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

==== 12.4.2.3 Wind ====

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'''Mean wind speed:''' There is ''high confidence'' of the slowdown in terrestrial near-surface wind speed (SWS) in Asia by approximately –0.1 m s <sup>–1</sup> per decade since the 1950s based on observations and reanalysis data, with the significant decreases in Central Asia among the highest in the world followed by EAS and SAS (J. [[#Wu--2018|]] [[#Wu--2018|Wu et al., 2018]] ; [[#Tian--2019|Tian et al., 2019]] ; R. [[#Zhang--2019|]] [[#Zhang--2019|]] [[#Zhang--2019|]] [[#Zhang--2019|Zhang et al., 2019]] ). But a short-term strengthening in SWS was observed during the winter since 2000 in eastern China ( ''medium confidence'' ) ( [[#Zeng--2019|Zeng et al., 2019]] ; [[#Zha--2019|Zha et al., 2019]] ).

There is ''medium confidence'' of future declining mean SWS in Asia, except in SAS and SEA, as global projections indicate a decreasing trend in all climate scenarios for most of northern Asia, TIB and East Asia by the mid-century ( [[#Karnauskas--2018a|Karnauskas et al., 2018a]] ; [[#Fedotova--2019|Fedotova, 2019]] ; [[#Jung--2019|Jung and Schindler, 2019]] ; [[#Ohba--2019|Ohba, 2019]] ; J. [[#Wu--2020|]] [[#Wu--2020|Wu et al., 2020]] ; [[#Zha--2020|Zha et al., 2020]] ; Figure 12.4m–o), with negative effects on wind energy potential. Decreases in North Asia are generally modest, not exceeding 10% for the mid-century and 20% for the end of century for the RCP8.5 and RCP4.5 scenarios (Figure 12.4m–o).

'''Severe wind storms:''' Consistent with the general mean decreasing surface winds, there is ''medium confidence'' that strong winds declined faster than weak winds in the past few decades in Asia in general ( [[#Vautard--2010|Vautard et al., 2010]] ; [[#Tian--2019|Tian et al., 2019]] ), but evidence is lacking for spatial patterns. There is ''low confidence'' that extra-tropical cyclones will decline in number in future climate scenarios over WCA, TIB, WSB and ESB, and intensify over the Arctic regions as a result of the poleward shift of storm tracks ( [[#Basu--2018|Basu et al., 2018]] ; Chapter 11). There is ''limited evidence'' for projection of changes in severe winds occurring in convective storms in Asia.

'''Tropical cyclone:''' There was an increase in the number and intensification rate of intense tropical cyclones (TC), such as Category 4–5 (wind speeds &gt;58 m s <sup>–1</sup> ), in the Western North Pacific (WNP) and Bay of Bengal since the mid-1980s ( ''medium confidence'' ) ( [[IPCC:Wg1:Chapter:Chapter-11#11.7|Section 11.7]] ; [[#Kim--2016|Kim et al., 2016]] ; [[#Mei--2016|Mei and Xie, 2016]] ; [[#Walsh--2016a|Walsh et al., 2016a]] ; [[#Knutson--2019|Knutson et al., 2019]] ). There is ''medium confidence'' that there has been a significant north-westward shift in TC tracks and a poleward shift in the average latitude where TCs reach their peak intensity in the WNP since the 1980s ( [[#Knutson--2019|Knutson et al., 2019]] ; J. [[#Sun--2019|]] [[#Sun--2019|]] [[#Sun--2019|Sun et al., 2019]] ; [[#Lee--2020|Lee et al., 2020]] ), increasing exposure to TC passage and more destructive landfall over eastern China, Japan, and Korea in the last few decades ( [[#Kossin--2016|Kossin et al., 2016]] ; [[#Li--2017|Li et al., 2017]] ; [[#Altman--2018|Altman et al., 2018]] ; [[#Liu--2019|Liu and Chan, 2019]] ), and decreasing exposure in the region of SAS and southern China ( [[#Cinco--2016|Cinco et al., 2016]] ; [[#Kossin--2016|Kossin et al., 2016]] ; see Chapter 11). However, while the analysis shows fewer typhoons, more extreme TCs have affected the Philippines ( ''low confidence'' ) ( [[#Takagi--2016|Takagi and Esteban, 2016]] ). The frequency and duration of tropical cyclones has significantly increased over time over the Arabian Sea and insignificantly decreased over the Bay of Bengal during 1977–2018 ( ''low confidence'' ) ( [[#Fan--2020|Fan et al., 2020]] ).

There is ''medium confidence'' that future TC numbers will decrease but the maximum TC wind intensities will increase in the western Pacific as elsewhere (Chapter 11, see Figure 11.24; [[#Choi--2019|Choi et al., 2019]] ; [[#Cha--2020|Cha et al., 2020]] ; [[#Knutson--2020|Knutson et al., 2020]] ). The simulations for the late 21st century for the RCP8.5 scenario yield considerably more TCs in the WNP that exceed 49.4 m s <sup>−1</sup> (Category 3) intensity ( [[#Mclay--2019|Mclay et al., 2019]] ). There is ''medium confidence'' that the average location of the maximum wind will migrate poleward (see Chapter 11), and TC translation speeds at the higher latitudes would decrease ( [[#Yamaguchi--2020|Yamaguchi et al., 2020]] ). As a consequence, the intensity of TCs affecting the Japan Islands would increase in the future under the RCP8.5 scenario ( [[#Yoshida--2017|Yoshida et al., 2017]] ), whereas the frequency of TCs affecting the Philippine region and Vietnam is projected to decrease ( [[#Kieu-Thi--2016|Kieu-Thi et al., 2016]] ; [[#Wang--2017|]] [[#Wang--2017|]] [[#Wang--2017|C. Wang et al., 2017]] ; [[#Gallo--2019|Gallo et al., 2019]] ) ( ''medium confidence'' ).

'''Sand and dust storm''' : The Asia-Pacific region contributes 26.8 per cent to global dust emissions as of 2012 ( [[#UNESCAP--2018|UNESCAP, 2018]] ). In West Asia, the frequency of dust events has increased markedly in some areas (east and north-east of Saudi Arabia, north-west of Iraq and east of Syria) from 1980 to the present ( [[#Nabavi--2016|Nabavi et al., 2016]] ; [[#Alobaidi--2017|Alobaidi et al., 2017]] ). This marked dust increase has been associated with drought conditions in the Fertile Crescent ( [[#Notaro--2015|Notaro et al., 2015]] ; [[#Yu--2015|Yu et al., 2015]] ), ''likely'' amplified by anthropogenic warming ( [[#Kelley--2015|Kelley et al., 2015]] ; Chapter 10). Dust storm frequency in most regions of northern China show a decreasing trend since the 1960s due to the decrease in surface wind speed ( ''medium confidence'' ) ( [[#Guan--2017|Guan et al., 2017]] ).

While dust activity has decreased greatly over EAS, current climate models are unable to reproduce the trends ( [[#Guan--2015|Guan et al., 2015]] , 2017; [[#Zha--2017|Zha et al., 2017]] ; [[#Wu--2018|]] [[#Wu--2018|C. Wu et al., 2018]] ). Thus, there is ''limited evidence'' for future trends of sand and dust storms in Asia.

'''In conclusion, surface wind speeds have been decreasing in Asia''' ( high confidence '''), but there is a large uncertainty in future trends. There is''' medium confidence '''that mean wind speeds will decrease in Central and northern Asia, and that tropical cyclones will have decreasing frequency and increasing intensity overall.'''

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