Editing IPCC:AR6/WGIII/Chapter-17 (section)

=== 17.3.3 Transitions ===

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Transitions will involve multiple sectoral- and cross-sectoral policies. [[#17.3.3|Section 17.3.3]] presents a range of studies and conclusions on the relationship between climate change mitigation goals and meeting the SDGs in order to identify major synergies and trade-offs. The interactions are manifold and complex ( [[#Nilsson--2016|Nilsson et al. 2016]] ; [[#Pradhan--2017|Pradhan et al. 2017]] ) ( [[IPCC:Wg3:Chapter:Chapter-4#4.3.1.2|Section 4.3.1.2]] ). Here we draw on conclusions from sectoral chapters and add additional studies as a basis for drawing more general conclusions about agriculture, food and land use, the water-energy-food nexus, industry, cities, infrastructure and transportation, cross-sectoral digitalisation, and mitigation and adaptation relations.

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==== 17.3.3.1 Forestry and Other Land Uses (AFOLU) ====

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Sustainable development and mitigation policies are closely linked in the agriculture, food and land-use sectors. We assess synergies and trade-offs between meeting the SDGs and reducing GHG emissions within the sectors based on modelling studies and case studies illustrating how trade-offs between SDG 2 (zero hunger, biomass for energy) and SDG 15 (life on land) can be addressed by cross-sectoral mitigation options.

[[IPCC:Wg3:Chapter:Chapter-7|Chapter 7]] emphasises the high expectations on land to deliver mitigation, yet the pressures on land have grown with population, dietary changes, the impacts of climate change and the conversion of uncultivated land to agriculture and other land uses. Agriculture, forestry and other land uses (AFOLU) are expected to play a vital role in the portfolio of mitigation options across all sectors. The AFOLU sector is also the only one in which it is currently feasible to achieve carbon dioxide removal (CDR) from the atmosphere, including afforestarion/reforestation (A/R), improved forest management and soil carbon sequestration (SCR) (Chapters 7 and 12). The AFOLU sector has a significant mitigation potential, with many scenarios showing a shift to net-negative CO 2 emissions during the 21st century. Total cumulative AFOLU CO 2 sequestration varies widely across scenarios, with as much as 415 GtCO 2 being sequestered between 2010 and 2100 in the most stringent mitigation scenarios. The largest share of net-GHG emissions reductions from AFOLU in both the 1.5°C and 2°C scenarios is from forestry-related measures, such as afforestation, reforestation and reduced deforestation. Afforestation, reforestation and forest management result in substantial CDR in many scenarios. CO 2 and CH 4 show larger and more rapid declines than N 2 O, an indication of the difficulties of reducing N 2 O emissions in agriculture (Chapter 3).

The Global Assessment on Biodiversity and Ecosystem Services Report ( [[#IPBES--2019|IPBES 2019]] , Chapter 5) assessed the relationship between meeting the goals of the Paris Agreement and SDGs 2 (zero hunger), 7 (affordable and clean energy) and 15 (life on land). It concluded that a large expansion of the amount of land used for bioenergy production would not be compatible with these SDGs. However, combining bioenergy options with other mitigation options, like more efficient land management and the restoration of nature, could contribute to welfare improvements and to accessing food and water. Demand-side climate-mitigation measures, like energy-efficiency improvements, reduced meat consumption and reduced food waste, were considered to be the most economically attractive and efficient options in order to support low GHG emissions, food security and biodiversity objectives. Implementing such options, however, can involve challenges in terms of lifestyle changes ( [[#IPBES--2019|IPBES 2019]] ).

The potential joint contribution of food and land-use systems to sustainable development and climate change has also been addressed in policy programmes by the UN, local governments and the private sector. These programmes address options for pursuing sustainable development and climate change jointly, such as agroforestry, agricultural intensification, better agriculture practices and avoided deforestation. ( [[#Griggs--2013|Griggs and Stafford-Smith 2013]] ) assess production- and consumption-based methods of achieving joint sustainability and climate-change mitigation in food systems, concluding that efficiency improvements in agricultural production systems can provide large benefits. Given the expectations of high levels of population growth and the strong increase in the demand for meat and dairy products, there is also a need for the careful management of dietary changes, as well for those areas which could be used most effectively for livestock and plant production.

Loss of biodiversity has been highlighted in several studies as a major trade-off of the low stabilisation scenarios ( [[#Prudhomme--2020|Prudhomme et al. 2020]] ). A wide range of mitigation and adaptation responses – for example, preserving natural ecosystems such as peatland, coastal lands and forests, reducing the competition for land, fire management, soil management and most risk-management options – have the potential to make positive contributions to sustainable development, ecosystems services and other social goals ( [[#McElwee--2020|McElwee et al. 2020]] ). ( [[#Smith--2019a|]] [[#Smith--2019|Smith et al. 2019]] a ) also stressed that agricultural practices (e.g., improving yields, agroforestry), forest conservation (e.g., afforestation, reforestation), soil carbon sequestration (e.g., biochar addition to soils) and the removal of carbon dioxide (e.g., BECCS) could contribute to climate change mitigation ( [[#Smith--2019a|]] [[#Smith--2019|Smith et al. 2019]] a ). However, there are also options that could improve biodiversity if they were implemented jointly with climate change mitigation in AFOLOU. In their study, ( [[#Leclère--2020|Leclère et al. 2020]] ) show that increasing conservation management, restoring degraded land and generalised landscape-level conservation planning could be positive for biodiversity. In general, the ambitious conservation efforts and transformations of food systems are central to an effective post-2020 biodiversity strategy.

The IPCC Special Report on Climate Change and Land ( [[#IPCC--2019|IPCC 2019]] ) emphasises the need for governance in order to avoid conflict between sustainable development and land-use management. It states: ‘Measuring progress towards goals is important in decision-making and adaptive governance to create common understanding and advance policy effectiveness’. The report concludes that measurable indicators are very useful in linking land-use policies, the NDCs and the SDGs.

One example of an area where special governance efforts have been called for is the protection of forestry, ecosystem services and local livelihoods in a context of the large-scale deployment of high-value crops like palm oil, short-term, high income-generating activities and sustainable development. Serious challenges are already being seen within these areas according to ( [[#IPBES--2019|IPBES 2019]] ).

Palm oil is one example of a product with potentially major trade-offs between meeting the SDGs and climate change mitigation in the agriculture, forest and other land uses (AFOLU) sector. Currently the area under oil palms is showing a tremendous increase, mostly in forest conversions to oil-palm plantations ( [[#Austin--2019|Austin et al. 2019]] ; [[#Gaveau--2016|Gaveau et al. 2016]] ; [[#Schoneveld--2019|Schoneveld et al. 2019]] ). The conversion of peat swamp forest and mineral forest to oil palms will yield different amounts of CO 2 . A study by ( [[#Novita--2020|Novita et al. 2020]] ) shows that the carbon stock of primary peat-swamp forest was 1770 MgC ha –1 compared to a carbon stock of oil palm of 759 MgC ha –1 . The study conducted by Guillaume et al. shows that the carbon stock in mineral soils was 284 MgC ha –1 compared to that in rainforest, which was 110.76 Mg C ha –1 ( [[#Guillaume--2018|Guillaume et al. 2018]] ).

Restoring peatlands is one of the most promising strategies for achieving nature-based CDR ( [[#Girardin--2021|Girardin et al. 2021]] ; [[#Seddon--2021|Seddon et al. 2021]] ). A study by ( [[#Novita--2021|Novita et al. 2021]] ) shows that significantly different CO 2 emissions for different land-use categories are influenced more by the water-table depth and latitude position for those locations relative to other observed parameters, such as bulk density, air temperature and rainfall.

Given that the frequent peatland fires in Indonesia were caused by land clearances in the replanting season, multi-stakeholder collaboration between oil-palm plantations, local communities and local governments over practices such as zero burning when clearing land might be one of the most effective ways to reduce the deforestation impact of oil palm ( [[#Jupesta--2020|Jupesta et al. 2020]] ). Behavioural changes as a mitigation option have been suggested as a major factor in aligning sustainable development, climate change and land management. In the absence of the policy intervention, the expansion of oil-palm plantations has provided limited benefits to indigenous and Afro-descended communities. Even when oil-palm expansion improves rural livelihoods, the benefits are unevenly distributed across the rural population ( [[#Andrianto--2019|Andrianto et al. 2019]] ; [[#Castellanos-Navarrete--2021|Castellanos-Navarrete et al. 2021]] ). In any case, while oil-palm production can improve smallholders’ livelihoods in certain circumstances, this sector offers limited opportunities for agricultural labourers, especially women ( [[#Castellanos-Navarrete--2019|Castellanos-Navarrete et al. 2019]] ).

Economy-wide mitigation costs can be effectively limited by lifestyle, technology and policy choices, as well as benefitting from synergies with the SDGs. Synergies come from the consumption side ''by'' managing demand. For example, reducing food waste leads to resources being saved because water, land use, energy consumption and greenhouse gas emissions are all reduced (Chapter 3).

[[IPCC:Wg3:Chapter:Chapter-12|Chapter 12]] emphasised that diets high in plant protein and low in meat, in particular red meat, are associated with lower GHG emissions. Emerging food-chain technologies such as microbial, plant, or insect-based protein promise substantial reductions in direct GHG emissions from food production. The full mitigation potential of such technologies can only be realised in low-GHG energy systems.

( [[#Springmann--2018|Springmann et al. 2018]] ) conclude that reductions in food waste could be a very important option for reducing agricultural GHG emissions, the demand for agricultural land and water, and nitrogen and phosphorous applications. In addition to the possibility to reduce food waste, their study analysed several other options for reducing the environmental effects of the food system, including dietary changes in the direction of healthier, more plant-based diets and improvements in technologies and management. It was concluded that, relative to a baseline scenario for 2050, dietary changes in the direction of healthier diets could reduce GHG emissions by 29% and 5–9% respectively in a dietary-guideline scenario, and by 56% and 6–22% respectively in a more plant-based diet scenario. Demand-side, service-oriented solutions vary between and within countries and regions, according to living conditions and context. Avoiding food waste reduces GHG emissions substantially. Dietary shifts to plant-based nutrition lead to healthier lives and reduce GHG emissions ( [[IPCC:Wg3:Chapter:Chapter-5#5.3|Section 5.3]] ).

A similar study also found a positive impact form zero food waste. The ‘no food waste’ scenario could decrease global average food calorie availability by 120 kcal person −1 d –1 and protein availability by 4.6 g protein person −1 d −1 relative to their baseline levels, thus reducing required crop and livestock production by 490 and 190 Mt respectively. This lower level of production reduces agricultural land use by 57 Mha and thus mitigates the associated side effects on the environment. The lower levels of production also reduce the requirements for fertilisers and water by 10 Mt and 110 km 3 respectively, and GHG emissions are reduced by 410 MtCO 2 -eq yr –1 relative to the 2030 baseline. Reducing food waste can contribute to lessening the demand for food, feed and other resources such as water and nitrogen, reducing the pressure on land and the environment while ending hunger ( [[#Hasegawa--2019|Hasegawa et al. 2019]] ).

