Editing IPCC:AR6/WGII/Chapter-13 (section)

=== 13.3.1 Observed Impacts and Projected Risks ===

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==== 13.3.1.1 Observed Impacts on Terrestrial and Freshwater Ecosystems ====

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European land and freshwater ecosystems (Figure 13.7) are already strongly impacted by a range of anthropogenic drivers ( ''very high confidence'' ), particularly habitats at the southern and northern margins, along the coasts, up mountains and in freshwater systems (Cross-Chapter Paper 1). Interacting with climate change are non-climatic hazards, such as habitat loss and fragmentation, overexploitation, water abstraction, nutrient enrichment and pollution, all of which reduce resilience of biotas and ecosystems ( ''very high confidence'' ). Peatlands in NEU and EEU and other historically important cultural landscapes in Europe are overexploited for forestry, agriculture and peat mining ( [[#Page--2016|Page and Baird, 2016]] ; [[#Tanneberger--2017|Tanneberger et al., 2017]] ; [[#Ojanen--2020|Ojanen and Minkkinen, 2020]] ). Inland wetland RAMSAR convention sites in Europe, which constitute 47% of the global sites have lost area in WCE and gained in SEU from 1980 to 2014 ( [[#Xi--2021|Xi et al., 2021]] ). Forests in WCE were impacted by the extreme heat and drought event of 2018, with effects lasting into 2019 ( [[#Schuldt--2020|Schuldt et al., 2020]] ) and losses in conifer timber sales in Europe ( [[#Hlásny--2021|Hlásny et al., 2021]] ).

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[[File:45e2f6156e97f9beffa26526d7c5e752 IPCC_AR6_WGII_Figure_13_007.png]]

'''Figure 13.7 |''' '''Köppen-Geiger climate classification and biodiversity hotspots in Europe.''' Boundaries are of the

'''(a)''' Northern European (NEU),

'''(b)''' Western–Central European (WCE),

'''(c)''' Southern European (SEU) and

'''(d)''' Eastern European (EEU) regions for 1985–2014 (left) and 2076–2100 (right, A1FI scenario, ~4°C GWL), based on [[#Rubel--2010|Rubel and Kottek (2010)]] .

Extirpation (e.g., local losses of species) have been observed in response to climate change in Europe ( ''medium confidence'' ) ( [[#Wiens--2016|Wiens, 2016]] ; [[#EEA--2017a|EEA, 2017a]] ; [[#Soroye--2020|Soroye et al., 2020]] ). Strong climate-induced declines have been detected in thermosensitive taxa ( [[#Hellmann--2016|Hellmann et al., 2016]] ), including many freshwater groups, insects ( [[#Habel--2019|Habel et al., 2019]] ; [[#Harris--2019|Harris et al., 2019]] ; [[#Seibold--2019|Seibold et al., 2019]] ; [[#Soroye--2020|Soroye et al., 2020]] ), amphibians, reptiles ( [[#Falaschi--2019|Falaschi et al., 2019]] ), birds ( [[#Lehikoinen--2019|Lehikoinen et al., 2019]] ) and fishes ( [[#Myers--2017a|Myers et al., 2017a]] ; [[#Jarić--2019|Jarić et al., 2019]] ). The loss of native species, especially specialised taxa, is changing biodiversity; however, overall biodiversity could remain stable because losses may be offset by range shifts of native, and the establishment of non-native, species ( [[#Dornelas--2014|Dornelas et al., 2014]] ; [[#McGill--2015|McGill et al., 2015]] ; [[#Hillebrand--2018|Hillebrand et al., 2018]] ; [[#Outhwaite--2020|Outhwaite et al., 2020]] ).

