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

==== 12.3.7.4 Impacts ====

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Increasing temperatures in SWS have impacted temperate forests ( ''high confidence'' ) ( [[#Peña--2014|Peña et al., 2014]] ; [[#Urrutia-Jalabert--2015|Urrutia-Jalabert et al., 2015]] ; [[#Camarero--2017|Camarero and Fajardo, 2017]] ; [[#Fontúrbel--2018|Fontúrbel et al., 2018]] ; [[#Venegas-González--2018b|Venegas-González et al., 2018b]] ; [[#Peña-Guerrero--2020|Peña-Guerrero et al., 2020]] ). Increasing temperatures and decreasing precipitation have increased the impacts of wildfires on terrestrial ecosystems ( ''high confidence'' ) ( [[#Boisier--2016|Boisier et al., 2016]] ; [[#Díaz-Hormazábal--2016|Díaz-Hormazábal and González, 2016]] ; [[#Martinez-Harms--2017|Martinez-Harms et al., 2017]] ; [[#de%20la%20Barrera--2018|de la Barrera et al., 2018]] ; [[#Gómez-González--2018|Gómez-González et al., 2018]] ; [[#Urrutia--2018|Urrutia et al., 2018]] ; [[#Bowman--2019|Bowman et al., 2019]] ), creating conditions for future landslides and floods ( [[#de%20la%20Barrera--2018|de la Barrera et al., 2018]] ).

Future projections show important changes in the productivity, structure and biogeochemical cycles of SWS temperate and rainforests ( ''medium confidence: medium evidence, high agreement'' ) ( [[#Gutiérrez--2014|Gutiérrez et al., 2014]] ; [[#Correa-Araneda--2020|Correa-Araneda et al., 2020]] ) and their fauna ( ''low confidence'' ) ( [[#Glade--2016|Glade et al., 2016]] ; [[#Bourke--2018|Bourke et al., 2018]] ). The Chilean Winter Rainfall-Valdivian Forests are a biodiversity hotspot ( [[#Manes--2021|Manes et al., 2021]] ) (Section [https://www.ipcc.ch/chapter/12#CCP1.2.2 CCP1.2.2] ) projected to suffer habitat change, with loss of vegetation cover in the future due to climate change ( ''medium confidence: medium evidence, high agreement'' ) ( [[#Jantz--2015|Jantz et al., 2015]] ; [[#Mantyka-Pringle--2015|Mantyka-Pringle et al., 2015]] ). Species are projected to suffer changes in their distribution, including a decrease in climatic refugia for vertebrates ( ''low confidence'' ) ( [[#Cuyckens--2015|Cuyckens et al., 2015]] ; [[#Warren--2018|Warren et al., 2018]] ).

Increasing temperatures have enlarged the number and areal extent of glacier lakes in the central Andes, northern Patagonia and southern Patagonia ( ''high confidence'' ) ( [[#Wilson--2018|Wilson et al., 2018]] ), while decreased rainfall and rapid glacier melting have provoked changes in the environmental, biogeochemical and biological properties of central-southern and Andes Chilean lakes ( ''low confidence'' ) ( [[#Pizarro--2016|Pizarro et al., 2016]] ).

Increasing glacier lake outburst floods (GLOFs), ice and rock avalanches, debris flows and lahars from ice-capped volcanoes have been observed in SWS ( [[#Iribarren%20Anacona--2015|Iribarren Anacona et al., 2015]] ; [[#Jacquet--2017|Jacquet et al., 2017]] ; [[#Reinthaler--2019b|Reinthaler et al., 2019b]] ). There is ''low evidence'' on the effects of warming and degrading permafrost on slope instability and landslides in these regions ( [[#Iribarren%20Anacona--2015|Iribarren Anacona et al., 2015]] ).

Increasing temperatures, decreasing precipitation regimes and an unprecedented long-term drought have decreased the annual average river streamflows that supply SWS megacities such as Santiago ( ''high confidence'' ) ( [[#Meza--2014|Meza et al., 2014]] ; [[#Muñoz--2020a|Muñoz et al., 2020a]] ), with important and negative effects on water quality ( [[#Bocchiola--2018|Bocchiola et al., 2018]] ; [[#Yevenes--2018|Yevenes et al., 2018]] ), threatening irrigated agriculture activities ( ''medium confidence: medium evidence, high agreement'' ) ( [[#Yevenes--2018|Yevenes et al., 2018]] ; [[#Oertel--2020|Oertel et al., 2020]] ; [[#Peña-Guerrero--2020|Peña-Guerrero et al., 2020]] ). Large reductions in the availability of groundwater in the SWS region ( [[#Meza--2014|Meza et al., 2014]] ) and a sustained decrease in the mean annual flows ( [[#Ragettli--2016|Ragettli et al., 2016]] ; [[#Bocchiola--2018|Bocchiola et al., 2018]] ), especially during the snowmelt season (Vargas et al., 2013), have been observed in SWS. Drought has affected wetlands ( ''low confidence'' ) ( [[#Zhao--2016|Zhao et al., 2016]] ; [[#Domic--2018|Domic et al., 2018]] ) and desert ecosystems ( ''medium confidence: medium evidence, high agreement)'' ( [[#Acosta-Jamett--2016|Acosta-Jamett et al., 2016]] ; [[#Neilson--2017|Neilson et al., 2017]] ; [[#Díaz--2019|Díaz et al., 2019]] ).