In 2007, Britain launched a nationwide initiative to reduce household food waste, which achieved a 21% reduction within five years ( [[#FAO--2019|FAO 2019]] ). The basis of this initiative was the ‘Love Food, Hate Waste’ radio, TV, print and online media campaign run by a non-profit organisation, the Waste and Resources Action Programme (WRAP). The campaign raised awareness among consumers about how much food they waste, how it affects their household budgets and what they can do about it. This initiative collaborated with food manufacturers and retailers to stimulate innovation, such as resealable packaging, shared meal-planning and food-storage tips. The total implementation costs during the five-year period were estimated at GBP26 million, from which it was households that derived the most benefit, estimated to be worth GBP6.5 billion. Local authorities also realised a substantial GBP86 million worth of savings in food-waste disposal costs. As for the private sector, the benefits took the form of increased product shelf lives and reduced product loss. While households started to consume more efficiently and companies may have experienced a decline in food sales, the latter also stated that the non-financial benefits, such as strengthened consumer relationships, had offset the costs.

The Asia Pacific Economic Cooperation (APEC) group of countries has also created several types of public-private partnership to tackle food waste and reduce losses. Most of these partnerships are focused on food-waste recycling in both developed and developing countries ( [[#Rogelj--2018|Rogelj et al. 2018]] ). APEC members stated that knowledge-sharing and improved policy and project management were the most important advantages of public-private partnerships.

The inextricably intertwined factors in decision-making are influenced by the characteristics of the person, in interaction with the characteristics of more sustainable practices and products, which interact with a particular context that includes the immediate environment (e.g., household, farm), the indirect environment (e.g., community) and macro-environmental factors (e.g., the political, financial and economic contexts) ( [[#Hoek--2021|Hoek et al. 2021]] ). Hence, to influence people to make decisions in favour of sustainable food production or consumption, a wider perspective is needed on decision-making processes and behavioural change, in which individuals are not targeted in isolation, but in interaction with this wider systemic environment.

In conclusion, the AFOLU sector offers many low-cost mitigation options, which, however, can also create trade-offs between land use for food, energy, forest and biodiversity. Some options can help to mitigate such trade-offs, like agricultural practices (e.g., improved yields, agroforestry), forest conservation (e.g., afforestation, reforestation), soil carbon sequestration (e.g., biochar addition to soils) and the removal of carbon dioxide (e.g., BECCS), which could contribute to climate change mitigation. Lifestyle changes, including dietary changes and reduced food waste, are tightly embedded in modes of behaviour that are influenced by the immediate environment (e.g., household, farm), the indirect environment (e.g., community) and macro-environmental factors (e.g., political, financial and economic contexts). Achieving zero food waste could reduce the demands for land (SDG 15), water use (SDG 6) and chemical fertilisers (SDG 9), leading to GHG emissions reductions (SDG 13) by encouraging sustainable consumption and production practices (SDG 12).

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==== 17.3.3.2 Water-Energy-Food Nexus ====

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This section addresses the links between water, energy and food in the context of sustainable development and the associated synergies and trade-offs, with links to related chapters. The focus outline includes scoping and the relationship with the SDGs, general climate change impacts on global water resources, energy-system impacts and the relationship to renewables, enabling strategies, trade-offs and cross-sectoral implications (see also Chapter 12), nexus-management tools and strategies, and a box with examples from India and South Africa.

The continually increasing pressures on natural resources, such as land and water, due to the rising demands from increases in population and living standards, which also require more energy, emphasises the need to integrate sustainable planning and exploitation ( [[#Bleischwitz--2018|Bleischwitz et al. 2018]] ).

The water-energy-food nexus (WEFN) is at the epicentre of these challenges, which are of global relevance and are the focus of policies and planning at all levels and sectors of global society. The nexus between water, energy and food (Zhang et al. 2018) is tight and complex, and needs careful attention and deciphering across spatio-temporal scales, sectors and interests to balance proper management and trade-offs and to pursue sustainable development ( [[#Biggs--2015|Biggs et al. 2015]] ; [[#Dai--2018|Dai et al. 2018]] ; [[#Hamiche--2016|Hamiche et al. 2016]] ). The WEFN touches upon the majority of the UN’s SDGs, such as SDG 2, SDG 6, SDG 7 and SDGs 11–15 ( [[#Bleischwitz--2018|Bleischwitz et al. 2018]] ), and deals with basic commodities, thus guaranteeing the basic livelihoods of the global population.

The task of gaining an improved understanding of WEFN processes across disciplines such as the natural sciences, economics, the social sciences and politics has been further exacerbated by climate change, population growth and resource depletion. In light of the system of interlinkages involved, the WEFN concept essentially also covers land ( [[#Ringler--2013|Ringler et al. 2013]] ) and climate ( [[#Brouwer--2018|Brouwer et al. 2018]] ; [[#Sušnik--2018|Sušnik et al. 2018]] ), and can be further assessed in light of the relevant economic, ecological, social and SDG aspects ( [[#Fan--2019a|Fan et al. 2019a]] ). The nexus approach was introduced in the early 2010s, when it was argued that advantages could be gained by adopting a nexus approach with regard to cross-sectoral and human–nature dependencies and by taking externalities into account ( [[#Hoffmann--2011|Hoffmann 2011]] ). Hence, within the nexus, obvious trade-offs exist with competing interests, such as water availability versus food production.

Climate change is projected to impact on the distribution, magnitude and variability of global water resources. A yearly increase in precipitation of 7% globally is expected by 2100 in a high-emissions scenario (RCP8.5), although with significant inter-model, inter-regional and inter-temporal differences ( [[#Giorgi--2019|Giorgi et al. 2019]] ). Similarly, extreme events related to the water balance, such as droughts and extreme precipitation, are projected to shift in the future (RCP4.5) towards 2100: for example, the number of consecutive dry days is projected to increase in the Mediterranean region, southern Africa, Australia and the Amazon ( [[#Chen--2014|Chen et al. 2014]] ). In impact terms, an increase of 20–30% in global water use is expected by 2050 due to the industrial and domestic demand for water. Already 4 billion people experience severe water scarcity for at least one month per year ( [[#WWAP-UNESCO--2019|WWAP-UNESCO 2019]] ).

Globally, climate change has been shown to cause increases of 4%, 8% and 10% in the share of population being exposed to water scarcities under the 1.5°C, 2°C and 3°C scenarios for global warming respectively (RCP8.5) ( [[#Koutroulis--2019|Koutroulis et al. 2019]] ). At the same time, climate change is projected to cause a general increase in extreme events and climate variability, placing a substantial burden on society and the economy ( [[#Hall--2014|Hall et al. 2014]] ). Other than the human influence on the global hydro-climate, human activities have been shown to surpass even the impact of climate change in low to moderate emission scenarios of the water balance ( [[#Haddeland--2014|Haddeland et al. 2014]] ). Similar conclusions have been found by ( [[#Destouni--2013|Destouni et al. 2013]] ; [[#Koutroulis--2019|Koutroulis et al. 2019]] ).

An obvious consequence of the impact of climate change on future hydro-climatic patterns is the fact that the energy system is projected to experience vast impacts through climate change ( [[#Fricko--2016|Fricko et al. 2016]] ; Van Vliet et al. 2016a; [[#van%20Vliet--2016b|van Vliet et al. 2016b]] ) (Chapter 6). In the short run, where fossil fuel sources make up a significant share of the global energy grid, climate impacts related to water availability and water temperatures will affect thermoelectric power generation, which relies mainly on water cooling ( [[#Larsen--2019|Larsen and Drews 2019]] ; [[#Pan--2018|Pan et al. 2018]] ); water is also used for pollution and dust control, cleaning, and so on ( [[#Larsen--2019|Larsen et al. 2019]] ). Currently, 98% of electricity generation relies on thermoelectric power (81%) and hydropower (17%) ( [[#van%20Vliet--2016a|van Vliet et al. 2016a]] ).

Of these thermoelectric sources, the vast majority employ substantial amounts of water for cooling purposes, although there is a trend currently towards implementing more hybrid or drier forms of cooling ( [[#Larsen--2019|Larsen et al. 2019]] ).

The renewable-energy conversion technologies that are currently dominant globally and are projected to remain so are less vulnerable to water deficiencies than fossil-based technologies, since no cooling is used. These renewable-energy conversion sources include, for example, wind, solar PV and wave energy. The implementation of such sources will, in the longer run, have the potential to reduce water usage by the energy sector substantially ( [[#Lohrmann--2019|Lohrmann et al. 2019]] ). Also, an increasing share of renewables within desalination, as well as improved irrigation efficiencies, have been shown to potentially improve the inter-sectorial WEFN water balance ( [[#Lohrmann--2019|Lohrmann et al. 2019]] ; [[#Caldera--2020|Caldera and Breyer 2020]] ). Some less dominant renewable-energy technologies do use water for cooling, such as geothermal energy and concentrating solar power (CSP), if wet cooling is employed. Despite the general detachment from water resources, wind and solar PV, for example, are highly dependent on climate change patterns, including variability depending on future energy-storage capacities and on-/off-grid solutions ( [[#Schlott--2018|Schlott et al. 2018]] ). Furthermore, regardless of whether or not they are based on renewables, climate change will affect energy usage across sectors, such as heating and cooling in the building stock. The energy systems in question need to be able to handle variations and extremes in demand ( [[#Larsen--2020|Larsen et al. 2020]] ).

For the 2080s compared to 1971–2000, an increase of 2.4% to 6.3% in the global gross hydropower potential, from the hydrological side alone, is seen across all scenarios ( [[#van%20Vliet--2016a|van Vliet et al. 2016a]] ) (Chapter 6). Alongside the global increase in hydropower potential, the global mean water-discharge cooling capacity, which also relates to water temperatures, experiences a decrease of 4.5% to 15% across the scenarios. In very general and global terms, when combined, these changes support the shift towards sources of renewable energy, including hydropower, in the energy mix. When it comes to ensuring stability in the management of the electricity grid, hydro-climatological extremes have the potential to pose vast difficulties in certain regions and/or seasons depending on the nature of the energy mix (Van Vliet et al. 2016c). Van Vliet et al. (2016b) showed significant reductions in both thermoelectric and hydropower electricity capacities, exemplified by the 2003 European drought, which resulted in reductions of 4.7% and 6.6%, respectively.

