Editing IPCC:AR6/WGII/Chapter-11 (section)

==== 11.3.1.2 Projected Impacts ====

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In the near term (2030–2060), climate change is projected to become an increasingly dominant stress on the region’s biodiversity, with some ecosystems experiencing irreversible changes in composition and structure and some threatened species becoming extinct ( ''high confidence'' ). Climate change will interact with current ecological conditions, threats and pressures, with cascading ecological impacts, including population declines, heat-related mortalities, extinctions and disruptions for many species and ecosystems ( ''high confidence'' ) (Table 11.5) '''.''' These include inadequate allocation of environmental flows for freshwater fish ( [[#Vertessy--2019|Vertessy et al., 2019]] ), native forest logging for old-growth-forest-dependent fauna ( [[#Lindenmayer--2015|Lindenmayer et al., 2015]] ; [[#Lindenmayer--2020a|Lindenmayer and Taylor, 2020a]] ; [[#Lindenmayer--2020b|Lindenmayer and Taylor, 2020b]] ), and invasive species ( [[#Scott--2018|Scott et al., 2018]] ). Climate change has synergistic and compounding impacts, particularly in bioregions already experiencing ecosystem degradation, threatened endemics and collapse of keystone species, including those of value to Indigenous Peoples, and high extinction rates as a consequence of human activities (Table 11.4) ( [[#Gordon--2009|Gordon, 2009]] ; [[#Australia%20SoE--2016|Australia SoE, 2016]] ; [[#Weeks--2016|Weeks et al., 2016]] ; [[#Cresswell--2017|Cresswell and Murphy, 2017]] ; [[#Hare--2019|Hare et al., 2019]] ; [[#MfE--2019|MfE, 2019]] ; [[#Lindenmayer--2020a|Lindenmayer and Taylor, 2020a]] ; [[#Lindenmayer--2020b|Lindenmayer and Taylor, 2020b]] ; [[#Bergstrom--2021|Bergstrom et al., 2021]] ). Some native species are projected to have potentially greater geographic range if they can colonise new areas, while other species may be resilient to projected climate change impacts ( [[#Bulgarella--2014|Bulgarella et al., 2014]] ; K.E. Lawrence et al., 2017; [[#Conroy--2019|Conroy et al., 2019]] ; [[#Rizvanovic--2019|Rizvanovic et al., 2019]] ).

'''Table 11.5 |''' An indicative selection of projected climate-change impacts on terrestrial and freshwater ecosystems and species in Australia and New Zealand respectively.

{| class="wikitable"
|-
! Ecosystem, species

! Climate-related pressure

! Projected Impact

! Source

|-
| Australia

|
|-
| Floristic composition of vegetation communities

| Increases in temperature and reductions in annual precipitation by 2070. Many plant species based on median projection from five global climate models (ACCESS1.0, CNRM-CM5, HADGEM2-CC, MIROC5, NorESM1-M) centred on the decade 2070 under RCP8.5

| 47% of vegetation types have characteristic plant species at risk of their climatic tolerances being exceeded from increasing mean annual temperature by 2070 with only 2% at risk from reductions in annual precipitation by 2070

| ( [[#Gallagher--2019|Gallagher et al., 2019]] )

|-
| Some south east Australian temperate forests

| Reduction in winter rainfall and rising spring temperatures resulting in an increase in the frequency of very high fire weather conditions and increased risk of catastrophic wildfires; based on output from 15 CMIP5 GCMs using RCP8.5 for years for 2060–2079 as compared to 1990–2009

| Increase in fire frequency prevents recruitment of obligate seeder resulting in changing dominant species and vegetation structure including long lasting or irreversible shift in formation from tall wet temperate eucalypt forests dominated by obligate seeder trees (e.g., alpine ash) to open forest or in worst case to shrubland

Declining rainfall and regolith drying, more unplanned, intense fires and declining productivity place stress on tree growth and compromise biodiversity in northern jarrah forest

| ( [[#Doherty--2017|Doherty et al., 2017]] ; [[#Zylstra--2018|Zylstra, 2018]] ; [[#Bowman--2019|Bowman et al., 2019]] ; [[#Dowdy--2019|Dowdy et al., 2019]] ; [[#Naccarella--2020|Naccarella et al., 2020]] )

