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

=== 12.3.1 Central America Sub-region ===

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==== 12.3.1.1 Hazards ====

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Since the mid-20th century, extreme warm temperatures have increased and extreme cold temperatures have decreased in the region ( ''medium confidence'' ). The magnitude and frequency of extreme precipitation events have increased, but droughts have mixed signals ( ''low confidence'' ) (WGI AR6 Table 11.13, Table 11.14, Table 11.15, [[#Seneviratne--2021|Seneviratne et al., 2021]] ). Spatially variable trends have been detected for the MSD timing, the amount of rainy-season precipitation, the number of consecutive and total dry days and extreme wet events at the local scale since the 1980s. At the regional scale, a positive trend in the duration, but not the magnitude, of the MSD was found ( [[#Anderson--2019|Anderson et al., 2019]] ).

Significant increases in tropical cyclone (TC) intensification rates in the Atlantic basin, highly unusual compared to model-based estimates of internal climate variations, have been observed ( [[#Bhatia--2019|Bhatia et al., 2019]] ). TCs contributed approximately 10% of the annual precipitation ( [[#Khouakhi--2017|Khouakhi et al., 2017]] ). During the TC season more TC-driven events of extreme sea level exceed a 10-year return period ( [[#Muis--2019|Muis et al., 2019]] ).

Massive heatwave events and increase in the frequency of warm extremes are projected at the end of the 21st century ( ''high confidence'' ). When comparing 2.0°C with 1.5°C of warming, the longest annual warm wave is projected to increase more than 60 d ( [[#Taylor--2018|Taylor et al., 2018]] ).

General decrease in the magnitude of heavy precipitation extremes ( [[#Chou--2014|Chou et al., 2014]] ; [[#Giorgi--2014|Giorgi et al., 2014]] ) (in 1.5°C projection) but increase in the frequency of extreme precipitation (R50mm) ( [[#Imbach--2018|Imbach et al., 2018]] ) are projected for both 2°C and 4°C global warming level (GWL). Strong declines in mean daily rainfall are projected for July in Belize ( [[#Stennett-Brown--2017|Stennett-Brown et al., 2017]] ; WGI AR6 Table 11.14, [[#Seneviratne--2021|Seneviratne et al., 2021]] ) and decreased rainfall through the year for all capital cities except Panama City ( ''medium confidence: limited evidence, high agreement'' ) ( [[#Pinzón--2017|Pinzón et al., 2017]] ).

The main climate impact drivers like extreme heat, drought, relative SLR, coastal flooding, erosion, marine heatwaves, ocean aridity ( ''high confidence'' ) and aridity, drought and wildfires will increase by mid-century ( ''medium confidence'' ) (Figure 12.6, WGI AR6 Table 12.6, [[#Ranasinghe--2021|Ranasinghe et al., 2021]] ).

The rainy season in CA will likely experience more pronounced MSD by the end of this century, with a signal for reduced minimum precipitation by mid-century for the June July August (JJA) and September October November (SON) quarters, and a broader second peak is projected, consistent with the future south displacement of the Intertropical Convergence Zone (ITCZ) ( ''high confidence'' ) ( [[#Fuentes-Franco--2015|Fuentes-Franco et al., 2015]] ; [[#Hidalgo--2017|Hidalgo et al., 2017]] ; [[#Maurer--2017|Maurer et al., 2017]] ; [[#Imbach--2018|Imbach et al., 2018]] ; [[#Naumann--2018|Naumann et al., 2018]] ; [[#Ribalaygua--2018|Ribalaygua et al., 2018]] ; [[#Corrales-Suastegui--2020|Corrales-Suastegui et al., 2020]] ).

Climate projections indicate a decrease in frequency of TCs in CA accompanied by an increased frequency of intense cyclones (WGI AR6 [[#12.4|Section 12.4.4.3]] , [[#Ranasinghe--2021|Ranasinghe et al., 2021]] ).

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==== 12.3.1.2 Exposure ====

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Of the 47 million Central Americans in 2015, 40% lived in rural areas, with Belize being the least urbanised (54% rural) and Costa Rica the most (21% rural) ( [[#CELADE--2019|CELADE, 2019]] ); 10.5 million lived in the Dry Corridor region, an area recently exposed to severe droughts that have resulted in 3.5 million people in need of humanitarian assistance ( [[#FAO--2016a|FAO, 2016a]] ). Except in Belize and Panama, the majority of the countries’ populations—ranging from 56% in Honduras to 95% in El Salvador—were exposed to two or more risks derived from natural extreme events, affecting between 57% and 96% of the GDP of the countries ( [[#UNISDR%20and%20CEPREDENAC--2014|UNISDR and CEPREDENAC, 2014]] ). CA is one of the regions most exposed to climatic phenomena; with long coastlines and lowland areas, the region is repeatedly affected by drought, intense rains, cyclones and ENSO events ( ''high confidence'' ) ( [[#ECLAC--2015|ECLAC et al., 2015]] ).