The energy sector is vulnerable to production losses caused mainly by heatwaves and droughts, whereas coastal and fluvial floods are also responsible for a large relative share of the energy sector’s vulnerability, as assessed by ( [[#Forzieri--2018|Forzieri et al. 2018]] ) for Europe in 2100. In total, heatwaves and droughts will be responsible for 94% of the damage costs to the European energy system compared to 40% today. Similarly, ( [[#Craig--2018|Craig et al. 2018]] ) show that, despite potentially minor spatio-temporally aggregated differences for various energy-system components, such as demand, thermoelectric power, wind, and so on, the aggregated impact of climate change across these components will cause a significant impact on the energy system, as currently exemplified by the USA. In terms of investments and management, it is important to unravel these cross-component relations in light of the projected nature of the future climate.

In the ongoing transition towards renewable sources of energy (see also Chapters 3, 4 and 6), the impact of the hydro-climate on energy production continues to be highly relevant ( [[#Jones--2016|Jones and Warner 2016]] ). As the shares of thermoelectric energy production in the energy grid go down along with the introduction of thermoelectric cooling technologies using smaller amounts of water, new energy sources and technologies are being introduced, and existing sources scaled up. Of these, hydropower, wind and solar energy are the key energy sources currently and will be in the near future, making up 2.5% and 1.8% of the total global primary energy supply in 2017 respectively ( [[#IEA--2019|IEA 2019]] ). Wind and solar energy are directly independent of water in themselves, but are dependent on atmospheric conditions related to processes that also drive the water balance and circulation. Hydropower, on the other hand, is directly influenced by and dependent on the supply of water, while at the same time being an essential counter-component to seasonality and climatological variation, as well as to current and future demand curves and diurnal variations, as against wind and solar energy ( [[#De%20Barbosa--2017|De Barbosa et al. 2017]] ).

Furthermore, policy instruments in power-system management, here exemplified by hydropower in a climate-change scenario, have been shown to enhance energy production during droughts ( [[#Gjorgiev--2018|Gjorgiev and Sansavini 2018]] ). The significant influence of variation in the planning of renewable energy for the 21st century has also been highlighted by ( [[#Bloomfield--2016|Bloomfield et al. 2016]] ). At the same time, the integration of renewables must account for lower thermoelectric efficiencies and capacities due to increases in temperature ( [[#van%20Vliet--2016a|van Vliet et al. 2016a]] ), power-plant closures during extreme weather events due to a lack of cooling capacity ( [[#Forzieri--2018|Forzieri et al. 2018]] ), and further efficiency reductions and penalties following the implementation of CCS technologies in the effort to reach the GHG mitigation targets ( [[#Byers--2015|Byers et al. 2015]] ). However, more recent studies find more promising amounts of water being used for energy conversion ( [[#IEAGHG--2020|IEAGHG 2020]] ; [[#Magneschi--2017|Magneschi et al. 2017]] ).

The extraction, distribution and wastewater processes of anthropogenic water-management systems similarly use vast amounts of energy, making the proper management of water essential to reduce energy usage and GHG emissions ( [[#Nair--2014|Nair et al. 2014]] )Chapter 11). One study reports that the water sector accounts for 5% of total US GHG emissions ( [[#Rothausen--2011|Rothausen and Conway 2011]] ). Within the WEFN, there is an obvious trade-off between water availability and food production, competing demands that pose a risk to the supply of the basic commodities of food, energy and water in line with the SDGs ( [[#Bleischwitz--2018|Bleischwitz et al. 2018]] ; [[#Gao--2019|Gao et al. 2019]] ), all of which have the potential for inter-sectorial or inter-regional conflicts ( [[#Froese--2019|Froese and Schilling 2019]] ). Currently, 24% of the global population live in regions with constant water-scarce food production, and 19% experience occasional water scarcities ( [[#Kummu--2014|Kummu et al. 2014]] ). To counterbalance the demand for food and comestibles in regions that experience constant or intermittent supplies, transportation is needed, which in itself requires suitable infrastructure, energy supplies, a well-functioning trading environment and support policies. Of the 2.6 billion people who experience constant or occasional water scarcities in food production, 55% rely on international trade, 21% on domestic trade and the remainder on water stocks ( [[#Kummu--2014|Kummu et al. 2014]] ).

The relations between the influence of hydro-climatic variability, socio-economic conditions and patterns of water scarcity have been addressed by ( [[#Veldkamp--2015|Veldkamp et al. 2015]] ). A key finding of this study was the ability of the hydro-climate and the socio-economy to interact, enforcing or attenuating each other, though with the former acting as the key immediate driver, and the influence of the latter emerging after six to ten years.

The trade-offs between competing demands have been investigated on a continental scale in the US Great Plains, highlighting the influence of irrigation in mitigating reductions in crop yields (Zhang et al. 2018). Despite crop-yield reductions of 50% in dry years compared to wet years, a key conclusion was that the irrigation should be counterbalanced against general water and energy savings within the context of trade-offs. In East Asia, the WEFN has been quantified, highlighting obvious trade-offs between economic growth, environmental issues and food security (White et al. 2018). This same study also highlights the concept of a virtual WEFN that includes water embodied within products that are traded and shipped. ( [[#Liu--2019|Liu et al. 2019]] ) find an urgent need for proper assessment methods, including of trade within the WEFN, due to the significant resource allocations.

Within the WEFN, the implementation of policies to achieve low stabilisation targets is strongly linked to sustainable development within the water sector with regard to water management and water conservation, indicating that additional coherence in policies affecting the water, energy and food sectors (among others) will be critical in achieving the SDGs (Chapter 7). Subsidised fertilisers, energy and crops can drive unsustainable levels of water usage and pollution in agriculture. More than half the world’s population, roughly 4.3 billion people in 2016, live in areas where the demand for water resources outstrips sustainable supplies for at least part of the year. Irrigated agriculture is already using around 70% of the available freshwater, and the large seasonal variations in water supply and the needs of different crops can create conflicts between water needs across sectors at different time scales ( [[#Wada--2016|Wada et al. 2016]] ). However, as there is little potential for increasing irrigation or expanding cropland ( [[#Steffen--2015|Steffen et al. 2015]] ), gaps in food production gaps must be closed by increasing productivity and cropping densities on currently harvested land by increasing either rain-fed yields or water-use efficiency ( [[#Alexandratos--2012|Alexandratos and Bruinsma 2012]] ).

It has been argued that applying an integrated approach to water-energy-climate-food resource management and policymaking is highly beneficial in properly addressing the co-benefits and trade-offs ( [[#Brouwer--2018|Brouwer et al. 2018]] ; [[#Howells--2013|Howells et al. 2013]] ), accommodating the SDGs ( [[#Rasul--2016|Rasul 2016]] ) and, in general, assessing enabling strategies to improve resource efficiency ( [[#Dai--2018|Dai et al. 2018]] ). For an integrated approach to analysing the WEFN, a number of modelling approaches, tools and frameworks have been proposed ( [[#Brouwer--2018|Brouwer et al. 2018]] ; [[#de%20Strasser--2016|de Strasser et al. 2016]] ; [[#Gao--2019|Gao et al. 2019]] ; [[#Larsen--2019|Larsen et al. 2019]] ; [[#Smajgl--2016|Smajgl et al. 2016]] ), often involving multi-objective calibration. Such tools enable decision-makers to evaluate the optimal water-allocation and energy-saving solutions for the specific geography in question. As an example, ( [[#Scott--2011|Scott 2011]] ) found the higher transportability of electricity, compared to water, pivotal in water-energy adaptation solutions in the USA, while arguing for the additional coordination of water and energy policies as a key instrument in balancing the trade-offs.

Common to all these integrated efforts is the challenge involved in making comparisons across studies due to the combined complexities of assumptions, model codes, regions, variables, forcings, and so on. To accommodate these challenges, ( [[#Larsen--2019|Larsen et al. 2019]] ) suggest employing shared criteria and forcing data to enable cross-model comparisons and uncertainty estimates, as also highlighted by ( [[#Brouwer--2018|Brouwer et al. 2018]] ). Other limitations in current WEFN research are partial system descriptions, the failure to address uncertainties, system boundaries, and evaluation methods and metrics (Zhang et al. 2018). The lack of proper access to WEFN data and data quality has been highlighted by ( [[#D’Odorico--2018|D’Odorico et al. 2018]] ; [[#Larsen--2019|Larsen et al. 2019]] ). Furthermore, gaps have been identified between theory and end-user applications in the lack of any focus on food nutritional values as opposed to calories alone, in the understanding of water availability in relation to management practices, in integrating new energy technologies and in the resulting environmental issues ( [[#D’Odorico--2018|D’Odorico et al. 2018]] ).

Therefore, looking ahead, future fields of WEFN research should provide greater insights into all these aspects. Holistic frameworks have been put forward to facilitate methods of WEFN management by focusing on, for example, the geographical complexities with regard to transboundary challenges within hydrological catchments ( [[#de%20Strasser--2016|de Strasser et al. 2016]] ), aligning policy incentives ( [[#Rasul--2016|Rasul 2016]] ) and making synergies and trade-offs in relation to WEFN SDG targets ( [[#Fader--2018|Fader et al. 2018]] ), and so on. The roles of all levels of government in optimal WEFN management are also highlighted in ( [[#Kurian--2017|Kurian 2017]] ), especially with regard to shaping the behaviour of individuals. Furthermore, ( [[#Kurian--2017|Kurian 2017]] ) highlights the challenges involved in science and policy communicating with one another and in the provision of optimal instruments and guidelines. Engaging non-experts and end-users in scientific processes is seen as essential to capturing previous failures and successes, and to ensure that understanding the challenges is updated to help shape the research questions.

Coordination of water use across different sectors and deltas is an important factor in sustainable water management. Examples of instruments and policies that support this from India and Sub-Saharan Africa in relation to the groundwater crisis are given below. India is the world’s largest user of groundwater for irrigation, which covers more than half of the country’s total irrigated agricultural area, is responsible for 70% of food production and supports more than 50% of the population (700 million people) (Chapter 7). However, excessive extraction of groundwater is depleting aquifers across the country, and falls in the water table have become pervasive. Improved water-use efficiency in irrigated agriculture is being considered, both globally and in India, as a way of meeting future food requirements with increasingly scarce water resources ( [[#Fishman--2015|Fishman et al. 2015]] ).

The entirety of Sub-Saharan Africa has an undeveloped potential for groundwater exploitation, despite the general perception of a global groundwater crisis, this being due to the absence of services to support groundwater development ( [[#Cobbing--2020|Cobbing 2020]] ). It is estimated that most Sub-Saharan countries in Africa utilise less than 5% of their national sustainable yields ( [[#Cobbing--2019|Cobbing and Hiller 2019]] ). The initial tool for driving sustainable groundwater exploitation is a change in the narrative of a lack of resources in order to stimulate increased agricultural production and increased fulfilment of the SDGs ( [[#Cobbing--2020|Cobbing 2020]] ). Quantitative measures of actual groundwater vulnerability based on multiple indicators have been calculated by, for example, ( [[#van%20Rooyen--2020|van Rooyen et al. 2020]] ), showing that 20.4% of South Africa’s current water resources are highly vulnerable and are projected to worsen fifty years into the future.

