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

==== 12.3.5.1 Hazards ====

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The region has ''likely'' experienced an increase in temperature, with significant increases in the intensity and frequency of hot extremes and significant decreases in the intensity and frequency of cold extremes ( [[#Donat--2013|Donat et al., 2013]] ) (WGI AR6 Table 11.13, [[#Seneviratne--2021|Seneviratne et al., 2021]] ).

A decrease in the frequency and magnitude of extreme precipitation was observed, but with ''low confidence'' , due to insufficient data coverage and trends in available data being generally insignificant. An increase in drought duration was observed with ''high confidence'' but ''medium confidence'' with respect to the increase of drought intensity (WGI AR6 Table 11.14, [[#Seneviratne--2021|Seneviratne et al., 2021]] ). Table 12.3 shows the estimates of changes in land area per sub-region affected by drought events; NES sub-region presented the highest changes in CSA.

'''Table 12.3 |''' Change in percentage of land area affected by extreme drought in 2010–2019, in relation to 1950–1959 using Standardised Precipitation-Evapotranspiration Index (SPEI); extreme drought is defined as SPEI ≤ −1.6 ( [[#Federal%20Office%20of%20Meteorology%20and%20Climatology%20MeteoSwiss--2021|Federal Office of Meteorology and Climatology MeteoSwiss, 2021]] ). Data were derived from Romanello et al. (2021).

{| class="wikitable"
|-
!
! colspan="3"| '''Average change in percentage of land area in drought in 2010–2019 with respect to 1950–1959'''

|-
! '''Sub-region'''

! '''At least 1 month in drought'''

! '''At least 3 months in drought'''

! '''At least 6 months in drought'''

|-
| Central America (CA)

| 38.8%

| 17.6%

| 6.1%

|-
| Northwestern South America (NWS)

| 51.8%

| 25.3%

| 7.0%

|-
| Northern South America (NSA)

| 52.5%

| 18.3%

| 2.5%

|-
| South America Monsoon (SAM)

| 48.0%

| 34.4%

| 12.2%

|-
| Northeastern South America (NES)

| 64.5%

| 38.4%

| 12.0%

|-
| Southeastern SouthAmerica (SES)

| 16.4%

| 6.7%

| 0.4%

|-
| Southwestern South America (SWS)

| 20.5%

| 13.9%

| 7.5%

|-
| Southern South America (SSA)

| −23.5%

| −8.8%

| —

|}

The projected warming for the extreme annual maximum temperatures (TXx) over NES is +2°C for the 1.5°C scenario and about +2.5°C for the 2°C scenario ( [[#Hoegh-Guldberg--2018|Hoegh-Guldberg et al., 2018]] ). An increased number of tropical nights with minimum temperatures exceeding the 20°C threshold is projected ( [[#Orlowsky--2012|Orlowsky and Seneviratne, 2012]] ). In general, extreme heat will increase and cold spells decrease with ''high confidence'' . A decrease in total precipitation is projected with ''high confidence'' , with an increase in heavy precipitation events and an increase in dryness ( ''medium confidence'' ). Increases in drought severity due to the combination of increased temperatures, less rainfall and lower atmospheric humidity (5 to 15% relative humidity reduction) create water deficits, which are projected for the entire region after 2041 (3–4 mm d −1 reduction), particularly over western NES and over the semiarid region ( [[#Marengo--2015|Marengo and Bernasconi, 2015]] ; [[#Marengo--2017|Marengo et al., 2017]] ). Fire will significantly increase ( ''high confidence'' ) (Figure 12.6).

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[[File:39389c4e6fe4c88471d70d7987ace51f IPCC_AR6_WGII_Figure_12_006.png]]

'''Figure 12.6 |''' '''Observed trends (WGI AR6 Tables 11.''' '''13, 11.14, 11.15)''' ( [[#Seneviratne--2021|Seneviratne et al., 2021]] ) and summary of confidence in direction of projected change in climatic impact drivers, representing their aggregate characteristic changes for mid-century for RCP4.5, SSP3-44 4.5 and SRES A1B scenarios, or above within each AR6 region, approximately corresponding (for CIDs that are independent of SLR) to global warming levels between 2°C and 2.4°C (WGI AR6 Table 12.6) ( [[#Ranasinghe--2021|Ranasinghe et al., 2021]] ).

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