The IPCC Working Group II contribution to the Sixth Assessment Report addresses the challenges of climate action in the context of sustainable development with a particular focus on climate change impacts, adaptation and vulnerability. This chapter frames the point of departure and key concepts building on the IPCC’s Fifth Assessment Report (IPCC, 2014a, b), the Special Report on Global Warming of 1.5°C (IPCC, 2018b), the Special Report on the Ocean and Cryosphere in a Changing Climate (SROCC) (IPCC, 2019b), and the Special Report on Climate Change and Land (SRCCL) (IPCC, 2019a); as well as the WGI contributions to the Sixth Assessment Report (IPCC, 2021a) and complements the contribution of the WGIII Sixth Assessment Report, which will be published after this report (IPCC, 2022).

Since IPCC AR5, human influence on the Earth’s climate has become unequivocal, increasingly apparent and widespread, reflected in both the growing scientific literature and in the perception and experiences of people worldwide (high confidence). Current changes in the climate system and those expected in the future will increasingly have significant and deleterious impacts on human and natural systems. The impacts of climate change and extreme weather events have adversely affected, or caused the loss of ecosystems including terrestrial, freshwater, ocean and coastal ecosystems, including tropical coral reefs; reduced food security; contributed to migration and displacement; damaged livelihoods, health and security of people; and increased inequality. Climate change impacts are concurrent and interact with other significant societal changes that have become more salient since AR5, including a growing and urbanising global population; significant inequality and demands for social justice; rapid technological change; continuing poverty, land and water degradation, biodiversity loss; food insecurity; and a global pandemic. {1.1.1; 1.3; Cross-Working Group Box ATTRIBUTION in Chapter 1}

Since AR5, climate action has grown in salience worldwide across all levels of government as well as among non-governmental organisations, small and large enterprises, and citizens (high confidence). At the international level the Paris Agreement and the Sustainable Development Goals (SDGs), along with other targets and frameworks, such as the Sendai Framework for Disaster Risk Reduction, the Convention on Biological Diversity (CBD) Aichi targets, the Addis Ababa Action Agenda for finance and the New Urban Agenda, provide overarching goals and policy context. These agreements also provide policy goals used by this IPCC Report to assess climate action across all levels of society. {1.1.2; 1.4.1; 1.4.3}

IPCC’s assessments have grown and changed substantially over the last three decades. Compared to earlier IPCC assessments, this report emphasises a common risk-solution framing across all three Working Groups. This report focuses on solutions for risk reduction and adaptation; provides more integration across the natural and social sciences; applies a more comprehensive risk framework; assesses adaptation directly in the context of sectoral or regional risks; engages with different forms of knowledge, including Indigenous knowledge and local knowledge; and includes an increasing focus on equity and justice. {1.1.4; 1.4.2; Cross-Chapter Box ADAPT in Chapter 1}

Adaptation plays a key role in reducing risks and vulnerability from climate change. Implementing adaptation and mitigation actions together with the SDGs helps to exploit synergies, reduce trade-offs and makes all three more effective. From a risk perspective, limiting atmospheric greenhouse gas (GHG) concentrations reduces climate-related hazards while adaptation and sustainable development reduce exposure and vulnerability to those hazards. Adaptation facilitates development, which is increasingly hindered by impacts and risks from climate change. Development facilitates adaptation by expanding the resources and capacity to reduce climate risks and vulnerability. {1.1.3; 1.5.1; 1.5.3}

The concepts of risk and risk management have become increasingly central to climate change literature, research, practice and decision making (medium confidence). Risk, defined as the potential for adverse consequences for human and ecological systems, recognising the diversity of values and objectives associated with such systems, provides a framework for understanding the increasingly severe, interconnected and often irreversible impacts of climate change; how these impacts differentially affect different regions, sectors and populations; how to allocate resources best to manage the resulting risks and how to evaluate the responses that reduce residual risks for current and future generations, economies and ecosystems. {1.2.1; 1.3.1; 1.4.2}