Despite the positive perspectives regarding Sub-Saharan groundwater resources, the 2015–2017 water crisis in South Africa, including in Cape Town, clearly predicts vulnerability to climate variability ( [[#Carvalho%20Resende--2019|Carvalho Resende et al. 2019]] ), which is predicted to increase. Serving as inspiration for the future mitigation of water depletion, ( [[#Olivier--2019|Olivier and Xu 2019]] ) suggest certain governance tools to improve the diversification of water sources and the management of existing supplies.

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<span id="industry"></span>
==== 17.3.3.3 Industry ====

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Industrial transformation is a core component in achieving sustainable development. Across all industrial sectors, the development and deployment of innovative technologies, business models and policy approaches at scale will be essential in accelerating progress both with meeting the economic and social development goals and with achieving low emissions. In this section, we assess the synergies and trade-offs between mitigation options and the SDGs, with a specific focus on asking whether economic growth and employment creation can work jointly with climate actions and other SDGs in least developed and developing countries. Examples of synergies and trade-offs are provided based on the conclusions of [[IPCC:Wg3:Chapter:Chapter-9|Chapter 9]] on the building sector and [[IPCC:Wg3:Chapter:Chapter-11|Chapter 11]] on industry. The potential for greening industry is discussed in relation to eco-industrial parks, with examples from Ethiopia, China, South Africa and Ghana.

[[IPCC:Wg3:Chapter:Chapter-11|Chapter 11]] concludes that achieving net zero emissions from the industrial sector are possible. This will require the provision of electricity free from greenhouse gas (GHG) emissions, including from other energy carriers, increased electrification, low-carbon feedstocks, and a combination of energy efficiency, reduced demand for materials, a more circular economy, electrification and carbon capture, use and storage (CCUS).

The potential co-benefits of mitigation options in industry has been mapped out in [[IPCC:Wg3:Chapter:Chapter-11|Chapter 11]] in relation to five categories of mitigation options: material efficiency and reductions in the demand for materials, the circular economy and industrial waste, carbon capture and storage, energy efficiency, and electrification and fuel switching (Figure 11.15). In particular, the first two categories of options are assessed as having several co-benefits for the SDGs, including SDGs 3, 5, 7, 8, 9 11, 12, and 15. Some studies also point out the potential trade-offs in respect of employment and the costs of cleaner production. The other options primarily impact on climate actions, decent work and employment, and industry as such.

( [[#Okereke--2019|Okereke et al. 2019]] ) offer important generic conclusions on green industrialisation and the transition based on a study of socio-technical transition in Ethiopia. The importance of drivers for changes in terms of clear policy goals and government support for green growth and climate policies, as well as support from a strong culture of innovation, is emphasised. The study also identifies key barriers in relation to stakeholder interactions, the availability of resources and the ongoing tensions between ambitions for high economic growth and climate change. Green innovation in industry critically depends on regulations. ( [[#Gramkow--2018|Gramkow and Anger-Kraavi 2018]] ) have assessed the role of fiscal policies in greening Brazilian industry based on an econometric analysis of 24 manufacturing sectors. They conclude that instruments like low-cost finance for innovation and support to sustainable practices effectively promote green innovation.

( [[#Luken--2019|Luken 2019]] ) have assessed the drivers, barriers and enablers for green industry in Sub-Saharan Africa, concluding that major barriers exist related to material and input costs, as well as product requirements in foreign markets, and that as a result there are trade-offs between economic and environmental performance. Studies of ten countries are reviewed, and although they suffer from limited information, they conclude similarly that further progress is being hindered by poor access to finance and weak government regulation. ( [[#Greenberg--2014|Greenberg and Rogerson 2014]] ). They similarly conclude that the greening of industry in South Africa is lagging behind due to economic barriers and weak governance, despite its high priority in government planning and among international partners.

Ghana has launched a ‘One District One Factory’ (1D1F) initiative, aimed at establishing at least one factory or enterprise in each of Ghana’s 216 districts as a means of creating economic growth poles to accelerate the development of these areas and create jobs for the country’s increasingly youthful population. The policy aims to transform the structure of the economy from one dependent on the production and export of raw materials to a value-added industrialised economy driven primarily by the private sector ( [[#Yaw--2018|Yaw 2018]] ). As has been pointed out by ( [[#Mensah--2021|Mensah et al. 2021]] ), in its initial design the programme did not take environmental quality into consideration. Although it was successful in creating economic growth, exports and employment, the environmental impacts have been negative. It has therefore been recommended that environmental regulations be imposed on foreign investments. Similar conclusions have been drawn by ( [[#Solarin--2017|Solarin et al. 2017]] ).

[[IPCC:Wg3:Chapter:Chapter-11|Chapter 11]] concludes that eco-industrial parks, in which businesses cooperate with each other in order to avoid environmental pressure and support sustainable development, have delivered several benefits in relation to overall reductions in both virgin materials and final wastes, implying significant reductions in industrial GHG emissions. Due to these advantages, eco-industrial parks have been actively promoted, especially in East Asian countries such as China, Japan and in the Republic of Korea (South Korea), where national indicators and governance exist ( [[#Geng--2019|Geng et al. 2019]] ; [[#Geng--2009|Geng and Hengxin 2009]] ).

( [[#Zeng--2020|Zeng et al. 2020]] ) have assessed the role of eco-industrial parks in China’s green transformation for 33 development zones in relation to contributions to GDP, industrial value added, exports, water and energy consumption, CO 2 levels and sulphur emissions. They concluded that industrial parks have played a very important role in China’s industrialisation, and that this structure has supported the decoupling of economic growth and energy and water consumption from the environmental impacts. However, improved environmental performance would require better access to finance and a higher priority by management.

Eco-industrial parks have been promoted in Ethiopia by the government and UNIDO, based on the expectation that they could help to boost the economy ( [[#UNIDO--2018|UNIDO 2018]] ). One of the success stories is an industrial park in Hawassa, a nation-level textile and garment industrial park with a ‘zero emissions commitment’ based on renewable energy and energy-efficient technologies. However, the concept of the industrial park, including feasible policies and institutional arrangements, is new to Ethiopia’s regulatory processes, and this has created problems for management, knowledge and governance, hindering their fast implementation.

A number of business associations have developed strategies for sustainable development and climate change, including corporate social responsibility (CSR). International initiatives have included the promotion of CSR initiatives by international investors in low-income countries to support a broad range of development priorities, including social working conditions, eliminating child labour and climate change ( [[#Lamb--2017|Lamb et al. 2017]] ). ( [[#Leventon--2015|Leventon et al. 2015]] ) evaluated the role of mining industries in Zambia in supporting climate-compatible development and concluded that, although the industry has played a positive role in avoiding migration and pressure on forest resources, there is a lack of coordination between government and industry initiatives.

It can be concluded that most of the mitigation options in industry considered in this section could have synergies with the SDGs, but also that some of the renewable-energy options could indicate some trade-offs in relation to land use, with implications for food- and water security and costs. Carbon capture and storage (CCS) could play an enabling role in the provision of reliable, sustainable and modern energy and could support decarbonisation, but it can also be costly ( [[#IEAGHG--2020|IEAGHG 2020]] ; [[#Mikunda--2021|Mikunda et al. 2021]] ). The provision of water for CCS can include both synergies and trade-offs with the SDGs due to recent progress in water-management technologies ( [[#Giannaris--2020|Giannaris et al. 2020]] ; [[#IEAGHG--2020|IEAGHG 2020]] ; [[#Mikunda--2021|Mikunda et al. 2021]] ).

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<span id="cities-infrastructure-and-transportation"></span>
==== 17.3.3.4 Cities, Infrastructure and Transportation ====

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With 80% of the global population expected to be urban by 2050, cities will shape development paths for the foreseeable future ( [[#United%20Nations--2018|United Nations 2018]] ). The challenge for many policymakers is to construct development paths that make cities clean, prosperous and liveable while mitigating climate change and building resilience to heatwaves, flooding and other climate risks. The IPCC SR1.5 report sees achieving these objectives as feasible: cities could potentially realise significant climate and sustainable-development benefits from shifting development paths ( [[#Wiktorowicz--2018|Wiktorowicz et al. 2018]] ). This section assesses the synergies and trade-offs between meeting the SDGs and climate change mitigation, as well as providing a general overview of mitigation options in cities and of enabling factors, including city networks and plans for jointly addressing the SDGs and climate change mitigation.

[[IPCC:Wg3:Chapter:Chapter-8|Chapter 8]] concludes that urban areas potentially offer several joint benefits between mitigation and the SDGs, and that since AR5, evidence of the co-benefits of urban mitigation continues to grow. In developing countries, a co-benefits approach that frames climate objectives alongside other development benefits arise increasingly being seen as an important concept justifying and driving climate change actions in developing countries ( [[#Sethi--2018|Sethi and Puppum De Oliveria 2018]] ; [[#Seto--2016|Seto et al. 2016]] ).

Evidence of the co-benefits of urban mitigation measures on human health has increased significantly since the IPCC AR5, especially through the use of health-impact assessments in cities like Geneva, where energy savings and cleaner energy-supply structures based on measures for urban planning, heating and transport have reduced CO 2 , NO x and PM 10 emissions and increased the opportunities for physical activity for the prevention of cardiovascular diseases ( [[#Diallo--2016|Diallo et al. 2016]] ).

There is increasing evidence that climate-mitigation measures can lower health risks that are related to energy poverty, especially in vulnerable groups, such as the elderly ( [[#Monforti-Ferrario--2019|Monforti-Ferrario et al. 2019]] ). Moreover, the use of urban forestry and green infrastructure as both a climate mitigation and an adaptation measure can reduce heat stress ( [[#Kim--2019|Kim and Coseo 2019]] ; [[#Privitera--2017|Privitera and La Rosa 2017]] ) while removing air pollutants to improve air quality ( [[#Scholz--2018|Scholz et al. 2018]] ; [[#De%20la%20Sota--2019|De la Sota et al. 2019]] ) and enhancing well-being, including contributions to local development and possible reductions of inequalities ( [[#Lwasa--2015|Lwasa et al. 2015]] ). Other studies evidence the potential to reduce premature mortality by up to 7000 in 53 towns and cities, to create 93,000 net new jobs and lower global climate costs, as well as reduce personal energy costs based on road maps for renewable-energy transformations ( [[#Jacobson--2018|Jacobson et al. 2018]] ).

