rlacombe/ClimateX huggingface dataset:
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 (IPCC AR6_WGII, confidence: medium)
Moreover, melting of ice decreases the ratio of sensible to latent heat flux, thus channelling more energy into evaporation (IPCC AR6_WGII, confidence: medium)
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) (IPCC AR6_WGII, confidence: medium)
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 (IPCC AR6_WGII, confidence: medium)
This has collapsed the timeline that organisms and natural communities have to acclimate or adapt to climate change (IPCC AR6_WGII, confidence: medium)
Marine Heat Waves Consensus is emerging that anthropogenic climate change has significantly increased the likelihood of recent marine heat waves (MHWs) (IPCC AR6_WGII, confidence: medium)
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 (IPCC AR6_WGII, confidence: high)
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’ (IPCC AR6_WGII, confidence: high)
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 (IPCC AR6_WGII, confidence: high)
Attribution is strong for species and species-interactions for which there is a robust mechanistic understanding of the role of climate on biological processes (IPCC AR6_WGII, confidence: high)
Changes of temperature extremes are often more important to these local extinction rates than changes of mean annual temperature (IPCC AR6_WGII, confidence: high)
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 (IPCC AR6_WGII, confidence: high)
The interaction between expansion of chytrid fungus globally and local climate change is implicated in the extinction of a wide range of tropical amphibians (IPCC AR6_WGII, confidence: high)
In summary, local population extinctions caused by climate-change-driven increases in extreme weather and climate events have been widespread among plants and animals (IPCC AR6_WGII, confidence: very high)
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 (IPCC AR6_WGII, confidence: high)
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 (IPCC AR6_WGII, confidence: medium)
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 (IPCC AR6_WGII, confidence: medium)
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 (IPCC AR6_WGII, confidence: medium)
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 (IPCC AR6_WGII, confidence: low)
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 (IPCC AR6_WGII, confidence: low)
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 (IPCC AR6_WGII, confidence: low)
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 (IPCC AR6_WGII, confidence: medium)
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 (IPCC AR6_WGII, confidence: low)
Evidence is weak for a consistent reduction in body size across taxonomic groups in terrestrial animals (IPCC AR6_WGII, confidence: low)
Several lines of evidence suggest the evolution of melanism in response to climate change (IPCC AR6_WGII, confidence: low)
Such changes may represent decreased phenotypic diversity and, potentially, genetic diversity (IPCC AR6_WGII, confidence: low)
Interactions between morphological changes and changes in phenology may facilitate or constrain adaptation to climate change (IPCC AR6_WGII, confidence: medium)
There is increasing evidence of the role of extreme events in disease outbreaks (IPCC AR6_WGII, confidence: very high)
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 (IPCC AR6_WGII, confidence: very high)
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 (IPCC AR6_WGII, confidence: high)
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 (IPCC AR6_WGII, confidence: very high)
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 (IPCC AR6_WGII, confidence: high)
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 (IPCC AR6_WGII, confidence: high)
The global extent of grasslands is declining significantly because of climate change (IPCC AR6_WGII, confidence: medium)
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 (IPCC AR6_WGII, confidence: medium)
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 (IPCC AR6_WGII, confidence: high)
Overall, human land use exerts an influence on wildfire trends for global terrestrial area as a whole that can be stronger than climate change (IPCC AR6_WGII, confidence: medium)
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 (IPCC AR6_WGII, confidence: high)
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 (IPCC AR6_WGII, confidence: high)
Field observations document accelerating mortality rates, rising background mortality and post-mortality vegetation shifts (IPCC AR6_WGII, confidence: high)
In summary, climate change has contributed to tree mortality in Europe (IPCC AR6_WGII, confidence: high)
Mammals that use trees as refugia showed declines with tree mortality (IPCC AR6_WGII, confidence: high)
Ground-nesting, ground-foraging, tree-hole nesting and bark-foraging birds increased most, but nectar-feeding and foliage-gleaning birds declined (IPCC AR6_WGII, confidence: high)
Within invertebrates, declines were strongest in ground-foraging predators and detritivores (IPCC AR6_WGII, confidence: medium)
Thus, tropical rainforests, Arctic permafrost and other ecosystems provide the global ecosystem service of naturally preventing carbon from contributing to climate change (IPCC AR6_WGII, confidence: high)
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 (IPCC AR6_WGII, confidence: high)
Conservation of high biodiversity areas, particularly in protected areas, protects ecosystem carbon, prevents emissions to the atmosphere and reduces the magnitude of climate change (IPCC AR6_WGII, confidence: high)
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 (IPCC AR6_WGII, confidence: medium)
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 (IPCC AR6_WGII, confidence: high)
In large, nutrient-poor lakes, warming-induced prolonged thermal stratification can reduce primary production (IPCC AR6_WGII, confidence: medium)
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 (IPCC AR6_WGII, confidence: medium)
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) (IPCC AR6_WGII, confidence: very high)
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’ (IPCC AR6_WGII, confidence: high)
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 (IPCC AR6_WGII, confidence: high)
