rlacombe/ClimateX huggingface dataset:
Regionally, projected interactions of climate-induced drivers, fisheries and other regional non-climate drivers can be both synergistic and antagonistic, varying across regions, functional groups and species, and can cause nonlinear dynamics with counterintuitive outcomes, underlining the importance of adaptations and associated trade-offs (IPCC AR6_WGII, confidence: high)
Heat stress and mass bleaching events caused decreases in live coral cover (virtually certain) (Graham et al., 2014; Hughes et al., 2018b), loss of sensitive species (extremely likely) (Donner and Carilli, 2019; Lange and Perry, 2019; Toth et al., 2019; Courtney et al., 2020), vulnerability to disease (extremely likely) (van Woesik and Randall, 2017; Hadaidi et al., 2018; Brodnicke et al., 2019; Howells et al., 2020) and declines in coral recruitment in the tropics (IPCC AR6_WGII, confidence: medium)
Changes in coral community structure due to bleaching have caused declines in reef carbonate production (IPCC AR6_WGII, confidence: high)
Bleaching and other drivers promote phase shifts to ecosystems dominated by macroalgae or other stress-tolerant species (very high confidence) (Graham et al., 2015; Stuart-Smith et al., 2018), leading to changes in reef-fish species assemblages (IPCC AR6_WGII, confidence: high)
Ocean acidification and associated declines in aragonite saturation state (Ω aragonite) decrease rates of calcification by corals and other calcifying reef organisms (very high confidence), reduce coral settlement (medium confidence) and increase bioerosion and dissolution of reef substrates (IPCC AR6_WGII, confidence: high)
However, experimental evidence suggests that coral responses to ocean acidification are species specific (IPCC AR6_WGII, confidence: medium)
The increased water depth due to coral loss and reef erosion, as well as reduced structural complexity, will limit wave attenuation and exacerbate the risk of flooding from SLR on reef- Table 3.3 | Summary of previous IPCC assessments of coral reefs Observations Projections AR5 (Hoegh-Guldberg et al., 2014; Wong et al., 2014) Coral reefs are one of the most vulnerable marine ecosystems (IPCC AR6_WGII, confidence: high)
Mass coral bleaching and mortality, triggered by positive temperature anomalies (IPCC AR6_WGII, confidence: high)
Ocean acidification reduces biodiversity and the calcification rate of corals (high confidence) while at the same time increasing the rate of dissolution of the reef framework (IPCC AR6_WGII, confidence: medium)
SROCC (Bindoff et al., 2019a) ‘New evidence since AR5 and SR15 confirms the impacts of ocean warming and acidification on coral reefs (high confidence), enhancing reef dissolution and bioerosion (high confidence), affecting coral species distribution and leading to community changes (IPCC AR6_WGII, confidence: high)
The rate of SLR (primarily noticed in small reef islands) may outpace the growth of reefs to keep up, although there is low agreement in the literature (low confidence).’ ‘Reefs are further exposed to other increased impacts, such as enhanced storm intensity, turbidity and increased runoff from the land (IPCC AR6_WGII, confidence: high)
Recovery of coral reefs resulting from repeated disturbance events is slow (IPCC AR6_WGII, confidence: high)
Only few coral reef areas show some resilience to global change drivers (low confidence).’‘Coral reefs will face very high risk at temperatures 1.5°C of global sea surface warming (very high confidence).’ ‘Almost all coral reefs will degrade from their current state, even if global warming remains below 2°C (very high confidence), and the remaining shallow coral reef communities will differ in species composition and diversity from present reefs (IPCC AR6_WGII, confidence: very high)
This will greatly diminish the services they provide to society, such as food provision (high confidence), coastal protection (high confidence) and tourism (medium confidence).’ ‘The very high vulnerability of coral reefs to warming, ocean acidification, increasing storm intensity and SLR under climate change, including enhanced bioerosion (IPCC AR6_WGII, confidence: high)
Local coral reef fish species richness is projected to decline due to the impacts of warming on coral cover and diversity (IPCC AR6_WGII, confidence: high)
Major reef crises in the past 300 million years were governed by hyperthermal events (medium confidence) (Section 3.2.4.4; Cross-Chapter Box PALEO in Chapter 1) longer in time scale than anthropogenic climate change, during which net coral reef accretion was more strongly affected than biodiversity (IPCC AR6_WGII, confidence: medium)
Recovery and restoration efforts that target heat- resistant coral populations and culture heat-tolerant algal symbionts have the greatest potential of effectiveness under future warming (IPCC AR6_WGII, confidence: high)