The co-benefits of energy-saving measures described by 146 signatories to a city climate network due to improved air quality have been quantified as 6596 avoided premature deaths (with a 95% confidence interval of 4356 to 8572 avoided premature deaths) and 68,476 years of life saved (with a 95% confidence interval of 45,403 and 89,358 years of life saved) ( [[#Monforti-Ferrario--2019|Monforti-Ferrario et al. 2019]] ). Better air quality further reinforces the health co-benefits of climate-mitigation measures based on walking and cycling, since the evidence suggests that increased physical activity in urban outdoor settings with low levels of black carbon improves lung function ( [[#Laeremans--2018|Laeremans et al. 2018]] ). [[IPCC:Wg3:Chapter:Chapter-9|Chapter 9]] shows that mitigation actions in buildings have multiple co-benefits resulting in substantial social and economic value beyond their direct impacts on reducing energy consumption and GHG emissions, thus contributing to the achievement of almost all the UN’s SDGs. Most studies agree that the value of these multiple benefits is greater than the value of the energy savings, while their quantification and inclusion in decision-making processes will strengthen the adoption of ambitious reduction targets and improve coordination across policy areas.

There are several examples of cities that have developed plans for meeting both the SDGs and mitigation, which demonstrates the feasibility of meeting these objectives jointly. Quito, Ecuador, a city with large carbon footprints ( [[#Global%20Opportunity%20Explorer--2019|Global Opportunity Explorer 2019]] ) and climate vulnerabilities, has adopted low-carbon plans that aim to achieve the climate goals while introducing net-zero energy buildings and reducing water stress ( [[#Ordoñez--2019|Ordoñez et al. 2019]] ; [[#Marcotullio--2018|Marcotullio et al. 2018]] ). Several cities in China, Indonesia and Japan have invested in green-city initiatives by means of green infrastructural investments, which is claimed to be a form of smart investment. Through this type of investment, economic growth and greenhouse gas (GHG) emissions reductions can be achieved in cities ( [[#Jupesta--2016|Jupesta et al. 2016]] ). Multi-level governance arrangements, public-private cooperation and robust urban-data platforms are among the factors enabling the pursuit of these objectives within countries ( [[#Corfee-Morlot--2009|Corfee-Morlot et al. 2009]] ; [[#Gordon--2015|Gordon 2015]] ; [[#Creutzig--2019|Creutzig et al. 2019]] ; [[#Yarime--2017|Yarime 2017]] ).

In addition to the mostly domestic enablers listed previously, some cities have also benefited from working with international networks. The Global Covenant of Mayors for Climate &amp; Energy ( [[#Covenant%20of%20Mayors--2019|Covenant of Mayors 2019]] ), the World Mayors Council on Climate Change, ECLEI, C40, and UNDRR ( [[#C40%20Cities--2019|C40 Cities 2019]] ; [[#ECLEI--2019|ECLEI 2019]] ; [[#UNDRR--2019|UNDRR 2019]] ) have provided targeted support, disseminated information and tools, and sponsored campaigns (Race to Zero) to motivate cities to embrace climate and sustainability objectives. Despite this support, it should be stressed that most cities are in the early stages of climate planning ( [[#Eisenack--2013|Eisenack and Reckien 2013]] ; [[#Reckien--2018|Reckien et al. 2018]] ; [[#Climate-ADAPT--2019|Climate-ADAPT 2019]] ). Furthermore, in some cases city policymakers may fail to highlight the synergies and trade-offs between climate and sustainable development or rebrand GHG-intensive practices as ‘sustainable’ in relevant plans ( [[#Tozer--2018|Tozer 2018]] ).

With regard to city networks, [[IPCC:Wg3:Chapter:Chapter-8#8.5|Section 8.5]] concludes that the importance of urban-scale policies for sustainability has increasingly been recognised by international organisations and national and regional governments. For example, in 2015, more than 150 national leaders adopted the UN’s 2030 Sustainable Development Agenda, including stand-alone SDG 11 (sustainable cities and communities) (UN 2015 p. 14). The following year, 170 countries agreed to the UN New Urban Agenda (NUA), a central part of which is recognising the importance of national urban policies (NUPs) as a key to achieving national economic, social and environmental goals ( [[#United%20Nations--2015a|United Nations 2015a]] 2017). Similarly, the Sendai Framework for Disaster Risk Reduction identifies the need to focus on unplanned and rapid urbanisation to reduce exposure and vulnerability to the risks of disasters ( [[#United%20Nations--2015b|United Nations 2015b]] ).

For many cities, a key to reorienting development paths will be investing in sustainable, low-carbon infrastructure. Because infrastructure has a long lifetime and influences everything from lifestyle choices to consumption patterns, decisions over an estimated USD90 trillion of infrastructure investment (from now to 2030) will be critical in order to avoid becoming locked-in to unsustainable paths ( [[#WRI--2016|WRI 2016]] ). This is particularly true in developing countries, where demands for new buildings, roads, energy and waste-management systems are already surging. To some extent, policies that accelerate building renovation rates, including voluntary programmes (Van der Heijden 2018), can support transitions down more sustainable paths ( [[#Kuramochi--2018|Kuramochi et al. 2018]] ). Factoring climate and sustainable development considerations into policy tools that facilitate the quantitative emission performance standard (EPS) and the inclusion of climate and sustainable development benefits and risks in infrastructure assessments or risk-adjusted returns on investments in development banks could also prove useful ( [[#Rydge--2015|Rydge et al. 2015]] ). Strong policy signals from the UNFCCC and from national climate policies and strategies (including NDCs) could facilitate uptake of the relevant policies and the use of these tools.

Infrastructural investments will also have wide-ranging implications for sustainable, low-carbon urban development, namely transport and mobility. To some extent, decision-making frameworks such as Avoid-Shift-Improve (ASI) could help make these patterns low carbon and sustainable ( [[#Dalkmann--2007|Dalkmann and Brannigan 2007]] ; [[#Wittneben--2009|Wittneben et al. 2009]] ). Mixed land-use planning and compact cities can not only help avoid emissions or shift travellers into cleaner modes ( [[#Cervero--2009|Cervero 2009]] ), they can also improve air quality, reduce commuting times, enhance energy security and improve connectivity ( [[#Zusman--2011|Zusman et al. 2011]] ; [[#Pathak--2016|Pathak and Shukla 2016]] ).

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<span id="mitigation-adaptation-relations"></span>
==== 17.3.3.5 Mitigation-adaptation Relations ====

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The section will consider the links between mitigation and adaptation options in the context of sustainable development and the associated synergies and trade-offs. Cross-cutting conclusions will be drawn based on [[IPCC:Wg3:Chapter:Chapter-3|Chapter 3]] and the sectoral chapters of AR6 WGIII and Chapter 18 of AR6 WGII. The focus will be on the following sectors: agriculture, food and land use; water-energy-food; industry and the circular economy; and urban areas.

IPCC AR6 WGII, concludes that coherent and integrated policy planning is needed in order to support integrated climate change adaptation and mitigation policies, and that this is a key component of climate-resilient development pathways. [[IPCC:Wg3:Chapter:Chapter-4#4.5|Section 4.5]] .2 assesses development pathways and the specific links between mitigation and adaptation, concluding that there can be co-benefits, and trade-offs, where mitigation implies maladaptation. However, adaptation can also be a prerequisite for mitigation. It is therefore concluded that making development pathways more sustainable can build the capacity for both mitigation and adaptation.

Climate actions, including climate change mitigation and adaptation, are highly scale-dependent, and solutions are very context-specific. Especially in developing countries, a strong link exists between sustainable development, vulnerability and climate risks, as limited economic, social and institutional resources often result in low adaptive capacities and high vulnerability. Similarly, the limitations in resources also constitute key elements weakening the capacity for climate change mitigation ( [[#Jakob--2014|Jakob et al. 2014]] ). The change to climate-resilient societies requires transformational or systemic changes, which also have important implications for the suite of available sustainable-development pathways ( [[#Kates--2012|Kates et al. 2012]] ; [[#Lemos--2013|Lemos et al. 2013]] ). [[#Thornton--2017|Thornton and Comberti (2017)]] point to the need for social-ecological transformations to take place if synergies between mitigation and adaptation are to be captured, based on the argument that incremental adaptation will not be sufficient when climate change impacts can be extreme or rapid and when deep decarbonisation simultaneously involves social change (Chapter 18 in AR6 WGII).

As discussed in AR6 WGII, Section 18.4, there are synergies and trade-offs between adaptation and sustainable development, as well as between mitigation and sustainable development, which is supported by comprehensive assessments such as that by [[#Dovie--2019|Dovie (2019)]] and [[#Sharifi--2020|Sharifi (2020)]] . Links between mitigation and adaptation options are identified in Chapter 18 in AR6 WGII, such as expected changes in energy demand due to climate change interacting with energy-system development and mitigation options, changes to agricultural production practices to manage the risks of potential changes in weather patterns affecting land-based emissions and mitigation strategies, or mitigation strategies that place additional demands on resources and markets. This increases the pressures on and costs of adaptation or ecosystem restoration linked to carbon sequestration and the benefits in terms of the resilience of natural and managed ecosystems, but it also could restrict mitigation options and increase costs. [[IPCC:Wg3:Chapter:Chapter-3|Chapter 3]] of AR6 WGIII similarly concludes that the connectedness and coherence of actions to mitigate climate change could support the conservation and adaptation of ecosystems and meet the Sustainable Development Goals more widely.

Options to reduce agricultural demand (e.g., dietary change, reducing food waste) can have co-benefits for adaptation through reductions in the demand for land and water ( [[#Smith--2019|Smith et al. 2019]] b). For example, [[#Grubler--2018|Grubler et al. (2018)]] show that stringent climate-mitigation pathways without reliance on BECCS can be achieved through efficiency improvements and reduced energy service and consumption levels in high-income countries.

Agriculture, food and land use is the sector where most climate policy options can simultaneously generate impacts on mitigation, adaptation and the SDGs ( [[#Locatelli--2015|Locatelli et al. 2015]] ; [[#Kongsager--2016|Kongsager et al. 2016]] ). [[#Bryan--2013|Bryan et al. (2013)]] identified a range of synergies and trade-offs across adaptation, mitigation and the SDGs in Kenya, given the diversity of its climatic and ecological conditions. Improved management of soil fertility and improved livestock-feeding practices could provide benefits to both climate change mitigation and adaptation, as well as increase income generation from farming. However, other improvements to agricultural management in Kenya, for example, soil water conservation, could only provide benefits across all three domains in some specific sub-regions.

