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3,300 | AR6_WGII | 219 | 11 | Extreme events are a natural and important part of many ecosystems, and many organisms have adapted to cope with long-term and short-term climate variability within the disturbance regime experienced during their evolutionary history | high | 2 | train |
3,301 | AR6_WGII | 219 | 12 | However, climate changes, disturbance regime changes and the magnitude and frequency of extreme events such as floods, droughts, cyclones, heat waves and fire have increased in many regions | high | 2 | train |
3,302 | AR6_WGII | 219 | 13 | These disturbances affect ecosystem functioning, biodiversity and ecosystem services | high | 2 | train |
3,303 | AR6_WGII | 219 | 17 | Increases in the frequency and severity of heat waves, droughts and aridity, floods, fires and extreme storms have been observed in many regions (Seneviratne et al., 2012; Ummenhofer and Meehl, 2017), and these trends are projected to continue | high | 2 | train |
3,304 | AR6_WGII | 219 | 24 | High climate velocity (Loarie et al., 2009) is expected to be associated with distribution shifts, incomplete range filling and species extinctions | high | 2 | train |
3,305 | AR6_WGII | 219 | 25 | It is generally assumed that the more rapid the rate of change, the greater the impact on species and ecosystems, but responses are taxonomically and geographically variable | high | 2 | test |
3,306 | AR6_WGII | 219 | 28 | The ability to track suitable climates is substantially reduced by habitat fragmentation and human modifications of the landscape such as dams on rivers and urbanisation | high | 2 | train |
3,307 | AR6_WGII | 220 | 2 | Many species, both terrestrial and freshwater, are not expected to be able to disperse fast enough to track suitable climates under mid- and high-emission scenarios | medium | 1 | train |
3,308 | AR6_WGII | 225 | 7 | Rivers already under stress from human activities such as urban development and farming on floodplains are prone to reduced resilience to future extreme events | medium | 1 | train |
3,309 | AR6_WGII | 225 | 10 | If instream habitat is strongly affected, recovery, if it occurs, takes much longer, resulting in a decline of biodiversity | medium | 1 | train |
3,310 | AR6_WGII | 225 | 14 | In summary, extreme events (heat waves, storms and loss of ice) affect lakes in terms of water temperature, water level, light, oxygen concentrations and nutrient dynamics, which, in turn, affect primary production, fish communities and GHG emissions | high | 2 | train |
3,311 | AR6_WGII | 225 | 16 | Droughts have a negative impact on water quality in streams and lakes by increasing water temperature, salinity, the frequency of algal blooms and contaminant concentrations, and reducing concentrations of nutrients and dissolved oxygen | medium | 1 | train |
3,312 | AR6_WGII | 225 | 22 | For RCP8.5, warming increases to 5.4°C and duration increases dramatically to 95.5 days | medium | 1 | train |
3,313 | AR6_WGII | 225 | 24 | Most prominently, monomictic lakes—undergoing one mixing event in most years—will become permanently stratified, while lakes that are currently dimictic—mix- ing twice per year—will become monomictic by 2080–2100 | medium | 1 | train |
3,314 | AR6_WGII | 225 | 29 | Moreover, melting of ice decreases the ratio of sensible to latent heat flux, thus channelling more energy into evaporation | medium | 1 | train |
3,315 | AR6_WGII | 226 | 1 | Introduction Increases in the frequency and magnitudes of extreme events, attributed to anthropogenic climate change by WGI (IPCC, 2021a), are now causing profound negative effects across all realms of the world (marine, terrestrial, freshwater and polar) | medium | 1 | train |
3,316 | AR6_WGII | 226 | 2 | Changes to population abundance, species distributions, local extirpations, and global extinctions are leading to long-term, potentially irreversible shifts in the composition, structure and function of natural systems | medium | 1 | train |
3,317 | AR6_WGII | 226 | 5 | This has collapsed the timeline that organisms and natural communities have to acclimate or adapt to climate change | medium | 1 | train |
3,318 | AR6_WGII | 226 | 8 | Marine Heat Waves Consensus is emerging that anthropogenic climate change has significantly increased the likelihood of recent marine heat waves (MHWs) | medium | 1 | train |
