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The 3rd version of the Climate Vulnerability Monitor (CVM3) is an independent global assessment of the impacts of climate change in the 21st century developed by a scientific consortium for the Climate Vulnerability Forum. It presents specific estimated climate change–attributable impact data that is internationally comparable in 32 biophysical, human health and economic indicators for most countries and all world regions. Based on the latest scenarios developed for the IPCC’s Sixth Assessment Report, the CVM3 assesses impacts for three scenarios (1.5°C scenario, a below 2°C scenario and a “no climate action” scenario) and three time slices (near-term (2030– mid-point year for 2021–2040), medium (2050) and end of the century (2090)).The free online tool “CVM Data Explorer” draws on information, data and results of the different work packages made available by the partners through three respective application programming interfaces (APIs). While the health data explorer shows potential changes in climate-related health risks, the economics data explorer illustrates the extent to which climate change is projected to alter macroeconomic indicators. The biophysical explorer presents estimate changes in indicators like near-surface air temperature and precipitation, offers an overview of present attributable impacts as well as covering current and future vulnerability of over 180 countries. based on the given emission scenarios. The tool displays these results of current and projected impacts with maps for the different pathways and timeframes and the underlying data is freely available for download.A multimedia part (“scrolly-telling”) of the tool takes a narrative-explorative approach to the results using different types of media such as video interviews, animations and interactive elements with local experts. These impact stories for five chosen countries (Bangladesh, Ghana, Kenya, Philippines, St. Lucia) aim to bring global databases together with regional to local impact and vulnerability information and showcase the CVM3 results in a narrative, concrete and exemplary manner.

Floods are one of many climate change extremes causing massive economic and non-economic losses and damages. The recent 6th Assessment Report of the IPCC highlights that flooding will be more widespread at 2°C compared to 1.5°C and even more pronounced at higher levels of global warming. To prevent or reduce impacts from flooding, structural measures for flood protection through hard infrastructure are the most common intervention, as they directly manage flood hazards by controlling flow through streams and prevent water overflow. Adaptation options specifically include dikes, flood control gates, weirs, dams, storage and proper waste management. While flood protection could substantially reduce the economic costs of flood events and counts as the most effective adaptation strategy in the water sector to climate change, scenarios for future flood protection are still in their infancy. Consequently, quantitative assessments of climate change (i.e., impact models), which themselves include numerous uncertainties, cannot adequately account for adaptative flood protection in current risk assessments. We propose a Flood Protection Index (FPI) that captures the current level of flood protection across the globe using various data sources. By identifying adaptation-relevant quantitative socioeconomic variables within the framework of the Shared Socioeconomic Pathways (SSPs) and accounting for future climatic risk, we will be able to project five scenarios for flood protection alongside the SSPs. For the first time, we will show how different socioeconomic trajectories could modulate future flood impacts. These scenarios can be included in quantitative assessments of climate change and improve risk assessments in the 21st century.

Sea-level rise poses a significant threat to Small Island Developing States (SIDS) due to the concentration of people, assets, and infrastructure in coastal zones. This review assesses literature on key emerging topics in sea level rise including: the lasting impact of near-term mitigation on long-term sea-level rise; new global coastal vertical elevation data and their impact on existing sea-level rise projections; and the interaction of sea-level rise with other hazards, including salinization, tropical cyclones and extreme precipitation. We characterize the regional nature of sea-level rise for SIDS and highlight associated impacts and risks. Finally, we review approaches to address sea-level rise as well as limits to adaptation and resultant economic and non-economic loss and damage that may be experienced by SIDS.

Climate change adaptation planning has rapidly expanded to assist with reducing vulnerability to current and projected impacts of climate change. In Caribbean small island developing states (SIDS), planned adaptation is viewed as essential to address their high vulnerability to climate change, and planning has begun in earnest across the region. However, there has been limited analysis of adaptation planning documents in the region to assess their quality and content. This study assesses adaptation planning documents from Caribbean SIDS, focusing on inclusion of key stages of adaptation planning that were identified from international and regionally specific adaptation guidance instruments. Eighty-nine Caribbean adaptation planning documents—including policies, strategies, programs, and projects—were assessed, revealing that they differ considerably from guidance instruments. Key areas for improvement include the need for (i) more direct linkages between identification of adaptation options and assessments of climate hazards, impacts, vulnerability, and risk; (ii) identification and appraisal of a range of adaptation options; and (iii) increased inclusion and usage of quantitative information about hazards and impacts. Addressing these deficiencies may help to improve the status of adaptation planning in the region and ultimately aid in reducing the high vulnerability of these island nations to the impacts of climate change.

