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

==== 12.3.6.4 Impacts ====

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Despite the observed increase in rainfall in the region, between 2014 and 2016 Brazil endured a water crisis that affected the population and economy of major capital cities in the SES region ( [[#Blunden--2014|Blunden and Arndt, 2014]] ; [[#Nobre--2016a|Nobre et al., 2016a]] ). Extremely long dry spells have become more frequent in southeastern Brazil, affecting 40 million people and the economies in cities such as Rio de Janeiro, São Paulo and Belo Horizonte, which are the industrial centres of the country ( ''medium confidence: medium evidence, medium agreement'' ) ( [[#PBMC--2014|PBMC, 2014]] ; [[#Nobre--2016a|Nobre et al., 2016a]] ; [[#Cunningham--2017|Cunningham et al., 2017]] ; [[#Marengo--2017|Marengo et al., 2017]] , 2020b; Lima and Magaña Rueda, 2018). They have also impacted agriculture, affecting food supply and rural livelihoods, especially in Minas Gerais ( [[#Nehren--2019|Nehren et al., 2019]] ). Agricultural prices increased by 30% in some cases, and harvest yields of sugar cane, coffee and fruits suffered a reduction of 15–40% in the region. The number of fires increased by 150%, and energy prices increased by 20–25%, as most electricity comes from hydroelectric power ( [[#Nobre--2016a|Nobre et al., 2016a]] ). In Argentina, projected changes in the hydrology of Andean rivers associated with glacier retreat are predicted to have negative impacts on the region’s fruit production ( ''low evidence, medium agreemen'' t) ( [[#Barros--2015|Barros et al., 2015]] ).

Heat islands affect ecosystems by increasing the energy consumption for cooling, the concentration of pollutants and the incidence of fires ( ''high confidence'' ) ( [[#Wong--2013|Wong et al., 2013]] ; [[#Akbari--2016|Akbari and Kolokotsa, 2016]] ; [[#Singh--2020b|Singh et al., 2020b]] ; [[#Ulpiani--2021|Ulpiani, 2021]] ). It also affects human health, as well increasing the incidence of respiratory and cardiovascular diseases ( ''medium confidence: medium evidence, medium agreement'' ) ( [[#Araujo--2015|Araujo et al., 2015]] ; [[#Barros--2016|Barros and Lombardo, 2016]] ; [[#de%20Azevedo--2018|de Azevedo et al., 2018]] ; [[#Geirinhas--2018|Geirinhas et al., 2018]] ).

Warming temperatures have been implicated in the emergence of dengue in temperate latitudes, increasing populations of ''Aedes aegypti'' ( ''high confidence'' ) ( [[#Natiello--2008|Natiello et al., 2008]] ; [[#Robert--2019|Robert et al., 2019]] , 2020; [[#Estallo--2020|Estallo et al., 2020]] ; [[#López--2021|López et al., 2021]] ) (Table 12.1), and field studies have demonstrated the role of local climate in vector activity ( [[#Benitez--2021|Benitez et al., 2021]] ). Figure 12.5 shows the modelled transmission suitability for dengue for two climate-change scenarios. Future increases in the number of months suitable for transmission of dengue will be highest in SES (see SM12.8 for additional information). There is additional evidence of the spread of arbovirus into southern temperate latitudes ( [[#Basso--2017|Basso et al., 2017]] ); however, a longer historical time series is needed to understand climate–disease interactions, given the relatively recent emergence of arborvirus in this region.

SLR impacts the port complex in Santa Catarina, which during the last 6 years has interrupted its activities 76 times due to strong winds or big waves, with estimated losses varying between USD 25,000 and 50,000 for each 24 idle hours ( [[#Ohz--2020|Ohz et al., 2020]] ). Historically, extratropical cyclones associated with frontal systems cause storm surges in the city of Santos. Although there are no fatality records, these events cause several socioeconomic losses, especially in vulnerable regions, including the Port of Santos, the largest port in Latin America (São Paulo). In an 88-year time span (1928–2016), the frequency of storm surge events was three times greater in the last 17 years (2000–2016) than in the previous period of 71 years (1928–1999) (Souza et al., 2019).

There are many projected impacts of climate change on natural systems. The impacts of SLR are habitat destruction and the invasion of exotic species, which affect biodiversity and the provision of ecosystem services (Figure 12.8) ( [[#Nagy--2019|Nagy et al., 2019]] ).

SES is a global priority for terrestrial biodiversity conservation and is home to two important biodiversity hotspots—the Atlantic Forest and Cerrado—which are among the world’s most studied biodiversity hotspots in connection with climate-change impact on biodiversity, especially for terrestrial vertebrates (Section [https://www.ipcc.ch/chapter/12#CCP1.2.2 CCP1.2.2] ; [[#Manes--2021|Manes et al., 2021]] ). An increasing number of studies show that the Atlantic Forest and Cerrado are at risk of biodiversity loss, largely due to projected reductions of species’ geographic distributions in many different taxa (e.g., Loyola et al. 2012, 2014; Ferro et al. 2014; Hoffmann et al. 2015; Martins et al. 2015; Aguiar et al. 2016b; Vale et al. 2018; Borges et al. 2019; Braz et al. 2019; Vale et al. 2021). Cerrado savannahs are projected to be the hotspot most negatively impacted by climate change within SA, mostly though range contraction of plant species ( ''very high confidence'' ), while the Atlantic Forest is projected to be highly impacted especially though the contraction of the distribution of endemic species ( ''very likely'' ) (Section [https://www.ipcc.ch/chapter/12#CCP1.2.2 CCP1.2.2] ; Figure 12.10) ( [[#Manes--2021|Manes et al., 2021]] ). Reductions in species’ distribution are also projected in the River Plate basin for sub-tropical amphibians ( [[#Schivo--2019|Schivo et al., 2019]] ) and the river tiger ( ''Salminus brasiliensis'' ), a keystone fish of economic value ( [[#Ruaro--2019|Ruaro et al., 2019]] ). Farming of mussels and oysters in the region is predicted to be negatively impacted by climate change, particularly SLR, and ocean warming and acidification ( [[#Gasalla--2017|Gasalla et al., 2017]] ). Some more localised habitats are also at risk of losing area due to climate change, such as the meadows of northwestern Patagonia ( [[#Crego--2014|Crego et al., 2014]] ) and mangroves of southern Brazil ( [[#Godoy--2015|Godoy and Lacerda, 2015]] ). Predicted changes in global climate along with agricultural expansion will strongly affect South American wetlands, which comprise around 20% of the continent and bring many benefits, such as biodiversity conservation and water availability ( [[#Junk--2013|Junk, 2013]] ).

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