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

==== [[#Atlas.5.4.2|Atlas.5.4.2]] Assessment and Synthesis of Observations, Trends and Attribution ====

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Within the last decade, there has been an increasing number of studies on climatic trends over South East Asia, carried out on a regional basis ( [[#Thirumalai--2017|Thirumalai et al., 2017]] ; [[#Cheong--2018|Cheong et al., 2018]] ) or focused on specific countries ( [[#Cinco--2014|Cinco et al., 2014]] ; [[#Villafuerte--2014|Villafuerte et al., 2014]] ; [[#Mayowa--2015|Mayowa et al., 2015]] ; [[#Villafuerte--2015|Villafuerte and Matsumoto, 2015]] ; [[#Guo--2017a|Guo et al., 2017a]] ; [[#Supari--2017|Supari et al., 2017]] ; [[#Sa’adi--2019|Sa’adi et al., 2019]] ; [[#Tan--2021|Tan et al., 2021]] ). They document ''virtually certain'' significant increases in mean as well as extreme temperature. The minimum temperature extremes ''very likely'' warmed faster compared to the maximum temperature. Temperatures, including extremes, are strongly influenced by ENSO in the region ( [[#Cinco--2014|Cinco et al., 2014]] ; [[#Thirumalai--2017|Thirumalai et al., 2017]] ; [[#Cheong--2018|Cheong et al., 2018]] ). Over much of the region, extreme high temperatures occurred mostly in April and almost all April extreme temperatures occur in El Niño years ( [[#Thirumalai--2017|Thirumalai et al., 2017]] ). In most of South East Asia (except for the north-eastern areas), there was ''likely'' an increase in the number of warm nights with El Niño episodes within the period 1972–2010 ( [[#Cheong--2018|Cheong et al., 2018]] ).

Changes in mean precipitation are less spatially coherent over South East Asia. Over Thailand, the average number of rain days has decreased by 1.3 to 5.9 days per decade while average daily rainfall intensity has increased by 0.24–0.73 mm day <sup>–1</sup> per decade ( [[#Limsakul--2016|Limsakul and Singhruck, 2016]] ). Precipitation is also affected by ENSO events ( [[#Tangang--2017|Tangang et al., 2017]] ; Supari et al., 2018). Over South East Asia, there has been a significant increase in the amount of precipitation and its extremes with La Niña episodes in the past decades, especially during the winter monsoon period ( ''high confidence'' ) ( [[#Villafuerte--2015|Villafuerte and Matsumoto, 2015]] ; [[#Limsakul--2016|Limsakul and Singhruck, 2016]] ; [[#Cheong--2018|Cheong et al., 2018]] ).

Figure Atlas.11 shows trends in mean temperature and precipitation during 1961–2015 for two global datasets, indicating a significant overall warming over South East Asia ( ''high confidence'' ), with higher rates of warming in Malaysia, Indonesia, and the southern areas of mainland South East Asia ( ''low confidence'' ). Annual mean precipitation trends ( [[#Atlas.1.4.1|Atlas.1.4.1]] and the Interactive Atlas, which includes the regional dataset Aphrodite) over the region are mostly not significant except for increases over parts of Malaysia, Vietnam and the southern Philippines ( ''medium confidence'' ).

It is important to note that the availability, quality, and temporal and spatial density of observation data may lead to uncertainties and varying results in South East Asia ( [[#Juneng--2016|Juneng et al., 2016]] ). Some efforts have been made to produce better observationally-based gridded datasets for the region (e.g., [[#Nguyen-Xuan--2016|Nguyen-Xuan et al., 2016]] ; [[#van%20den%20Besselaar--2017|van den Besselaar et al., 2017]] ; [[#Yatagai--2020|Yatagai et al., 2020]] ).

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