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

==== [[#Atlas.5.3.2|Atlas.5.3.2]] Assessment and Synthesis of Observations, Trends and Attribution ====

<div id="h3-25-siblings" class="h3-siblings"></div>

Recent studies show that annual mean land temperatures over Indiawarmed at a rate of around 0.6°C per century during 1901–2018, which was primarily contributed by a significant increase in annual maximum temperature of 1.0°C per century, while the annual minimum temperature showed a lesser increasing trend of 0.18°C per century during this period, with a significant rise only in the recent few decades (1981–2010) at a rate of 0.17°C per decade ( [[#Srivastava--2017|Srivastava et al., 2017]] , 2019). The annual average of daily maximum and minimum temperatures has increased over almost all Pakistan with a faster increasing trend in the south ( ''high confidence'' ). Minimum temperatures have increased faster (0.17°C–0.37°C per decade) than maximum temperatures (0.17°C–0.29°C per decade) with the diurnal temperature range reduced (–0.15°C to –0.08°C per decade) in some regions ( [[#Khan--2019|Khan et al., 2019]] ).

There has been a noticeable declining trend in rainfall with monsoon deficits occurring with higher frequency in different regions in South Asia (see also [[IPCC:Wg1:Chapter:Chapter-8#8.3.2.4|Section 8.3.2.4]] on the South Asian monsoon). Concurrently, the frequency of heavy precipitation events has increased over India, while the frequency of moderate rain events has decreased since 1950 ( ''high confidence'' ) ( [[#Goswami--2006|Goswami et al., 2006]] ; [[#Dash--2009|Dash et al., 2009]] ; [[#Christensen--2013|Christensen et al., 2013]] ; [[#Krishnan--2016|Krishnan et al., 2016]] ; [[#Kulkarni--2017|Kulkarni et al., 2017]] ; [[#Roxy--2017|Roxy et al., 2017]] ). There is a considerable spread in the seasonal and annual mean precipitation climatology and interannual variability among the different observed precipitation datasets over India ( [[#Collins--2013|Collins et al., 2013]] ; [[#Prakash--2014|Prakash et al., 2014]] ; [[#Kim--2018|Kim et al., 2018]] ; [[#Ramarao--2019|Ramarao et al., 2019]] ). Yet, the regions of agreement among datasets lend ''high confidence'' that there has been a decrease in mean rainfall over most parts of the eastern and central north regions of India ( [[#Singh--2014|Singh et al., 2014]] ; [[#Roxy--2015|Roxy et al., 2015]] ; [[#Juneng--2016|Juneng et al., 2016]] ; [[#Krishnan--2016|Krishnan et al., 2016]] ; [[#Guhathakurta--2017|Guhathakurta and Revadekar, 2017]] ; [[#Jin--2017|Jin and Wang, 2017]] ; [[#Latif--2017|Latif et al., 2017]] ). A global modelling study with high resolution over South Asia ( [[#Sabin--2013|Sabin et al., 2013]] ) indicated that a juxtaposition of regional land-use changes, anthropogenic-aerosol forcing and the rapid warming signal of the Equatorial Indian Ocean was crucial to simulate the observed Indian summer monsoon weakening in recent decades ( ''medium confidence'' ).

A dipole-like structure in summer monsoon rainfall trends is observed over the northern Indo-Pakistan area with significant increases over Pakistan and decreases over central north India resulting from strengthening (weakening) of vertically integrated meridional moisture transport over the Arabian Sea (Bay of Bengal) ( ''low confidence'' ) ( [[#Latif--2017|Latif et al., 2017]] ). Positive annual precipitation trends are observed in global and regional datasets (Figure Atlas.11 and the Interactive Atlas) during 1961–2015 and over arid provinces of Pakistan (for rabi and kharif cropping seasons) during 1951–2015 of 2.8–34.8 mm per decade ( [[#Khan--2020|Khan et al., 2020]] ) imply ''high confidence'' for increased precipitation in Pakistan. Observations located in the monsoon-dominated strip in Pakistan indicate that the mean monsoon onset became earlier during 1971–2010 ( [[#Ali--2020|Ali et al., 2020]] ).

Snow and glaciers are major water resources of all countries in South Asia. Glacier melting is mainly controlled by natural phenomena but anthropogenic emissions of black carbon (BC) are now making a significant contributing to total glacial melting in the Hindu Kush Himalaya (HKH) region ( [[#Menon--2002|Menon, 2002]] ; [[#Ramanathan--2007|Ramanathan et al., 2007]] ; [[#Ramanathan--2008|Ramanathan and Carmichael, 2008]] ). BC concentration is seven to 10 times higher in mid-altitudes (1000–4000 metres above sea level) than at high altitudes (&gt;4000 metres above sea level). The concentration of BC sampled from the surface of snow/ice samples as well as ice-core records shows decreasing ice albedo and an acceleration in glacier melting (Cross-Chapter Box 10.4; [[#Wester--2019|Wester et al., 2019]] ). Karakoram and western HKH snow cover is increasing, a phenomena known as the ‘Karakoram anomaly’, and partially attributed to an increase in the strength of westerly disturbances ( [[#Wester--2019|Wester et al., 2019]] ).

Significant glacier retreat has been observed since 1960 in TIB with lower rates in the interior of the region ( [[#Yao--2007|Yao et al., 2007]] ). A large inter-decadal variation in snow cover is also observed from 1960 to 2010. Observations and model simulations showed that the increasing temperature of frozen grounds is leading to thawing and reduced depth of permafrost, with further significant reductions projected under future global warming scenarios ( ''medium confidence'' ) ( [[#Yang--2019|Yang et al., 2019]] ).

<div id="Atlas.5.3.3" class="h3-container"></div>

<span id="atlas.5.3.3-assessment-of-model-performance"></span>