Range shifts are leading to northward and upwards expansions of warm-adapted taxa ( ''very high confidence'' ) (Figure 13.8; Chapter 2). These shifts have altered species living in the boreal and alpine tundra ( [[#Elmhagen--2015|Elmhagen et al., 2015]] ; [[#Post--2019|Post et al., 2019]] ; [[#Mekonnen--2021|Mekonnen et al., 2021]] ) and are greening the high Arctic tundra with shrubs and trees ( [[#Myers-Smith--2020|Myers-Smith et al., 2020]] ). Plants display more stable distributions at low than at higher mountain altitudes ( [[#Rumpf--2018|Rumpf et al., 2018]] ). Microclimatic variability in some locations can buffer warming impacts ( ''medium confidence'' ) ( [[#Suggitt--2018|Suggitt et al., 2018]] ; [[#Zellweger--2020|Zellweger et al., 2020]] ; [[#Carnicer--2021|Carnicer et al., 2021]] ). Northward shifts of tree species distributions is documented in north-western Europe ( [[#Bryn--2018|Bryn and Potthoff, 2018]] ; [[#Mamet--2019|Mamet et al., 2019]] ) but not consistently detected ( [[#Cudlín--2017|Cudlín et al., 2017]] ; [[#Vilà-Cabrera--2019|Vilà-Cabrera et al., 2019]] ).

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[[File:46e6c883f7284e04944163e568e77d6c IPCC_AR6_WGII_Figure_13_008.png]]

'''Figure 13.8 |''' '''Summary of major impacts on, and risks for, terrestrial and freshwater ecosystems in Europe for 1''' '''.''' '''5°C and 3°C GWL''' (Table SM13.2)

The timing of many processes, including spring leaf unfolding, autumn senescence and flight rhythms, have changed in response to changes in seasonal temperatures, water and light availability ( ''very high confidence'' ) (Chapter 2; [[#Szabó--2016|Szabó et al., 2016]] ; [[#Asse--2018|Asse et al., 2018]] ; [[#Peaucelle--2019|Peaucelle et al., 2019]] ; [[#Menzel--2020|Menzel et al., 2020]] ; [[#Rosbakh--2021|Rosbakh et al., 2021]] ), resulting, for example, in earlier arrival dates for many birds and butterflies ( [[#Karlsson--2014|Karlsson, 2014]] ; [[#Bobretsov--2019|Bobretsov et al., 2019]] ; [[#Lehikoinen--2019|Lehikoinen et al., 2019]] ). The largest increase in length of growing season in plants has been detected in WCE, NEU and EEU, but shortening in parts of SEU driven by later senescence ( [[#Garonna--2014|Garonna et al., 2014]] ), increasing population growth for butterflies and moths ( [[#Macgregor--2019|Macgregor et al., 2019]] ) and birds ( [[#Halupka--2017|Halupka and Halupka, 2017]] ), and residence time for migrant birds ( [[#Newson--2016|Newson et al., 2016]] ).

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==== 13.3.1.2 Projected Risks for Terrestrial and Freshwater Ecosystems ====

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Risks for terrestrial ecosystems will increase with warming ( ''very high confidence'' ) with high impacts at &gt;2.4°C GWL and very high impacts &gt;3.5°C GWL ( ''medium confidence'' ) ( [[#13.10.3|Section 13.10.3.1]] ). Land-use changes will increase extirpation and extinction risk ( ''very high confidence'' ) ( [[#Vermaat--2017|Vermaat et al., 2017]] ). In NEU, biodiversity vulnerability is projected to be lower as new climate and habitat space is becoming available ( [[#Warren--2018|Warren et al., 2018]] ; [[#Harrison--2019|Harrison et al., 2019]] ). Warming &lt;1.5°C GWL would limit risks to biodiversity, while 4°C GWL and intensive land use could lead to a loss of suitable climate and habitat space for most species ( ''low confidence'' ) ( [[#Warren--2018|Warren et al., 2018]] ; [[#Harrison--2019|Harrison et al., 2019]] ).