Context: It is now widely accepted that the climate is changing, and that societal responses will need to be rapid and comprehensive to prevent the most severe impacts. A key milestone in global climate governance is to assess progress on adaptation. To-date, however, there has been negligible robust, systematic synthesis of progress on adaptation or adaptation-relevant responses globally. Aim: The purpose of this review protocol is to outline the methods used by the Global Adaptation Mapping Initiative (GAMI) to systematically review human adaptation responses to climate-related changes that have been documented globally since 2013 in the scientific literature. The broad question underpinning this review is: Are we adapting to climate change? More specifically, we ask ‘what is the evidence relating to human adaptation-related responses that can (or are) directly reducing risk, exposure, and/or vulnerability to climate change?’ This work responds to the recognition of the need for high-level syntheses of adaptation research to inform global and regional climate assessments.Methods: We review scientific literature 2013-2019 to identify documents empirically reporting on observed adaptation-related responses to climate change in human systems that can directly reduce risk. We exclude non-empirical (theoretical & conceptual) literature and adaptation in natural systems that occurs without human intervention. Included documents were coded across a set of questions focused on: Who is responding? What responses are documented? What is the extent of the adaptation-related response? What is the evidence that adaptation-related responses reduce risk, exposure and/or vulnerability? Once articles are coded, we conduct a quality appraisal of the coding and develop ‘evidence packages’ for regions and sectors. We supplement this systematic mapping with an expert elicitation exercise, undertaken to assess bias and validity of insights from included/coded literature vis a vis perceptions of real-world adaptation for global regions and sectors, with associated confidence assessments. Related protocols: This protocol represents Part 1 of a 5-part series outlining the phases of methods for this initiative. Part 1 provides an introduction to the Global Adaptation Mapping Initiative (GAMI) and an overview of methods.

We present the first systematic, global stocktake of the academic literature on human adaptation. We screen 48,316 documents and identify 1,682 articles that present empirical research documenting human efforts to reduce risk from climate change and associated hazards. Coding and synthesizing this literature highlights that the overall extent of adaptation across global regions and sectors is low. Adaptations are largely local and incremental rather than transformative. Behavioural adjustments by individuals and households are more prevalent than any other type of response, largely motivated by drought and precipitation variability. Local governments and civil society are engaging in risk reduction across all sectors and regions, particularly in response to flooding. Urban technological and infrastructural adaptations to flood risk are prevalent in Europe, while shifts in farming practices dominate reporting from Africa and Asia. Despite increasing evidence of adaptation responses, evidence that these responses are reducing risks (observed and projected) remains limited.

Assessing global progress on human adaptation to climate change is an urgent priority. Although the literature on adaptation to climate change is rapidly expanding, little is known about the actual extent of implementation. We systematically screened >48,000 articles using machine learning methods and a global network of 126 researchers. Our synthesis of the resulting 1,682 articles presents a systematic and comprehensive global stocktake of implemented human adaptation to climate change. Documented adaptations were largely fragmented, local and incremental, with limited evidence of transformational adaptation and negligible evidence of risk reduction outcomes. We identify eight priorities for global adaptation research: assess the effectiveness of adaptation responses, enhance the understanding of limits to adaptation, enable individuals and civil society to adapt, include missing places, scholars and scholarship, understand private sector responses, improve methods for synthesizing different forms of evidence, assess the adaptation at different temperature thresholds, and improve the inclusion of timescale and the dynamics of responses. Determining progress in adaptation to climate change is challenging, yet critical as climate change impacts increase. A stocktake of the scientific literature on implemented adaptation now shows that adaptation is mostly fragmented and incremental, with evidence lacking for its impact on reducing risk.