3,319 | AR6_WGII | 226 | 12 | Modelling suggests rapid shifts in the geographic distributions of important fish species in response to MHWs (Cheung and Frolicher, 2020), with projected decreased biomass and distributional shifts of fish at least four times faster and larger than the effects of decadal-scale mean changes throughout the 21st century under RCP8.5 | high | 2 | train |
3,320 | AR6_WGII | 226 | 14 | The Arctic region is warming more than twice as fast as the global mean, and polar organisms and ecosystems are likely to be particularly vulnerable to heat waves due to their specific thermal niches and physiological thresholds and also the lack of poleward ‘refugia’ | high | 2 | train |
3,321 | AR6_WGII | 227 | 6 | Terrestrial Heat Waves Heat waves are now regularly occurring that exceed the physiological thresholds of some species, including birds and other small endotherms such as flying foxes | high | 2 | train |
3,322 | AR6_WGII | 230 | 17 | Attribution is strong for species and species-interactions for which there is a robust mechanistic understanding of the role of climate on biological processes | high | 2 | train |
3,323 | AR6_WGII | 231 | 9 | Changes of temperature extremes are often more important to these local extinction rates than changes of mean annual temperature | high | 2 | train |
3,324 | AR6_WGII | 231 | 27 | Major declines have been recorded for several species, population extinctions have occured at lower elevations since the early 2000s, and the white sub-species of the lemuroid ringtail possum (Hemibelideus lemuroides) in Queensland, Australia, disappeared after heat waves in 2005 | high | 2 | train |
3,325 | AR6_WGII | 232 | 1 | The interaction between expansion of chytrid fungus globally and local climate change is implicated in the extinction of a wide range of tropical amphibians | high | 2 | train |
3,326 | AR6_WGII | 232 | 8 | In summary, local population extinctions caused by climate-change-driven increases in extreme weather and climate events have been widespread among plants and animals | very high | 3 | train |
3,327 | AR6_WGII | 235 | 7 | As novel climate conditions develop, novel communities made up of new combinations of species are emerging as populations and species adapt and shift their ranges differentially, not always with negative consequences | high | 2 | train |
3,328 | AR6_WGII | 235 | 10 | However, observations, experimental mesocosms (Bastazini et al., 2021), and theoretical models (Lurgi et al., 2012; Sentis et al., 2021) provide support that novel communities will continue to emerge with climate change | medium | 1 | train |
3,329 | AR6_WGII | 236 | 21 | The 15% of species that did both (shifting northward by 113.1 km and advancing their flight period by 2.7 days per decade, on average, over a 20-year period) had the largest population increases, and the 40% of species that showed no response had the largest population declines.2.4.2.6 Observed Changes to Physiology and Morphology Driven by Climate Change Impacts on species physiology in terrestrial and freshwater systems have been observed, and attributed to climate change | medium | 1 | train |
3,330 | AR6_WGII | 236 | 25 | Behavioural plasticity (flexibility) such as nest-site selection can provide a partial buffer from the effects of increasing temperature by placing the individual in a slightly cooler microclimate, but there are environmental and physical limits to this plasticity | medium | 1 | train |
3,331 | AR6_WGII | 236 | 26 | Plasticity in heat tolerance (e.g., due to reversible acclimation or acclimatisation) can also potentially compensate for rising temperatures (Angilletta Jr, 2009), but ectotherms have relatively low acclimation in thermal tolerance and acclimation is expected to only slightly reduce the risk of overheating in even the most plastic taxa | low | 0 | train |
3,332 | AR6_WGII | 236 | 28 | In many ectotherms, plasticity in thermal tolerance increases polewards, as thermal seasonality increases (Chown et al., 2004), contributing to higher vulnerability to warming in tropical organisms | low | 0 | train |
3,333 | AR6_WGII | 236 | 30 | The most heat-tolerant species, such as those from extreme environments, may therefore be at a greater risk of warming because of an inability to physiologically adjust to thermal change | low | 0 | test |
