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

==== 12.3.5.4 Impacts ====

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The impacts of intense drought have been reported in NES since 1780, with severe losses in agricultural production, livestock death, increase in agricultural prices and human death (Figure 12.9) ( [[#Marengo--2017|Marengo et al., 2017]] , 2020c; [[#Martins--2019|Martins et al., 2019]] ; [[#Government%20of%20Brazil--2020|Government of Brazil, 2020]] ; Silva et al., 2020). The rural population already suffers from natural water scarcity in the countryside. The drought in 2012 was responsible for reducing up to 99% of the corn production in Pernambuco state ( [[#Government%20of%20Brazil--2020|Government of Brazil, 2020]] ). A predicted increase in drought, coupled with inadequate soil management practices by small farmers and agribusiness, increases the region’s susceptibility to desertification ( [[#Spinoni--2015|Spinoni et al., 2015]] ; [[#Vieira--2015|Vieira et al., 2015]] ; [[#Mariano--2018|Mariano et al., 2018]] ; [[#Tomasella--2018|Tomasella et al., 2018]] ; [[#Marengo--2020c|Marengo et al., 2020c]] ). In NES, 70,000 km 2 have reached a point at which agriculture is no longer possible ( [[#Government%20of%20Brazil--2020|Government of Brazil, 2020]] ). Intense droughts have triggered migration to urban centres within and outside NES ( [[#Confalonieri--2014a|Confalonieri et al., 2014a]] ; [[#Government%20of%20Brazil--2020|Government of Brazil, 2020]] ). More than 10 million people have been impacted by the drought of 2012/2014 in the region, which was responsible for water shortage and contamination, increasing death by diarrhoea ( [[#Marengo--2015|Marengo and Bernasconi, 2015]] ; [[#Government%20of%20Brazil--2020|Government of Brazil, 2020]] ).

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'''Figure 12.9 |''' '''Observed and projected impacts for sub-regions of CSA.''' Impacts are distinguished for main sectors and for their corresponding systems (or components). Observed impacts relate to the last several decades. Projected impacts represent a synthesis across several emission and warming scenarios, indicative of a time period from the middle to end of the 21st century. For each system (e.g., coral reefs) climate-change impacts are identified as being low, medium or high. The references underlying this assessment can be found in SM12.4.1.

There is growing evidence of the impacts of climate change on human health in NES, mostly linked to food and water insecurity caused by recurrent long droughts (e.g., gastroenteritis and hepatitis) ( ''high confidence'' ) (Figure 12.9) ( [[#Sena--2014|Sena et al., 2014]] ; [[#de%20Souza%20Hacon--2019|de Souza Hacon et al., 2019]] ; [[#Marengo--2019|Marengo et al., 2019]] ; [[#Government%20of%20Brazil--2020|Government of Brazil, 2020]] ; [[#Salvador--2020|Salvador et al., 2020]] ). From 2071 to 2099, thermal conditions in NES might improve for vectors of dengue, chikungunya and Zika ( [[#de%20Souza%20Hacon--2019|de Souza Hacon et al., 2019]] ). Additionally, a high risk of mortality associated with climatic stress in the period of 2071–2099 is expected in the São Francisco river basin ( [[#de%20Oliveira--2019|de Oliveira et al., 2019]] ; [[#de%20Souza%20Hacon--2019|de Souza Hacon et al., 2019]] ).

Recent studies predict strong negative impacts of climate change on NES’s agriculture ( ''high confidence'' ) (Ferreira Filho and Moraes, 2015; [[#Nabout--2016|Nabout et al., 2016]] ; [[#Gateau-Rey--2018|Gateau-Rey et al., 2018]] ) (Figure 12.9; Table 12.4). NES concentrates the bulk of the predicted loss of regional gross domestic product (GDP) associated with agriculture in Brazil (Ferreira Filho and Moraes, 2015; [[#Forcella--2015|Forcella et al., 2015]] ). Although agriculture makes a modest contribution to the region’s economy, its drop could have a severe impact on the poorest rural household by shrinking the agricultural labour market and increasing food prices (Ferreira Filho and Moraes, 2015; [[#Government%20of%20Brazil--2020|Government of Brazil, 2020]] ). The expected increase in dryness is also predicted to impact the region’s hydroelectric power generation ( [[#Marengo--2017|Marengo et al., 2017]] ; [[#de%20Jong--2018|de Jong et al., 2018]] ). SLR has also been reported to impact coastal cities such as Salvador, destroying urban constructions ( [[#Government%20of%20Brazil--2020|Government of Brazil, 2020]] ). SLR, increased ocean temperature and acidification may also negatively impact NES’s shrimp aquaculture production (Figure 12.8) ( [[#Gasalla--2017|Gasalla et al., 2017]] ). Along with climate change, overfishing has driven exploited marine fish species to collapse ( [[#Verba--2020|Verba et al., 2020]] ).

Biodiversity in NES is severely threatened by climate change in terrestrial ( ''medium confidence: medium evidence, high agreement'' ) and freshwater ( ''low confidence: low evidence, high agreement'' ) ecosystems (Figure 12.9). There are few studies projecting the likely impact of climate change on NES’s biodiversity, especially its endemic freshwater fish. Recent studies have already reported the reduction in several endemic plant species affecting pollination and seed dispersal ( [[#Bech%20Gaivizzo--2019|Bech Gaivizzo et al., 2019]] ; [[#Cavalcante--2019|Cavalcante and Duarte, 2019]] ; [[#Silva--2019b|Silva et al., 2019b]] ). Studies with terrestrial animals predict that most groups will be negatively impacted by climate change ( [[#de%20Oliveira--2012|de Oliveira et al., 2012]] ; [[#Arnan--2018|Arnan et al., 2018]] ; [[#da%20Silva--2018b|da Silva et al., 2018b]] ; [[#Montero--2018|Montero et al., 2018]] ). Changes in the abundance of coral reef community and extreme reduction in coral cover have been observed in NES ( [[#de%20Moraes--2019|de Moraes et al., 2019]] ; [[#Duarte--2020|Duarte et al., 2020]] ). A number of observed coral bleaching events associated with an abnormal increase in sea temperatures have occurred in NES ( [[#Krug--2013|Krug et al., 2013]] ; [[#Leão--2016|Leão et al., 2016]] ; [[#de%20Oliveira%20Soares--2019|de Oliveira Soares et al., 2019]] ) (Figure 12.8), but thus far mortality has remained low and corals have been able return to normal values or remain stable following sea water temperature rise ( ''medium confidence: medium evidence, high agreement'' ) ( [[#Leão--2016|Leão et al., 2016]] ). Mangroves in the region have shown increased mortality, but they have also expanded their range inland (Figure 12.6) ( [[#Godoy--2015|Godoy and Lacerda, 2015]] ; [[#Cohen--2018|Cohen et al., 2018]] ). Future projections include mangrove landward expansion and lower migration rates by 2100 ( [[#Cohen--2018|Cohen et al., 2018]] ).

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