Editing IPCC:AR6/WGII/Chapter-1 (section)

=== 1.1.3 Adaptation Efforts and Gaps ===

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Adaptation to climate change plays a key role in reducing climate-related risks along with mitigation and sustainable development. From a risk perspective (Section 1.2), emission reductions and carbon removal can both reduce GHG forcing and thus climate-related hazards, while adaptation and sustainable development reduce exposure and vulnerability to those hazards.

Important synergies and trade-offs exist among adaptation and mitigation actions (Section 1.5, Chapter 18). Limiting atmospheric concentrations of GHGs reduces the extent of adaptation needed to keep risk within tolerable levels (Section 1.3, Chapter 16). From a global perspective, understanding adaptation and its limits can inform judgements about the best balance among levels of mitigation and adaptation. Such judgements underlie the mitigation goals of the Paris Agreement. From a more local perspective, there is a wide range of mitigation scenarios (Cross-Chapter Box CLIMATE in Chapter 1), including those which meet or miss the Paris Agreement goals, and overshoot scenarios in which global mean temperature exceed targets for several decades before dropping to desired levels. Such scenarios inform assessments of the level of adaptation that may be required (Section 1.4; Chapter 17).

Adaptation and sustainable development are also interlinked (Section 18.1). Adaptation facilitates development, which is hindered by impacts and risks from climate change. Development facilitates adaptation by expanding the resources and capacity available to manage climate risks. Viewed from a climate justice perspective, some argue that a more just society is more capable of successful adaptation, while others argue that only adaptation that results in a more just society can be judged successful (Section 1.4.1; Chapter 18).

Two concepts—adaptation gaps and limits to adaptation—help frame this report’s assessment of the extent to which current adaptation efforts are adequate to meet societal goals. '''Adaptation gaps''' are defined as ‘the difference between actually implemented adaptation and a societally set goal, determined largely by preferences related to tolerated climate change impacts and reflecting resource limitations and competing priorities’ (UNEP et al., 2021). Limits to adaptation describe the extent to which no plausible level of adaptation can meet societal goals (Section 1.4.4). Within the limits, adaptation gaps can be closed by increased and more successful adaptation actions. Beyond the limits, only mitigation can close adaptation gaps.

Numerous climate-related impacts already cause severe damage in many places and are projected to increase in the future (Chapter 16). Adaptation can reduce these risks, often significantly, but limits to adaptation have already been reached or are being approached in some sectors and regions (Sections 16.3.1; 16.4). While natural systems worldwide are changing in response to climate change, many are not adapting sufficiently quickly to retain their resilience in the face of current and projected future climate change (Section 16.4). For human systems, numerous lines of evidence suggest that in many regions and sectors current infrastructure, settlement patterns, policies, practices and institutions remain inadequate for current changes in climate conditions (Section 16.2). Inadequate or insufficient adaptation to current conditions is called an adaptation deficit.

In response, adaptation efforts have increased significantly since AR5 (Sections 16.3; 17.2; 17.5.2; Cross-Chapter Box ADAPT in Chapter 1). Assessing the adequacy and effectiveness of these efforts as called for in Article 7 of the Paris Agreement remains challenging (Section 1.3.2.2), because much adaptation is not recorded in the literature and because assessment depends on judgements of effectiveness (Section 1.4.1.2), judgements about societal goals including climate justice (Section 1.4.1.1), and expectations about future GHG concentration pathways and other socioeconomic conditions (Section 16.5, Cross-Chapter Box DEEP in Chapter 17).

Knowledge about adaptation has significantly expanded since AR5 (Cross-Chapter Box ADAPT in Chapter 1). While understanding regarding the extent of adaptation gaps remains limited, the available evidence suggests significant adaptation gaps exist ( ''high confidence'' ). Many current adaptation efforts constitute adaptation planning, rather than implementation (Section 16.3). Most current implementation efforts represent incremental as opposed to transformational adaptation despite the proximity to adaptation limits (Sections 17.2; 17.5.2). Some current adaptation efforts are considered maladaptive because they increase some climate-related risks even if they reduce others (Sections 1.4.2.4; 17.5; Chapter 16). Gaps exist in key enablers of adaptation, such as finance (Cross-Chapter Box FINANCE in Chapter 17). Given the long time scales involved with many adaptation actions and the potential to significantly reduce longer-term costs with near-term actions, closing many adaptation gaps requires actions over the next few years by governments, business, civil society and individuals at a scale and speed significantly faster than that represented by current trends.