3,334 | AR6_WGII | 236 | 31 | Physiological changes have observable impacts on morphology, such as changes in body size (and length of appendages), and colour changes in butterflies, dragonflies and birds | medium | 1 | train |
3,335 | AR6_WGII | 241 | 2 | However, the lack of systematic empirical evidence in fresh waters, and confounding effects such as interactions between temperature, nutrient availability and predation, limit generalisations in attributing observed body size changes to climate change | low | 0 | train |
3,336 | AR6_WGII | 241 | 3 | Evidence is weak for a consistent reduction in body size across taxonomic groups in terrestrial animals | low | 0 | train |
3,337 | AR6_WGII | 241 | 6 | Several lines of evidence suggest the evolution of melanism in response to climate change | low | 0 | train |
3,338 | AR6_WGII | 241 | 7 | Such changes may represent decreased phenotypic diversity and, potentially, genetic diversity | low | 0 | train |
3,339 | AR6_WGII | 241 | 10 | Interactions between morphological changes and changes in phenology may facilitate or constrain adaptation to climate change | medium | 1 | train |
3,340 | AR6_WGII | 242 | 3 | There is increasing evidence of the role of extreme events in disease outbreaks | very high | 3 | train |
3,341 | AR6_WGII | 242 | 20 | These documented changes in climate, hosts and pathogens have been linked to a higher incidence and more frequent outbreaks of disease in livestock across Europe | very high | 3 | train |
3,342 | AR6_WGII | 243 | 9 | At least six major VBDs affected by climate drivers have recently emerged in Nepal and are now considered endemic, with climate change implicated as a primary driver as LULCC has been assessed to have a minimal influence on these diseases | high | 2 | train |
3,343 | AR6_WGII | 243 | 16 | In concert with these poleward shifts of hosts and vectors, pathogens, particularly tick-borne pathogens and helminth infections, have increased dramatically in incidence and severity from once-rare occurrences and have appeared in new regions | very high | 3 | train |
3,344 | AR6_WGII | 244 | 5 | These increases in introduction risk compounded with climate change have already begun to harm Indigenous Peoples dependent on hunting and herding livestock (horses and reindeer) that are suffering increased pathogen infection | high | 2 | train |
3,345 | AR6_WGII | 248 | 10 | In summary, with our present knowledge, evolution is not expected to be sufficient to prevent the extinction of whole species if a species’ climate space disappears within the region they inhabit | high | 2 | train |
3,346 | AR6_WGII | 251 | 4 | The global extent of grasslands is declining significantly because of climate change | medium | 1 | train |
3,347 | AR6_WGII | 254 | 16 | In summary, new studies since AR5 have explicitly estimated the effects of warming and browning on freshwaters in boreal areas, with complex positive and negative repercussions on water temperature profiles (lower vs. upper water) (high confidence) and primary production | medium | 1 | train |
3,348 | AR6_WGII | 255 | 4 | In summary, field evidence shows that anthropogenic climate change has increased the area burned by wildfire above natural levels across western North America in the period 1984–2017, at GMST increases of 0.6°C–0.9°C, increasing burned area up to 11 times in one extreme year and doubling it (over natural levels) in a 32-year period | high | 2 | train |
3,349 | AR6_WGII | 255 | 18 | Overall, human land use exerts an influence on wildfire trends for global terrestrial area as a whole that can be stronger than climate change | medium | 1 | train |
3,350 | AR6_WGII | 257 | 2 | Deforestation, peat draining, agricultural expansion or abandonment, fire suppression and inter-decadal cycles such as the ENSO exert a stronger influence than climate change on wildfire trends in numerous regions outside of North America | high | 2 | train |
3,351 | AR6_WGII | 259 | 5 | Nevertheless, the evidence from the forests of western North America shows that human-caused climate change has, at least on one continent, clearly driven increases in wildfire.Box FAQ 2.3 (continued) In summary, anthropogenic climate change caused drought-induced tree mortality of up to 20% in the period 1945–2007 in western North America, the African Sahel and North Africa, via global temperature increases of 0.3°C–0.9°C above the pre-industrial period and increases in aridity, and it contributed to over 100 other cases of drought-induced tree mortality in Africa, Asia, Australia, Europe and North and South America | high | 2 | train |