The level of detail to understand the impacts associated with different levels of global temperature increase across space and time is increasing with and since the publication of the IPCC Special Report on Global Warming of 1.5°C (SR1.5). However, current adaptation assessments are limited in picking up this information to understand what the implications of different impact pathways are for adaptation. Yet, the intensity, frequency and timing of impacts are critical determinants of the feasibility of different adaptation options and their associated costs.There is increasing awareness that limits to adaptation are likely to be approached or crossed with higher levels of warming, however differential analyses of adaptation needs as a consequence of different warming pathways are so far limited. While case study based assessment of warming- and scenario-depend adaptation responses are emerging, so far an aggregated regional to global assessment is lacking.Adaptation is often seen as a process that can draw on existing approaches that have been successfully implemented elsewhere, assuming that a linear increase of impacts would allow impacted regions to scale existing approaches to deal with hazards. However, climate impacts are unlikely to increase in a linear fashion across space and time and we are likely to enter new regimes of impacts in terms of intensity and frequency, with implications on recovery times. As a consequence, existing approaches are unlikely to be able to respond to these fundamentally changed conditions and limits to adaptation as we know it are likely to be reached. Understanding adaptation needs and potentials at different levels of global warming is therefore an urgent need in order to understand the full scale of the challenge. Such information is also critical in understanding the full cost of different mitigation pathway choices.This contribution presents a framework for the systematic assessment of warming-level dependent adaptation needs and potentials across sectors and presents first results of this approach in the context of adaptation in the water sector. Our results highlight the need for differentiated approaches to planning adaptation, drawing a strong link to available impacts and vulnerability science to avoid mal-adaptation and to understand the full scope of the challenge. Where transformational adaptation will be required and current warming trajectories, early action may reduce associated costs of such measures across different dimensions, including financial, social or cultural aspects.

Climate impacts increase with higher warming and evidence is mounting that impacts increase strongly above 1.5°C. Therefore, adaptation needs also rise substantially at higher warming levels. Further, limits to adaptation will be reached above 1.5°C and loss and damage will be inferred. Coastal Nature-based Solutions (NbS) have arisen as popular adaptation options, particularly for coastal developing economies and Small Island Developing States (SIDS), because of their lower overall costs compared to traditional grey infrastructure approaches such as seawalls and levees; their economic co-benefits through positive effects on sectors such as tourism and fisheries; and a broader desire to shift toward so-called blue economies. Two NbS of particular interest for coastal protection are: 1) coral reefs, which reduce coastal erosion and flooding through wave attenuation; and 2) mangroves, which provide protection from storms, tsunamis and coastal erosion. Although there is international enthusiasm to implement these solutions, there is limited understanding of the future viability of these ecosystems, particularly in their capacities as coastal adaptation service providers, in a warmer world.In this presentation, we highlight how long and with how much coverage coral and mangrove ecosystems can provide coastal protection services for future climate scenarios, using air temperature and sea level rise as climate change indicators. A mathematical model for each ecosystem is developed, based on the physical parameters necessary for the sustainability of these ecosystems. We investigate the protective capabilities of each ecosystem under warming and sea level rise scenarios compatible with: below 1.5°C warming; below 2°C warming; warming based on current global commitments to carbon emissions reductions (3-3.5°C); and with no carbon mitigation (6°C). Results show what temperature and sea level rise values beyond which these ecosystems can no longer provide coastal protective services. These results have also been framed in a temporal window to show when these services may not be feasible, beyond which more costly adaptation measures and/or loss and damage may be incurred.

Differentiating the impacts of climate change between 1.5°C and 2°C requires a regional and sector-specific perspective. Whereas for some regions and sectors the difference in climate variables might be indistinguishable from natural variability, other areas especially in the tropics and subtropics will experience significant shifts. In addition to region-specific changes in climatic conditions, vulnerability and exposure also differ substantially across the world. Even small differences in climate hazards can translate into sizeable impact differences for particularly vulnerable regions or sectors. Here, we review scientific evidence of regional differences in climate hazards at 1.5°C and 2°C and provide an assessment of selected hotspots of climate change, including small islands as well as rural, urban, and coastal areas in sub-Saharan Africa and South Asia, that are particularly affected by the additional 0.5°C global mean temperature increase. We interlink these with a review of the vulnerability and exposure literature related to these hotspots to provide an integrated perspective on the differences in climate impacts between 1.5°C and 2°C.

Water is an essential input to the majority of human activities. Often, access to sufficient water resources is limited by quality and infrastructure aspects, rather than by resource availability alone, and each activity has different requirements regarding the nature of these aspects. This paper develops an integrated approach to assess the adequacy of water resources for the three major water users: the domestic, agricultural and industrial sectors. Additionally, we include environmental water requirements. We first outline the main determinants of water adequacy for each sector. Subsequently, we present an integrated approach using fuzzy logic, which allows assessing sector-specific as well as overall water adequacy. We implement the approach in two case study settings to exemplify the main features of the approach. Using results from two climate models and two forcing RCPs (representative concentration pathways), as well as population projections, we further assess the impacts of climate change in combination with population growth on the adequacy of water resources. The results provide an important step forward in determining the most relevant factors, impeding adequate access to water, which remains an important challenge in many regions of the world. The methodology allows one to directly identify the factors that are most decisive in determining the adequacy of water in each region, pointing towards the most efficient intervention points to improve conditions. Our findings underline the fact that, in addition to water volumes, water quality is a limitation for all sectors and, especially for the environmental sector, high levels of pollution are a threat to water adequacy.