The concepts of adaptation, vulnerability, resilience and risk provide overlapping, alternative entry points for the climate change challenge (high confidence). Vulnerability is a component of risk, but also an important focus independently, improving understanding of the differential impacts of climate change on people of different gender, race, wealth, social status and other attributes. Vulnerability also provides an important link between climate adaptation and disaster risk reduction. Resilience, which can refer to either a process or outcome, encompasses not just the concept of maintaining essential function, identity and structure, but also maintaining a capacity for transformation. Such transformations bring forth questions of justice, power and politics. {1.2.1; 1.4.1}

Risks from climate change differ through space and time and cascade across and within regions and systems. The total risk in any location may thus differ from the sum of individual risks if these interactions, as well as risks from responses themselves, are not considered (high confidence). The risks of climate change responses include the possibility of mitigation or adaptation responses not achieving their intended objectives or having trade-offs or adverse side effects for other societal objectives. Another core area of complexity in climate risk is the behaviour of systems, which includes multiple stressors unfolding together, cascading or compounding interactions within and across sectors and regions, and nonlinear responses and the potential for surprises. All of this is crucial for effective decision making and decision-support methods. The key risks assessed in this report become important in interaction with the cultures, values, ethics, identities, experiences and knowledge systems of affected communities and societies. {1.3.1}

Increasingly, impacts are detected and attributed to the changing climate. Improved understanding of deep history (palaeoclimate and biotic responses) suggests that past climate changes have already caused substantial ecological, evolutionary and socioeconomic impacts (high confidence). Many recent impacts are not detected, due to a shortage of monitoring and robust attribution analysis (high confidence). Detection and attribution assessments inform risk assessment by demonstrating the sensitivity of a system to climate change, and they can inform loss and damage estimates including those involved in potential climate litigation cases. Robust detection and attribution methods now exist and play a significant role in increasing awareness and willingness to act among decision makers and the general population. {1.3.2.1; Cross-Working Group Box ATTRIBUTION in Chapter 1; Cross-Chapter Box PALEO in Chapter 1}

Narratives play an important role in communicating climate risks and motivating solutions. A narrative describes a chronological chain of events, often with a premise and conclusions. In the AR6, as in previous IPCC assessments, climate change scenarios and related narratives (also called storylines) are central in the analysis, synthesis and communication of climate change impacts and of adaptation and mitigation responses. AR6 employs narratives to describe the assumptions, evolution and driving forces for the representative concentration pathways (RCPs) and shared socioeconomic pathways (SSPs) and links these to global warming levels (GWLs) as a complement to RCPs and SSPs for framing impacts (Cross-Chapter Box CLIMATE in Chapter 1). Narratives can also be enablers of transformation by communicating societal goals and the actions needed to achieve them {1.2.2; 1.3.3; 1.5.2}

AR6 highlights adaptation solutions and the extent to which they are successful and adequate at reducing climate risk, increasing resilience and pursuing other climate-related societal goals. For adaptation, a solution is defined as an option which is effective, feasible and conforms to principles of justice. Effectiveness refers to the extent to which an action is anticipated or is observed to reduce climate-related risk. Feasibility refers to the extent to which a measure is considered possible and desirable in a particular context. A successful action is one observed to be effective, feasible and just. Adequacy refers to a set of solutions that together are sufficient to avoid dangerous, intolerable, or severe climate risks. {1.4}

Indigenous knowledge and local knowledge (IK and LK) can provide important understanding for acting effectively on climate risk and can help diversify knowledge that may enrich adaptation policy and practice (high confidence) . Indigenous Peoples have been faced with adaptation challenges for centuries and have developed strategies for resilience in changing environments that can enrich and strengthen current and future adaptation efforts. Valuing IK and LK is also important for recognition, a key component of climate justice. {1.3.2.3}