Disruption of habitat connectivity reduces resilience and is projected to impact 30% of lake and river catchments in Europe by 2030, through drought and reduced river flows ( ''medium evidence'' ) ( [[#Markovic--2017|Markovic et al., 2017]] ). Average wetland area is not projected to change at 1.7°C GWL across Europe, while for &gt;4°C GWL expanding sites in NEU are not sufficient to balance losses in SEU and WCE ( ''high confidence'' ) ( [[#Xi--2021|Xi et al., 2021]] ). At 3°C GWL the alpine tundra habitat and its associated species are projected to be lost in the Pyrenees and shrink dramatically in NEU, WCE and EEU ( [[#Anisimov--2017|Anisimov et al., 2017]] ; [[#Barredo--2020|Barredo et al., 2020]] ).

Population range shifts (Figures 13.7, 13.10) are projected to continue ( ''medium confidence'' at 1.5° GWL, ''high confidence'' at 3.0°C GWL) (Figure 13.8). The largest losses of suitable climatic conditions are projected for plants and insects, with different taxon-specific regions of highest risk, while proportions of species projected to lose suitable climates are lower for other groups ( ''medium confidence'' ) (Figure Box 13.1.1; Table SM13.3; [[#Warren--2018|Warren et al., 2018]] ). Temperatures &gt;1.5°C GWL will lead to a progressive subtropicalisation in SEU, expanding into WCE at &gt;3°C GWL, a northward shift in the temperate domain into NEU ( ''medium confidence'' ) ( [[#Feyen--2020|Feyen et al., 2020]] ) and an expansion of desert biomes in EEU ( [[#Sergienko--2016|Sergienko and Konstantinov, 2016]] ). Changes in distribution are projected for major tree species in all European regions at 1.7°C GWL ( [[#Dyderski--2018|Dyderski et al., 2018]] ; [[#Leskinen--2020|Leskinen et al., 2020]] ), with economic implications for managed forests ( [[#13.5.1.4|Section 13.5.1.4]] ). The longer growth season in NEU and WCE will support the establishment of invasive species (Cross-Chapter Paper 1). Temperatures &lt;1.5°C GWL would limit expansion and novel appearances of pests, while &gt;3.4°C GWL would make large parts of SEU and WCE suitable for pests, for example, wood beetles ( [[#Urvois--2021|Urvois et al., 2021]] ), and increase economic losses due to lower harvest quality of timber ( [[#Toth--2020|Toth et al., 2020]] ).

Risks emerging from climate change for phenology are uncertain, given asynchrony between species, taxa and trophic responses ( [[#Thackeray--2016|Thackeray et al., 2016]] ; [[#Posledovich--2018|Posledovich et al., 2018]] ; [[#Keogan--2021|Keogan et al., 2021]] ) and the complexity of phenological events and their cues ( ''medium confidence'' ) ( [[#Delgado--2020|Delgado et al., 2020]] ; [[#Ettinger--2020|Ettinger et al., 2020]] ). Spring events may continue to occur earlier ( [[#Gaüzère--2016|Gaüzère et al., 2016]] ), but reduced chilling may decrease this temporal shift ( [[#Wang--2020|Wang et al., 2020]] ). Projections for autumn are mixed, with continuing delays ( [[#Prislan--2019|Prislan et al., 2019]] ) or earlier onset of leaf senescence ( [[#Wu--2018|Wu et al., 2018]] ), but reduced chilling may also decrease these developments ( [[#Wang--2020|Wang et al., 2020]] ). Advancement, combined with longer autumn growth, may extend the growing season of trees by two days per decade in SEU ( [[#Prislan--2019|Prislan et al., 2019]] ). Warming to &gt;3°C GWL will impact forest planning in NEU ( [[#Caffarra--2014|Caffarra et al., 2014]] ).

