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

=== CCP1.2.2 Terrestrial ===

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The 177 terrestrial hotspots assessed here (including 142 G200) cover about 61,000,000 km 2 (41% of global land area), with a 37% overlap with freshwater hotspots (Table CCP1.1; Figure CCP1.2). They include wet and dry forests, woodland and scrub, highlands, mangroves, deserts, steppe, savanna, grasslands, moorlands and tundra (Figures CCP1.8-1.11). Over 77% of publications on climate change impacts on hotspots since AR5 have been on terrestrial ecosystems, most on projected (as opposed to observed) impacts ( [[#Manes--2021|Manes et al., 2021]] ).

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'''Figure CCP1.1 1 |''' '''Island biodiversity hotspots.''' Photos by Galice Hoarau (top two) and Mark Costello (other four).

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'''Figure CCP1.1 0 |''' '''African biodiversity hotspots.''' Photos by Denis Costello (top row and left second row) and Mark Costello (with elephant) for Drakensberg region, and Frank Zachos (lower four).

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'''Figure CCP1.9 |''' '''Polar and boreal biodiversity hotspots in the Arctic (Norway) taiga.''' Photos by Galice Hoarau (top three) and Mark Costello (bottom two).

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'''Figure CCP1.8 |''' '''Terrestrial biodiversity hotspots in the Americas, Asia and New Zealand.''' Photos by Denis Costello (top four), Mariana M. Vale (Brazil), and Mark Costello (other three).

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==== CCP1.2.2.1 Observed Impacts ====

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There is ''high confidence'' that climate change has already had impacts in North American hotspots. Phenological and range shifts have been reported for bird and mammal species within the boreal forest hotspot ( [[#Davidson--2020|Davidson et al., 2020]] ), and earlier egg laying in birds in tundra hotspots (H3, 5) owing to changes in snowmelt ( [[#Grabowski--2013|Grabowski et al., 2013]] ). Woody vegetation is already shifting north into the tundra ( [[#Larsen--2014|Larsen et al., 2014]] ).

In Central and South America, observed impacts within Mesoamerica (H15, 16) and the Tropical Andes hotspots (H26, 27, 28, 32, 33) comprise upward altitudinal range shifts of birds, frogs, beetles and butterflies ( [[#Narins--2014|Narins and Meenderink, 2014]] ; [[#Molina-Martínez--2016|Molina-Martínez et al., 2016]] ; [[#Moret--2016|Moret et al., 2016]] ; [[#Freeman--2018|Freeman et al., 2018]] ) ( ''medium confidence'' ). A shift of the Guianan-Amazon mangroves (H37) to higher grounds inland was attributed to the effects of observed sea level rise ( ''low confidence'' ) ( [[#Cohen--2018|Cohen et al., 2018]] ).

In Europe, the Mediterranean hotspot (H216) has seen increases in wildfires and droughts attributed to anthropogenic climate change ( [[#Gudmundsson--2017|Gudmundsson et al., 2017]] ; [[#Barbero--2020|Barbero et al., 2020]] ). Range shifts in birds have been observed at higher elevations ( ''medium confidence'' ) ( [[#Tellería--2020|Tellería, 2020]] ).

In Africa, multiple lines of evidence suggest woody plants are increasing in area, density and cover in previously lightly wooded savanna and grassland hotspots (H65, 82) ( [[#Poulsen--2015|Poulsen and Hoffman, 2015]] ; [[#Stevens--2017|Stevens et al., 2017]] ). Significant vulture and cheetah range reductions in these hotspots are at least partially attributable to bush encroachment ( [[#Nghikembua--2016|Nghikembua et al., 2016]] ; [[#Wolter--2016|Wolter et al., 2016]] ; [[#Santangeli--2018|Santangeli et al., 2018]] ). Thus, climate-driven bush encroachment has adversely affected unique mammal and bird diversity ( ''robust evidence, medium agreement, medium confidence'' ). Warming and drying trends have historically been shown to reduce the range of the Ethiopian wolf ( ''Canis simensis'' ), and they interact with land use pressures in the Ethiopian hotspot (H68) ( [[#Sintayehu--2018|Sintayehu, 2018]] ) and plant species richness in the Cape Fynbos (H65) of southern Africa to reduce post-wildfire recruitment ( ''low confidence'' ) ( [[#Slingsby--2017|Slingsby et al., 2017]] ).

