Editing IPCC:AR6/WGII/Chapter-11 (section)

== Executive Summary ==

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====== Observed changes and impacts ======

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'''Ongoing climate trends have exacerbated many extreme events (''' '''''very high confidence''''' ''')''' . The Australian trends include further warming and sea level rise sea level rise (SLR), with more hot days and heatwaves, less snow, more rainfall in the north, less April–October rainfall in the southwest and southeast and more extreme fire weather days in the south and east. The New Zealand trends include further warming and sea level rise (SLR), more hot days and heatwaves, less snow, more rainfall in the south, less rainfall in the north and more extreme fire weather in the east. There have been fewer tropical cyclones and cold days in the region. Extreme events include Australia’s hottest and driest year in 2019 with a record-breaking number of days over 39°C, New Zealand’s hottest year in 2016, three widespread marine heatwaves during 2016–2020, Category 4 Cyclone Debbie in 2017, seven major hailstorms over eastern Australia and two over New Zealand from 2014–2020, three major floods in eastern Australia and three over New Zealand during 2019–2021 and major fires in southern and eastern Australia during 2019–2020. {11.2.1, Table 11.2, 11.3.8}

'''Climate trends and extreme events have combined with exposure and vulnerabilities to cause major impacts for many natural systems, with some experiencing or at risk of irreversible change in Australia (''' '''''very''''' '''''high confidence''''' ''')''' '''and in New Zealand (''' '''''high confidence''''' ''')''' '''''.''''' For example, warmer conditions with more heatwaves, droughts and catastrophic wildfires have negatively impacted terrestrial and freshwater ecosystems. The Bramble Cay melomys, an endemic mammal species, became extinct due to loss of habitat associated with sea level rise (SLR) and storm surges in the Torres Strait. Marine species abundance and distributions have shifted polewards, and extensive coral bleaching events and loss of temperate kelp forests have occurred due to ocean warming and marine heatwaves across the region. In New Zealand’s southern Alps, from 1978 to 2016, the area of 14 glaciers declined 21%, and extreme glacier mass loss was at least 6 times more likely in 2011 and 10 times more likely in 2018 due to climate change. The end-of-summer snowline elevation for 50 glaciers rose 300 m from 1949 to 2019. {11.3.1.1, 11.3.2.1, Table 11.2b, Table 11.4, Table 11.6, Table 11.9}

'''Climate trends and extreme events have combined with exposure and vulnerabilities to cause major impacts for some human systems (''' '''''high confidence''''' ''').''' Socioeconomic costs arising from climate variability and change have increased. Extreme heat has led to excess deaths and increased rates of many illnesses. Nuisance and extreme coastal flooding have increased due to sea level rise (SLR) superimposed upon high tides and storm surges in low-lying coastal and estuarine locations, including impacts on cultural sites, traditions and lifestyles of Aboriginal and Torres Strait Islander Peoples in Australia and Tangata Whenua Māori in New Zealand. Droughts have caused financial and emotional stress in farm households and rural communities. Tourism has been negatively affected by coral bleaching, fires, poor ski seasons and receding glaciers. Governments, business and communities have experienced major costs associated with extreme weather, droughts and sea level rise (SLR). {11.3, 11.4, 11.5.2, Table 11.2, Boxes 11.1–11.6}

'''Climate impacts are cascading and compounding across sectors and socioeconomic and natural systems (''' '''''high confidence''''' ''').''' Complex connections are generating new types of risks, exacerbating existing stressors and constraining adaptation options. An example is the impacts that cascade between interdependent systems and infrastructure in cities and settlements. Another example is the 2019–2020 southeast Australia wildfires, which burned 5.8 to 8.1 million hectares, with 114 listed threatened species losing at least half of their habitat and 49 losing over 80%, over 3,000 houses destroyed, 33 people killed, a further 429 deaths and 3230 hospitalisations due to cardiovascular or respiratory conditions, AUD$1.95 billion in health costs, AUD$2.3 billion in insured losses and AUD$3.6 billion in losses for tourism, hospitality, agriculture and forestry. {11.5.1, Box 11.1}

'''Increasing climate risks are projected to exacerbate existing vulnerabilities and social inequalities and inequitie''' '''''s''''' '''(''' '''''high confidence''''' ''').''' These include inequalities between Indigenous and non-Indigenous Peoples and between generations, rural and urban areas, incomes and health status, increasing the climate risks and adaptation challenges faced by some groups and places. Resultant climate change impacts include the displacement of some people and businesses and threaten social cohesion and community well-being. {11.3.5, 11.3.6, 11.3.10, 11.4}

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====== Projected impacts and key risks ======