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==== 13.3.1.3 Observed Impacts and Projected Risks of Wildfires ====

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Fires affect over 400,000 ha every year in the EU ( [[#San-Miguel-Ayanz--2019|San-Miguel-Ayanz et al., 2019]] ), with 85% of the area located in SEU ( [[#Khabarov--2016|Khabarov et al., 2016]] ; [[#de%20Rigo--2017|de Rigo et al., 2017]] ; [[#Gomes%20Da%20Costa--2020|Gomes Da Costa et al., 2020]] ), where ‘fire weather’ conditions (determined by temperature, precipitation, wind speed and relative humidity) are most pronounced (Figure 13.10). Fire hazard conditions, including heatwaves ( [[#Boer--2017|Boer et al., 2017]] ), increased throughout Europe from 1980 to 2019 (Figure 13.10), with substantive increases in SEU and WCE ( ''high confidence'' ) ( [[#Urbieta--2019|Urbieta et al., 2019]] ; [[#Di%20Giuseppe--2020|Di Giuseppe et al., 2020]] ; [[#Fargeon--2020|Fargeon et al., 2020]] ). Extreme wildfires have been observed in recent years, including 2017 in Portugal, 2018 in Sweden ( [[#Krikken--2021|Krikken et al., 2021]] ) and 2021 in south-eastern Europe. In SEU, WCE and NEU human activities have caused more than 90–95% of the fires, while natural ignition accounts for a substantial portion of burned areas in EEU ( [[#Wu--2015|Wu et al., 2015]] ; [[#Filipchuk--2018|Filipchuk et al., 2018]] ).

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'''Figure 13.9 |''' '''Species projected to remain within their suitable climate conditions at increasing levels of climate change.''' Colour shading represents the proportion of species projected to remain within their suitable climates averaged over 21 CMIP5 climate models ( [[#Warren--2018|Warren et al., 2018]] ). Areas shaded in green retain a large number of species with suitable climate conditions, while those in purple represent areas where climates become unsuitable for more than 80% of species without dispersal (Table SM13.3).

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'''Figure 13.10 |''' '''Geographical variability and dynamic changes in fire danger in Europe over recent decades.''' Significant increases in fire hazard at the multi-decadal scale and unprecedented years of elevated fire hazard have occurred over the past decade in Southern and Western Central Europe (SEU, WCE). The environmental conditions required for fires to spread and intensify were evaluated using fire hazard estimates (Fire Weather index, FWI, based on meteorological variables such as temperature, precipitation, wind speed and relative humidity). The FWI trends were calculated with the ECMWF ERA-5 FWI reanalysis dataset ( [[#Copernicus--2019|Copernicus, 2019]] ; [[#Copernicus--2020a|Copernicus, 2020a]] ; [[#Copernicus--2020b|Copernicus, 2020b]] ).

Except for Portugal, burned area in SEU has shown a slightly decreasing trend since 1980, with high interannual variability (Cross-Chapter Paper 4; [[#Turco--2016|Turco et al., 2016]] ; [[#de%20Rigo--2017|de Rigo et al., 2017]] ). In SEU, burned terrestrial biomass declined from 2003 to 2019 ( [[#Turco--2016|Turco et al., 2016]] ), despite increasing fire risks. This trend is parallel to increasing fire management measures implemented ( [[#Fernandez-Anez--2021|Fernandez-Anez et al., 2021]] ). The slight increase in burned biomass in WCE and NEU is associated with more hazardous landscape configurations and warming in recent decades ( [[#Turco--2016|Turco et al., 2016]] ; [[#Urbieta--2019|Urbieta et al., 2019]] ).