AR6 highlights three principles of climate justice: distributive justice, procedural justice and recognition. Distributive justice refers to the allocation of burdens and benefits among individuals, nations and generations. Procedural justice refers to who decides and participates in decision making. Recognition entails basic respect and robust engagement with and fair consideration of diverse cultures and perspectives. This report considers all three principles in the assessment of adaptation options and evaluates the extent to which better outcomes are obtained by choosing just ones. Since potential trade-offs exist among the principles, adaptation assessments will in general involve normative judgements, as well as science-based evidence. {1.4.1.1}

Concepts of justice and measures of well-being are increasingly used to evaluate the extent to which climate change adaptation is equitable and effective (medium confidence). AR6 employs evaluation frameworks based on both single and multi-criteria to assess adaptation effectiveness and consistency with principles of justice. Single criteria frameworks aggregate many attributes into a one number or ranking, often quantified using benefit–cost analysis or measures of social welfare. Existing decision processes often favour such single criteria, which also correlate well with many measures of social progress and sustainable development. Multi-criteria frameworks simultaneously report several different biophysical and socioeconomic attributes, which provides more information on potential trade-offs and synergies and can engage with emerging concepts of well-being. {1.4.1.1; 1.4.1.2}

The concepts of enablers, catalysts and the solution space help AR6 assess ways to speed the implementation and expand the range of adaptation solutions. Many potential solutions have not yet been implemented, despite the gap between current and adequate levels of adaptation. Enablers enhance the feasibility of adaptation options and include governance, finance and knowledge . Catalysts accelerate and motivate the adaptation decision making process. The concept of solution space—defined as the space within which opportunities and constraints determine why, how, when and who adapts to climate risks—helps this in assessing how human choices and exogenous changes can expand and contract the set of effective, feasible and just solutions. {1.4.2}

Effective governance, adaptation finance and nature-based solutions are important enablers for expanding the solutions space and reducing adaptation gaps (high confidence). Actors at many scales and in many sectors are already adapting, and can take additional and more significant adaptation action. These actors include individuals and households, communities, governments at all levels, private sector businesses, non-governmental organisations, religious groups and social movements. Many forms of adaptation (depending on the type of climatic risk and societal context) are likely to be more effective, cost-efficient and potentially also more equitable when organised collectively. Stronger governance and adaptation finance capabilities are usually associated with more ambitious adaptation plans and more effective implementation of such plans. {1.4.2; 1.5.2}

Monitoring and evaluation (M&E) of adaptation refers to a broad range of activities necessary for tracking adaptation progress over time, improving adaptation effectiveness and successful iterative risk management. Monitoring usually refers to continuous information gathering, whereas evaluation denotes more comprehensive assessments of effectiveness and equity, often resulting in recommendations for decision makers. In some literatures, M&E refers solely to efforts undertaken after implementation. In other literatures, M&E refers both to efforts conducted before and after implementation. Since AR5, a growing literature provides initial inventories of adaptation plans and implementation worldwide, but information on effectiveness remains scare (high confidence). {1.4.3; Cross-Chapter Box ADAPT in Chapter 1}

The concept of limits to adaptation is dynamic in terms of the temporal, spatial and contextual dimensions of climate change risks, impacts and response. Socioeconomic, technological, governance and institutional systems or policies can be changed or transformed in response to the different dimensions of adaptation limits to climate change and extreme events. Adaptation limits can be soft or hard. Soft adaptation limits occur when options may exist but are currently not available to avoid intolerable risks through adaptive actions. Hard adaptation limits occur when no adaptive actions are possible to avoid intolerable risks. The levels of GHG emissions reduction, adaptation and risk management measures are the key factors determining if and when adaptation limits are reached. When a limit (soft) is reached, then intolerable risks and impacts may occur and additional adaptations (incremental or transformational) would be required. Transformational adaptation can allow a system to extend beyond its soft limits and prevent soft limits from becoming hard limits. The loss and damage associated with the future climate change impacts, beyond the limits to adaptation, is an area of increasing focus. However, it is yet to be fully developed in terms of assessment methods, including non-economic values and identifying means to avoid and reduce both economic (loss of asset, infrastructure, land etc.) and non-economic (loss of societal beliefs and values, cultural heritage, biodiversity and ecosystem services) losses and damages. {1.4.4.1; 1.4.4.2}