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 (IPCC AR6_WGII, confidence: high)
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 (IPCC AR6_WGII, confidence: medium)
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 (IPCC AR6_WGII, confidence: high)
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) (IPCC AR6_WGII, confidence: high)
While evidence is robust for an increase in primary production in nutrient rich lakes along with warming trends (IPCC AR6_WGII, confidence: high)
This has caused waters to become brown, resulting in an acceleration of upper-water warming and an overall cooling of deep water (IPCC AR6_WGII, confidence: high)
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 (IPCC AR6_WGII, confidence: medium)
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 (IPCC AR6_WGII, confidence: high)
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 (IPCC AR6_WGII, confidence: medium)
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 (IPCC AR6_WGII, confidence: high)
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 (IPCC AR6_WGII, confidence: high)
Terrestrial ecosystems sequester and store globally critical stocks of carbon, but these stocks are at risk from deforestation and climate change (IPCC AR6_WGII, confidence: high)
In the Arctic, increased temperatures have thawed permafrost at numerous sites, dried some areas and increased fires, causing net emissions of carbon from soils (IPCC AR6_WGII, confidence: high)
Globally, increases in temperature, aridity and drought have increased the length of fire seasons and doubled the potentially burnable land area (IPCC AR6_WGII, confidence: medium)
Increases in the area burned have been attributed to anthropogenic climate change in North America (IPCC AR6_WGII, confidence: high)
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) (IPCC AR6_WGII, confidence: medium)
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 (IPCC AR6_WGII, confidence: high)
Species’ losses are projected to be worst in northern South America, southern Africa, most of Australia and at northern high latitudes (IPCC AR6_WGII, confidence: medium)
Ten-twenty percent losses represent high and very high risk of biodiversity losses, respectively, substantial enough to reduce ecosystem integrity and functioning (IPCC AR6_WGII, confidence: medium)
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 (IPCC AR6_WGII, confidence: medium)
All groups fare substantially better at 2°C, with extinction projections reducing to <3% for all groups, except salamanders at 7% (IPCC AR6_WGII, confidence: medium)
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 (IPCC AR6_WGII, confidence: high)
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 (IPCC AR6_WGII, confidence: high)
In particular, in cold (boreal and tundra) regions, as well as in dry regions (IPCC AR6_WGII, confidence: high)
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 (IPCC AR6_WGII, confidence: medium)
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 (IPCC AR6_WGII, confidence: medium)
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 (IPCC AR6_WGII, confidence: high)
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 (IPCC AR6_WGII, confidence: high)
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 (IPCC AR6_WGII, confidence: high)
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 (IPCC AR6_WGII, confidence: high)
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 (IPCC AR6_WGII, confidence: high)
SR1.5 classified tundra and boreal forests as particularly vulnerable to degradation and encroachment by woody shrubs (IPCC AR6_WGII, confidence: high)
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 (IPCC AR6_WGII, confidence: very high)
Models of vegetation response to climate project acceleration in the coming decades of observed increases in shrub dominance and boreal forest encroachment that have been driven by recent warming (Settele et al., 2014), leading to a shrinking of the area of tundra globally (IPCC AR6_WGII, confidence: medium)
Therefore, the trends of changing vegetation cover identified in simulations of transient warming continue to show up in simulations that hold climate change at low levels of warming (IPCC AR6_WGII, confidence: medium)
Projected climate change could expose an extensive part of the global protected area to disappearing and novel climate conditions (IPCC AR6_WGII, confidence: high)
Projected disappearance of suitable climate conditions in protected areas increase risks to the survival of species and vegetation types of conservation concern in tropical, temperate and boreal ecosystems (IPCC AR6_WGII, confidence: high)
Protected areas conserve refugia from climate change under a temperature increase of 4°C, which is important for biodiversity conservation but is limited to <10% of the current protected area (IPCC AR6_WGII, confidence: medium)
In summary, under a high-emission scenario that increases global temperature 4°C by 2100, climate change could increase the global burned area by 50–70% and the global mean fire frequency by ~30%, with increases on one- to two-thirds and decreases on one-fifth of global land (IPCC AR6_WGII, confidence: medium)
Lower emissions that would limit the global temperature increase to <2°C would reduce projected increases of burned area to ~35% and projected increases of fire frequency to ~20% (IPCC AR6_WGII, confidence: medium)
Increased wildfire, combined with erosion due to deforestation, could degrade water supplies (IPCC AR6_WGII, confidence: high)
For ecosystems with an historically low fire frequency, a projected 4°C rise in global temperature increases risks of fire, contributing to potential tree mortality and conversion of over half the Amazon rainforest to grassland and thawing of the Arctic permafrost that could release 11–200 GtC that could substantially exacerbate climate change (IPCC AR6_WGII, confidence: medium)
Similar to tropical peatlands, given projected human population growth and socioeconomic changes, the continued conversion of forests and savannas into agricultural or pasture systems very likely poses a significant risk of rapid carbon loss which will amplify the climate change-induced risks substantially (IPCC AR6_WGII, confidence: high)