Island states are especially at risk of climate impacts and are already feeling the effects of rising sea levels, acidification, climate extremes and other impacts. Small islands face several unique challenges: They usually have limited resources to react, but are exceptionally exposed due to their physical setting and limited livelihood options. In addition, they are remote and not easily reached in time of crisis, making adaptation an imperative. This contribution presents the concept for an integrated database on climate impacts and adaptation, focussing specifically on the requirements of small island states. The database contains information on climate impact projections, linked to examples of existing adaptation projects. The database provides a structured overview of success-factors and limitations, piecing together fragmented knowledge and fostering knowledge exchange across regions in order to support science-based adaptation. While adaptation experience is increasing, including an evolving understanding of prerequisites and limitations to specific forms of adaptation, knowledge is still fragmented, due to the mostly local nature of adaptation. Island states across the world can benefit from a structured exchange, focussing on the transferability of success-criteria for adaptation. An improved knowledge base is also important for other regions, which will face similar challenges in the coming years.

We explore the link between improvements in human development and greenhouse gas emission. We argue that a disaggregated view on human development is required to understand the potential for decoupling of development from greenhouse gas emissions. To do so, we relate 16 elements from the livelihood index to emissions. Improvements in livelihood are decoupled from emissions for 10 elements, while only 6 are related to significant emissions. We operate the proposed framework for the example of food consumption and related emissions and find a reduction potential of about 13% compared to the total emissions from this sector.

The Paris Agreement sets a long-term temperature goal of holding the global average temperature increase to well below 2 °C, and pursuing efforts to limit this to 1.5 °C above pre-industrial levels. Here, we present an overview of science and policy aspects related to this goal and analyse the implications for mitigation pathways. We show examples of discernible differences in impacts between 1.5 °C and 2 °C warming. At the same time, most available low emission scenarios at least temporarily exceed the 1.5 °C limit before 2100. The legacy of temperature overshoots and the feasibility of limiting warming to 1.5 °C, or below, thus become central elements of a post-Paris science agenda. The near-term mitigation targets set by countries for the 2020-2030 period are insufficient to secure the achievement of the temperature goal. An increase in mitigation ambition for this period will determine the Agreement's effectiveness in achieving its temperature goal.

The relevance of climate change is especially apparent through the impacts it has on natural and societal systems. A standardised methodology to assess these impacts in order to produce comparable results is still lacking. We propose a semi-quantitative approach to calculate vulnerability to climate change, with the ability to capture complex mechanisms in human-environmental systems. The key mechanisms are delineated and translated into a deterministic graph (impact chain). A fuzzy logic algorithm is then applied to address uncertainty regarding the definition of clear threshold values. We exemplify our approach by analysing the direct impacts of climate change on human health in North Rhine-Westphalia, Germany, where the urban heat island potential, the percentage of elderly population as well as the occurrence of heat waves determine impact intensity. Increases in heatwaves and elderly population will aggravate the impacts. While the influence of climatic changes is apparent on larger spatial scales, societal factors determine the small scale distribution of impacts within our regional case study. In addition to identifying climate change impact hot spots, the structured approach of the impact chain and the methodology of aggregation enable to infer from the results back to the main constituents of vulnerability. Thus, it can provide a basis for decision-makers to set priorities for specific adaptation measures within the complex field of climate change impacts.

Water is an essential input to the majority of human activities. Often, access to sufficient water resources is limited by quality and infrastructure aspects, rather than by resource availability alone, and each activity has different requirements regarding the nature of these aspects. This paper develops an integrated approach to assess the adequacy of water resources for the three major water users, the domestic, agricultural and industrial sectors. Additionally, we include environmental water requirements. We first outline the main determinants of water adequacy for each sector. Subsequently, we present an integrated approach using fuzzy logic, with allows assessing sector-specific as well as overall water adequacy. We implement the approach in two case study settings to exemplify the main features of the approach. Using results from two climate models and two forcing RCPs (Representative Concentration Pathways) as well as population projections, we further assess the impacts of climate change and population growth on the adequacy of water resources. The results provide an important step forward in determining the most relevant factors, impeding adequate access to water, which remains an important challenge in many regions of the world. The methodology allows to directly identify those factors most decisive in determining the adequacy of water in each region, pointing towards the most efficient intervention points to improve conditions. Our findings underline the fact that in addition to water volumes, water quality is a limitation for all sectors and especially for the environmental sector, high levels of pollution are a threat to water adequacy.

