rise in greenhouse gas emissions and concentrations has accelerated recently, and it is expected to accelerate further in the absence of targeted policy interventions. Taken together, these findings point to an increased urgency of implementing mitigation policies as well as comprehensive and equitable adaptation policies.

de Bruin et al. (Clim Change, 2009) report on an expert assessment aimed at prioritizing adaptation options in several climate-sensitive sectors of the Netherlands. Their results show that even in a country with high economic, institutional and technical capacity, it is not currently feasible to prioritize national-level adaptation options based on social cost-benefit analysis because of methodological difficulties and insufficient quantitative data. Multi-criteria analysis based on qualitative indicators can help prioritizing adaptation options but the analysis detected strong conflicts between priority and feasibility criteria. The specific results of the ranking exercise should be treated with caution due to weaknesses in the selection of adaptation options and the definition of evaluation criteria. The authors assert that their methods can be transferred to other regions but substantial modifications are likely required in developing countries with large current climate risks, fewer economic resources, and substantial social inequalities.

Planned adaptation to climate change denotes actions undertaken to reduce the risks and capitalize on the opportunities associated with global climate change. This paper summarizes current thinking about planned adapta- tion. It starts with an explanation of key adaptation con- cepts, a description of the diversity of adaptation contexts, and a discussion of key prerequisites for effective adapta- tion. On the basis of this introduction, major approaches to climate impact and adaptation assessment and their evo- lution are reviewed. Finally, principles for adaptation assessment are derived from decision-analytical consider- ations and from the experience with past adaptation assessments.

The term ‘vulnerability’ is used in many different ways by various scholarly communities. The resulting disagreement about the appropriate definition of vulnerability is a frequent cause for misunderstanding in interdisciplinary research on climate change and a challenge for attempts to develop formal models of vulnerability. Earlier attempts at reconciling the various conceptualizations of vulnerability were, at best, partly successful. This paper presents a generally applicable conceptual framework of vulnerability that combines a nomenclature of vulnerable situations and a terminology of vulnerability concepts based on the distinction of four fundamental groups of vulnerability factors. This conceptual framework is applied to characterize the vulnerability concepts employed by the main schools of vulnerability research and to review earlier attempts at classifying vulnerability concepts. None of these one-dimensional classification schemes reflects the diversity of vulnerability concepts identified in this review. The wide range of policy responses available to address the risks from global climate change suggests that climate impact, vulnerability, and adaptation assessments will continue to apply a variety of vulnerability concepts. The framework presented here provides the much-needed conceptual clarity and facilitates bridging the various approaches to researching vulnerability to climate change.

Vulnerability is an emerging concept for climate science and policy. Over the past decade, efforts to assess vulnerability to climate change triggered a process of theory development and assessment practice, which is reflected in the reports of the Intergovernmental Panel on Climate Change (IPCC). This paper reviews the historical development of the conceptual ideas underpinning assessments of vulnerability to climate change. We distinguish climate impact assessment, first- and second-generation vulnerability assessment, and adaptation policy assessment. The different generations of assessments are described by means of a conceptual framework that defines key concepts of the assessment and their analytical relationships. The purpose of this conceptual framework is two-fold: first, to present a consistent visual glossary of the main concepts underlying the IPCC approach to vulnerability and its assessment; second, to show the evolution of vulnerability assessments. This evolution is characterized by the progressive inclusion of non-climatic determinants of vulnerability to climate change, including adaptive capacity, and the shift from estimating expected damages to attempting to reduce them. We hope that this paper improves the understanding of the main approaches to climate change vulnerability assessment and their evolution, not only within the climate change community but also among researchers from other scientific communities, who are sometimes puzzled by the unfamiliar use of technical terms in the context of climate change.

The computational burden associated with applications of theTolerable Windows Approach (TWA) considerably exceeds that oftraditional integrated assessments of global climate change. Aspart of the ICLIPS (Integrated Assessment of Climate ProtectionStrategies) project, a computationally efficient climate model hasbeen developed that can be included in integrated assessmentmodels of any kind. The ICLIPS climate model (ICM) is implementedin GAMS. It is driven by anthropogenic emissions of CO2,CH4, N2O, halocarbons, SF6, andSO2. Theoutput includes transient patterns of near-surface airtemperature, total column-integrated cloud cover fraction,precipitation, humidity, and global mean sea-level rise. Thecarbon cycle module explicitly treats the nonlinear sea watercarbon chemistry and the nonlinear CO2 fertilized biosphereuptake. Patterns of the impact-relevant climate variables arederived form empirical orthogonal function (EOF) analysis andscaled by the principal component of temperature change. Theevolution of the latter is derived from a box-model-typedifferential analogue to its impulse response function convolutionintegral. We present a description of the ICM components and someresults to demonstrate the model's applicability in the TWA setting.

A critical issue for policymakers in defining mitigationstrategies for climate change is the availability ofappropriate evaluation tools. The development of climate impactresponse functions (CIRFs) is our reaction to this challenge.CIRFs depict the response of selected climate-sensitive impactsectors across a wide range of plausible futures. They consist ofa limited number of climate-change-related dimensions andsensitivities of sector-specific impact models. The concept ofCIRFs is defined and the procedure to develop them is presented.The use of climate change scenarios derived from various GCMexperiments and the adopted impact assessment models areexplained.The CIRFs presented here consider climate change impacts onnatural vegetation, crop production, and water availability. Theyare part of the ICLIPS integrated assessment framework based onthe tolerable windows approach. CIRFs can be applied both in`forward' and in `inverse' mode. In the latter, they help totranslate thresholds for climate impacts perceived by stakeholders(so-called impact guardrails) into constraints for climatevariables (so-called climate windows). This enables the results ofdetailed impact models to be incorporated into intertemporallyoptimizing integrated assessment models, such as the ICLIPS model.

An integrated assessment model (IAM) conceived in the vein ofthe inverse approach is introduced. The model is designed tohelp social actors in making informed judgments about climatechange impact targets, mitigation costs, and implementation mechanisms.Based on these normative decisions, the model verifies whetherthere exist long-term future emission paths that satisfy theuser-defined constraints. If they do, the model determines anemission corridor containing all permissible emission trajectories.An overview of the IAM is provided and short descriptions ofthe model components are presented. Forward and inverse modesof application are explained. Examples based on impacts of climatechange on aggregated potential crop production in Western Europeand South Asia illustrate how the model can be applied in differentmodes. The examples demonstrate how the inverse approach separatessocial judgments shaping climate policy from the model-basedanalysis of their implications. The examples also show the differencein climate change tolerance between developed regions in temperatezones and less developed regions in already warm climate zones.

(2002). Exploring Options for Global Climate Policy. A New Analytical Framework. Environment: Science and Policy for Sustainable Development: Vol. 44, No. 5, pp. 22-34.