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

==== CCP1.2.2.2 Projected Impacts ====

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Most terrestrial species in biodiversity hotspots in North America have been projected to be negatively impacted by climate change ( ''medium evidence, medium agreement'' , ''medium confidence'' ). About ~80% of projections for assessed species showed a negative impact of climate change, with ~25% at very high risk of extinction (Figure CCP1.7; [[#Manes--2021|Manes et al., 2021]] ). Alterations to vegetation that would have ecosystem-wide impacts, such as a shift from oak-dominated forests to predominantly hickory and maple species in the Appalachian Forests (H17) ( [[#Ma--2016|Ma et al., 2016]] ) or the continued shrinking of tundra ecosystems, have also been projected. Range shifts have been projected for a variety of plants ( [[#Beltrán--2014|Beltrán et al., 2014]] ; [[#Riordan--2014|Riordan and Rundel, 2014]] ) and vertebrate taxa ( [[#Warren--2014|Warren et al., 2014]] ; [[#Stralberg--2015|Stralberg et al., 2015]] ; [[#McKelvy--2017|McKelvy and Burbrink, 2017]] ). Sizeable range loss, which particularly affects endemic species, is projected with higher levels of climate change. Adaptation in the agricultural sector poses an additional risk to remaining wildlife habitat (e.g., wine in California: [[#Roehrdanz--2016|Roehrdanz and Hannah, 2016]] ).

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'''Figure CCP1.7 |''' '''The projected impacts of climate change on species in 232 studies''' '''(a)''' '''terrestrial and''' '''(b)''' '''marine hotspots (adapted from Manes e''' '''t al.''' ''', 2021), illustrating the number and percentage of species showing positive (blue) and negative (orange) responses to climate change, and threatened with extinction (red).''' Note Oceania includes Australia, New Zealand, Wallacea, New Guinea, New Caledonia, Polynesia and Micronesia and overlaps the global Small Islands category, which excludes Australia. The Small Islands category represents oceanic and continent-associated small islands, and thus overlaps with Oceania and continental data.

In Central and South America, risks have been assessed in at least 24 terrestrial hotspots, especially within the Atlantic Forest, Cerrado, Mesoamerica and the Caribbean, the most studied hotspots in the world in terms of climate change impacts (H47, 44, 15, 16, 20, respectively) ( [[#Manes--2021|Manes et al., 2021]] ). About 85% of projections for assessed species showed a negative impact of climate change ( ''high confidence'' ), with ~26% projecting species extinctions (Figure CCP1.7; [[#Manes--2021|Manes et al., 2021]] ). Projected impacts include contraction or loss of species’ geographic range, loss of diversity and high species turnover ( ''high confidence'' ). Most studies had focused on vertebrates and plants in the Atlantic Forest (H47) and Cerrado (H44) ( [[#Loyola--2014|Loyola et al., 2014]] ; [[#de%20Oliveira--2015|de Oliveira et al., 2015]] ; [[#Vale--2018|Vale et al., 2018]] ; [[#Vasconcelos--2018|Vasconcelos et al., 2018]] ; [[#Hidasi-Neto--2019|Hidasi-Neto et al., 2019]] ; [[#Lima--2019|Lima et al., 2019]] ; [[#Lourenço-de-Moraes--2019|Lourenço-de-Moraes et al., 2019]] ; [[#Vasconcelos--2019|Vasconcelos and Prado, 2019]] ; [[#Velazco--2019|Velazco et al., 2019]] ). Several insect species are projected to lose suitable climatic conditions, including moths in Cerrado (H44) ( [[#Khormi--2014|Khormi and Kumar, 2014]] ). There were projected negative impacts on vegetation such as rupestrian grasslands in Cerrado (H44) ( [[#Fernandes--2018|Fernandes et al., 2018]] ) and tropical and temperate forests in Mesoamerica (H15, H16) ( [[#Mendoza-Ponce--2018|Mendoza-Ponce et al., 2018]] ; [[#Mendoza-Ponce--2019|Mendoza-Ponce et al., 2019]] ). Endemic species face consistent risks of decrease in suitable habitat in the Atlantic Forest (H47) ( [[#Vale--2018|Vale et al., 2018]] ), Cerrado (H44) ( [[#Vasconcelos--2014|Vasconcelos, 2014]] ), Tumbes-Chocó-Magdalena (H28, H23) ( [[#Hermes--2018|Hermes et al., 2018]] ), and Mesoamerica (H15, H16) ( [[#Garcia--2014|Garcia et al., 2014]] ; [[#Ramírez-Amezcua--2016|Ramírez-Amezcua et al., 2016]] ). Climate change may also benefit invasive plant species in terms of range expansion ( [[#Wang--2017|Wang et al., 2017]] ) and physiology ( [[#de%20Faria--2018|de Faria et al., 2018]] ) in the region.

In European biodiversity hotspots, about 75% of projections for assessed species showed a negative impact of climate change, with ~30% at very high risk of extinction ( ''medium confidence'' ) (Figure CCP1.7; [[#Manes--2021|Manes et al., 2021]] ). These threats are projected to be worse under higher levels of warming. Increased wildfire size and frequency is projected to have a strong effect on the Mediterranean basin (H216) ecosystems ( ''medium confidence'' ) ( [[#Lozano--2017|Lozano et al., 2017]] ). Range reductions have been projected for endemic plants ( [[#Pérez-García--2013|Pérez-García et al., 2013]] ; [[#Casazza--2014|Casazza et al., 2014]] ), reptiles ( [[#Ahmadi--2019|Ahmadi et al., 2019]] ), birds ( [[#Abolafya--2013|Abolafya et al., 2013]] ) and insects ( [[#Sánchez-Guillén--2013|Sánchez-Guillén et al., 2013]] ) ( ''medium confidence'' ).