Climate change will have adverse impacts on many different sectors of society, with manifold consequences for human livelihoods and well-being. However, a systematic method to quantify human well-being and livelihoods across sectors is so far unavailable, making it difficult to determine the extent of such impacts. Climate impact analyses are often limited to individual sectors (e.g. food or water) and employ sector-specific target measures, while systematic linkages to general livelihood conditions remain unexplored. Further, recent multi-model assessments have shown that uncertainties in projections of climate impacts deriving from climate and impact models, as well as greenhouse gas scenarios, are substantial, posing an additional challenge in linking climate impacts with livelihood conditions. This article first presents a methodology to consistently measure what is referred to here as AHEAD (Adequate Human livelihood conditions for wEll-being And Development). Based on a trans-disciplinary sample of concepts addressing human well-being and livelihoods, the approach measures the adequacy of conditions of 16 elements. We implement the method at global scale, using results from the Inter-Sectoral Impact Model Intercomparison Project (ISI-MIP) to show how changes in water availability affect the fulfilment of AHEAD at national resolution. In addition, AHEAD allows for the uncertainty of climate and impact model projections to be identified and differentiated. We show how the approach can help to put the substantial inter-model spread into the context of country-specific livelihood conditions by differentiating where the uncertainty about water scarcity is relevant with regard to livelihood conditions – and where it is not. The results indicate that livelihood conditions are compromised by water scarcity in 34 countries. However, more often, AHEAD fulfilment is limited through other elements. The analysis shows that the water-specific uncertainty ranges of the model output are outside relevant thresholds for AHEAD for 65 out of 111 countries, and therefore do not contribute to the overall uncertainty about climate change impacts on livelihoods. In 46 of the countries in the analysis, water-specific uncertainty is relevant to AHEAD. The AHEAD method presented here, together with first results, forms an important step towards making scientific results more applicable for policy decisions.

Climate change impacts will affect many important societal sectors, with potential negative consequences for human well-being and livelihoods, however an integrated and systematic measure to assess the state of livelihood conditions in this context is not available. At the same time, human livelihoods and wellbeing are an important part of (social) sustainability. Yet, aspects of human needs and well-being within assessments of sustainability are criticised for being arbitrary and incomplete. This paper presents a systematic approach to assess Adequate Human livelihood conditions for wEll-being And Development (AHEAD) on a regional to global scale. Based on an interdisciplinary literature review, we first select a consistent set of elements that allow to describe and quantify well-being and livelihoods. In a second step, we analyze documented associations between the elements to outline climate impact pathways and indirect effects of changes in single system components, using an influence matrix. The novel approach provides an important first step to point towards climate change adaptation measures, which most effectively increase human well-being, while identifying potential unintended side-effects. Even though there are some limitations to assessing well-being and livelihoods on a global scale, a consistent measure of AHEAD is of utmost importance for future sustainability and climate impact analyses.

Inadequate access to water is already a problem in many regions of the world and processes of global change are expected to further exacerbate the situation. Many aspects determine the adequacy of water resources: beside actual physical water stress, where the resource itself is limited, economic and social water stress can be experienced if access to resource is limited by inadequate infrastructure, political or financial constraints. Further, water quality is an essential determinant of adequate water access. All human activities as well as ecosystems require water in sufficient quantity and quality for their functioning. To assess the adequacy of water availability for human use, integrated approaches are needed that allow to view the multiple determinants in conjunction and provide sound results as a basis for informed decisions. This contribution gives an overview of existing knowledge on different aspects to measure water scarcity and points out gaps in existing approaches. It then proposes two parts of an integrated approach to look at the multiple dimensions of water scarcity. It first outlines the AHEAD approach to measure Adequate Human livelihood conditions for wEll-being And Development. The approach allows viewing impacts of climate change, e.g. changes in water availability, within the wider context of AHEAD conditions. However, adequate water access is not determined by water availability alone. To assess the water requirements for different sectors in more detail, we present a second approach to assess the multiple determinants of water adequacy, including aspects of quantity, quality as well as access, in an integrated way.