Large urban centres are located on mountains or away from the shore, with the notable exceptions of Panama City, Belmopan and Managua, capital cities housing around 3 million people. Urban development in the capital cities and suburbs has almost tripled in the last 40 years, reaching population densities as high as 11,000 inhabitants/km 2 in Guatemala City and Tegucigalpa, with the spread of poor neighbourhoods in steep ravines and other marginal high-risk areas ( [[#Programa%20Estado%20de%20la%20Nación%20–%20Estado%20de%20la%20Región--2016|Programa Estado de la Nación – Estado de la Región, 2016]] ).

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==== 12.3.1.3 Vulnerability ====

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Climate change is exacerbating socioeconomic vulnerability in CA, a region with high levels of socioeconomic, ethnic and gender inequality, high rates of child and maternal mortality and morbidity, high levels of malnutrition and inadequate access to food and drinking water ( [[#ECLAC--2015|ECLAC et al., 2015]] ). Disasters from adverse natural events exacerbate CA’s economic vulnerability, accounting for substantial human and economic losses ( [[#UNISDR%20and%20CEPREDENAC--2014|UNISDR and CEPREDENAC, 2014]] ). Vulnerability in most sectors is considered high or very high ( ''high confidence'' ) (Figure 12.7).

Approximately 40% of the CA population live in poverty. Guatemala (62%), Honduras (60%), Nicaragua (46%) and Belize (42%, 2009) had the highest poverty rates in CSA in 2018 ( [[#ECLAC--2019b|ECLAC, 2019b]] ; [[#BCIE--2020|BCIE, 2020]] ). Rural poverty rates are higher—82% in Honduras and 77% in Guatemala in 2014—as is poverty among Indigenous Peoples, up to 79% in Guatemala. Rural poor are the most sensitive to climate extremes as their main economic activity is based on agriculture in vulnerable terrains (NU [[#CEPAL--2018|CEPAL, 2018]] ). In 2014, all CA countries, except for El Salvador (excluding Belize), had higher GINI coefficients (more inequality) than the average for Latin America (0.473), which in itself is the most unequal region in the world ( [[#ECLAC--2019b|ECLAC, 2019b]] ); in 2018 the situation remained similar, with El Salvador showing the lowest GINI coefficient (40) and the remaining countries showing values higher than the Latin American average ( [[#BCIE--2020|BCIE, 2020]] ).

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==== 12.3.1.4 Impacts ====

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The countries in the region are consistently ranked highest in the world by risk of being impacted by extreme events ( ''high confidence'' ). The economic costs of climate-change impacts in 2010 were estimated as being from 2.9% of GDP for Guatemala to 7.7% for Belize ( [[#ECLAC--2015|ECLAC et al., 2015]] ). For the period 1992–2011, Honduras, Nicaragua and Guatemala were among the 10 most impacted countries in the world by extreme weather events ( [[#UNISDR%20and%20CEPREDENAC--2014|UNISDR and CEPREDENAC, 2014]] ). The number of these events has increased 3% annually in the last 30 years ( [[#Bárcena--2020a|Bárcena et al., 2020a]] ).

Human and economic losses, changing water availability and increasing food insecurity are the most studied impacts of climate change in CA (Figure 12.9) ( [[#Harvey--2018|Harvey et al., 2018]] ; [[#Hoegh-Guldberg--2019|Hoegh-Guldberg et al., 2019]] ). Hydro-meteorological events, such as storm surges and TCs, are the most frequent extreme events and have the highest impact ( ''high confidence'' ) ( [[#Reyer--2017|Reyer et al., 2017]] ). From 2005 to 2014, the cumulative impacts were over 3410 people dead, hundreds of thousands displaced and damages estimated around USD 5.8 billion ( [[#Ishizawa--2016|Ishizawa and Miranda, 2016]] ). One standard deviation in the intensity of a hurricane windstorm leads to a decrease in both the growth of total GDP per capita (0.9% to 1.6%) and total income and labour income by 3%, whereas it increases moderate and extreme poverty by 1.5% in CA ( [[#Ishizawa--2016|Ishizawa and Miranda, 2016]] ).