( [[#Wardell-Johnson--2015|Wardell-Johnson et al., 2015]] )

|-
|
| Tree line stasis or regression (snow gum)

| ( [[#Doherty--2017|Doherty et al., 2017]] ); ( [[#Bowman--2019|Bowman et al., 2019]] ; [[#Naccarella--2020|Naccarella et al., 2020]] )

|-
|
| Increase in lightning-ignited landscape fires along with contracting palaeo-endemic refugia due to warmer and drier climates

| Population collapse and severe range contraction of slow-growing, fire-sensitive palaeo-endemic temperate rainforest species (e.g., pencil pine)

| ( [[#Doherty--2017|Doherty et al., 2017]] ); ( [[#Bowman--2019|Bowman et al., 2019]] )

|-
|
| Rhizosphere responses or accelerated rates of soil organic matter decomposition

| Plant nutrient availability may be enhanced

| ( [[#Hasegawa--2015|Hasegawa et al., 2015]] ; [[#Ochoa-Hueso--2017|Ochoa-Hueso et al., 2017]] )

|-
| Alpine ecosystems

| Increasing global warming and rising temperatures, ongoing reduction in snow cover and winter rain and increasing frequency and magnitude of wildfires

| Loss of alpine vegetation communities (snow patch feldmark and short alpine herb fields) and increased stress on snow-dependent plant and animal species; changing suitability for invasive species

| ( [[#Slatyer--2010|Slatyer, 2010]] ; [[#Morrison--2013|Morrison and Pickering, 2013]] ; [[#Pepler--2015a|Pepler et al., 2015a]] ; [[#Williams--2015|Williams et al., 2015]] ; [[#Harris--2017|Harris et al., 2017]] )

|-
| Northern tropical savannahs

| Rainfall and CO 2 effects

| Potentially resulting in an increase in ecosystem carbon storage

| ( [[#Scheiter--2015|Scheiter et al., 2015]] )

|-
| Murray-Darling River Basin

| Drought

| Reduced river flow; mass fish kills

| ( [[#Grafton--2014|Grafton et al., 2014]] ; [[#AAS--2019|AAS, 2019]] )

|-
| Unimpaired river basins

| Elevated CO 2 levels

| Increase plant water use reduces stream flow

| ( [[#Ukkola--2016|Ukkola et al., 2016]] )

|-
| Bearded dragons (lizards), ''Pogona'' spp.

| Changes in precipitation

| ''P. henrylawsoni'' and ''P. microlepidota'' to gain suitable habitat, ''P. nullarbor'' and ''P. vitticeps'' showing the most potential loss

| ( [[#Wilson--2017|Wilson and Swan, 2017]] ; [[#Silva--2018|Silva et al., 2018]] )

|-
| Xeric bees

| Broad temperate tolerances, arid climate adapted

| Climate-resilient, only small response

| ( [[#Silva--2018|Silva et al., 2018]] )

|-
| ''Great desert skink Liopholis kintorei''

| Buffering capacity of underground microclimates, for nocturnal and crepuscular ectotherms

| Warming impacts projected to be indirect

| ( [[#Moore--2018|Moore et al., 2018]] )

|-
| 22 narrow-range fish species in imminent risk of extinction

| Projected changes in rainfall, run-off, air temperatures and the frequency of extreme events (drought, fire, flood) compound risk from other key threats especially invasive species

| Extinction projected within next 20 years

| ( [[#Lintermans--2020|Lintermans et al., 2020]] )

|-
| Freshwater taxa (freshwater fish, crayfish, turtles and frogs)

| Changed hydrological regimes

| Substantial changes to the composition of faunal assemblages in Australian rivers well before the end of this century, with gains/losses balanced for fish but suitable habitat area predicted to decrease for many crayfish and turtle species and nearly all frog species

| ( [[#James--2017|James et al., 2017]] )

|-
| '''New Zealand'''

|
|-
| Modified lowland wetlands

| Intersection of warming, drought and heavy rainfall (ex-tropical cyclones)

| Prolonged anoxic conditions in waterways (blackwater events) leading to mortality of fish (e.g., shortfin eels) and invertebrates, while botulism outbreaks can lead to impacts on waterfowl

| ( [[#Pingram--2021|Pingram et al., 2021]] )

|-
| Native forests and lands

| Elevated CO 2 levels, warming, increased precipitation.