In summary, additional evidence since SROCC and SR15 (Table 3.3) finds that living coral and reef growth are declining due to warming and MHWs (IPCC AR6_WGII, confidence: very high)
Coral reefs are under threat of transitioning to net erosion with >1.5°C of global warming (IPCC AR6_WGII, confidence: high)
The effectiveness of conservation efforts to sustain living coral area, coral diversity and reef growth is limited for the majority of the world’s reefs with >1.5°C of global warming (IPCC AR6_WGII, confidence: high)
For example, the collapse of sea star populations in the Northeast Pacific due to a MHW-related disease outbreak (Hewson et al., 2014; Menge et al., 2016; Miner et al., 2018; Schiebelhut et al., 2018), including 80–100% loss of the common predatory sunflower star, Pycnopodia helianthoides (IPCC AR6_WGII, confidence: very high)
Multiple lines of evidence find that foundational calcifying organisms such as mussels are at high risk of decline due to both the individual and synergistic effects of warming, acidification and hypoxia (IPCC AR6_WGII, confidence: high)
Experiments show that ocean acidification negatively impacts mussel physiology (IPCC AR6_WGII, confidence: very high)
Net calcification and abundance of mussels and other foundational species, including oysters, are expected to decline due to ocean acidification (very high confidence) (Kwiatkowski et al., 2016; Sunday et al., 2016; McCoy et al., 2018; Meng et al., 2018), causing the reorganisation of communities (IPCC AR6_WGII, confidence: high)
Experiments indicate that warming reduces calcification by coralline algae (IPCC AR6_WGII, confidence: high)
The upper vertical limits of some species will also be constrained by climate change (IPCC AR6_WGII, confidence: high)
Experimental evidence since previous assessments further indicates that acidification decreases abundance and richness of calcifying species (IPCC AR6_WGII, confidence: high)
Synergistic effects of warming and acidification will promote shifts towards macroalgal dominance in some ecosystems (medium confidence) and lead to reorganisation of communities (IPCC AR6_WGII, confidence: medium)
Recent research (Straub et al., 2019; Butler et al., 2020; Filbee-Dexter et al., 2020b; Tait et al., 2021) supports the findings of previous assessments (Table 3.5) that kelp and other seaweeds in most regions are undergoing mass mortalities from high temperature extremes and range shifts from warming (IPCC AR6_WGII, confidence: very high)
The most prominent effects are range shifts of species in response to ocean warming (high confidence) and changes in species distribution and abundance (high confidence) mostly in relation to ocean warming and acidification.’ ‘The dramatic decline of biodiversity in mussel beds of the Californian coast has been attributed to large-scale processes associated with climate-related drivers [...] (high confidence).’‘The abundance and distribution of rocky shore species will continue to change in a warming world (IPCC AR6_WGII, confidence: high)
For example, the long-term consequences of ocean warming on mussel beds of the northeast Pacific are both positive (increased growth) and negative (increased susceptibility to stress and of exposure to predation) (medium confidence).’ ‘Observations performed near natural CO 2 vents in the Mediterranean Sea show that diversity, biomass and trophic complexity of rocky shore communities will decrease at future pH levels (high confidence).’ SR15 (Hoegh-Guldberg et al., 2018a) ‘Changes in ocean circulation can have profound impacts on [temperate] marine ecosystems by connecting regions and facilitating the entry and establishment of species in areas where they were unknown before (‘tropicalization’ ...) as well as the arrival of novel disease agents (medium agreement, limited evidence).’‘In the transition to 1.5°C, changes to water temperatures are expected to drive some species (e.g., plankton, fish) to relocate to higher latitudes and cause novel ecosystems to assemble (IPCC AR6_WGII, confidence: high)
Other ecosystems (e.g., kelp forests, coral reefs) are relatively less able to move, however, and are projected to experience high rates of mortality and loss (IPCC AR6_WGII, confidence: very high)
SROCC (Bindoff et al., 2019a) Intertidal rocky shores ecosystems are highly sensitive to ocean warming, acidification and extreme heat exposure during low tide emersion (IPCC AR6_WGII, confidence: high)
These ecosystems have low to moderate adaptive capacity, as they are highly sensitive to ocean temperatures and acidification.’ ‘Benthic species will continue to relocate in the intertidal zones and experience mass mortality events due to warming (IPCC AR6_WGII, confidence: high)