Key concepts in this report provide a framework for assessing the urgency of climate change adaptation. Adaptation is urgent to the extent that soft adaptation limits are currently being approached or exceeded and that achieving levels of adaptation adequate to address these soft limits requires action at a speed and scale faster than that represented by current trends (high confidence). In addition, adaptation is urgent to the extent that any needed expansion of the future solution space requires near-term strengthening and expansion of enablers, such as governance, finance and information. {1.1.3; 1.4.4; 1.5.1}

AR6 highlights the role of transformation in meeting the Paris Agreement, the SDGs and other policy goals. Transformation, and the related term transition, are pluralistic concepts, embracing the idea of major, fundamental changes in society or natural systems as opposed to changes that are minor, marginal or incremental. AR6 has a particular focus on transformational adaptation, which changes the fundamental attributes of a socioeconomic system in anticipation of climate change and its impacts. AR6 describes transitions in five systems: energy, land and ecosystems, urban and infrastructure, industrial and societal. In the past, transformations of such scale have been associated not only with technological and economic changes, but also with shifts in most aspects of society. {1.2.1.3; 1.4.4; 1.5.1}

Future transformation could be deliberate, envisioned and intended by at least some societal actors, who seek to expand the solution space, overcome soft limits to adaptation, reduce residual risk to tolerable levels and achieve societal goals. If such a transformation is not pursued or is not successful and risk remains above intolerable levels, a forced transformation may occur that is less consistent with societal goals. The literature describes incremental and transformational change as linked processes. The transformational adaptation literature suggests shifts from incremental to transformational processes are made possible by knowledge and skills, as well adjustments to vision, agendas and coalitions achieved through monitoring and learning. The socio-ecological and sustainability transitions literature suggests that actors seeking deliberate transformation may take incremental steps that aim to induce societal tipping point behaviour in the near or longer term. Alternative pathways for pursuing deliberate transformations range from a focus on modernisation of sectors such as energy, agriculture and the use of natural resources to proposals for degrowth that intentionally aim to decrease both gross domestic product (GDP) and coupled GHG emissions. {1.2.1.3; 1.4.4; 1.5.1}

Transformation is understood as a collective action challenge among actors with both common and differing values interacting with a mix of competition and cooperation. Significant innovations often begin in niches or protected spaces, sometimes introduced by new entrants or outsiders. The drivers of transformation are multi-dimensional, involving social, cultural, economic, environmental, technical and political processes. The combination of these creates the potential for abrupt and systemic change, the stability of entrenched and interlocked power structures, and the importance of individual beliefs and behaviours. Decision frameworks that consider multiple objectives and multiple scenarios can avoid privileging some views over others and help multiple actors to identify resilient and equitable solutions to complex, deeply uncertain challenges. Nonetheless, common goals and narratives are both enablers of transformation and help align the activities of multiple, loosely co-ordinated actors. {1.5.2}

This report employs the climate resilient development concept to inform co-ordinated implementation of adaptation and mitigation solutions to support sustainable development for all. As a transformation that emerges from the choices of many different actors, climate resilient development follows no single or preferred pathway and no single best combination of adaptation, mitigation and sustainable development strategies. All pathways involve complex trade-offs and synergies among different actions. The climate resilient development concept helps assess the extent to which solutions currently exist to meet societal goals or the extent to which an expanded solution space is required. The concept also helps assess the role of various actors, including governments, citizens, civil society, knowledge institutions, media, investors and businesses as well as the need for arenas of engagement in which they can interact. {1.2.3; 1.5.2; 1.5.3}