| Short-term beneficial effects on carbon storage; droughts in eastern areas would decrease productivity and rates of carbon storage in the medium term

| ( [[#Ausseil--2019b|Ausseil et al., 2019b]] )

|-
|
| Increased fire intensity and frequency in hot and dry parts of New Zealand

| Much of the native vegetation has no fire adaptations, causing vulnerability to local extinction due to ‘interval squeeze’

| ( [[#Perry--2014|Perry et al., 2014]] )

|-
| Freshwater rivers

| Rainfall variation

| Cascading effects of warming, drought, floods and algal blooms compounded by water abstraction

| ( [[#Macinnis-Ng--2021|Macinnis-Ng et al., 2021]] )

|-
| Three species of naturalised woody weeds

| Warming and increased CO 2 levels

| Increased geographic range

| ( [[#Sheppard--2014|Sheppard and Stanley, 2014]] )

|-
| Kauri tree, ''Agathis australis''

| Lower than average rainfall stimulates a drought-deciduous response in this evergreen species

| Increased litter fall

| ( [[#Macinnis-Ng--2015|Macinnis-Ng and Schwendenmann, 2015]] )

|-
| Windmill palm

| Warming

| Increased geographic range

| ( [[#Aguilar--2017|Aguilar et al., 2017]] )

|-
| New Zealand tussock grasslands

| Warming

| Enhanced respiration

| ( [[#Graham--2014|Graham et al., 2014]] )

|-
| Invasive species

| Warming

| Increased invasive species abundance and increased predation on native species

| ( [[#Tompkins--2013|Tompkins et al., 2013]] ; [[#Macinnis-Ng--2021|Macinnis-Ng et al., 2021]] )

|-
|
| Warming

| Expanded ranges of invasive species in higher/cooler areas

| ( [[#Sheppard--2014|Sheppard and Stanley, 2014]] ; [[#Walker--2019|Walker et al., 2019]] )

|-
|
| Warming

| Change in flowering phenology and pollination competition

| ( [[#Giejsztowt--2020|Giejsztowt et al., 2020]] )

|-
|
| Warming

| Increase in invasive plants, insects and pathogens from sub-tropical/tropical climates

| ( [[#Macinnis-Ng--2021|Macinnis-Ng et al., 2021]] )

|-
| Tuatara (reptile), ''Sphenodon punctatus''

| Warming

| Temperature-dependent sex determination with more male hatches threatening small, isolated populations

| ( [[#Grayson--2014|Grayson et al., 2014]] )

|-
|
| Warming

| Increased geographic range

| ( [[#Carter--2018|Carter et al., 2018]] )

|-
| Cattle tick

| Warming

| Increased geographic range and risk of tick-spread anaemia in cattle

| (K.E. Lawrence et al., 2017)

|-
| Brown mudfish, ''Neochanna apoda''

| Drought

| Reduced flow regimes associated with drought interact with reduced habitat due to land use change, leading to population declines and potential local extinction

| ( [[#White--2016b|White et al., 2016b]] ; [[#White--2017|White et al., 2017]] )

|-
| Suter’s skink (lizard) ''Oligosoma suteri''

| Warming

| Increased suitable range but unclear if dispersal is possible because habitats are isolated

| ( [[#Stenhouse--2018|Stenhouse et al., 2018]] )

|-
| Threatened endemic passerine bird, ''Notiomystis cincta''

| Fluctuations in total precipitation, particularly increased and more variable rainfall

| Heavy rainfall can flood nests and kill fledglings while droughts can cause population-wide reproductive failure

| ( [[#Correia--2015|Correia et al., 2015]] )

|-
| Feral cats

| Warming

| Increased geographic range

| ( [[#Aguilar--2015b|Aguilar et al., 2015b]] )

|}

In southern Australia, some forest ecosystems (alpine ash, snow gum woodland, pencil pine, northern jarrah) are projected to transition to a new state or collapse due to hotter and drier conditions with more fires ( ''high confidence'' ) (Table 11.5). In Australia, most native eucalyptus forest plants have a range of traits that enable them to persist with recurrent fire through recovery buds (sprouters) or regenerate through seeding ( [[#Collins--2020|Collins, 2020]] ), affording them a high level of resilience. For high-end projected 2060–2080 fire weather conditions in southeast Australia ( [[#Clarke--2019|Clarke and Evans, 2019]] ), stand-killing wildfires could occur at a severity and frequency greater than the regenerative capacity of seeders ( [[#Enright--2015|Enright et al., 2015]] ; [[#Clarke--2019|Clarke and Evans, 2019]] ). Most New Zealand native plants are not fire resistant and are projected to be replaced by fire-resistant introduced species following climate-change-related fires ( [[#Perry--2014|Perry et al., 2014]] ).