3,352 | AR6_WGII | 259 | 6 | Field observations document accelerating mortality rates, rising background mortality and post-mortality vegetation shifts | high | 2 | train |
3,353 | AR6_WGII | 260 | 12 | In summary, climate change has contributed to tree mortality in Europe | high | 2 | train |
3,354 | AR6_WGII | 260 | 17 | Mammals that use trees as refugia showed declines with tree mortality | high | 2 | train |
3,355 | AR6_WGII | 260 | 19 | Ground-nesting, ground-foraging, tree-hole nesting and bark-foraging birds increased most, but nectar-feeding and foliage-gleaning birds declined | high | 2 | train |
3,356 | AR6_WGII | 260 | 20 | Within invertebrates, declines were strongest in ground-foraging predators and detritivores | medium | 1 | train |
3,357 | AR6_WGII | 260 | 31 | Thus, tropical rainforests, Arctic permafrost and other ecosystems provide the global ecosystem service of naturally preventing carbon from contributing to climate change | high | 2 | train |
3,358 | AR6_WGII | 261 | 10 | These ecosystems form natural sinks that prevent the emission to the atmosphere of 1400– 1800 GtC that would otherwise increase the magnitude of climate change | high | 2 | train |
3,359 | AR6_WGII | 261 | 21 | Conservation of high biodiversity areas, particularly in protected areas, protects ecosystem carbon, prevents emissions to the atmosphere and reduces the magnitude of climate change | high | 2 | train |
3,360 | AR6_WGII | 262 | 7 | These factors combined—recent impacts of climate change on undisturbed forest, coupled with deforestation and agricultural expansion, along with associated intentional burning—have caused Amazon rainforest to become an overall net carbon emitter | medium | 1 | train |
3,361 | AR6_WGII | 262 | 15 | Tropical deforestation, the draining and burning of peatlands and the thawing of Arctic permafrost due to climate change have caused these ecosystems to emit more carbon to the atmosphere than they naturally remove through vegetation growth | high | 2 | train |
3,362 | AR6_WGII | 263 | 5 | In large, nutrient-poor lakes, warming-induced prolonged thermal stratification can reduce primary production | medium | 1 | train |
3,363 | AR6_WGII | 263 | 9 | However, increases or declines of algae cannot entirely be attributed to climate change; they are lake-specific and modulated through weather conditions, lake morphology, salinity, land use and restoration and biotic interactions | medium | 1 | train |
3,364 | AR6_WGII | 263 | 11 | Global and regional meta-analyses of diverse systems, habitats and taxonomic groupings document that approximately half of all species with long-term records have shifted their ranges poleward and/or upward in elevation and ~2/3 have advanced their timing of spring events (phenology) | very high | 3 | train |
3,365 | AR6_WGII | 263 | 12 | Changes in abundance tend to match predictions from climate warming, with warm-adapted species significantly outperforming cold-adapted species in warming habitats (Feeley et al., 2020) and the composition of local communities becoming more ‘thermophilised’, that is, experiencing an ‘increase in relative abundance of heat-loving or heat-tolerant species’ | high | 2 | train |
3,366 | AR6_WGII | 263 | 13 | New studies since AR5, with more sophisticated analyses designed to capture complex responses, indicate that past estimates of the proportion of species impacted by recent climate change were underestimates due to unspoken assumptions that local or regional warming should lead solely to poleward/upward range shifts and advancements of spring timing | high | 2 | train |
3,367 | AR6_WGII | 263 | 14 | More complex analyses have documented cases of winter warming driving delayed spring timing of northern temperate species due to chilling requirements, and increased precipitation driving species’ range shifts downslope in elevation, and eastward and westward in arid regions | high | 2 | train |
3,368 | AR6_WGII | 263 | 15 | Further new studies have shown that phenological changes have, in some cases, successfully compensated for local climate change and reduced the extent of range shifts | medium | 1 | train |