Food insecurity is a serious impact of climate change in a region where 10% of the GDP depends on agriculture, livestock and fisheries ( ''very high confidence'' ) ( [[#ECLAC--2015|ECLAC et al., 2015]] ; [[#CEPAL--2018|CEPAL et al., 2018]] ; [[#Harvey--2018|Harvey et al., 2018]] ; [[#BCIE--2020|BCIE, 2020]] ). Crop losses largely result from highly variable rainfall and seasonal droughts, which have increased significantly in recent decades (Table 12.3) ( [[#CEPAL%20and%20CAC-SICA--2020|CEPAL and CAC-SICA, 2020]] ), particularly the observed changes in the MSD that reduces rainfall at the onset of the rainy season (May–June) ( [[#Anderson--2019|Anderson et al., 2019]] ). Small and subsistence farmers experience the highest impact because they practice rainfed agriculture ( [[#Imbach--2017|Imbach et al., 2017]] ), along with poor neighbourhoods, which face socioeconomic and physical barriers for adapting to climate change ( [[#Kongsager--2017|Kongsager, 2017]] ). In 2015, precipitation diminished between 50% and 70% of its historic average, causing a loss of up to 80% of beans and 60% of maize, leaving 2.5 million people food insecure, 1.6 million of whom were in the Dry Corridor of CA ( [[#ECLAC--2015|ECLAC et al., 2015]] ; [[#FAO--2016a|FAO, 2016a]] ). In 2019, the region entered its fifth consecutive drought year, with 1.4 million people in need of food aid. Seasonal-scale droughts are projected to lengthen by 12–30%, intensify by 17–42% and increase in frequency by 21–42% in RCP4.5 and RCP8.5 scenarios by the end of the century ( [[#Depsky--2021|Depsky and Pons, 2021]] ).

Studies have shown that the incidence of some vector-borne and zoonotic diseases in CA is correlated to climatic variables, particularly temperature and rainfall ( ''high confidence'' ) (Figure 12.4; Table 12.1). In Honduras, rainfall and relative humidity were positively correlated with the occurrence of haemorrhagic dengue cases ( [[#Zambrano--2012|Zambrano et al., 2012]] ). In Costa Rica, temperature and rainfall were correlated to cattle rabies outbreaks and mortality during 1985–2016 ( [[#Hutter--2018|Hutter et al., 2018]] ); incidence of leishmaniasis showed cycles of 3 years related to temperature changes ( [[#Chaves--2006|Chaves and Pascual, 2006]] ); and snakebites were more likely to occur at high temperatures and were significantly reduced after the rainy season for the period 2005–2013 ( [[#Chaves--2015|Chaves et al., 2015]] ). In Panama, rainfall was associated with an increased number of malaria cases among the Gunas, an Indigenous People with high vulnerability living in poverty conditions on small islands affected by SLR ( [[#Hurtado--2018|Hurtado et al., 2018]] ). These correlations point to a possible change in disease incidence with climate change; evidence of that change is yet to be reported in the literature because longitudinal studies are lacking in the region.

Heat stress is another health concern in this already warm and humid part of the world ( ''high confidence'' ) (Table 12.2); it is an increasing occupational health hazard with potential impacts on kidney disease ( [[#Sheffield--2013|Sheffield et al., 2013]] ; [[#Dally--2018|Dally et al., 2018]] ; [[#Johnson--2019|Johnson et al., 2019]] ). SLR exacerbating wave-driven flooding is expected to impact infrastructure and freshwater availability in small islands and atolls off the coast of Belize ( [[#Storlazzi--2018|Storlazzi et al., 2018]] ). Observed and expected impacts in the coastal and ocean ecosystems of the sub-region are described in Figure 12.9.

Decreasing water availability is another impact of climate change ( ''high confidence'' ). Under a climate-change scenario of 3.5°C warming and a 30% reduction in rainfall, a reduction in the production and export of crops and livestock is projected, affecting the wages and decreasing the GDP of Guatemala by 1.2%, thereby increasing food insecurity ( [[#Vargas--2018b|Vargas et al., 2018b]] ). By 2100, water availability per capita is projected to decrease 82% and 90% on average for the region under B2 (low emissions) and A2 (high emissions) scenarios respectively (Figure 12.3) ( [[#CEPAL--2010|CEPAL, 2010]] ).

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[[File:408541c0d0dc7dd04b0db72c155d851d IPCC_AR6_WGII_Figure_12_003.png]]

'''Figure 12.3 |''' '''Reduction of water availability per capita projected to 2100 without climate change (baseline scenario) and with two climate-change scenarios ( [[#CEPAL--2010|CEPAL, 2010]] ).'''