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'''Further climate change is inevitable, with the rate and magnitude largely dependent on the emission pathway (''' '''''very high confidence''''' [[#footnote-001|1]] ''').''' Ongoing warming is projected, with more hot days and fewer cold days ( ''very high confidence'' ). Further sea level rise (SLR), ocean warming and ocean acidification are projected ( ''very high confidence'' ). Less winter and spring rainfall is projected in southern Australia, with more winter rainfall in Tasmania, less autumn rainfall in southwestern Victoria and less summer rainfall in western Tasmania ( ''medium confidence'' ), with uncertain rainfall changes in northern Australia. In New Zealand, more winter and spring rainfall is projected in the west and less in the east and north, with more summer rainfall in the east and less in the west and central North Island ( ''medium confidence'' ). In New Zealand, ongoing glacier retreat is projected ( ''very high confidenc'' e). More extreme fire weather is projected in southern and eastern Australia ( ''high confidence'' ) and over northern and eastern New Zealand ( ''medium confidence'' ). Increased drought frequency is projected for southern and eastern Australia and northern New Zealand ( ''medium confidence'' ). Increased heavy rainfall intensity is projected, with fewer tropical cyclones and a greater proportion of severe cyclones ( ''medium confidence'' ). {11.2.2, Table 11.3, Box 11.6}

'''Climate risks are projected to increase for a wide range of systems, sectors and communities, which are exacerbated by underlying vulnerabilities and exposures (''' '''''high confidence''''' ''')''' {11.3; 11.4} . Nine key risks have been identified, based on magnitude, likelihood, timing and adaptive capacity {11.6, Table 11.14} :

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====== Ecosystems at critical thresholds, where recent climate change has caused significant damage and further climate change may cause irreversible damage, with limited scope for adaptation ======

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# Loss and degradation of coral reefs and associated biodiversity and ecosystem service values in Australia due to ocean warming and marine heatwaves. For example three marine heatwaves on the Great Barrier Reef (GBR) during 2016–2020 caused significant bleaching and loss ''(very high confidence)'' . {11.3.2.1, 11.3.2.2, Box 11.2}
# Loss of alpine biodiversity in Australia due to less snow. For example loss of alpine vegetation communities (snow patch Feldmark and short alpine herb-fields) and increased stress on snow-dependent plant and animal species ''(high confidence)'' . {11.3.1.1, 11.3.1.2}

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====== Key risks that have potential to be severe but can be reduced substantially by rapid, large-scale and effective mitigation and adaptation ======

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# Transition or collapse of alpine ash, snowgum woodland, pencil pine and northern jarrah forests in southern Australia due to hotter and drier conditions with more fires. For example declining rainfall in southern Australia over the past 30 years, has led to drought-induced canopy dieback across a range of forest and woodland types and death of fire-sensitive tree species due to unprecedented wildfires ''(high confidence)'' . {11.3.1.1, 11.3.1.2}
# Loss of kelp forests in southern Australia and southeast New Zealand due to ocean warming, marine heatwaves and overgrazing by climate-driven range extensions of herbivore fish and urchins. For example less than 10% of giant kelp in Tasmania was remaining by 2011 due to ocean warming ''(high confidence)'' . {11.3.2.1, 11.3.2.2}
# Loss of natural and human systems in low-lying coastal areas due to sea level rise (SLR). For example for 0.5 m sea level rise (SLR), the value of buildings in New Zealand exposed to 1-in-100-year coastal inundation could increase by NZ$12.75 billion and the current 1-in-100-year flood in Australia could occur several times a year ''(high confidence)'' . {11.3.5; Box 11.6}
# Disruption and decline in agricultural production and increased stress in rural communities in southwestern, southern and eastern mainland Australia due to hotter and drier conditions. For example by 2050, a decline in median wheat yields of up to 30% in southwestern Australia and up to 15% in South Australia and increased heat stress in livestock by 31–42 days per year ''(high confidence)'' . {11.3.4; 11.3.5; Box 11.3}
# Increase in heat-related mortality and morbidity for people and wildlife in Australia due to heatwaves. For example heat-related excess deaths in Melbourne, Sydney and Brisbane are projected to increase by about 300/year (low emission pathway) to 600/year (high emission pathway) during the 2031–2080 period relative to 142/year in the period 1971–2020 ''(high confidence)'' . {11.3.1, 11.3.5.1, 11.3.5.2, 11.3.6.1, 11.3.6.2}

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====== Key cross-sectoral and system-wide risk ======

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# Cascading, compounding and aggregate impacts on cities, settlements, infrastructure, supply chains and services due to wildfires, floods, droughts, heatwaves, storms and sea level rise (SLR). For example in New Zealand, extreme snow, heavy rainfall and wind events have combined to impact road networks, power and water supply, interdependent wastewater and stormwater services and business activities ''(high confidence)'' {11.3.3, 11.5.1, 11.8.1} .

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====== Key implementation risk ======

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# Inability of institutions and governance systems to manage climate risks. For example the scale and scope of projected climate impacts overwhelm the capacity of institutions, organisations and systems to provide necessary policies, services, resources and coordination to address socioeconomic impacts ''(high confidence)'' {11.5.1.2, 11.5.1.3, 11.5.2.3, 11.7.1, 11.7.2, 11.7.3} .