3,369 | AR6_WGII | 263 | 17 | Responses in freshwater species are consistent with responses in terrestrial species, including poleward and upward range shifts, earlier timing of spring plankton development, earlier spawning by fish and the extension of the growing season | high | 2 | train |
3,370 | AR6_WGII | 263 | 18 | Observed changes in freshwater species are strongly related to anthropogenic climate change-driven changes in the physical environment (e.g., increased water temperature, reduced ice cover, reduced mixing in lakes, loss of oxygen and reduced river connectivity) | high | 2 | train |
3,371 | AR6_WGII | 263 | 19 | While evidence is robust for an increase in primary production in nutrient rich lakes along with warming trends | high | 2 | train |
3,372 | AR6_WGII | 263 | 21 | This has caused waters to become brown, resulting in an acceleration of upper-water warming and an overall cooling of deep water | high | 2 | train |
3,373 | AR6_WGII | 263 | 22 | Browning may accelerate primary production through the input of nutrients associated with DOM in nutrient-poor lakes and increases the growth of cyanobacteria, which cope better with low light intensity | medium | 1 | train |
3,374 | AR6_WGII | 263 | 23 | Field research since the AR5 has detected biome shifts at numerous sites, poleward and upslope, that are consistent with increased temperatures and altered precipitation patterns driven by climate change, and support prior studies that attributed such shifts to anthropogenic climate change | high | 2 | train |
3,375 | AR6_WGII | 263 | 25 | Globally, woody encroachment into open areas (grasslands, arid regions and tundra) is likely being driven by climate change and increased CO 2, in concert with changes in grazing and fire regimes | medium | 1 | train |
3,376 | AR6_WGII | 264 | 1 | Analyses of causal factors have attributed increasing tree mortality at sites in Africa and North America to anthropogenic climate change, and field evidence has detected tree mortality due to drought, wildfires and insect pests in temperate and tropical forests around the world | high | 2 | train |
3,377 | AR6_WGII | 264 | 2 | Water stress, leading to plant hydraulic failure, is a principal mechanism of drought-induced tree mortality, along with the indirect effects of climate change mediated by community interactions | high | 2 | train |
3,378 | AR6_WGII | 264 | 3 | Terrestrial ecosystems sequester and store globally critical stocks of carbon, but these stocks are at risk from deforestation and climate change | high | 2 | train |
3,379 | AR6_WGII | 264 | 5 | In the Arctic, increased temperatures have thawed permafrost at numerous sites, dried some areas and increased fires, causing net emissions of carbon from soils | high | 2 | train |
3,380 | AR6_WGII | 264 | 6 | Globally, increases in temperature, aridity and drought have increased the length of fire seasons and doubled the potentially burnable land area | medium | 1 | train |
3,381 | AR6_WGII | 264 | 7 | Increases in the area burned have been attributed to anthropogenic climate change in North America | high | 2 | test |
3,382 | AR6_WGII | 264 | 11 | The changes in biodiversity and ecosystem health that we have observed, and project will continue, pose a risk of declines in human health and well-being (e.g., tourism, recreation, food, livelihoods and quality of life) | medium | 1 | train |
3,383 | AR6_WGII | 268 | 28 | AR5 stated: ‘a large fraction of terrestrial and freshwater species face increased extinction risk under projected climate change during and beyond the 21st century, especially as climate change interacts with other pressures | high | 2 | train |
3,384 | AR6_WGII | 270 | 5 | Species’ losses are projected to be worst in northern South America, southern Africa, most of Australia and at northern high latitudes | medium | 1 | train |
3,385 | AR6_WGII | 270 | 8 | Ten-twenty percent losses represent high and very high risk of biodiversity losses, respectively, substantial enough to reduce ecosystem integrity and functioning | medium | 1 | train |
3,386 | AR6_WGII | 270 | 14 | The roughly equivalent estimate of this risk as expressed in AR4 (Fischlin et al., 2007) is indicated by the dotted block indicating the medium confidence statement ‘Approximately 20–30% of plant and animal species assessed so far (in an unbiased sample) are likely to be at increasingly high risk of extinction as global mean temperatures exceed a warming of 2–3°C above pre-industrial levels | medium | 1 | train |