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'''Box 1.1 | Summary of IPCC AR5 and Special Report findings'''
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The IPCC WGII AR6 builds upon key findings of the IPCC AR5, three subsequent special reports and the simultaneous assessment of the IPCC WGI and WGIII AR6. The findings and assessment approaches adopted across these reports have implications for the point of departure in the WGII AR6. They include the strong recognition of the urgency for climate action, the enhanced focus on risk and the aim to connect the search for near-term climate solutions with longer-term transitions. Headline conclusions of the IPCC AR5 include the following, directly quoted ( [[#IPCC--2014a|IPCC, 2014a]] ):

* Human influence on the climate system is clear.
* Recent climate changes have had widespread impacts on human and natural systems.
* Continued emission of greenhouse gases will cause further warming and long-lasting changes in all components of the climate system, increasing the likelihood of severe, pervasive and irreversible impacts for people and ecosystems.
* Adaptation and mitigation are complementary strategies for reducing and managing the risks of climate change.
* Substantial emissions reductions over the next few decades can reduce climate risks in the 21st century and beyond, increase prospects for effective adaptation, reduce the costs and challenges of mitigation in the longer term and contribute to climate-resilient pathways for sustainable development.
* Effective implementation depends on policies and cooperation at all scales and can be enhanced through integrated responses that link adaptation and mitigation with other societal objectives.

Compared to previous IPCC assessments of impacts, adaptation and vulnerability, the IPCC WGII AR5 assessment highlighted new data for attributing observed climate changes and impacts ( [[#Cramer--2014|Cramer et al., 2014]] ; [[#IPCC--2014c|IPCC, 2014c]] ), a more formal approach to risk ( [[#IPCC--2014c|IPCC, 2014c]] ; [[#Jones--2014|Jones et al., 2014]] ), and an expanded assessment of adaptation ( [[#Chambwera--2014|Chambwera et al., 2014]] ; [[#IPCC--2014c|IPCC, 2014c]] ; [[#Klein--2014a|Klein et al., 2014a]] ; [[#Mimura--2014|Mimura et al., 2014]] ; [[#Noble--2014|Noble et al., 2014]] ).

At the time of the IPCC AR5, very few scientific studies relevant to the impacts of global warming of 1.5°C above pre-industrial levels were available. In 2018, the IPCC concluded a Special Report on the impacts of global warming of 1.5°C levels and related global GHG emission pathways, following an invitation expressed in the Decision text of the Paris Agreement ( [[#UNFCCC--2015a|UNFCCC, 2015a]] ). The report assessed available literature on global warming of 1.5°C and on comparisons between global warming of 1.5°C and 2°C above pre-industrial levels. It also addressed possible pathways for achieving the ambitious goals of the Paris Agreement. Key findings from this report include the following, directly quoted ( [[#IPCC--2018c|IPCC, 2018c]] ):

* Global warming is ''likely'' to reach 1.5°C between 2030 and 2052 if it continues to increase at the current rate.
* Climate-related risks for natural and human systems are higher for global warming of 1.5°C than at present, but lower than at 2°C. Most adaptation needs will be lower for global warming of 1.5°C compared to 2°C.
* In model pathways with no or limited overshoot of 1.5°C, global net anthropogenic CO 2 emissions decline by about 45% from 2010 levels by 2030 (40–60% interquartile range), reaching net zero around 2050 (2045–2055 interquartile range).
* Pathways reflecting current nationally stated mitigation ambitions as submitted under the Paris Agreement would not limit global warming to 1.5°C, even if supplemented by very challenging increases in the scale and ambition of emissions reductions after 2030.

In 2019, a Special Report on the Ocean and Cryosphere in a Changing Climate (SROCC) was published, motivated by the observation that many of the world’s people most exposed to risks caused by climate change live in the mountains or near the coast. Key findings include the following, directly quoted ( [[#IPCC--2019c|IPCC, 2019c]] ):

* Over the last decades, global warming has led to widespread shrinking of the cryosphere and unabated ocean warming with an uptake of more than 90% of the excess heat in the climate system. Marine heatwaves have doubled in frequency since 1982 and the oceans acidify ( ''virtually certain'' ). Global mean sea level is rising, with acceleration in recent decades. Increases in tropical cyclone winds and rainfall exacerbate extreme sea level events and coastal hazards.
* All these trends have impacted ecosystems, food security, water resources, water quality, livelihoods, health and well-being, infrastructure, transportation, tourism and recreation, as well as the culture of human societies, particularly for Indigenous Peoples.
* The Greenland and Antarctic Ice Sheets are projected to lose mass at an increasing rate throughout the 21st century and beyond. Projected ecosystem responses include losses of species habitat and diversity, and degradation of ecosystem functions. Warm-water corals are at high risk already and are projected to transition to very high risk even if global warming is limited to 1.5°C.
* Increased mean and extreme sea level, alongside ocean warming and acidification, are projected to exacerbate risks for human communities in low-lying coastal areas. People with the highest exposure and vulnerability are often those with lowest capacity to respond.
* Services provided by ocean and cryosphere-related ecosystems can be supported by protection, restoration, precautionary ecosystem-based management of renewable resource use, and the reduction of pollution and other stressors.
* Coastal communities face challenging choices in crafting context-specific and integrated responses to sea level rise that balance costs, benefits and trade-offs of available options and that can be adjusted over time.