There are important interactions between mitigation and adaptation policies and their implementation ( '''''high confidence''''' ''').''' Integrated policies in interdependent systems across biodiversity, water quality, water availability, energy, transport, land use and forestry for mitigation can support synergies between adaptation and mitigation. These have co-benefits for the management of land use, water and associated conflicts and for the functioning of cities and settlements. For example, projected increases in fire, drought, pest incursions, storms and wind place forests at risk and affect their ongoing role in meeting New Zealand’s emissions reduction goals. {11.3.4.3, 11.3.10.2, 11.3.5.3, Box 11.5}

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====== Challenges and solutions ======

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'''The ambition, scope and progress of the adaptation process have increased across governments, non-government organisations, businesses and communities (''' '''''high confidence''''' ''').''' This process includes vulnerability and risk assessments, identification of strategies and options, planning, implementation, monitoring, evaluation and review. Initiatives include legislated institutional frameworks for risk assessment and national adaptation planning and monitoring in New Zealand, a National Recovery and Resilience Agency and National Disaster Risk Reuction Framework in Australia, deployment of new national guidance, decision tools, collaborative governance approaches and the introduction of climate risk and disclosure regimes for the private sector. The focus, however, has been on adaptation planning, rather than on implementation. {11.5.1, 11.7.1.1, Box 11.6, Table 11.15a, Table 11.15b, Table 11.17}

'''Adaptation progress is uneven, due to gaps, barriers and limits to adaptation and adaptive capacity deficits (''' '''''very high confidence''''' ''').''' Progress in adaptation planning, implementation, monitoring and evaluation is lagging. Barriers include lack of consistent policy direction, competing objectives, divergent risk perceptions and values, knowledge constraints, inconsistent information, fear of litigation, up-front costs and lack of engagement, trust and resources. Adaptation limits are being approached for some species and ecosystems. Adaptive capacity to address the barriers and limits can be built through greater engagement with groups and communities to build trust and social legitimacy through the inclusion of diverse values, including those of Aboriginal and Torres Strait Islander Peoples and Tangata Whenua Māori. {11.4, 11.5, 11.6, 11.7, 11.8, Table 11.4, Table 11.5, Table 11.6, Table 11.16, Box 11.2}

'''A range of incremental and transformative adaptation options and pathways is available as long as enablers are in place to implement them (''' '''''high confidence''''' ''').''' Key enablers for effective adaptation include shifting from reactive to anticipatory planning, integration and coordination across levels of government and sectors, inclusive and collaborative institutional arrangements, government leadership, policy alignment, nationally consistent and accessible information and decision-support tools, along with adaptation funding and finance, and robust, consistent and strategic policy commitment. Over 75% of people in Australia and New Zealand agree that climate change is occurring and over 60% believe climate change is caused by humans, giving climate adaptation and mitigation action further social legitimacy. {11.7.3, Table 11.17}

'''New knowledge on system complexity, managing uncertainty and how to shift from reactive to adaptive implementation is critical for accelerating adaptation (''' '''''high confidence''''' ''').''' Priorities include a greater understanding of impacts on natural system dynamics; the exposure and vulnerability of different groups within society, including Indigenous Peoples; the relationship between mitigation and adaptation; the effectiveness and feasibility of different adaptation options; the social transitions needed for transformative adaptation; and the enablers for new knowledge to better inform decision-making (e.g., monitoring data repositories, risk and vulnerability assessments, robust planning approaches, sharing adaptation knowledge and practice). {11.7.3.3}

'''Aboriginal and Torres Strait Islander Peoples and Tangata Whenua Māori can enhance effective adaptation''' t '''hrough the passing down of knowledge about climate change planning that promotes collective action and mutual support across the region (''' '''''high confidence''''' ''').''' Supporting Aboriginal and Torres Strait Islander Peoples and Tangata Whenua Māori institutions, knowledge and values enable self-determination and create opportunities to develop adaptation responses to climate change. Actively upholding the UN Declaration on the Rights of Indigenous Peoples and Māori interests under the Treaty of Waitangi at all levels of government enables intergenerational approaches for effective adaptation. {11.3, 11.4, 11.6, 11.7.3; Cross-Chapter Box INDIG in Chapter 18}

'''A step change in adaptation is needed to match the rising risks and to support climate resilient development (''' '''''very high confidence''''' ''').''' Current adaptation is largely incremental and reactive. A shift to transformative and proactive adaptation can contribute to climate resilient development. The scale and scope of cascading, compounding and aggregate impacts require new, larger-scale and timely adaptation. Monitoring and evaluation of the effectiveness of adaptation progress and continual adjustment is critical. The transition to climate resilient development pathways can generate major co-benefits, but complex interactions between objectives can create trade-offs. {11.7, 11.8.1, 11.8.2}

'''Delay in implementing adaptation and emission reductions will impede climate resilient development, resulting in more costly climate impacts and greater scale of adjustments''' '''(''' '''''very high confidence''''' ''')''' . The region faces an extremely challenging future. Reducing the risks would require significant and rapid emission reductions to keep global warming to 1.5°C–2.0°C, as well as robust and timely adaptation. The projected warming under current global emissions reduction policies would leave many of the region’s human and natural systems at very high risk and beyond adaptation limits. {11.8, Table 11.1, Table 11.14, Figure 11.6}

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