Editing IPCC:AR6/WGIII/Chapter-3 (section)

=== 3.7.6 Biodiversity (Land and Water) ===

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Biodiversity covers life below water (SDG 14) and life on land (SDG 15). Ecosystem services are relevant to the goals of zero hunger (SDG 2), good health and well-being (SDG 3), clean water and sanitation (SDG 6) and responsible consumption and production (SDG 12), as well as being essential to human existence (IPBES 2019).

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==== 3.7.6.1 Benefits of Avoided Climate Impacts Along Mitigation Pathways ====

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===== Terrestrial and freshwater aquatic ecosystems =====

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Climate change is a major driver of species extinction and terrestrial and freshwater ecosystems destruction ( ''high confidence'' ) (AR6 WGII Chapter 2). Analysis shows that approximately half of all species with long-term records have shifted their ranges in elevation and about two thirds have advanced their timing of spring events ( [[#Parmesan--2015|Parmesan and Hanley 2015]] ). Under 3.2°C warming, 49% of insects, 44% of plants and 26% of vertebrates are projected to be at risk of extinction. At 2°C, this falls to 18% of insects, 16% of plants and 8% of vertebrates and at 1.5°C, to 6% of insects, 8% of plants and 4% of vertebrates ( [[#Warren--2018|Warren et al. 2018]] ). Incidents of migration of invasive species, including pests and diseases, are also attributable to climate change, with negative impacts on food security and vector-borne diseases. Moreover, if climate change reduces crop yields, cropland may expand – a primary driver of biodiversity loss – in order to meet food demand ( [[#Molotoks--2020|Molotoks et al. 2020]] ). Land restoration and halting land degradation under all mitigation scenarios has the potential for synergy between mitigation and adaptation.

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===== Marine and coastal ecosystems =====

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Marine ecosystems are being affected by climate change and growing non-climate pressures including temperature change, acidification, land-sourced pollution, sedimentation, resource extraction and habitat destruction ( ''high confidence'' ) ( [[#Bindoff--2019|Bindoff et al. 2019]] ; [[#IPCC--2019b|IPCC 2019b]] ). The impacts of climate drivers and their combinations vary across taxa (AR6 WGII Chapter 3). The danger or warming and acidification to coral reefs, rocky shores and kelp forests is well established ( ''high confidence'' ) (AR6 WGII Chapter 3). Migration towards optimal thermal and chemical conditions ( [[#Burrows--2019|Burrows et al. 2019]] ) contributes to large-scale redistribution of fish and invertebrate populations, and major impacts on global marine biomass production and maximum sustainable yield ( [[#Bindoff--2019|Bindoff et al. 2019]] ).

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==== 3.7.6.2 Implications of Mitigation Efforts Along Pathways ====

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Mitigation measures have the potential to reduce the progress of negative impacts on ecosystems, although it is ''unlikely'' that all impacts can be mitigated ( ''high confidence'' ) ( [[#Ohashi--2019|Ohashi et al. 2019]] ). The specifics of mitigation achievement are crucial, since large-scale deployment of some climate mitigation and land-based CDR measures could have deleterious impacts on biodiversity ( [[#Santangeli--2016|Santangeli et al. 2016]] ; [[#Hof--2018|Hof et al. 2018]] ).

Climate change mitigation actions to reduce or slow negative impacts on ecosystems are ''likely'' to support the achievement of SDGs 2, 3, 6, 12, 14 and 15. Some studies show that stringent and constant GHG mitigation practices bring a net benefit to global biodiversity even if land-based mitigation measures are also adopted ( [[#Ohashi--2019|Ohashi et al. 2019]] ), as opposed to delayed action which would require much more widespread use of BECCS. Scenarios based on demand reductions of energy and land-based production are expected to avoid many such consequences, due to their minimised reliance on BECCS ( [[#Conijn--2018|Conijn et al. 2018]] ; [[#Grubler--2018|Grubler et al. 2018]] ; [[#Bowles--2019|Bowles et al. 2019]] ; [[#Soergel--2021a|Soergel et al. 2021a]] ). Stringent mitigation that includes reductions in demand for animal-based foods and food waste could also relieve pressures on land use and biodiversity ( ''high confidence'' ), both directly by reducing agricultural land requirements ( [[#Leclère--2020|Leclère et al. 2020]] ) and indirectly by reducing the need for land-based CDR ( [[#van%20Vuuren--2018|van Vuuren et al. 2018]] ).

As environmental conservation and sustainable use of the Earth’s terrestrial species and ecosystems are strongly related, recent studies have evaluated interconnections among key aspects of land and show a pathway to the global sustainable future of land ( [[#Popp--2014|Popp et al. 2014]] ; [[#Erb--2016|Erb et al. 2016]] ; [[#Obersteiner--2016|Obersteiner et al. 2016]] ; [[#Humpenöder--2018|Humpenöder et al. 2018]] ). Most studies agree that many biophysical options exist to achieve global climate mitigation and sustainable land use in future. Conserving local biodiversity requires careful policy design in conjunction with land-use regulations and societal transformation in order to minimise the conversion of natural habitats.

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