Projections of wildfire risks are uncertain due to multiple factors, including compound events, fire–vegetation interaction and social factors ( [[#Thompson--2011|Thompson and Calkin, 2011]] ; [[#San-Miguel-Ayanz--2019|San-Miguel-Ayanz et al., 2019]] ). Wildfire risks could increase across all regions of Europe at 1.5°C and 3°C GWL ( ''medium to high confidence'' ) (Figure 13.8). In SEU, the frequency of heat-induced fire weather is projected to increase by 14% at 2.5°C GWL and rise to 30% at 4.4°C GWL ( [[#Turco--2018|Turco et al., 2018]] ; [[#Gomes%20Da%20Costa--2020|Gomes Da Costa et al., 2020]] ; [[#Ruffault--2020|Ruffault et al., 2020]] ). In the European Arctic, the extent and duration of extreme fire seasons will increase because of increasing extreme fire weather, increased lightning activity, and drier vegetation and ground fuel conditions due to prolonged droughts ( [[#McCarty--2021|McCarty et al., 2021]] ). Projections suggest that new fire-prone regions in Europe could emerge, particularly in WCE and NEU where wildfires have been uncommon and fire management capacity is slowly increasing ( [[#Wu--2015|Wu et al., 2015]] ; [[#Forzieri--2021|Forzieri et al., 2021]] ).

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==== 13.3.1.4 Observed Impacts and Projected Risks on Ecosystem Functions and Regulating Services ====

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European temperate and boreal forests, wetlands and peatlands hold important carbon stocks ( [[#Bukvareva--2016|Bukvareva and Zamolodchikov, 2016]] ; [[#Yousefpour--2018|Yousefpour et al., 2018]] ). Effects of warming and increasing droughts on soil moisture, respiration and carbon sequestration have been detected across European regions ( ''high confidence'' ) (Figure 13.8; [[#Sanginés%20de%20Cárcer--2018|Sanginés de Cárcer et al., 2018]] ; [[#Carnicer--2019|Carnicer et al., 2019]] ; [[#Green--2019|Green et al., 2019]] ; [[#Schuldt--2020|Schuldt et al., 2020]] ). Forest expansion in boreal regions results in net warming ( [[#Bright--2017|Bright et al., 2017]] ), possibly influencing cloud formation and rainfall patterns ( ''medium confidence'' ) ( [[#Teuling--2017|Teuling et al., 2017]] ). These changes are affecting climate, pollination and soil protection services (Figure 13.8; [[#Verhagen--2018|Verhagen et al., 2018]] ). If not managed through increased reforestation and/or revegetation or peatland restoration, future climate-change impacts will progressively limit the climate regulation capacity of European terrestrial ecosystems ( ''medium confidence'' ) (Figure 13.8), especially in SEU ( [[#Peñuelas--2018|Peñuelas et al., 2018]] ; [[#Xu--2019|Xu et al., 2019]] ). Predominantly positive CO 2 fertilisation effects at current warming will change into increasingly negative effects of warming and drought on forests at higher temperatures ( ''medium confidence'' ) ( [[#Peñuelas--2017|Peñuelas et al., 2017]] ; [[#Green--2019|Green et al., 2019]] ; [[#Ito--2020|Ito et al., 2020]] ; Wang 2020; [[#Yu--2021|Yu et al., 2021]] ). In NEU and EEU, peatlands are projected to shrink with 1.7°C GWL, and become carbon sources at 3°C GWL ( [[#Qiu--2020|Qiu et al., 2020]] ), peat bogs to lose 50% carbon at 2°C GWL, and blanket peatland to shrink or regionally disappear ( [[#Gallego-Sala--2010|Gallego-Sala et al., 2010]] ; [[#Ferretto--2019|Ferretto et al., 2019]] ).

Declines in pollinator ranges in response to climate change are occurring for many groups in Europe ( ''high confidence'' ) (Figure Box 13.1.1; Figure 13.8; [[#Kerr--2015|Kerr et al., 2015]] ; [[#Soroye--2020|Soroye et al., 2020]] ; [[#Zattara--2020|Zattara and Aizen, 2020]] ), with observed shifts to higher elevations in southern and lower elevation in northern species ( [[#Kerr--2015|Kerr et al., 2015]] ) resulting in higher pollinator richness in NEU ( [[#Franzén--2012|Franzén and Öckinger, 2012]] ). Lags in responses to climate change suggest that current impacts on pollination have not been fully realised ( [[#IPBES--2018|IPBES, 2018]] ). Pollinators are also declining due to lack of suitable habitat, pollution, pesticides, pathogens and competing invasive alien species ( [[#Settele--2016|Settele et al., 2016]] ; [[#Steele--2019|Steele et al., 2019]] ).