3,387 | AR6_WGII | 270 | 28 | All groups fare substantially better at 2°C, with extinction projections reducing to <3% for all groups, except salamanders at 7% | medium | 1 | train |
3,388 | AR6_WGII | 272 | 19 | In sum, climate change is expected to expand and redistribute the burden of vector-borne and other environmentally transmitted diseases of wild animals, domesticated animals and humans, by shifting many regions toward the thermal optima of VBD transmission for multiple parasites, thereby increasing risk of transmission, while pushing temperatures above optimal and towards upper thermal limits for other vectors and pathogens, thus decreasing their transmission | high | 2 | train |
3,389 | AR6_WGII | 274 | 2 | Large discrepancies exist between models and between scenarios regarding the region and the speed of change (Gonzalez et al., 2010; Pereira et al., 2010; Pecl et al., 2017), but robust understanding is emerging in that the degree of impact increases in high-emission and high-warming scenarios | high | 2 | train |
3,390 | AR6_WGII | 274 | 6 | In particular, in cold (boreal and tundra) regions, as well as in dry regions | high | 2 | train |
3,391 | AR6_WGII | 274 | 11 | However, ‘novel ecosystems’, that is, communities with no current or historical equivalent because of the novel combinations of abiotic conditions under climate change, are expected to be increasingly common in the future | medium | 1 | train |
3,392 | AR6_WGII | 274 | 12 | The possibility of these novel ecosystems and the communities that live within them are a challenge for current modelling of ecosystem shifts, and new approaches to conservation will be required that are designed to adapt to rapid changes in species composition and the ensuing challenges.2.5.2.3 Risk to Arid Regions Shifts in arid system structure and functioning that have been observed to date (Section 2.4.3.3) are projected to continue | medium | 1 | train |
3,393 | AR6_WGII | 275 | 16 | Similarly, much of the MTEs are open shrublands and grasslands and proposed extensive tree-planting to sequester atmospheric CO 2 could result in a loss of biodiversity and threaten water security (Doblas-Miranda et al., 2017; Bond et al., 2019).2.5.2.5 Risk to Grasslands and Savannas Worldwide, woody cover is increasing in savannas (Buitenwerf et al., 2012; Donohue et al., 2013; Stevens et al., 2017), as a result of interactions of elevated CO 2 and altered fire and herbivory impacts, some of which stems from LULCC | high | 2 | train |
3,394 | AR6_WGII | 275 | 19 | Increases in woody vegetation in grassy ecosystems could provide some carbon increase (medium confidence) (Zhou et al., 2017; Mureva et al., 2018), but is expected to decrease biodiversity (Smit and Prins, 2015; Abreu et al., 2017; Andersen and Steidl, 2019) and water availability (Honda and Durigan, 2016; Stafford et al., 2017) and alter ecosystem services like grazing and wood provision | high | 2 | train |
3,395 | AR6_WGII | 275 | 21 | It has been shown that simulation studies that do not account for CO 2 interactions but only consider climate change impacts do not realistically capture the future distribution of savannas | high | 2 | train |
3,396 | AR6_WGII | 275 | 25 | Future fire-spread is expected to be reduced with increased woody dominance (Scheiter et al., 2015; Knorr et al., 2016b; Scheiter et al., 2020), feeding back to further increase tree-to-grass ratios | high | 2 | train |
3,397 | AR6_WGII | 276 | 27 | As a consequence, boreal tree species are expected to move northwards (or in mountainous regions, upwards) into regions dominated by tundra, unless constrained by edaphic features, and temperate species are projected to grow in regions currently occupied by southern boreal forest | high | 2 | train |
3,398 | AR6_WGII | 278 | 2 | SR1.5 classified tundra and boreal forests as particularly vulnerable to degradation and encroachment by woody shrubs | high | 2 | train |
3,399 | AR6_WGII | 278 | 3 | The SROCC projected climate-related changes to arctic hydrology, wildfires and abrupt thaw (high confidence) and the broad disappearance of arctic near-surface permafrost this century, with important consequences for global climate | very high | 3 | train |
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