A loss of alpine biodiversity in the southeast Australian Alps bioregion is projected in the near-term as a result of less snow on snow patch feldmark and short alpine herb fields as well as increased stress on snow-dependent plant and animal species ( ''high confidence'' ) (Table 11.3, Table 11.5). In Australia, invasive plants’ and weeds’ response rates are expected to be faster than for native species, and climate change could foster the appearance of a new set of weed species, with many bioregions facing increased impacts from non-native plants ( ''medium confidence'' ) ( [[#Gallagher--2013|Gallagher et al., 2013]] ; [[#Scott--2014|Scott et al., 2014]] ; [[#March-Salas--2020|March-Salas and Pertierra, 2020]] ) (Table 11.5), along with declines in some listed weeds ( [[#Duursma--2013|Duursma et al., 2013]] ; [[#Gallagher--2013|Gallagher et al., 2013]] ). In New Zealand, climate change is projected to enable invasive species to expand to higher elevations and southwards ( ''medium confidence'' ) (Table 11.5) ( [[#Giejsztowt--2020|Giejsztowt et al., 2020]] ; [[#MfE--2020a|MfE, 2020a]] ).

Projected responses of ecosystem processes are uncertain in part due to complex interactions of climate change with soil respiration, plant nutrient availability ( [[#Hasegawa--2015|Hasegawa et al., 2015]] ; [[#Orwin--2015|Orwin et al., 2015]] ; [[#Ochoa-Hueso--2017|Ochoa-Hueso et al., 2017]] ) and changing fire regimes (Table 11.5) ( [[#Scheiter--2015|Scheiter et al., 2015]] ; [[#Dowdy--2019|Dowdy et al., 2019]] ). For aquatic biota, responses will reflect seasonal differences in water temperature ( [[#Wallace--2015|Wallace et al., 2015]] ) and changes in rainfall intensity, productivity and biodiversity ( [[#Jardine--2015|Jardine et al., 2015]] ). Extreme floods may have negative impacts on New Zealand river biota, by mobilising nutrients, sediments and toxic chemicals and aiding the dispersal of invasive species. These effects are compounded by homogenisation of rivers through channelisation ( [[#Death--2015|Death et al., 2015]] ).

Improved coastal modelling, experiments and ''in situ'' studies are reducing uncertainties at a local scale about the impact of future sea level rise (SLR) on coastal freshwater terrestrial wetlands ( ''medium confidence'' ) ( [[#Shoo--2014|Shoo et al., 2014]] ; [[#Bayliss--2018|Bayliss et al., 2018]] ; [[#Grieger--2019|Grieger et al., 2019]] ). Low-lying coastal wetlands are susceptible to saltwater intrusion from sea level rise (SLR) ( [[#Shoo--2014|Shoo et al., 2014]] ; [[#Kettles--2015|Kettles and Bell, 2015]] ; [[#Finlayson--2017|Finlayson et al., 2017]] ) with consequences for species dependent on freshwater habitats ( [[#Houston--2020|Houston et al., 2020]] ). Saline habitat conditions will move inland and new coastal ecosystem states may emerge, including the World Heritage listed Kakadu’s freshwater wetland ( [[#Bayliss--2018|Bayliss et al., 2018]] ) (Table 11.5). Increasingly, sea level rise (SLR) will shrink the intertidal zone, having implications for wading birds which use this zone ( [[#Tait--2019|Tait and Pearce, 2019]] ) (Box 11.6). The ecology of freshwater wetlands in New Zealand are projected to be impacted by the intersection of warming, drought and heavy rainfall ( [[#Pingram--2021|Pingram et al., 2021]] ) (Table 11.5).

The impacts on species from projected global warming depend on their physiological and ecological responses for which knowledge is limited (Table 11.5) ( [[#Bulgarella--2014|Bulgarella et al., 2014]] ; [[#Carter--2018|Carter et al., 2018]] ; [[#Green--2021|Green et al., 2021]] ). Knowledge of projected impacts is constrained by uncertainties about the influence of physiological limits, barriers to dispersal, competition, the availability of habitat resources ( [[#Worth--2014|Worth et al., 2014]] ) and disruptions to ecological interactions ( [[#Lakeman-Fraser--2013|Lakeman-Fraser and Ewers, 2013]] ; [[#Parida--2015|Parida et al., 2015]] ; [[#Porfirio--2016|Porfirio et al., 2016]] ). Gaps in ecological modelling of future climate impacts include consideration of long-term rainfall and temperature changes ( [[#Grimm-Seyfarth--2017|Grimm-Seyfarth et al., 2017]] ; [[#Grimm-Seyfarth--2018|Grimm-Seyfarth et al., 2018]] ), species dispersal rates, evolutionary capacity and phenotypic plasticity and the thresholds at which they are considered adequate to counter the impacts of climate change ( [[#Ofori--2017b|Ofori et al., 2017b]] ), as well as indirect effects including sea level rise (SLR) and altered fire regimes ( [[#Shoo--2014|Shoo et al., 2014]] ; [[#Cadenhead--2016|Cadenhead et al., 2016]] ; [[#He--2016|He et al., 2016]] ).

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