Observed impacts in Asia were mostly restricted to the Himalaya (H95, 98, 99), Sundaland (H109, 110, 111, 112, 117, 118) and Indo-Burma (H105, 106, 107, 114, 115) hotspots, showing negative impacts through increased invasion by exotic plants, decreased suitable area for endemic species and significant changes in phenology ( ''medium confidence'' ) ( [[#Telwala--2013|Telwala et al., 2013]] ; [[#Braby--2014|Braby et al., 2014]] ; [[#Padalia--2015|Padalia et al., 2015]] ; [[#Lamsal--2017|Lamsal et al., 2017]] ). In the Central Asian mountain landscape (H87), studies have shown increased aridity induced by climate change impacts on several shrub species ( [[#Seim--2016|Seim et al., 2016]] ). Some positive effects were observed for native species in terms of an increase of suitable habitat ( ''limited evidence, low agreement'' ) ( [[#Priti--2016|Priti et al., 2016]] ; [[#Tang--2017|Tang et al., 2017]] ; [[#Rathore--2019|Rathore et al., 2019]] ).

In Australia, climate change has been implicated in: drought-induced canopy dieback across a range of forest and woodland types due to decades of declining rainfall in the southwestern hotspot (H133); fires in the palaeo-endemic pencil pine forests (Tasmania H142); declines in vertebrates in the Australian Wet Tropics World Heritage Area, which overlaps with the eastern part of the northern Australia hotspot (H131), related to warming and increased length of the dry season; and declines in grass and increases in shrubs in the Bogong High Plains ( ''high confidence'' ) ( [[#Hoffmann--2019|Hoffmann et al., 2019]] ). The Australian Alps have seen increased species diversity following retreat of the snow line ( [[#Slatyer--2010|Slatyer, 2010]] ), replacement of long-lived trees by short-lived shrubs following multiple wildfires ( [[#Zylstra--2018|Zylstra, 2018]] ), and changing ecological interactions due to climate-related snow loss, drought and fires ( ''high confidence'' ) ( [[#Hoffmann--2019|Hoffmann et al., 2019]] ). While warming is allowing mangroves to expand their range in coastal hotspots of Asia and Australia ( [[#Ward--2016|Ward et al., 2016]] ; [[#Hughes--2019a|Hughes et al., 2019a]] ), drought and associated salinity stress has killed mangroves in northern Australia hotspots ( [[#Babcock--2019|Babcock et al., 2019]] ).

Approximately 76% of biodiversity hotspots within this assessment either contain, or are comprised of islands &gt;100 km 2 (Table CCP1.1). However, just 0.08% of these hotspots were represented in post-AR5 literature examining climate change impacts on terrestrial biodiversity. Most observed impacts were assessed with ''low evidence'' , but ''high agreement'' , and focused on plants and insects. Impacts described included abundance changes and extirpations ( [[#Jenouvrier--2014|Jenouvrier et al., 2014]] ), altitudinal range shifts ( [[#Koide--2017|Koide et al., 2017]] ), increased invasive alien species’ abundance and extent in Madagascar (H76, 77), Balearic (H51) and Pacific islands ( [[#Ghulam--2014|Ghulam, 2014]] ; [[#Silva-Rocha--2015|Silva-Rocha et al., 2015]] ; [[#Goulding--2016|Goulding et al., 2016]] ; [[#Dawson--2017|Dawson et al., 2017]] ), increased temperature affecting physiology, body size and behaviour of frogs in the Caribbean (H20) ( [[#Narins--2014|Narins and Meenderink, 2014]] ) and phenological alterations ( [[#Fontúrbel--2018|Fontúrbel et al., 2018]] ). One positive observation was the high resilience to recovery of intact forest ecosystems to tropical cyclones within Caribbean (H20) and Pacific islands ( ''medium confidence'' ) ( [[#Keppel--2014|Keppel et al., 2014]] ; [[#Marler--2014|Marler, 2014]] ; [[#Shiels--2014|Shiels et al., 2014]] ).

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==== 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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