There is ''low evidence'' on shoreline retreat attributed to climate change ( [[#Martínez--2018|Martínez et al., 2018]] ; [[#Ministerio%20de%20Medio%20Ambiente%20de%20Chile--2019|Ministerio de Medio Ambiente de Chile, 2019]] ), although increasing wind intensity along the central Chilean coast has caused serious damage in coastal infrastructure and buildings ( [[#Winckler--2017|Winckler et al., 2017]] ) and changes in seawater properties and processes ( ''low confidence'' ) ( [[#Schneider--2017|Schneider et al., 2017]] ; [[#Aguirre--2018|Aguirre et al., 2018]] ). Ocean and coastal ecosystems in SWS are sensitive to upwelling intensity, which affects the abundance, diversity, physiology and survivorship of coastal species ( ''high confidence'' ) ( [[#Anabalón--2016|Anabalón et al., 2016]] ; [[#Jacob--2018|Jacob et al., 2018]] ; [[#Ramajo--2020|Ramajo et al., 2020]] ) (Figure 12.8). Increasing radiation and temperatures and reduced precipitation, in conjunction with increased nutrient load, have increased HAB events, producing massive fauna mortalities ( ''high confidence'' ) ( [[#León-Muñoz--2018|León-Muñoz et al., 2018]] ; [[#IPCC--2019b|IPCC, 2019b]] , SPM A8.2 and B8.3; [[#Quiñones--2019|Quiñones et al., 2019]] ; [[#Soto--2019|Soto et al., 2019]] ; [[#Armijo--2020|Armijo et al., 2020]] ). Multiple resources subjected to fisheries and aquaculture are highly vulnerable to storms, alluvial disasters, ocean warming, ocean acidification, increasing ENSO extreme events and lower oxygen availability ( ''high confidence'' ) (Figure 12.8; [[#García-Reyes--2015|García-Reyes et al., 2015]] ; [[#Silva--2015|Silva et al., 2015]] ; [[#Duarte--2016|Duarte et al., 2016]] , 2018; [[#Lagos--2016|Lagos et al., 2016]] ; [[#Navarro--2016|Navarro et al., 2016]] ; [[#Lardies--2017|Lardies et al., 2017]] ; [[#IPCC--2019b|IPCC, 2019b]] ; [[#Mellado--2019|Mellado et al., 2019]] ; [[#Ramajo--2019|Ramajo et al., 2019]] ; [[#Silva--2019a|Silva et al., 2019a]] ; [[#Bertrand--2020|Bertrand et al., 2020]] ). Ocean and coastal ecosystems, especially EEZs, will be highly impacted by climate change in the near and long term ( ''high confidence'' ) (Figure 12.8; Table SM12.3; [[#Silva--2015|Silva et al., 2015]] ; [[#Silva--2019a|Silva et al., 2019a]] ).

Changes in temperature and droughts have impacted crops significantly ( ''medium confidence: medium evidence, high agreement'' ) ( [[#Ray--2015|Ray et al., 2015]] ; [[#Zambrano--2016|Zambrano et al., 2016]] ; [[#Lesjak--2017|Lesjak and Calderini, 2017]] ; [[#Ferrero--2018|Ferrero et al., 2018]] ; [[#Piticar--2018|Piticar, 2018]] ; [[#Haddad--2019|Haddad et al., 2019]] ; [[#Zúñiga--2021|Zúñiga et al., 2021]] ). Table 12.4 shows the changes in crop growth duration, which affects yields. Higher negative numbers then indicate yield reduction for the crop. Increasing temperatures and decreasing precipitation are expected to impact the agriculture sector (i.e., fruits crops and forests) across the entire sub-region, with the largest impacts in the northern and central zone ( ''high confidence'' ) ( [[#Mera--2015|Mera et al., 2015]] ; [[#Zhang--2015|Zhang et al., 2015]] ; [[#Silva--2016|Silva et al., 2016]] ; [[#Lizana--2017|Lizana et al., 2017]] ; [[#Reyer--2017|Reyer et al., 2017]] ; [[#Toro-Mujica--2017|Toro-Mujica et al., 2017]] ; [[#Beyá-Marshall--2018|Beyá-Marshall et al., 2018]] ; [[#Lobos--2018|Lobos et al., 2018]] ; [[#O’Leary--2018|O’Leary et al., 2018]] ; [[#Aggarwal--2019|Aggarwal et al., 2019]] ; [[#Ávila-Valdés--2020|Ávila-Valdés et al., 2020]] ; [[#Fernandez--2020|Fernandez et al., 2020]] ; [[#Melo--2021|Melo and Foster, 2021]] ). Observed impacts and future projections warn that increasing temperatures and decreasing precipitation will largely impact water demand by agricultural sectors ( ''high confidence'' ) ( [[#Novoa--2019|Novoa et al., 2019]] ; [[#Peña-Guerrero--2020|Peña-Guerrero et al., 2020]] ; [[#Webb--2020|Webb et al., 2020]] ). Extreme climate events have caused Indigenous Peoples (e.g., Mapuche, Uru and Aymara) to experience water scarcity, a reduction in agricultural production and a displacement of their traditional knowledge and practices ( ''medium confidence: low evidence, high agreement'' ) ( [[#Parraguez-Vergara--2016|Parraguez-Vergara et al., 2016]] ; [[#Meldrum--2018|Meldrum et al., 2018]] ; [[#Perreault--2020|Perreault, 2020]] ).

