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

==== 12.3.8.4 Impacts ====

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The potential impact of climate change is of special concern in arid and semiarid Patagonia, a &gt;700,000 km 2 region of steppe-like plains in Argentina. Thus, melting snow and ice in the glaciers of Patagonia and the Andes will alter surface runoff into interior wetlands. A SLR of 20–60 cm will destroy coastal marshes, and an increase in extreme events, such as storms, floods and droughts, will affect biodiversity in wet grasslands ( ''medium confidence: low evidence, high agreement'' ) (after Junk et al. 2013; Joyce et al. 2016). Three species of lizard from Patagonia are at risk of extinction as a result of global warming ( [[#Kubisch--2016|Kubisch et al., 2016]] ).

Patagonian ice fields in SA are the largest bodies of ice outside of Antarctica in the Southern Hemisphere. They are losing volume due partly to rapid changes in their outlet glaciers, which end up in lakes or the ocean, becoming the largest contributors to eustatic SLR in the world per unit area ( [[#Foresta--2018|Foresta et al., 2018]] ; [[#Moragues--2019|Moragues et al., 2019]] ; [[#Zemp--2019|Zemp et al., 2019]] ). Most calving glaciers in the southern Patagonia ice field retreated during the last century ( ''high confidence'' ). Upsala glacier retreat generated slope instability, and a landslide movement destroyed the western edge in 2013. The Upsala Argentina Lake has become potentially unstable and may generate new landslides ( [[#Moragues--2019|Moragues et al., 2019]] ). The climate effect on the summer stratification of piedmont lakes is another issue in connection with glacier dynamics ( [[#Isla--2010|Isla et al., 2010]] ).

Between 41° and 56° South latitude, the absolute glacier area loss was 5450 km 2 (19%) in the last approximately 150 years, with an annual area reduction increase of 0.25% yr −1 for the period 2005–2016 ( [[#Meier--2018|Meier et al., 2018]] ). The small glaciers in the northern part of the Northern Patagonian Ice Field had over all periods the highest rates of 0.92% a −1 . In this sub-region, increased melting of ice is leading to changes in the structure and functioning of river ecosystems and in freshwater inputs to coastal marine ecosystems ( ''medium confidence: low evidence, high agreement'' ) ( [[#Aguayo--2019|Aguayo et al., 2019]] ). In addition, in the case of coastal areas, the importance of tides and rising sea levels in the behaviour of river floods has been demonstrated ( [[#Jalón-Rojas--2018|Jalón-Rojas et al., 2018]] ).

Suitable areas for meadows (very productive areas for livestock production) will decrease by 7.85% by 2050 given predicted changes in climate ( ''low confidence'' ) ( [[#Crego--2014|Crego et al., 2014]] ).

A major drought from 1998 to 1999, coincident with a very hot summer, led to extensive dieback in a ''Nothofagus'' species ( [[#Suarez--2004|Suarez et al., 2004]] ). In another dominant ''Nothofagus'' species, several periodic droughts have triggered forest decline since the 1940s ( [[#Rodríguez-Catón--2016|Rodríguez-Catón et al., 2016]] ).

Climate-change-impacted ocean ecosystems by reducing kelp coverage, increasing reproductive failure and chick mortality of penguins and spurring the poleward expansion of saltmarshes in the Atlantic Patagonia. SSA houses the Patagonian Steppe Global-200 terrestrial ecoregion, which is a conservation priority on a global scale, but with a clear lack of studies on likely future climate-change impacts (Section [https://www.ipcc.ch/chapter/12#CCP1.2.2.2 CCP1.2.2.2] ) ( [[#Manes--2021|Manes et al., 2021]] ). The Patagonian Steppe may suffer pronounced expansion in invasive species’ ranges under climate change ( ''low confidence'' ) ( [[#Wang--2017a|Wang et al., 2017a]] ).

Fire has been found to promote or halt biological invasions ( ''medium confidence: medium evidence, high agreement'' ). For example, an analysis of ''Pinus'' spread following wildfires in Patagonia revealed a high risk that pines will become invasive if ignition frequency increases as a result of climate change ( [[#Raffaele--2016|Raffaele et al., 2016]] ). According to Inostroza et al. (2016), the Magellan Region is one of the most fragile regions in Patagonia, and despite its low population densities, it is undergoing a silent process of anthropogenic alteration where between 53.1% and 68.1% of the area needs to be considered to be influenced by humans who are occupying pristine ecosystems, even some with extensive conservation designations ( [[#Inostroza--2016|Inostroza et al., 2016]] ). Fire exposure can result in several health problems for human populations; Table 12.5 shows that SSA is the region with the highest exposure to wildfire danger.

'''Table 12.5 |''' Change in population-weighted exposure to very high or extremely high wildfire risk. Data were derived from Fire Danger Indices (FDIs) produced by the Copernicus Emergency Management Service for the European Forest Fire Information System (EFFIS) (available at Copernicus Emergency Management Service [2021]). High and very high wildfire danger are defined as FDI ≥ 5. Data were derived from Romanello et al. (2021).

{| class="wikitable"
|-
!
! colspan="3"| '''Population-weighted mean days of exposure to extremely high and very high wildfire danger'''

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

! '''2001–2004'''

! '''2017–2020'''

! '''Change from 2001–2004 to 2017–2020'''

|-
| Central America (CA)

| 30.4

| 26.9

| −3.5

|-
| Northwestern South America (NWS)

| 4.2

| 4.6

| 0.5

|-
| Northern South America (NSA)

| 19.7

| 21.2

| 1.5

|-
| South America Monsoon (SAM)

| 16.0

| 27.8

| 11.8

|-
| Northeastern South America (NES)

| 47.9

| 53.3

| 5.4

|-
| Southeastern SouthAmerica (SES)

| 4.2

| 8.2

| 4.0

|-
| Southwestern SouthAmerica (SWS)

| 31.9

| 58.4

| 26.5

|-
| Southern South America (SSA)

| 88.7

| 104.9

| 16.2

|}

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