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

==== 9.6.2.4 Freshwater Ecosystems ====

<div id="h3-31-siblings" class="h3-siblings"></div>

Above 2°C global warming, the proportion of freshwater fish species vulnerable to climate change increases substantially ( ''high confidence'' ) (Figure 9.19). At 2°C, 36.4% of fish species are projected to be vulnerable to local or global extinction by 2100, increasing to 56.4% under 4°C warming (average of values from ( [[#Nyboer--2019|Nyboer et al., 2019]] ; [[#Barbarossa--2021|Barbarossa et al., 2021]] ) (Figure 9.19). Global warming reduces available habitat for freshwater species due to reduced precipitation and increased drought leading to increasing water temperatures above optimal physiological limits in floodplains, estuaries, wetlands, ephemeral pools, rivers and lakes ( [[#Dalu--2017|Dalu et al., 2017]] ; [[#Kalacska--2017|Kalacska et al., 2017]] ; [[#Nyboer--2018|Nyboer and Chapman, 2018]] ). Along the Zambezi River, projected flow reductions could cause a 22% reduction in annual spawning habitat and depletion of food resources for fry and juvenile fish that could impede fish migration and reduce stocks ( [[#Kangalawe--2017|Kangalawe, 2017]] ; [[#Martínez-Capel--2017|Martínez-Capel et al., 2017]] ; [[#Tamatamah--2020|Tamatamah and Mwedzi, 2020]] ). More aquatic species will have the capacity to cope with 2°C compared to 4°C global warming, with more negative effects on physiological performance at 4°C ( [[#Dallas--2016|Dallas, 2016]] ; [[#Pinceel--2016|Pinceel et al., 2016]] ; [[#Zougmoré--2016|Zougmoré et al., 2016]] ; [[#Nyboer--2017|Nyboer and Chapman, 2017]] ; [[#Ross-Gillespie--2018|Ross-Gillespie et al., 2018]] ). Endemic, specialised fish species will have a lower capacity to adjust to elevated water temperatures compared to hardier generalist fishes ( [[#McDonnell--2015|McDonnell and Chapman, 2015]] ; [[#Nyboer--2017|Nyboer and Chapman, 2017]] ; [[#Lapointe--2018|Lapointe et al., 2018]] ; [[#Reizenberg--2019|Reizenberg et al., 2019]] ). More work is needed to understand the risk for invertebrates ( [[#Dallas--2014|Dallas and Rivers-Moore, 2014]] ; [[#Cohen--2016|Cohen et al., 2016]] ), and to understand the potential effects of reduced mixing of water and other climate risks on freshwater biodiversity.

<div id="9.6.2.5" class="h3-container"></div>

<span id="climate-change-and-ecosystem-services"></span>