In African biodiversity hotspots, about 80% of projections for assessed species showed a negative impact of climate change, with ~10% at very high risk of extinction, especially of endemic species including birds, plants, bees across several taxa and hotspots if warming exceeds 2°C ( ''high confidence'' ) (Figure CCP1.7; [[#Huntley--2012|Huntley and Barnard, 2012]] ; [[#Kuhlmann--2012|Kuhlmann et al., 2012]] ; [[#Baker--2015|Baker et al., 2015]] ; [[#Lee--2016|Lee and Barnard, 2016]] ; [[#Young--2016|Young et al., 2016]] ; [[#Hannah--2020|Hannah et al., 2020]] ; [[#Manes--2021|Manes et al., 2021]] ).

In Asia, there is a bias in studies towards Indo-Burma (H105, 106, 107, 114, 115), followed by Himalaya (H95, 98, 99) and Southeast Asian montane tropical and temperate forests. About ~70% of projections for assessed species showed a negative impact of climate change, with ~30% at very high risk of extinction ( ''medium confidence'' ) (Figure CCP1.7; [[#Manes--2021|Manes et al., 2021]] ). Impacts include species’ range changes, habitat loss for endemic plants, expansion of invasive species, decreased connectivity and overall species richness decline ( ''high confidence'' ) ( [[#DasGupta--2013|DasGupta and Shaw, 2013]] ; [[#Telwala--2013|Telwala et al., 2013]] ; [[#Sridhar--2014|Sridhar et al., 2014]] ; [[#Zomer--2014|Zomer et al., 2014]] ; [[#Ali--2015|Ali and Begum, 2015]] ; [[#Aryal--2016|Aryal et al., 2016]] ). A projected decrease in habitat suitability for large species like the Asiatic black bear ( ''Ursus thibetanus'' ) is of concern as alternative habitats are outside protected areas, and may lead to human–wildlife conflicts ( [[#Farashi--2018|Farashi and Erfani, 2018]] ). The few positive impacts of climate change were projected as increases in suitable habitat and distribution range for a few endangered plants and mammals ( ''medium confidence'' ) ( [[#Banag--2015|Banag et al., 2015]] ; [[#Shrestha--2018|Shrestha et al., 2018]] ). Animals benefiting from increased fruit and seed production in Southeast Asian forests during warm El Niño cycles were also projected to increase with climate warming ( [[#Corlett--2011|Corlett, 2011]] ).

All projections for assessed species in Australia and New Zealand terrestrial biodiversity hotspots showed a negative impact of climate change, with half at very high risk of extinction ( ''low confidence'' ) ( [[#Manes--2021|Manes et al., 2021]] ). Observed impacts in the Australian Alps were projected to continue under future climate change ( [[#Zylstra--2018|Zylstra, 2018]] ). The northern Australia savanna (H131) may experience increased rainfall and carbon dioxide due to climate change ( [[#Scheiter--2015|Scheiter et al., 2015]] ), and the range of exotic grasses was projected to be reduced under climate warming ( [[#Gallagher--2009|Gallagher et al., 2009]] ). In Australian tropical wet forests, ground-living vertebrates may be more sensitive than arboreal species to unstable climates ( [[#Scheffers--2017|Scheffers et al., 2017]] ). [[#Bellard--2016|Bellard et al. (2016)]] projected losses of land due to sea level rise in the East Australian Forest hotspot (H140), and [[#González-Orozco--2016|González-Orozco et al. (2016)]] projected the contraction of eucalyptus species towards the coast of the Southwest Australia hotspot (H134), exposing them to sea level rise. In New Zealand forests (H139), native plants may be replaced by more fire-resistant introduced species following climate change-related fires ( [[#Perry--2014|Perry et al., 2014]] ). While forest growth is projected to potentially increase due to carbon dioxide fertilization, this may be compromised by drought ( ''low confidence'' ) ( [[#Ausseil--2013|Ausseil et al., 2013]] ). Seed production in native New Zealand beech forests is projected to increase due to climate warming, fuelling the abundance of invasive rats and stoats, which then predate native species and lead to loss of endemic fauna and flora ( ''medium confidence'' ) ( [[#Tompkins--2013|Tompkins et al., 2013]] , Ch. 11).

About 80% of projections for assessed terrestrial species within insular biodiversity hotspots showed a negative impact of climate change, with ~50% at very high risk of extinction, including 100% of endemic species ( ''medium confidence'' ) (Figure CCP1.7; [[#Manes--2021|Manes et al., 2021]] ). In addition to habitat loss and species range reductions, changes in precipitation are projected to be a major driver impacting tropical and subtropical island species ( ''medium confidence'' ) ( [[#Maharaj--2013|Maharaj and New, 2013]] ; [[#Harter--2015|Harter et al., 2015]] ; [[#Struebig--2015|Struebig et al., 2015]] ; [[#Vogiatzakis--2016|Vogiatzakis et al., 2016]] ; [[#Maharaj--2018|Maharaj et al., 2018]] ). Compared to continents, island species are projected to undergo greater impacts from changing climate, especially birds and amphibians ( ''high confidence'' ) ( [[#Fortini--2015|Fortini et al., 2015]] ; [[#Holmes--2015|Holmes et al., 2015]] ; [[#Manes--2021|Manes et al., 2021]] , Box CCP1.1). Of all biodiversity hotspots, island species face the highest proportion of extirpation risk at high elevations due to decreasing habitat area (e.g., [[#Brown--2015|Brown et al., 2015]] ) and at low elevations from sea level rise, habitat loss and introduced species ( ''medium confidence'' ) ( [[#Bellard--2014a|Bellard et al., 2014a]] ).

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