SWS cities have been largely impacted by wildfires, water scarcity and landslides affecting highways and local roads, as well as potable water supply ( [[#Sepúlveda--2015|Sepúlveda et al., 2015]] ; [[#Araya-Muñoz--2016|Araya-]] [[#Muñoz--2016|Muñoz et al., 2016]] ). Increasing temperature and heat extreme events in cities have increased the demand for water, damage to urban infrastructure ( [[#Monsalves-Gavilán--2013|Monsalves-Gavilán et al., 2013]] ) and accelerated ageing and death of trees ( ''high confidence'' ) ( [[#Moser-Reischl--2019|Moser-Reischl et al., 2019]] ). Increasing temperature will modify energy demand in cities in northern and central Chile ( [[#Rouault--2019|Rouault et al., 2019]] ).

Increasing temperature, heat extreme events and air pollution in SWS have significantly impacted population health (cardiac complications, heat stroke and respiratory diseases) ( ''high confidence'' ) (Table 12.2; Leiva G et al., 2013; [[#Monsalves-Gavilán--2013|Monsalves-Gavilán et al., 2013]] ; [[#Pino--2015|Pino et al., 2015]] ; [[#Herrera--2016|Herrera et al., 2016]] ; [[#Henríquez--2017|Henríquez and Urrea, 2017]] ; [[#Ugarte-Avilés--2017|Ugarte-Avilés et al., 2017]] ; [[#de%20la%20Barrera--2018|de la Barrera et al., 2018]] ; [[#Johns--2018|Johns et al., 2018]] ; [[#Bowman--2019|Bowman et al., 2019]] ; [[#González--2019|González et al., 2019]] ; Matus C and Oyarzún G, 2019; [[#Sánchez--2019|Sánchez et al., 2019]] ; [[#Terrazas--2019|Terrazas et al., 2019]] ; [[#Cakmak--2021|Cakmak et al., 2021]] ; [[#Zenteno--2021|Zenteno et al., 2021]] ). There is ''low confidence'' regarding areal changes in Chagas disease ( [[#Tapia-Garay--2018|Tapia-Garay et al., 2018]] ; [[#Garrido--2019|Garrido et al., 2019]] ) and transmission rates in the future ( [[#Ayala--2019|Ayala et al., 2019]] ).

'''Table 12.4 |''' Average percentage change in crop growth duration for the period 2015–2019. Crop growth duration refers to the time taken in a year for crops to accumulate the reference period (1981–2010) average growing season accumulated temperature total (ATT). As temperatures rise, the ATT is reached earlier (higher negative changes), the crop matures too quickly, and thus yields are lower. “No data” means no data are available for the growth of that crop in the specified region. NP means that the crop is not present in significant areas in that region. Data were derived from Romanello et al. (2021).

{| class="wikitable"
|-
! '''Region'''

! '''Winter wheat'''

! '''Spring wheat'''

! '''Rice'''

! '''Maize'''

! '''Soybean'''

|-
| Central America (CA)

| −4.8%

| No data

| −1.9%

| −5.0%

| −4.7%

|-
| Northwestern South America (NWS)

| −3.8%

| −5.2%

| −5.2%

| −5.6%

| −3.1%

|-
| Northern South America (NSA)

| NP

| NP

| −0.7%

| −3.1%

| 0.0%

|-
| South America Monsoon (SAM)

| −5.3%

| −0.7%

| −1.4%

| −2.9%

| −1.5%

|-
| Northeastern South America (NES)

| −1.0%

| −1.3%

| −0.7%

| −3.5%

| −2.6%

|-
| Southeastern South America (SES)

| −2.3%

| −3.5%

| −2.3%

| −2.4%

| −2.7%

|-
| Southwestern South America (SWS)

| −2.3%

| −5.2%

| −10.0%

| −5.2%

| No data

|-
| Southern South America (SSA)

| −0.8%

| −6.5%

| No data

| −1.6%

| No data

|}

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