Editing IPCC:AR6/WGI/Chapter-12 (section)

==== 12.4.1.3 Wind ====

<div id="h3-37-siblings" class="h3-siblings"></div>

'''Mean wind speed:''' Decreasing trends in wind speeds have occurred in many parts of Africa ( ''low confidence'' due to observations with limited homogeneity) ( [[#McVicar--2012|McVicar et al., 2012]] ; AR5 WGI). There is ''high confidence'' in climate change-induced future decreasing mean wind, wind energy potential and strong winds in North Africa and Mediterranean regions as a consequence of the poleward shift of the Hadley cell ( [[#Karnauskas--2018a|Karnauskas et al., 2018a]] ; [[#Kjellström--2018|Kjellström et al., 2018]] ; [[#Sivakumar--2018|Sivakumar and Lucio, 2018]] ; [[#Tobin--2018|Tobin et al., 2018]] ; [[#Jung--2019|Jung and Schindler, 2019]] ) in the RCP4.5 and RCP8.5 scenarios by the middle of the century or beyond, and for a GWL of 2°C or higher. Over Western Africa and Southern Africa a future significant increase in wind speeds and wind energy potential is expected ( ''medium confidence'' ) (Figure 12.4m–o; [[#Karnauskas--2018a|Karnauskas et al., 2018a]] ; [[#Jung--2019|Jung and Schindler, 2019]] ).

'''Severe wind storm:''' A limited number of studies allow an assessment of past trends in wind storms. In West Africa and specifically in the Sahel band, more intense storms have occurred since the 1980s ( ''low confidence, limited evidence'' ). A persistent and large increase of frequency of Sahelian mesoscale convective storms has been found in several studies ( [[#Panthou--2014|Panthou et al., 2014]] ; C.M. [[#Taylor--2017|]] [[#Taylor--2017|Taylor et al., 2017]] ), with consequences for extreme rainfalls, and potentially extreme winds ( ''low confidence, limited evidence'' ). There is ''low confidence'' of a general increasing trend in extreme winds across Western, Central, Eastern and Southern Africa in a majority of regions by the middle of the century even in high-end scenarios. The frequency of Mediterranean wind storms reaching North Africa, including Medicanes, is projected to decrease, but their intensities are projected to increase, by the mid-century and beyond under SRES A1B, SRES A2 and RCP8.5 ( ''medium confidence'' ) (Chapter 11; [[#Cavicchia--2014|Cavicchia et al., 2014]] ; [[#Walsh--2014|Walsh et al., 2014]] ; [[#Tous--2016|Tous et al., 2016]] ; [[#Romera--2017|Romera et al., 2017]] ; [[#Romero--2017|Romero and Emanuel, 2017]] ; [[#González-Alemán--2019|González-Alemán et al., 2019]] ).

'''Tropical cyclone:''' In the South Indian Ocean, an increase in Category 5 cyclones has been observed in recent decades ( [[#Fitchett--2018|Fitchett, 2018]] ) as in other basins ( [[IPCC:Wg1:Chapter:Chapter-11#11.7|Section 11.7]] ). However, there is a projected decrease in the frequency of tropical cyclones making landfall over Madagascar, South Eastern Africa and East Southern Africa in a 1°C, 2°C and 3°C warmer world ( ''medium confidence'' ) ( [[#Malherbe--2013|Malherbe et al., 2013]] ; [[#Roberts--2015|Roberts et al., 2015]] , 2020; [[#Muthige--2018|Muthige et al., 2018]] ; [[#Knutson--2020|Knutson et al., 2020]] ). There is ''medium confidence'' in general increasing intensities for cyclones in such studies for African regions.

'''Sand and dust storm:''' North Africa and the Sahel, and to a lesser extent Southern Africa, are prone to dust storms, having consequences on health ( [[#Querol--2019|Querol et al., 2019]] ), transmission of infectious diseases ( [[#Agier--2013|Agier et al., 2013]] ; [[#Wu--2016|Wu et al., 2016]] ), and solar power generation and related maintenance costs. There is ''limited evidence'' and ''low agreement'' of secular 20th century trends in wind speeds or dust emissions (limited length of data records, large variability). Dust variations are controlled by changes in surface winds, precipitation and vegetation, which in turn are modulated at multiple time scales by dominant modes of internal climate variability (Chapter 10). In North Africa, wind variability explains both the observed high concentrations between the 1970s and 1980s and lower concentrations thereafter ( [[#Ridley--2014|Ridley et al., 2014]] ; [[#Evan--2016|Evan et al., 2016]] ). Yet, the effect of vegetation changes may not be negligible ( [[#Pu--2017|Pu and Ginoux, 2017]] , 2018).

Changes to the frequency and intensity of dust storms also remain largely uncertain due to uncertainty in future regional wind and precipitation as the climate warms, CO <sub>2</sub> fertilization effects on vegetation ( [[#Huang--2017|Huang et al., 2017]] ), and anthropogenic land use and land-cover change due to land management and invasive species ( [[#Ginoux--2012|Ginoux et al., 2012]] ; [[#Webb--2018|Webb and Pierre, 2018]] ). Dust loadings and related air pollution hazards (from fine particles that affect health) are projected to generally decrease in many regions of the Sahara and Sahel due to the changing winds ( [[#Evan--2016|Evan et al., 2016]] ) and slightly increase over the Guinea coast and West Africa ( ''low confidence'' ) ( [[#Ji--2018|Ji et al., 2018]] ).

'''In summary, there is''' high confidence '''of a decrease in mean wind speed and wind energy potential in North Africa and''' medium confidence '''of an increase in Southern and Western Africa, by the middle of the century regardless of climate scenario or global warming level equal or superior to 2°C,''' high confidence '''of a decrease in frequency of cyclones landing in SEAF, ESAF and MDG, and''' low confidence '''of a general increase in wind storms in most African regions located south of the Sahel. The evolution of dust storms remains largely uncertain.'''

<div id="12.4.1.4" class="h3-container"></div>

<span id="snow-and-ice-1"></span>