Also in 2019, IPCC published a Special Report on Climate Change and Land, addressing GHG fluxes in land-based ecosystems, land use and sustainable land management in relation to climate change adaptation and mitigation, desertification, land degradation and food security. Key findings include the following, directly quoted ( [[#IPCC--2019c|IPCC, 2019c]] ):

* Human use directly affects more than 70% of the global, ice-free land surface. Land also plays an important role in the climate system. Climate change has adversely impacted food security and terrestrial ecosystems as well as contributed to desertification and land degradation in many regions. Changes in land conditions, either from land use or climate change, affect global and regional climate.
* Pathways with higher demand for food, feed, and water, more resource-intensive consumption and production, and more limited technological improvements in agriculture yields result in higher risks from water scarcity in drylands, land degradation, and food insecurity. Most of the response options assessed contribute positively to sustainable development and other societal goals. Sustainable land management, including sustainable forest management, can prevent and reduce land degradation, maintain land productivity, and sometimes reverse the adverse impacts of climate change on land degradation. It can also contribute to mitigation and adaptation.
* Response options throughout the food system, from production to consumption, including food loss and waste, can be deployed and scaled up to advance adaptation and mitigation. All assessed modelled pathways that limit warming to 1.5°C or well below 2°C require land-based mitigation and land use change.
* The effectiveness of decision-making and governance is enhanced by the involvement of local stakeholders (particularly those most vulnerable to climate change including Indigenous Peoples and local communities, women, and the poor and marginalised) in policies for land-based climate change adaptation and mitigation.
* Near-term action to address climate change adaptation and mitigation, desertification, land degradation and food security can bring social, ecological, economic and development co-benefits.

In 2021, IPCC Working Group 1 published its Sixth Assessment Report on The Physical Science Basis. Key findings from the report include the following, directly quoted from its Summary for Policymakers (SPM) quoted ( [[#IPCC--2019c|IPCC, 2019c]] ):

* The scale of recent changes across the climate system as a whole and the present state of many aspects of the climate system are unprecedented over many centuries to many thousands of years.
* Global surface temperature will continue to increase until at least the mid-century under all emissions scenarios considered. Global warming of 1.5°C and 2°C will be exceeded during the 21st century unless deep reductions in carbon dioxide and other greenhouse gas emissions occur in the coming decades.
* Many changes due to past and future greenhouse gas emissions are irreversible for centuries to millennia, especially changes in the ocean, ice sheets and global sea level.
* With further global warming, every region is projected to increasingly experience concurrent and multiple changes in climatic impact-drivers. Changes in several climatic impact-drivers would be more widespread at 2°C compared to 1.5°C global warming and even more widespread and/or pronounced for higher warming levels. Low-likelihood outcomes, such as ice sheet collapse, abrupt ocean circulation changes, some compound extreme events and warming substantially larger than the assessed very likely range of future warming cannot be ruled out and are part of risk assessment.
* From a physical science perspective, limiting human-induced global warming to a specific level requires limiting cumulative CO 2 emissions, reaching at least net zero CO 2 emissions, along with strong reductions in other greenhouse gas emissions. Strong, rapid and sustained reductions in emissions would also limit the warming effect resulting from declining aerosol pollution and would improve air quality.

Other assessment processes also inform the IPCC AR6. For example, a recent joint workshop between the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) and IPCC, the first of its kind, made key observations relevant to the work of IPCC WGII AR6 ( [[#Poertner--2021|Pörtner et al., 2021]] ). In this broad context, the workshop explored diverse facets of the interaction between climate and biodiversity, from current trends to the role and implementation of nature-based solutions and the sustainable development of human society. Key highlights of the workshop include the following, directly quoted from the workshop report:

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Box 1.1

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<li>Limiting global warming to ensure a habitable climate and protecting biodiversity are mutually supporting goals, and their achievement is essential for sustainably and equitably providing benefits to people.
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<p>Box 1.1</p>

<li>Several land- and ocean-based actions to protect, sustainably manage and restore ecosystems have co-benefits for climate mitigation, climate adaptation and biodiversity objectives.</li>
<li>Measures narrowly focused on climate mitigation and adaptation can have direct and indirect negative impacts on nature and nature’s contributions to people.</li>
<li>Measures narrowly focusing on protection and restoration of biodiversity have generally important knock-on benefits for climate change mitigation, but those benefits may be sub-optimal compared to measures that account for both biodiversity and climate.</li>
<li>Treating climate, biodiversity and human society as coupled systems is key to successful outcomes from policy interventions.</li>
<li>Transformative change in governance of socio-ecological systems can help create climate and biodiversity resilient development pathways.</li></ul>

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