Conservation agriculture can yield mitigation co-benefits through improved fertiliser use or the efficient use of machinery and fossil fuels ( [[#Harvey--2014|Harvey et al. 2014]] ; [[#Pradhan--2018|Pradhan et al. 2018]] ; [[#Cui--2019|Cui et al. 2019]] ). Climate-smart agriculture (CSA) ties mitigation to adaptation through its three pillars of increased productivity, mitigation and adaptation ( [[#Lipper--2014|Lipper et al. 2014]] ), although managing trade-offs among the three pillars requires care ( [[#Kongsager--2016|Kongsager et al. 2016]] ; [[#Thornton--2017|Thornton and Comberti 2017]] ; [[#Soussana--2019|Soussana et al. 2019]] ). Sustainable intensification also complements CSA ( [[#Campbell--2014|Campbell et al. 2014]] ). Enhanced sustainable adaption can lead to effective emission-reduction benefits, such as climate-smart agricultural technologies ( [[#Nefzaoui--2012|Nefzaoui et al. 2012]] ; [[#Poudel--2014|Poudel 2014]] ) and ecosystem-based adaptation. (Berry, P et al. 2015; [[#Geneletti--2016|Geneletti and Zardo 2016]] ; [[#Warmenbol--2018|Warmenbol and Smith 2018]] ) have shown how increases in livelihoods can contribute to climate change mitigation in Europe.

Agroforestry can sustain or increase food production in some systems and increase farmers’ resilience to climate change ( [[#Jones--2013|Jones et al. 2013]] ). Some sustainable agricultural practices have trade-offs, and their implementation can have negative effects on adaptation or other ecosystem services. Agricultural practices can aid both mitigation and adaptation on the ground, but yields may be lower, so there may be a trade-off between resilience to climate change and efficiency. Interconnections within the global agricultural system may also lead to deforestation elsewhere ( [[#Erb--2016|Erb et al. 2016]] ). Implementation of sustainable agriculture can increase or decrease yields, depending on context ( [[#Pretty--2006|Pretty et al. 2006]] ) (Chapter 4).

Land-based mitigation and adaptation will not only help reduce greenhouse gas (GHG) emissions in the AFOLU sector, but also help augment the sector’s role as a carbon sink by increasing forest and tree cover through afforestation and agroforestry activities, and other eco-system-based approaches. Some of these options, however, can also have negative impacts on GHG emissions in the form of indirect impacts on land use (Córdova 2019) (for a more detailed discussion, see Chapter 7). If managed and regulated appropriately, the land use, land-use change and forestry (LULUCF) sector could play a key role in mitigation and be a key sector for emissions reductions beyond 2025 instead of contributing substantially to emissions reductions beyond 2025 ( [[#Córdova--2019|Córdova et al. 2019]] ; [[#Keramidas--2018|Keramidas et al. 2018]] ). However, the large-scale deployment of intensive bioenergy plantations, including monocultures, replacing natural forests and subsistence farmlands are likely to have negative impacts on biodiversity and can threaten food and water security, as well as local livelihoods, partly by intensifying social conflicts, partly by reducing resilience ( [[#Díaz--2019|Díaz et al. 2019]] ). Expansion on to abandoned or unused croplands and pastures nonetheless presents significant global potential, and will avoid the sustainability risks of expanding agriculture into natural vegetation ( [[#Næss--2021|Næss et al. 2021]] ).

Based on a literature review, (Berry, P et al. 2015) identified water-saving and irrigation techniques in agriculture as attractive adaptation options that have positive synergies with mitigation in increasing soil carbon, reducing energy consumption and reducing CH 4 emissions from intermittent rice-paddy irrigation. These measures could, however, reduce water flows in rivers and adversely affect wetlands and biodiversity. The study also concluded that afforestation could reduce peak water flows and increase carbon sequestration, but trade-offs could emerge in relation to the increased demand for water.

Fast-growing tree monocultures or biofuel crops may enhance carbon stocks but reduce downstream water availability and the availability of agricultural land ( [[#Harvey--2014|Harvey et al. 2014]] ). Similarly, in some dry environments, agroforestry can increase competition with crops and pastureland, decreasing productivity and reducing the yields of catchment water ( [[#Schrobback--2011|Schrobback et al. 2011]] ) (Chapter 7).

Hydropower dams are among the low-cost mitigation options, provided the cost of constructing the plant is taken into account, but they could have serious trade-offs in relation to key sustainable-development aspects, since in respect of water and land availability dams can have negative effects on ecosystems and livelihoods, thereby implying increased vulnerabilities. [[#17.3.3.2|Section 17.3.3.2]] on the water-energy-food nexus includes examples of trade-offs between the benefits of producing electricity from hydropower dams and the trade-offs with ecosystem services and using land for agriculture and livelihoods.

There are several potentially strong links between climate change adaptation in industry and climate change mitigation. Various supply chains can be affected by climate change, energy supply and water supply, and other resources can be disrupted by climate events. Adaptation measures can influence GHG emissions in their turn and thus mitigation because of the demand for basic materials, for example, as well as by influencing outdoor environments and labour productivity ( [[IPCC:Wg3:Chapter:Chapter-11#11.1|Section 11.1]] 7.1.4).

Implementing adaptation options in industry can also imply increasing the demand for packaging materials such as plastics and for access to refrigeration. These are among the adaptation options that are dependent on temperature and storage possibilities, as well as being major sources of GHG emissions.

An increasing number of cities are becoming involved in voluntary actions and networks aimed at drawing up integrated plans for sustainable development and climate change mitigation and adaptation, including cities in both high- and low-income countries around the world. ( [[#Grafakos--2019|Grafakos et al. 2019]] ; [[#Sanchez%20Rodriguez--2018|Sanchez Rodriguez et al. 2018]] ) concluded that cities are an obvious place for the development of plans that can capture several synergies between sustainable development and climate-resilient pathways. ( [[#Kim--2019|Kim and Grafakos 2019]] ; [[#Landauer--2019|Landauer et al. 2019]] ) similarly concluded that cities are an obvious platform for the development of integrated planning efforts because of the scale of policies and actions, which could potentially match the different policy domains. ( [[#Kim--2019|Kim and Grafakos 2019]] ) assessed the level of integration of mitigation and adaptation in urban climate change plans across 44 major Latin American cities, concluding that the integration of climate change mitigation and adaption plans was very weak in about half the cities and that limited donor finance was a main barrier. The authors also mention barriers in relation to governance and the weakness or lack of legal frameworks. The integration of SDGs with adaptation could help increase the willingness of politicians to implement climate actions, as well as provide stronger arguments for investing the required resources ( [[#Sanchez%20Rodriguez--2018|Sanchez Rodriguez et al. 2018]] ).

The local integration of planning and policy implementation practices was also examined by ( [[#Newell--2018|Newell et al. 2018]] ) in a study of 11 Canadian communities. It was concluded that, in order to put plans into practice, a deeper understanding needs to be established of the potential synergies and trade-offs between sustainable development and climate change mitigation and adaptation. A model was applied to the evaluation of key impacts, including energy innovation, transportation, the greening of cities and city life. The impact assessment came to the conclusion that multiple benefits, costs and conflicting areas could be involved, and that bringing a broad range of stakeholders into policy implementation was therefore to be recommended.

There are several links between mitigation and adaptation options in the building sector, as pointed out in Chapter 9. Adaptation can increase energy consumption and associated GHG emissions ( [[#Kalvelage--2013|Kalvelage et al. 2013]] ; [[#Campagnolo--2019|Campagnolo and Davide 2019]] ), for example, in relation to the demand for energy to meet indoor thermal comfort requirements in a future warmer climate ( [[#de%20Wilde--2012|de Wilde and Coley 2012]] ; [[#Li--2012|Li and Yao 2012]] ; [[#Clarke--2018|Clarke et al. 2018]] ). Mitigation alternatives using passive approaches may increase resilience to the impacts of climate change on thermal comfort and could reduce cooling needs ( [[#Wan--2012|Wan et al. 2012]] ; [[#Andrić--2019|Andrić et al. 2019]] ). However, climate change may reduce their effectiveness ( [[#Ürge-Vorsatz--2014|Ürge-Vorsatz et al. 2014]] ).

Mitigation and the co-benefits of adaptation in urban areas in relation to air quality, health, green jobs and equality issues are dealt with in [[IPCC:Wg3:Chapter:Chapter-8#8.2|Section 8.2]] , where it is concluded that most mitigation options will have positive impacts on adaptation, with the exception of compact cities, with trade-offs between mitigation and adaptation. This is because decreasing urban sprawl can increase the risks of flooding and heat stress. Detailed mapping between mitigation and adaptation in urban areas shows that there are many, very close interactions between the two policy domains and that coordinated governance across sectors is therefore called for.

Rebuilding and refurbishment after climate hazards can increase energy consumption and GHG emissions in the construction and building materials sectors, as it could make the existing building stock more climate-resilient ( [[#Hallegatte--2009|Hallegatte 2009]] ; [[#de%20Wilde--2012|de Wilde and Coley 2012]] ; [[#Pyke--2012|Pyke et al. 2012]] ) and thus also support implementation of the Sendai Framework on Disaster Risk Reduction ( [[#United%20Nations--2015b|United Nations 2015b]] ). Climate change in the form of extremely high temperatures, intense rainfall leading to flooding, more intense winds and/or storms and sea level rises (SLRs) can seriously impact transport infrastructure, including the operations and mobility of road, rail, shipping and aviation; [[IPCC:Wg3:Chapter:Chapter-10|Chapter 10]] assesses the impacts on subsectors within transportation. At the same time, these sectors are major targets for GHG mitigation options, and many countries are currently examining what to do in terms of combined mitigation-adaptation efforts, using the need to mitigate climate change through transport-related GHG emissions reductions and pollutants as the basis for adaptation action ( [[#Thornbush--2013|Thornbush et al. 2013]] ; [[#Wang--2019|Wang and Chen 2019]] ). For example, urban sprawl indirectly affects climate processes, increasing emissions and vulnerability, which worsens the ability to adapt ( [[#Congedo--2014|Congedo and Munafò 2014]] ). Hence greater use of rail by passengers and freight will reduce the pressures on the roads, while having less urban sprawl will reduce the impacts on new infrastructure, often in more vulnerable areas ( [[#IPCC--2019|IPCC 2019]] ; [[#Newman--2017|Newman et al. 2017]] ).

Despite many links between mitigation and adaptation options, including synergies and trade-offs, [[IPCC:Wg3:Chapter:Chapter-13|Chapter 13]] concludes that there are few frameworks for integrated policy implementation. One review of climate legislation in Europe found a lack of coordination between mitigation and adaptation, their implementation varying according to different national circumstances ( [[#Nachmany--2015|Nachmany et al. 2015]] ).

In developing and least-developed countries (LDCs), there are many examples of climate policies in the NDCs that have been drawn up in the context of sustainable development and that cover both mitigation and adaptation ( [[#Beg--2002|Beg 2002]] ; [[#Duguma--2014|Duguma et al. 2014]] )) (Chapter 13). However, there are many barriers to joint policy implementation. Despite the emphasis on both mitigation and adaptation policies, there is very limited literature on how to design and implement integrated policies ( [[#Di%20Gregorio--2017|Di Gregorio et al. 2017]] ; [[#Shaw--2014|Shaw et al. 2014]] ). For example, the links within the water-energy-food nexus require coordination among sectoral institutions and capacity-building in innovative frameworks linking science, practice and policy at multiple levels (Cook and [[#Chu--2018|Chu 2018]] ; [[#Nakano--2017|Nakano 2017]] ; [[#Shaw--2014|Shaw et al. 2014]] ).

