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

==== 9.5.3.1 Temperature ====

<div id="h3-16-siblings" class="h3-siblings"></div>

<div id="9.5.3.1.1" class="h4-container"></div>

<span id="observations-2"></span>
===== 9.5.3.1.1 Observations =====

<div id="h4-9-siblings" class="h4-siblings"></div>

Observed mean annual and seasonal temperatures have increased 1–3°C since the mid-1970s with the highest increases in the Sahara and Sahel (Figures 9.13a; [[#Cook--2015|Cook and Vizy, 2015]] ; [[#Lelieveld--2016|Lelieveld et al., 2016]] ; [[#Dosio--2017|Dosio, 2017]] ; [[#Nikiema--2017|Nikiema et al., 2017]] ; [[#Gutiérrez--2021|Gutiérrez et al., 2021]] ; [[#Ranasinghe--2021|Ranasinghe et al., 2021]] ) and positive trends in mean annual maximum (TX) and minimum (TN) of 0.16°C and 0.28°C per decade, respectively ( [[#Mouhamed--2013|Mouhamed et al., 2013]] ; [[#Moron--2016|Moron et al., 2016]] ; [[#Russo--2016|Russo et al., 2016]] ; [[#Barry--2018|Barry et al., 2018]] ). The frequency of very hot days (TX &gt; 35°C) and tropical nights has increased by 1–9 days and 4–13 nights per decade between 1961–2014 (Moron et al 2016), and cold nights have become less frequent ( [[#Fontaine--2013|Fontaine et al., 2013]] ; [[#Mouhamed--2013|Mouhamed et al., 2013]] ; [[#Barry--2018|Barry et al., 2018]] ). In the 21st century, heatwaves have become hotter, longer and more extended compared to the last two decades of the 20th century ( [[#Mouhamed--2013|Mouhamed et al., 2013]] ; [[#Moron--2016|Moron et al., 2016]] ; [[#Russo--2016|Russo et al., 2016]] ; [[#Barbier--2018|Barbier et al., 2018]] ).

<div id="9.5.3.1.2" class="h4-container"></div>

<span id="projections-2"></span>
===== 9.5.3.1.2 Projections =====

<div id="h4-10-siblings" class="h4-siblings"></div>

At 1.5°C, 2°C and 3°C of global warming above pre-industrial levels, mean annual temperatures in west Africa are projected to be on average, 0.6°C, 1.1°C and 2.1°C warmer than the 1994–2005 average, respectively (Figure 9.16a). Under mid- and high-emission scenarios end of century summer temperatures are projected to increase by 2°C and 5°C, respectively ( [[#Sylla--2015a|Sylla et al., 2015a]] ; [[#Russo--2016|Russo et al., 2016]] ; [[#Dosio--2017|Dosio, 2017]] ). The annual number of hot days is projected to increase at all global warming levels with larger increases at higher warming levels (Figure 9.16b). By 2060 the frequency of hot nights is projected to be almost double the 1981–2010 average at GWL 2°C ( [[#Dosio--2017|Dosio, 2017]] ; [[#Bathiany--2018|Bathiany et al., 2018]] ; [[#Gutiérrez--2021|Gutiérrez et al., 2021]] ; [[#Ranasinghe--2021|Ranasinghe et al., 2021]] ). Heatwave frequency and intensity are projected to increase under all scenarios, but limiting global warming to 1.5°C leads to a decreased heatwave magnitude (–35%) and frequency (–37%) compared to 2°C global warming ( [[#Dosio--2017|Dosio, 2017]] ; [[#Weber--2018|Weber et al., 2018]] ; [[#Nangombe--2019|Nangombe et al., 2019]] ). Children born in 2020, under a 1.5°C-compatible scenario will be exposed to 4–6 times more heatwaves in their lifetimes compared to people born in 1960; this exposure increases to 7–9 times more heatwaves at GWL 2.4°C ( [[#Thiery--2021|Thiery et al., 2021]] ).

The number of dangerous heat days (TX &gt;40.6°C) is projected to increase from approximately 60 per year in 1985–2005 to approximately 110, 130 and 140 under RCP2.6, RCP4.5 and RCP8.5, respectively, in the 2060s and to 105, 145 and 196 in the 2090s ( [[#Rohat--2019|Rohat et al., 2019]] ). Over tropical west Africa, heat-related mortality risk through increased heat and humidity is 6–9 times higher than the 1950–2005 average at GWL 2°C, 8–15 times at GWL 2.65°C and 15–30 times at GWL 4.12°C ( [[#Ahmadalipour--2018|Ahmadalipour and Moradkhani, 2018]] ) ( [[#Coffel--2018|Coffel et al., 2018]] ). The number of potentially lethal heat days per year is projected to increase from &lt;50 during 1995–2005 to 50–150 at GWL 1.6°C, 100–250 at GWL 2.5°C and 250–350 at GWL 4.4°C, with highest increases in coastal regions ( [[#Mora--2017|Mora et al., 2017]] ). Increasing urbanisation concentrates this exposure in cities, such as Lagos, Niamey, Kano and Dakar ( [[#9.9.3|Section 9.9.3.1]] ; [[#Coffel--2018|Coffel et al., 2018]] ; [[#Rohat--2019|Rohat et al., 2019]] ).

<div id="9.5.3.2" class="h3-container"></div>

<span id="precipitation-1"></span>