Editing IPCC:AR6/WGII/Chapter-9 (section)

==== 9.6.2.2 Terrestrial Biodiversity ====

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Local extinction is when a species is extirpated from a local site. The magnitude and extent of local extinctions predicted across Africa increase substantially under all future GWLs ( ''high confidence'' ) (Table 9.5; Figure 9.19). Above 2°C, the risk of sudden disruption or loss of local biodiversity increases and becomes more widespread, especially in central, west and east Africa ( [[#Trisos--2020|Trisos et al., 2020]] ).

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[[File:d2c9e11f54cfd15d667d0193002e6a07 IPCC_AR6_WGII_Figure_9_019.png]]

'''Figure 9.19 |''' '''The loss of African biodiversity under future climate change is projected to be widespread and increasing substantially with every 0.5° above the current (2001–2020) level of global warming (''' high confidence ''').'''

'''(a)''' Projected biodiversity loss, quantified as percentage change in species abundance, range size or area of suitable habitat increases with increasing global warming levels (relative to 1850–1900). Above 1.5°C global warming, half of all assessed species are projected to lose &gt;30% of their population, range size or area of suitable habitat, with losses increasing to &gt;40% for &gt;2°C. The 2001–2020 level of global warming is around 1°C higher than 1850–1900 ( [[#IPCC--2021|IPCC, 2021]] ). Boxplots show the median (horizontal line), 50% quantiles (box), and points are studies of individual species or of multiple species (symbol size indicates the number of species in a study).

'''(b–c)''' The mean projected local extinction of vertebrates, plants and insects within 100 km grid cells increases in severity and extent under increased global warming (relative to 1850–1900). Local extinction &gt;10% is widespread by 1.5°C. Pixel colour shows the projected percentage of species undergoing local extinction and the agreement between multiple biodiversity models.

'''(d–e)''' The mean projected increase in species of freshwater fish vulnerable to local extinction within 10 km grid cells for future global warming. Around a third of fish species are projected to be vulnerable to extinction by 2°C global warming. Pixel colour shows the projected percentage of species vulnerable to extinction and agreement between multiple vulnerability models. In (a), data were obtained from 22 peer-reviewed papers published since 2012 investigating the impacts of projected climate change on African biodiversity. When a paper provided impact projections for several time periods, climate change scenarios or for more than one species, each impact was recorded as an individual biodiversity impact projection, resulting in a database of 1165 biodiversity impact projections. Data were initially collected by [[#Manes--2021|Manes et al. (2021)]] as part of a larger literature review for [https://www.ipcc.ch/chapter/cross-chapter-paper-1 Cross-Chapter Paper 1] on Biodiversity Hotspots and then expanded to include areas outside of African priority conservation areas (see Table SM 9.4). The literature review was limited to peer-reviewed publications that reported quantifiable risks to biodiversity, eliminating non-empirical studies. In (b–c), projections are based on intersecting current and future modelled species distributions at ~10 km spatial resolution from two recent global assessments of climate change impacts on terrestrial vertebrates ( [[#Newbold--2018|Newbold, 2018]] ; [[#Warren--2018|Warren et al., 2018]] ). In (d-e) projections are based on intersecting future species vulnerabilities from two recent assessments of climate change vulnerability of freshwater fish species ( [[#Nyboer--2019|Nyboer et al., 2019]] ; [[#Barbarossa--2021|Barbarossa et al., 2021]] ).

Global extinction is when a species is extirpated from all areas. At 2°C global warming, 11.6% of African species (mean 11.6%, 95% CI 6.8–18.2%) assessed are at risk of global extinction, placing Africa second only to South America in the magnitude of projected biodiversity losses ( [[#Urban--2015|Urban, 2015]] ). At &gt;2°C, 20% of north African mammals may lose all suitable climates ( [[#Soultan--2019|Soultan et al., 2019]] ), and over half of the dwarf succulents in South African Karoo may lose &gt;90% of their suitable habitat ( [[#Young--2016|Young et al., 2016]] ). Among the thousands of species at risk, many are species of ecological, cultural and economic importance such as African wild dogs ( [[#Woodroffe--2017|Woodroffe et al., 2017]] ) and Arabica coffee ( [[#Moat--2019|Moat et al., 2019]] ).

With increasing warming, there is a lower likelihood species can migrate rapidly enough to track shifting climates, increasing global extinction risk and biodiversity loss across more of Africa ( ''high confidence'' ). Immigration of species from elsewhere may partly compensate for local extinctions and lead to local biodiversity gains in some regions ( [[#Newbold--2018|Newbold, 2018]] ; [[#Warren--2018|Warren et al., 2018]] ). However, more regions face net losses than net gains. At 1.5°C global warming, &gt;46% of localities face net declines in vertebrate species richness of &gt;10%, with net increases projected for less than 15% of localities ( [[#Barbet-Massin--2015|Barbet-Massin and Jetz, 2015]] ; [[#Newbold--2018|Newbold, 2018]] ). At &gt;2°C, 9% of species face complete range loss by 2100, regardless of their dispersal ability ( [[#Urban--2015|Urban, 2015]] ). With &gt;4°C global warming, a net loss of &gt;10% of vertebrate species richness is projected across 85% of Africa ( [[#Barbet-Massin--2015|Barbet-Massin and Jetz, 2015]] ; [[#Mokhatla--2015|Mokhatla et al., 2015]] ; [[#Newbold--2018|Newbold, 2018]] ; [[#Warren--2018|Warren et al., 2018]] ). Mountain top endemics and species in north and southern Africa are at risk due to disappearing cold climates ( [[#Milne--2015|Milne et al., 2015]] ; [[#Garcia--2016|Garcia et al., 2016]] ; [[#Bentley--2018|Bentley et al., 2018]] ; [[#Soultan--2019|Soultan et al., 2019]] ). For hot regions such as the Sahara, Congo Basin and Kalahari, no warmer-adapted species are available elsewhere to compensate for local extinctions, so the resilience of local biodiversity will depend entirely on the persistence of species ( [[#Burrows--2014|Burrows et al., 2014]] ; [[#Garcia--2014|Garcia et al., 2014]] ). The capacity for species to avoid extinction through behavioural thermoregulation, plasticity or evolution is uncertain but will become increasingly ''unlikely'' under higher warming scenarios ( [[#Conradie--2019|Conradie et al., 2019]] ).

'''Table 9.5 |''' Risk of local extinction increases across Africa with increasing global warming.

{| class="wikitable"
|-
! '''Global warming level (relative to 1850–1900)'''

! '''Taxa'''

! '''Percentage of species at a site at risk of local extinction'''

! '''Extent across Africa (percentage of the land area of Africa)'''

! '''Areas at risk'''

! '''References'''

|-
| 1.5°C

| Plants, insects, vertebrates

| &gt;10%

| &gt;90%

| Widespread. Hot and/or arid regions especially at risk, including Sahara, Sahel and Kalahari

| Figure 9.29b; [[#Newbold--2018|Newbold (2018)]] ; [[#Warren--2018|Warren et al. (2018)]]

|-
| &gt;2°C

| Plants, insects, vertebrates

| &gt;50%

| 18%

| Widespread

| [[#Newbold--2018|Newbold (2018)]] ; [[#Warren--2018|Warren et al. (2018)]]

|-
| &gt;4°C

| Plants, insects, vertebrates

| &gt;50%

| 45–73%

| Widespread. Higher uncertainty for central African tropical forests due to lower agreement between biodiversity models

| Fig. 9.29c; [[#Newbold--2018|Newbold (2018)]] ; [[#Warren--2018|Warren et al. (2018)]]

|}

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