Interactive effects between acidification and warming will exacerbate the negative impacts on rocky shore communities, causing a shift towards a less diverse ecosystem in terms of species richness and complexity, increasingly dominated by macroalgae (IPCC AR6_WGII, confidence: high)
Warming is driving range contraction and extirpation at the warm edge of species’ ranges and expansions at the cold range edge (IPCC AR6_WGII, confidence: very high)
Local declines in populations of kelp and other canopy-forming seaweeds driven by MHWs and other stressors have caused irreversible shifts to turf- or urchin-dominated ecosystems, with lower productivity and biodiversity (high confidence) (Filbee-Dexter and Scheibling, 2014; Filbee-Dexter and Wernberg, 2018; Rogers-Bennett and Catton, 2019; Beas-Luna et al., 2020; Stuart-Smith et al., 2021), ecosystems dominated by warm- affinity seaweeds or coral (IPCC AR6_WGII, confidence: high)
While reducing non-climate drivers can help prevent kelp loss from warming and MHWs, there is limited potential for restoration of kelp ecosystems after transition to urchin-dominant ecosystems (IPCC AR6_WGII, confidence: high)
Active reseeding of wild kelp populations through transplantation and propagation of warm-tolerant genotypes (Coleman et al., 2020b; Alsuwaiyan et al., 2021) can overcome low dispersal rates of many kelp species and facilitate effective restoration (IPCC AR6_WGII, confidence: medium)
Building on the conclusions of SROCC, this assessment finds that kelp ecosystems are expected to decline and undergo changes in community structure in the future due to warming and increasing frequency and intensity of MHWs (IPCC AR6_WGII, confidence: high)
Risk of loss of kelp ecosystems Table 3.5 | Summary of previous IPCC assessments of kelp ecosystems Observations Projections AR5 (Wong et al., 2014) ‘Kelp forests have been reported to decline in temperate areas in both hemispheres, a loss involving climate change (IPCC AR6_WGII, confidence: high)
Decline in kelp populations attributed to ocean warming has been reported in southern Australia and the north coast of Spain.’‘Kelp ecosystems will decline with the increased frequency of heatwaves and sea temperature extremes as well as through the impact of invasive subtropical species (high confidence).’ ‘Climate change will contribute to the continued decline in the extent of [...] kelps in the temperate zone (medium confidence) and the range of [...] kelps in the Northern Hemisphere will expand poleward (high confidence).’ SR15 (Hoegh-Guldberg et al., 2018a) Observed movement of kelp ecosystems not assessed.‘In the transition to 1.5°C of warming, changes to water temperatures will drive some species (e.g., plankton, fish) to relocate to higher latitudes and cause novel ecosystems to assemble (IPCC AR6_WGII, confidence: high)
Other ecosystems (e.g., kelp forests, coral reefs) are relatively less able to move, however, and are projected to experience high rates of mortality and loss (very high confidence).’ SROCC (Bindoff et al., 2019a) ‘Kelp forests have experienced large-scale habitat loss and degradation of ecosystem structure and functioning over the past half century, implying a moderate to high level of risk at present conditions of global warming (high confidence).’ ‘The abundance of kelp forests has decreased at a rate of ~2% per year over the past half century, mainly due to ocean warming and marine heat waves [...], as well as from other human stressors (high confidence).’ ‘Changes in ocean currents have facilitated the entry of tropical herbivorous fish into temperate kelp forests decreasing their distribution and abundance (medium confidence).’ ‘The loss of kelp forests is followed by the colonisation of turfs, which contributes to the reduction in habitat complexity, carbon storage and diversity (high confidence).’Kelp forests will face moderate to high risk at temperatures above 1.5°C global sea surface warming (IPCC AR6_WGII, confidence: high)
Although these coastal ecosystems have historically been sensitive to erosion-accretion cycles driven by sea level, drought and storms (high confidence) (Peteet et al., 2018; Wang et al., 2018c; Jones et al., 2019b; Urrego et al., 2019; Hapsari et al., 2020; Zhao et al., 2020b), they were impacted for much of the 20th century primarily by non-climate drivers (IPCC AR6_WGII, confidence: very high)
Nevertheless, the influence of climate-induced drivers has become more apparent over recent decades (IPCC AR6_WGII, confidence: medium)
Estuarine biota are sensitive to warming (IPCC AR6_WGII, confidence: high)
MHWs can be more severe in estuaries than in adjacent coastal seas (Lonhart et al., 2019), causing conspicuous impacts (IPCC AR6_WGII, confidence: very high)
Relative SLR extends the upstream limit of saline waters (high confidence) (Harvey et al., 2020; Jiang et al., 2020) and alters tidal ranges (IPCC AR6_WGII, confidence: high)