Projected climate impacts on pollinators show mixed responses across Europe but are greater under 3°C GWL ( ''medium confidence'' ) ( [[#Rasmont--2015|Rasmont et al., 2015]] ). Increasing homogenisation of populations may increase vulnerability to extreme events ( [[#Vasiliev--2021|Vasiliev and Greenwood, 2021]] ). Geographical changes to the climatic niche of pollinators are similar to those of insects, with mixed trends, depending on group and location (Figure 13.9; [[#Kaloveloni--2015|Kaloveloni et al., 2015]] ; [[#Rasmont--2015|Rasmont et al., 2015]] ; [[#Radenković--2017|Radenković et al., 2017]] ). In NEU, species richness may increase for some groups ( [[#Rasmont--2015|Rasmont et al., 2015]] ), with unclear trends for bumblebees ( [[#Fourcade--2019|Fourcade et al., 2019]] ; [[#Soroye--2020|Soroye et al., 2020]] ). Future land use will have important effects on pollinator distribution (Marshall, 2018) as habitat fragmentation in densely populated Europe decreases opportunities for range shifts and microclimatic buffering ( [[#Vasiliev--2021|Vasiliev and Greenwood, 2021]] ).

Soil erosion varies across Europe, with higher rates in parts of SEU and WCE, but lower rates in NEU ( ''high confidence'' ) (Figure 13.8; [[#Petz--2016|Petz et al., 2016]] ; [[#Polce--2016|Polce et al., 2016]] ; [[#Borrelli--2020|Borrelli et al., 2020]] ), related to vegetation type and amount of cover, slope and soil type ( [[#Panagos--2015a|Panagos et al., 2015a]] ). Short-term land-use change and management may impact soil erosion more than climate ( [[#Verhagen--2018|Verhagen et al., 2018]] ). Where conservation agriculture is practised or vegetation cover increasing, erosion is slightly decreasing ( [[#Panagos--2015b|Panagos et al., 2015b]] ; [[#Guerra--2016|Guerra et al., 2016]] ). Reduced soil loss due to reduced spring snowmelt has been observed in EEU ( [[#Golosov--2018|Golosov et al., 2018]] ), while fire exacerbates soil loss especially in SEU ( [[#Borrelli--2016|Borrelli et al., 2016]] ; [[#Borrelli--2017|Borrelli et al., 2017]] ).

Projected increase in rainfall could increase soil erosion, while warming enhances vegetation cover, leading to overall mixed responses ( ''medium confidence'' ) ( [[#Berberoglu--2020|Berberoglu et al., 2020]] ; [[#Ciampalini--2020|Ciampalini et al., 2020]] ). In Europe, rainfall erosion could increase by &gt;81% ( [[#Panagos--2017|Panagos et al., 2017]] ) at 2°C GWL, especially in NEU ( [[#Borrelli--2020|Borrelli et al., 2020]] ) where risks can be limited by soil erosion control ( [[#Polce--2016|Polce et al., 2016]] ). Decreased rainfall projected for parts of SEU could reduce erosion, although increases in rainfall intensity could offset this ( [[#Serpa--2015|Serpa et al., 2015]] ). Soil losses from fire will increase in SEU in response to 2°C GWL ( [[#Pastor--2019|Pastor et al., 2019]] ), especially if combined with extreme rainfall ( [[#Morán-Ordóñez--2020|Morán-Ordóñez et al., 2020]] ). In northern regions, reduced soil losses are projected during spring snowmelt ( [[#Svetlitchnyi--2020|Svetlitchnyi, 2020]] ).

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