Another challenge is the shortage of financial, technical and human resources for implementing joint adaptation and mitigation policies ( [[#Antwi-Agyei--2018b|Antwi-Agyei et al. 2018b]] ; [[#Chu--2018|Chu 2018]] ; [[#David--2019|David and Venkatachalam 2019]] ; [[#Kedia--2016|Kedia 2016]] ; [[#Satterthwaite--2017|Satterthwaite 2017]] ). Several studies have stressed that the lack of finance for integrating policy implementation between sustainable development and climate change mitigation and adaptation may constitute barriers to the implementation of adaptation projects to protect least-developed countries (LDCs) with many vulnerabilities.

( [[#Locatelli--2016|Locatelli et al. 2016]] ) come to similar conclusions regarding finance based on interviews with multilateral development banks, green funds and government organisations in respect of the agricultural and forestry sectors. International climate finance has been totally dominated by mitigation projects. Those who were interviewed were asked about their willingness to change this balance and to commit more resources to projects that address both climate change mitigation and adaptation. More than two thirds of those interviewed, however, raised concerns that integrated projects could be too complicated and that a greater alignment of financial models across different policy domains could entail greater financial risks. Another barrier mentioned in respect of finance was that mitigation projects were primarily aimed at GHG emissions reductions, while adaptation projects had more national benefits and were also more suitable for community development and promoting equality and fairness. In an assessment of 201 projects in the forestry and agricultural sectors in the tropics, ( [[#Kongsager--2016|Kongsager et al. 2016]] ), found that a majority of the projects contributed to both adaptation and mitigation or at least had the potential to do so, despite the separation between these two objectives by international and national institutions.

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==== 17.3.3.6 Cross-sectoral Digitalisation ====

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In this section, the potential role of digitalisation as a facilitator of a fast transition to sustainable development and low-emission pathways is assessed based on sectoral examples. The contributions of digital technology could contribute to efficiency improvements, cross-sectoral coordination, including new IT services, and decreasing resource use, implying several synergies with the SDGs, as well as trade-offs, for example, in relation to reduced employment, increasing energy demand and the increasing demand for services, possibly increasing GHG emissions.

The COVID-19 pandemic caused radical temporary breaks with past energy-use trends. How post-pandemic recovery will impact on the longer-term energy transition is unclear. Recovering from the pandemic with energy-efficient practices embedded in new patterns of travel, work, consumption and production reduces climate mitigation challenges ( [[#Kikstra--2021|Kikstra et al. 2021]] ). The potential of digital contact tracing to slow the spread of a virus had been quietly explored for over a decade before the COVID-19 pandemic thrust the technology into the spotlight ( [[#Cebrian--2021|Cebrian 2021]] ). The COVID-19 crisis is among the most disruptive events in recent decades and has had consequences for consumer behaviour. During the lockdowns in most countries, consumers have turned to online shopping for food products, personal hygiene and disinfection ( [[#Cruz-Cárdenas--2021|Cruz-Cárdenas et al. 2021]] ), making society more digitally literate.

The cost of new services provided by digitalisation can be high, and this could imply barriers for low-income countries in joining new global information-sharing systems and markets. Altogether this implies that any assessment of the contribution of digitalisation to support the SDGs and low-carbon pathways will only be able to provide very context-specific results. Digital technologies could potentially disrupt production processes in nearly every sector of the economy. However, as an emerging area experiencing the rapid penetration of many sectors, there could be a window of opportunity for integrating sustainable development and low-emission pathways. ( [[#IIASA--2020|IIASA 2020]] ) concludes that the digital revolution is characterised by many innovative technologies, which can create both synergies and trade-offs with the SDGs ( [[#IIASA--2020|IIASA 2020]] ).

Digital technologies could potentially disrupt production processes in nearly every sector of the economy. However, as an emerging area experiencing the rapid penetration of many sectors, there could be a window of opportunity for integrating sustainable development and low-emission pathways. TWI2050 (2020) concludes that the digital revolution is characterised by many innovative technologies, which can create both synergies and trade-offs with the SDGs ( [[#IIASA--2020|IIASA 2020]] ).

WBSD (2019) has assessed the potential of communication technologies (ICT) to contribute to the transition to a global low-carbon economy in the energy, transportation, building, industry, and other sectors. The potential is estimated to be around 15% CO 2 -eq emissions reductions in 2020 compared with a business-as-usual scenario. A range of ICT solutions have been highlighted, including smart motors and industrial process-management in industry, traffic-flow management, efficient engines for transport, smart logistics and smart-energy systems.

The TWI2050 2019 report ( [[#IIASA--2019|IIASA 2019]] ) assessed both the positive and negative impacts of digitalisation in the context of sustainable development. It found that efficiency improvements, reduced resource consumption and new services can support the SDGs, but also that there were challenges, including in relation to equality, facing the least-developed and developing countries because of their low level of access to technologies. The necessary preconditions for successful digital transformation include prosperity, social inclusion, environmental sustainability, protection of jobs and good governance of sustainability transitions. One negative impact of digitalisation could be the rebound effects, where easier access to services could increase demand and with it GHG emissions. Digitalisation in the manufacturing sector could also provide a comparative advantage to developed countries due to the falling importance of labour costs, while the barriers to emerging economies seeking to enter global markets could accordingly be increased.

In respect of governance, ( [[#Krishnan--2020|Krishnan et al. 2020]] ) point out that the creation of synergies between sustainable development and low-emission urbanisation based on digitalisation could face barriers in the form of inadequate knowledge of structures and value creation through ecosystems that would need to be addressed by means of smart digitalising, requiring organisational measures to support transformation processes.

Urban areas are one of the main arenas for new digital solutions due to rapid urbanisation rates and high concentrations of settlements, businesses and supply systems, which offer great potential for large-scale digital systems. The emergence of smart cities has supported the uptake of smart integrated energy, transportation, water and waste-management systems, while synergies have been created in terms of more flexible and efficient systems. In its 2018 Policy and Action document, the Japanese Business Federation (Keidanren) launched Society 5.0, which includes plans for smart-city development ( [[#Carraz--2019|Carraz and Yuko 2019]] ; [[#Narvaez%20Rojas--2021|Narvaez Rojas et al. 2021]] ). To achieve smart cities, Society 5.0 aimed to facilitate diverse lifestyles and business success, while the quality of life offered by these options will be enhanced. It also aims to offer high-standard medical and educational services. Autonomous vehicles will be available and integrated with smart-grid systems in order to facilitate mobility and flexibility in energy supply with a high share of renewable energy.

[[IPCC:Wg3:Chapter:Chapter-6|Chapter 6]] of this report on ‘Energy Systems’ points out that there are many smart-energy options with the potential to support sustainable development by facilitating the integration of high shares of fluctuating renewable energy in electricity systems, potentially storing energy in electric vehicle (EV) batteries or fuel cells, and applying load shifting by varying prices over time. It is concluded that very large efficiency gains are expected to emerge from digitalisation in the energy sector (Figure 6.18).

[[IPCC:Wg3:Chapter:Chapter-9#9.9.2|Section 9.9.2]] in [[IPCC:Wg3:Chapter:Chapter-9|Chapter 9]] concludes that the improved energy efficiency and falling costs in the building sector that could result from digitalisation could have rebound effects in increasing both energy consumption and comfort levels. Increasing GHG emissions could be the result, but if low-income consumers are given faster access to affordable energy, this could agree with the SDGs, making it desirable to integrate policies targeting mitigation.

[[IPCC:Wg3:Chapter:Chapter-10#10.1.2|Section 10.1.2]] in [[IPCC:Wg3:Chapter:Chapter-10|Chapter 10]] discusses how the sharing economy, which, for example, could be facilitated by ICT platforms, could influence both mitigation and the SDGs. On the one hand, sharing has the potential to save transport emissions, especially if EVs are supplied with decarbonised grid electricity. However, an increase in transport emissions could result from this if increasing demand and higher comfort levels are facilitated, for example, by making access to EVs relatively easy compared with mass transit. Another possible trade-off is that the supply of public transport services would be limited to the elderly and other user groups.

Green innovation in agriculture is another emerging area in which digitalisation is making huge progress. From the perspective of water provision, weather data can be used to predict rain amounts so that farmers can better manage the application of farm chemicals to minimise polluting aquifers and surface-water systems used for drinking water. Meanwhile, smart meters, on-site and remote sensors and satellite data connected to mobile devices allow real-time monitoring of crop-water and optimal irrigation requirements. On the supply side, remote tele-control systems and efficient irrigation technologies enable farmers to control and optimise the quantity and timing of water applications, while minimising the energy-consumption trade-offs of pressurised irrigation in both rural and urban agricultural contexts ( [[#Germer--2011|Germer et al. 2011]] ; [[#Ruiz-Garcia--2009|Ruiz-Garcia et al. 2009]] ).

Technology-driven precision agriculture, which combines geomorphology, satellite imagery, global positioning and smart sensors, enables enormous increases in efficiency and productivity. Taken together, these technologies provide farmers with a decision-support system in real time for the whole farm. Arguably, the world could feed the projected rise in population without radical changes to current agricultural practices if food waste can be minimised or eliminated. Digital technologies will contribute to minimising these losses through increased efficiencies in supply chains, better shipping and transit systems, and improved refrigeration.

In conclusion, in most cases digitalisation options may have both positive synergistic impacts on mitigation and the SDGs and some negative trade-offs. Energy-sector options are assessed primarily as having synergies, while some digitalisation options in transport could increase the demand for emission-intensive modes of transport. Digital platforms for the sharing economy could have both positive and negative impacts depending on the goods and services that are actually exchanged (Cross-Chapter Box 6 in Chapter 7). Options related to agriculture and the water-energy-food nexus (WEFN) could help manage resources more efficiently across sectors, which could create synergies. Digitalisation can also raise a number of ethical challenges according to ( [[#Clark--2019|Clark et al. 2019]] ). Wider public discussion of internet-based activities was accordingly recommended, including topics such as the negotiation of online consent and the use of data for which consent has not been obtained.

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==== 17.3.3.7 Cross-sectoral Overview of Synergies and Trade-offs Between Climate Change Mitigation and the SDGs ====

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Based on a qualitative assessment in the sectoral Chapters 6, 7, 8, 9, 10, and 11, Figure 17.1 below provides an overview of the most likely links between sectoral mitigation options and SDGs in terms of synergies and trade-offs. The general overview provided in the figure is supplemented by specific sector-by-sector comments on how the synergies and trade-offs mapped depend on the scale of implementation and the overall development context of places where the mitigation options are implemented. For some mitigation options these scaling and context-specific issues imply that there can be both synergies and trade-offs in relation to specific SDGs. In addition to the information provided in Figure 17.1, Supplementary Material Table 17.SM.1 includes the detailed background material provided by the sectoral chapters in terms of qualitative information for each of the synergies and trade-offs mapped.