Elevated water levels also alter submergence patterns for intertidal habitat (high confidence) (Andres et al., 2019), moving high-water levels inland (high confidence) (Peteet et al., 2018; Appeaning Addo et al., 2020; Liu et al., 2020e) and increasing the salinity of coastal water tables and soils (IPCC AR6_WGII, confidence: high)
These processes favour inland and/or upstream migration of intertidal habitat, where it is unconstrained by infrastructure, topography or other environmental features (IPCC AR6_WGII, confidence: high)
Overall, changing salinity and submergence patterns decrease the ability of shoreline vegetation to trap sediment (Xue et al., 2018), reducing accretion rates and increasing the vulnerability of estuarine shorelines to submergence by SLR and erosion by wave action (IPCC AR6_WGII, confidence: medium)
The same phenomena alter salinity gradients, which are the primary drivers of estuarine species distributions (IPCC AR6_WGII, confidence: high)
Acidification of estuarine water is a growing hazard (medium confidence) (Doney et al., 2020; Scanes et al., 2020a; Cai et al., 2021), and resident organisms display sensitivity to altered pH in laboratory settings (IPCC AR6_WGII, confidence: medium)
Warming (including MHWs) and eutrophication interact to decrease estuarine oxygen content and pH, increasing the vulnerability of animals to MHWs (Brauko et al., 2020) and exacerbating the incidence and impact of dead zones (IPCC AR6_WGII, confidence: medium)
All these impacts are projected to escalate under future climate change, but their magnitude depends on the amount of warming, the socioeconomic development pathway and implementation of adaptation strategies (IPCC AR6_WGII, confidence: medium)
Modelling studies (Lopes et al., 2019; Rodrigues et al., 2019; White et al., 2019; Zhang and Li, 2019; Hong et al., 2020; Krvavica and Ružić, 2020; Liu et al., 2020e; Shalby et al., 2020) suggest that responses of estuaries to SLR will be complex and context dependent (Khojasteh et al., 2021), but project that salinity, tidal range, storm-surge amplitude, depth and stratification will increase with SLR (medium confidence), and that marine-dominated waters will penetrate farther upstream (IPCC AR6_WGII, confidence: high)
Without careful management of freshwater inputs, sediment augmentation and/or the restoration of shorelines to more natural states, transformation and loss of intertidal areas and wetland vegetation will increase with SLR (high confidence) (Doughty et al., 2019; Leuven et al., 2019; Yu et al., 2019; Raw et al., 2020; Shih, 2020; Stein et al., 2020), with small, shallow microtidal estuaries being more vulnerable to impacts than deeper estuaries with well-developed sediments (IPCC AR6_WGII, confidence: medium)
Warming and MHWs will enhance stratification and deoxygenation in shallow lagoons (IPCC AR6_WGII, confidence: medium)
Since AR5 and SROCC, syntheses have emphasised that the vulnerability of rooted wetland ecosystems to climate-induced drivers is exacerbated by non-climate drivers (high confidence) (Elliott et al., 2019; Ostrowski et al., 2021; Williamson and Guinder, 2021) and climate Table 3.6 | Summary of previous IPCC assessments of estuaries, deltas and coastal lagoons Observations Projections AR5 (Wong et al., 2014) Humans have impacted lagoons, estuaries and deltas (high to very high confidence), but non-climate drivers have been the primary agents of change (IPCC AR6_WGII, confidence: very high)
In estuaries and lagoons, nutrient inputs have driven eutrophication, which has modified food-web structures (high confidence) and caused more-intense and longer-lasting hypoxia, more-frequent occurrence of harmful algal blooms and enhanced emissions of nitrous oxide (IPCC AR6_WGII, confidence: high)
In deltas, land-use changes and associated disruption of sediment dynamics and land subsidence have driven changes that have been exacerbated by relative SLR and episodic events, including river floods and oceanic storm surges (IPCC AR6_WGII, confidence: very high)
Increased coastal flooding, erosion and saltwater intrusions have led to degradation of ecosystems (very high confidence).Future changes in climate impact-drivers such as warming, acidification, waves, storms, sea level rise (SLR) and runoff will have consequences for ecosystem function and services in lagoons and estuaries (IPCC AR6_WGII, confidence: high)
Warming, changes in precipitation and changes in wind strength can interact to alter water-column salinity and stratification (medium confidence), which could impact water column oxygen content (IPCC AR6_WGII, confidence: medium)
Land-use change, SLR and intensifying storms will alter deposition-erosion dynamics, impacting shoreline vegetation and altering turbidity (IPCC AR6_WGII, confidence: medium)