Impacts on rural livelihoods, particularly for small and medium-sized farmers and Indigenous Peoples in mountains, include an overall reduction in production, yield (Table 12.4), suitable farming area and water availability ( ''high confidence'' ) ( [[#Walshe--2016|Walshe and Argumedo, 2016]] ; [[#Bouroncle--2017|Bouroncle et al., 2017]] ; [[#Hannah--2017|Hannah et al., 2017]] ; [[#Imbach--2017|Imbach et al., 2017]] ; [[#Harvey--2018|Harvey et al., 2018]] ; [[#Batzín--2019|Batzín, 2019]] ; [[#Donatti--2019|Donatti et al., 2019]] ). Bean production in El Salvador, Nicaragua, Honduras and Guatemala, is projected to decrease, using the Decision Support for Agro-Technology Transfer (DSSAT) under the A2 scenario, by 19% for 2050, whereas maize production, depending on the water retention capacity of soils, will drop between 4% and 21% by 2050 ( [[#CEPAL--2018|CEPAL et al., 2018]] ). In Guatemala, the yield of rainfed maize is expected to decrease by 16% by 2050 under RCP8.5 using the Global Gridded Crop Model Intercomparison GGCMI; yields for rainfed sugarcane are expected to drop by 44% and irrigated sugarcane by 36% under the same modelling conditions ( [[#Castellanos--2018|Castellanos et al., 2018]] ). Rice production is expected to decrease by 23% under scenario A2 by 2050 ( [[#CEPAL%20and%20CAC/SICA--2013|CEPAL and CAC/SICA, 2013]] ).

The extent and quality of suitable areas for basic grains are expected to contract ( ''high confidence'' ). The suitable area for maize will experience a 35% reduction of cultivated area expected by 2100 under the A2 scenario. The area suitable for beans is expected to shrink by 2050. Projections show that suitable areas with excellent capacity under current conditions will decrease by 14%, mainly in Panama (41%) Costa Rica (21%) and El Salvador (20%). The Species Distribution Model, using the IPSL GCM, projects that the suitable zones for cacao and coffee will shrink between 25% and 75% under RCP6.0 ( [[#Fernandez-Manjarrés--2018|Fernandez-Manjarrés, 2018]] ; [[#Fernández%20Kolb--2019|Fernández Kolb et al., 2019]] ). Warmer and dryer lower areas will become unsuitable for coffee and will drive its production to higher land ( [[#Läderach--2013|Läderach et al., 2013]] ; [[#Bunn--2015|Bunn et al., 2015]] ). Under the A2 climate-change scenario, areas with excellent capacity for Arabica coffee will decrease by 12% in CA; coffee yield will decrease in suitable zones whereby the extent of high yield (&gt;0.8 T ha −1 ) zones is projected to shrink from 34% to 12%, whereas low-yield (&lt;0.3 T ha −1 ) zones will expand from 14% to 36% by 2100 under the A2 scenario ( [[#CEPAL%20and%20CAC/SICA--2014|CEPAL and CAC/SICA, 2014]] ).

Mesoamerica, a biodiversity hotspot spanning across CA and southern Mexico, is a global priority for terrestrial biodiversity conservation, and it is projected to be negatively impacted by climate change, especially through the contraction of distribution of native species as the area becomes increasingly dryer ( ''high confidence'' ) (Section [https://www.ipcc.ch/chapter/12#CCP1.2.2 CCP1.2.2] ) ( [[#Feeley--2013|Feeley et al., 2013]] ; [[#Manes--2021|Manes et al., 2021]] ). A significant reduction in net primary productivity in tropical forests is expected under both RCP4.5 and RCP8.5 as a result of temperature increase, precipitation reduction and droughts ( [[#Lyra--2017|Lyra et al., 2017]] ; [[#Castro--2018|Castro et al., 2018]] ; [[#Stan--2020|Stan et al., 2020]] ). Aridity index models show that the dry, sub-humid vegetation of the dry corridor will expand to neighbouring areas and replace the humid forests in the Pacific lowlands and the northern parts of Guatemala by 2050 under RCP4.5 and RCP8.5 scenarios ( [[#Pons--2018|Pons et al., 2018]] ; [[#CEPAL%20and%20CAC-SICA--2020|CEPAL and CAC-SICA, 2020]] ). A warming of 3°C would shrink the tropical rainforest and replace it with savannah grassland. Wetlands are also expected to be highly affected by climate change in the region ( [[#Hoegh-Guldberg--2019|Hoegh-Guldberg et al., 2019]] ).

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