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[[File:e2aa4f4023c9634000360c7f7de62aec IPCC_AR6_WGIII_Figure_17_1.png]]

'''Figure 17.1 | Trade-offs and synergies between sectoral mitigation options and the Sustainable Developmen''' '''t Goals (SDGs).'''

The assessment of synergies and trade-offs presented in Figure 17.1 depends on the underlying literature assessed by the sectoral chapters. In cases where no information about the links between specific mitigation options and SDGs are indicated, this does not imply that there are no links, but rather that the links have not been assessed by the literature.

Most of the energy-sector options are assessed as having synergies with several SDGs, but there could be mixed synergies and trade-offs between SDG 2 (zero hunger) for wind and solar energy, and for hydropower due to land-use conflicts and fishery damage. Offshore wind could also have both synergies and trade-offs with SDG 14 (life below water) dependent on scale and implementation site, and it is emphasised that land-use should be coordinated with biodiversity concerns. Both wind and solar energy are assessed as having trade-offs with SDG 12 (responsible production and consumption) due to significant material consumption and disposal needs.

Geothermal energy is assessed as having synergies with SDG 1 (no poverty) due to energy access, and mixed synergies and trade-offs in relation to SDG 3 (good health and well-being) due to reduced air pollution, but with some risks in relation to water pollution, and in relation to SDG 6 (clean water and sanitation), if it is not well managed. Nuclear power is assessed as having synergies with SDG 3 (good health and well-being) due to reduced air pollution, but potential trade-offs in relation to SDG 6 (clean water and sanitation) due to high water consumption, and water consumption issues are also possible in relation to many of the other mitigation options in the energy sector. Synergies are identified in relation to SDG 12 (responsible production and consumption) for nuclear power due to low material consumption. CCUS has been assessed as having trade-offs in relation to SDG 1 (no poverty) due to high costs and SDG 6 (clean water and sanitation) due to high water consumption. Synergies are related to SDG 3 (good health and well-being), and to SDG 9 (industry, innovation and infrastructure) due to the facilitation of decarbonisation of industrial processes. Both synergies and trade-offs could arrive in relation to SDG 12 (responsible production and consumption), since some rare chemicals and other inputs could in some cases be used with large-scale applications.

Bioenergy use as a fuel is assessed as one of the energy-sector mitigation options with most synergies and trade-offs with the SDGs. There could be synergies with SDG 1 (no poverty), with SDG 8 (decent work and economic growth) and SDG 9 (industry, innovation and infrastructure). This option, however, if combined with CCS, can be expensive and can compromise SDG 1 (no poverty) due to the high costs involved.

Agriculture, forestry and other land use (AFOLU) mitigation options are very closely linked to the SDGs and offer both synergies and trade-offs, which in many cases are highly dependent on the scale of implementation. All the mitigation options included in Figure 17.1 are assessed as potentially having synergies with SDG 1 (no poverty), but trade-offs could also happen if large areas are used for biocrops and taken away from other activities, thus causing poverty, as well as in relation to food costs if healthier diets are made more expensive. In relation to SDG 2 (zero hunger), most of the mitigation options are assessed as being associated with both synergies and trade-offs. Trade-offs are particularly a risk with large-scale applications of afforestation projects, bioenergy crops and other land-hungry activities, which can crowd out food production.

SDG 3 (good health and well-being) can be supported by many mitigation options in the agriculture, forestry and food sectors, primarily due to the reduced environmental impacts, and the same is the case with SDG 14 (life below water) due to decreased nutrient loads, and SDG 15 (life on land) due to increased biodiversity, with the caveat however, that SDGs 14 and 15 could have both synergies and trade-offs dependent on land use. It is considered that there could be both synergies and trade-offs in relation to SDG 8 (decent work and economic growth) due to competition over land use related to the mitigation options reducing deforestation and reforestation and restoration, and the same is the case in relation to SDG 7 (affordable and clean energy) depending on the economic outcome of the mitigation options. Similarly, the mitigation option of reduced CH 4 and N 2 O emissions from agriculture are assessed as having mixed impacts on SDG 8 (decent work and economic growth), and SDG 9 (industry, innovation and infrastructure) depending on innovative food production. The mitigation options of reforestation and forest management are assessed as having mixed impacts on SDG 10 (reduced inequalities) depending on the involvement of local communities in projects. The assessment emphasises that the synergies and trade-offs of the mitigation options with the SDGs in this sector are very context- and scale-dependent, depending on how measures are carried out, for example, in relation to the enhanced production of renewables needed to replace fossil fuel-based products. If done on a massive scale and not adapted to local circumstances, there are adverse implications for food security, livelihoods and biodiversity.

All the urban mitigation options that have been assessed are considered to have synergies with the SDGs, and in a few cases both synergies and trade-offs are identified. In general, many links between mitigation options in the urban area and the SDGs have been identified in the literature. Urban land use and spatial planning, for example, can support SDG 1 (no poverty), and can also reduce vulnerability to climate change if integrated planning is undertaken, while access to food (SDG 2: zero hunger), and water (SDG 6: clean water and sanitation) can also be achieved if supported by integrated planning. Electrification, district heating, and green-and-blue infrastructure in urban areas are expected to have synergies with all the SDGs addressed by the reviewed studies.

Mitigation options like waste-prevention minimisation and management are also assessed as having many synergies with the SDGs, but trade-offs could depend on the application of air-pollution control technologies, and on the character of informal waste-recycling activities. The impacts of the possible synergies and/or trade-offs with the SDGs will change according to the specific urban context. Synergies and/or trade-offs may be more significant in certain contexts than others. Regarding the SDGs, urban mitigation can support shifting pathways of urbanisation towards sustainability. The feasibility of urban mitigation options is also malleable and can increase with more enablers. Strengthened institutional capacity that also supports the scale and coordination of the mitigation options can increase the synergies between urban mitigation options and the SDGs.

As for the urban mitigation options, the reviewed building-sector studies reveal a lot of links between mitigation and the SDGs. Highly efficient building envelopes are expected to have synergies with the SDGs in all cases except those with potential trade-offs in relation to SDG 10 (reduced inequalities). Many SDG synergies are also identified for the building design and performance, heating, ventilation and air conditioning, and efficient appliances mitigation options. However, some trade-offs could appear in relation to SDG 8 (decent work and economic growth) due to macroeconomic impacts of reduced energy consumption, decreasing prices and stranded investments. Similar issues related to the economic impacts of reduced energy demand are also highlighted for all the other mitigation options, including for the building sector. In relation to construction materials and the circular economy, some trade-offs have been identified in relation to SDG 6 (clean water and sanitation) and SDG 15 (life on land) related to the use of bio-based materials.

Consideration of the building sector highlights important context-specific issues related to synergies and trade-offs between mitigation options and SDGs such as the economic impacts (synergies and trade-offs) associated with reduced energy demand, resulting in lower energy prices, energy-efficiency investments, the fostering of innovation and improvements in labour productivity. Furthermore, the distributional costs of some mitigation policies may hinder the implementation of these measures. In this case, appropriate access policies should be designed to shield poor households efficiently from the burden of carbon taxation. Under real-world conditions, improved cookstoves have shown smaller, and in many cases limited, long-term health and environmental impacts than expected, as the households use these stoves irregularly and inappropriately, and fail to maintain them, so that their usage declines over time. Specific distributional issues are highlighted in relation to various cookstove programmes.

The mitigation options in the transportation sector are assessed as having synergies with SDG 1 (no poverty) and SDG 3 (good health and well-being) due to reduced environmental pollution, with exceptions in relation to pollution from biofuels and the risks of traffic accidents. Trade-offs are also mentioned in relation SDG 2 (zero hunger) where the production of biofuels takes land away from food production. Synergies are assessed in relation to SDG 7 (affordable and clean energy), SDG 8 (decent work and economic growth) and SDG 9 (industry, innovation and infrastructure). It is emphasised that some mitigation options, like the increased penetration of electric vehicles, require innovative business models, and that digitalisation and automatic vehicles will support the socio-economic structures that impede adoption of EVs and the urban structures that enable reduced car dependence. In conclusion, there is a need for investments in infrastructure that can support alternative fuels for light-duty vehicles (LDVs). The large-scale electrification of LDVs requires the expansion of low-carbon power systems, while charging or battery-swapping infrastructure is needed for some segments.

The mitigation options in the industrial sector have been assessed primarily as having synergies with meeting the SDGs. Several options, including energy efficiency, material recycling and electrification, are assessed has being able to create increased employment and business opportunities related to SDG 8 (decent work and economic growth), but material-efficiency improvements could reduce tax revenues. Electrification is assessed as having many synergies with SDGs, such as supporting SDG 1 (no poverty), SDG 2 (zero hunger), and SDG 3 (good health and well-being). CCS applied in industry is assessed as having synergies in terms of the control of non-CO 2 pollutants (such as sulphur dioxide), but increases in non-CO 2 pollutants (such as particulate matter, nitrogen oxide and ammonia). The conclusion is that 15–25% additional energy will be required by CCS technologies compared with conventional plants, implying that production costs could increase significantly. For the industrial sector in general, it is concluded that the balance between synergies and trade-offs between mitigation options and SDGs in industry depends on technology and the scale of the sharing of co-benefits across regions, as well as on the sharing of benefits in business models over whole value chains.

Thus, a number of cross-sectoral conclusions on synergies and trade-offs between mitigation options and the SDGs appear from the overview provided in Figure 17.1. There are many synergies in all sectors between mitigation options and the SDGs, and in a few cases there are also significant trade-offs that it is very important to address, since they can compromise major SDGs including SDG 1 (no poverty), SDG 2 (zero hunger), and in some cases SDG 14 (life below water) and SDG 15 (life on land). In particular, mitigation options in relation to land use, such as afforestation and reforestation and bioenergy crops, can in some cases imply trade-offs with access to food and local sharing of benefits, but synergies can also exist if proper land management and cross-sectoral policies take sustainable land use into account. The impacts and trade-offs for this sector are highly scale- and context-dependent, so the final outcome of mitigation policies should be considered in detail.

The urban systems and transportation could potentially achieve many synergies between mitigation policies and the SDGs, but integrated planning and infrastructure management are critical to avoiding trade-offs. Similarly, the buildings sector and industry have identified many potential synergies between mitigation options and the SDGs, but that raises issues related to the costs of new technologies, and in relation to households and buildings, important equity issues are emerging in relation to the ability of low-income groups to afford the introduction of new technologies. Altogether these cross-sectoral conclusions call for a need to support policies that aid coordination between different sectoral domains and that include context-specific assessments of the sharing of benefits and costs related to the implementation of mitigation options.

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