The projected impacts of climate change on deltas are associated mainly with pluvial floods and SLR, which will amplify observed impacts of interacting climate and non-climate drivers (IPCC AR6_WGII, confidence: high)
Estuaries, deltas and lagoons were not assessed in this report.Under both a 1.5°C and 2°C of warming, relative to the pre-industrial era, deltas are expected to be highly threatened by SLR and localised subsidence (IPCC AR6_WGII, confidence: high)
The slower rate of SLR associated with 1.5°C of warming poses smaller risks of flooding and salinisation (high confidence), and facilitates greater opportunities for adaptation, including managing and restoring natural coastal ecosystems and infrastructure reinforcement (IPCC AR6_WGII, confidence: medium)
Other feedbacks, such as landward migration of wetlands and the adaptation of infrastructure, remain important (medium confidence).’ SROCC (Bindoff et al., 2019a) Increased seawater intrusion caused by SLR has driven upstream redistribution of marine biotic communities in estuaries (medium confidence) where physical barriers, such as the availability of benthic substrates, do not limit availability of suitable habitats (IPCC AR6_WGII, confidence: medium)
Warming has driven poleward range shifts in species’ distributions among estuaries (IPCC AR6_WGII, confidence: medium)
Interactions between warming, eutrophication and hypoxia have increased the incidence of harmful algal blooms (high confidence), pathogenic bacteria, such as Vibrio species, (low confidence) and mortalities of invertebrates and fish communities (medium confidence).‘Salinisation and expansion of hypoxic conditions will intensify in eutrophic estuaries, especially in mid and high latitudes with microtidal regimes (high confidence).’ ‘The effects of warming will be more pronounced in high-latitude and temperate shallow estuaries with limited exchange with the open ocean [...] and seasonality that already leads to dead zone development [...] (medium confidence).’ Interaction between SLR and changes in precipitation will have greater impacts on shallow than deep estuaries (IPCC AR6_WGII, confidence: medium)
Estuaries characterised by large tidal exchanges and associated well-developed sediments will be more resilient to projected SLR and changes in river flow (IPCC AR6_WGII, confidence: medium)
Human activities that inhibit sediment dynamics in coastal deltas increase their vulnerability to SLR (IPCC AR6_WGII, confidence: medium)
Global rates of mangrove loss have been extensive but are slowing (IPCC AR6_WGII, confidence: high)
From 2000 to 2010 mangrove loss averaged 0.16% yr–1, globally, but with greatest loss in Southeast Asia (IPCC AR6_WGII, confidence: high)
Salt-marsh ecosystems have also suffered extensive losses (up to 60% in places since the 1980s), especially in developed and rapidly developing countries (IPCC AR6_WGII, confidence: medium)
Similarly, 29% of seagrass meadows were lost from 1879–to 2006 due primarily to coastal development and degradation of water quality, with climate-change impacts escalating since 1990 (IPCC AR6_WGII, confidence: medium)
Local examples of habitat stability or growth (e.g., de los Santos et al., 2019; Laengner et al., 2019; Sousa et al., 2019; Suyadi et al., 2019; Derolez et al., 2020; Goldberg et al., 2020; McKenzie and Yoshida, 2020) indicate some resilience to climate change in the absence of non-climate drivers (IPCC AR6_WGII, confidence: high)
Nevertheless, previous declines have left wetland ecosystems more vulnerable to impacts from climate-induced drivers and non-climate drivers (IPCC AR6_WGII, confidence: high)
Warming is allowing some, but not all (Rogers and Krauss, 2018; Saintilan et al., 2018), mangrove Table 3.7 | Summary of previous IPCC assessments of mangroves, salt marshes and seagrass beds Observations Projections AR5 (Wong et al., 2014) Seagrasses occurring close to their upper thermal limits are already stressed by climate change (IPCC AR6_WGII, confidence: high)
As a result, interactions between climate change and non-climate drivers will continue to cause declines in estuarine vegetated systems (IPCC AR6_WGII, confidence: very high)
SR15 (Hoegh-Guldberg et al., 2018a) Vegetated blue carbon systems were not assessed in this report.Intact wetland ecosystems can reduce the adverse impacts of rising sea levels and intensifying storms by protecting shorelines (IPCC AR6_WGII, confidence: medium)
Under 1.5°C of warming, natural sedimentation rates are projected to outpace SLR (medium confidence), but ‘other feedbacks, such as landward migration of wetlands and the adaptation of infrastructure, remain important (medium confidence).’ SROCC (Bindoff et al., 2019a; Oppenheimer et al., 2019) Coastal ecosystems, including salt marshes, mangroves, vegetated dunes and sandy beaches, can build vertically and expand laterally in response to SLR, though this capacity varies across sites (IPCC AR6_WGII, confidence: high)