rlacombe/ClimateX huggingface dataset:
However, as a consequence of human actions that fragment wetland habitats and restrict landward migration, coastal ecosystems progressively lose their ability to adapt to climate-induced changes and provide ecosystem services, including acting as protective barriers (IPCC AR6_WGII, confidence: high)
Examples include mangrove encroachment into subtropical salt marshes (high confidence) and contraction in extent of low-latitude seagrass meadows (IPCC AR6_WGII, confidence: high)
Plants with low tolerance to flooding and extreme temperatures are particularly vulnerable, increasing the risk of extirpation (IPCC AR6_WGII, confidence: medium)
Extreme-weather events, including heatwaves, droughts and storms, are causing mass mortalities and changes in community composition in coastal wetlands (IPCC AR6_WGII, confidence: high)
Severe disturbance of wetlands or transitions among wetland community types can favour invasive species (IPCC AR6_WGII, confidence: medium)
The degradation or loss of vegetated coastal ecosystems reduces carbon storage, with positive feedbacks to the climate system (high confidence).‘Seagrass meadows (high confidence) [...] will face moderate to high risk at temperature above 1.5°C global sea surface warming.’ ‘The transition from undetectable to moderate risk in salt marshes [...] takes place between 0.7°C–1.2°C of global sea surface warming (medium/high confidence), and between 0.9°C–1.8°C (medium confidence) in sandy beaches, estuaries and mangrove forests.’ ‘The ecosystems at moderate to high risk under future emission scenarios are mangrove forests (transition from moderate to high risk at 2.5°C–2.7°C of global sea surface warming), estuaries and sandy beaches (2.3°C–3.0°C) and salt marshes (transition from moderate to high risk at 1.8°C–2.7°C and from high to very high risk at 3.0°C–3.4°C) (medium confidence).’ ‘Global coastal wetlands will lose between 20–90% of their area depending on emissions scenario with impacts on their contributions to carbon sequestration and coastal protection (IPCC AR6_WGII, confidence: high)
But SLR and warming are projected to drive global loss of up to 90% of vegetated wetlands by the end of the century under the RCP8.5 (medium confidence), especially if landward migration and sediment supply are limited by human modification of shorelines and river flows (IPCC AR6_WGII, confidence: medium)
This expansion can affect species interactions (Guo et al., 2017; Friess et al., 2019), and enhance sediment accretion and carbon storage rates in some instances (IPCC AR6_WGII, confidence: medium)
Drought, low sea levels and MHWs can cause significant die-offs among mangroves (IPCC AR6_WGII, confidence: medium)
Seagrasses are similarly vulnerable to warming (high confidence) (Repolho et al., 2017; Duarte et al., 2018; Jayathilake and Costello, 2018; Savva et al., 2018), which has been attributed as one cause of observed changes in distribution and community structure (IPCC AR6_WGII, confidence: medium)
MHWs, together with storm-driven turbidity and structural damage, can cause seagrass die-offs (high confidence) (Arias-Ortiz et al., 2018; Kendrick et al., 2019; Smale et al., 2019; Strydom et al., 2020), shifts to small, fast-growing species (IPCC AR6_WGII, confidence: high)
The sensitivity of salt marshes and mangroves to RSLR depends on whether they accrete inorganic sediment and/or organic material at rates equivalent to rising water levels (IPCC AR6_WGII, confidence: very high)
Otherwise, wetland ecosystems must migrate either inland or upstream, or face gradual submergence in deeper, increasingly saline water (IPCC AR6_WGII, confidence: very high)
Submergence drives changes in community structure (high confidence) (Jones et al., 2019b; Yu et al., 2019; Douglass et al., 2020; Langston et al., 2020) and functioning (high confidence) (Charles et al., 2019; Buffington et al., 2020; Stein et al., 2020), and will eventually lead to extirpation of the most sensitive vegetation (medium confidence) (Schepers et al., 2017; Scalpone et al., 2020) and associated animals (IPCC AR6_WGII, confidence: low)
On the basis of paleorecords (Table 3.8), we assess that mangroves and salt marshes are likely at high risk from future SLR, even under SSP1-1.9, with impacts manifesting in the mid- term (IPCC AR6_WGII, confidence: medium)
Under SSP5-8.5, wetlands are very likely at high risk from SLR, with larger impacts manifesting before 2040 (IPCC AR6_WGII, confidence: medium)
By 2100, these ecosystems are at high risk of impacts under all scenarios except SSP1-1.9 (high confidence), with impacts most severe along coastlines with gently sloping shorelines, limited sediment inputs, small tidal ranges and limited space for inland migration (IPCC AR6_WGII, confidence: very high)
Other species, such as Posidonia oceanica in the Mediterranean, might lose as much as 75% of their habitat by 2050 under RCP8.5 and become functionally extinct (IPCC AR6_WGII, confidence: low)
Observed impacts of MHWs (Kendrick et al., 2019; Strydom et al., 2020; Serrano et al., 2021) indicate that increasing intensity and frequency of MHWs (Section 3.2.2.1) will have escalating impacts on seagrass ecosystems (IPCC AR6_WGII, confidence: high)
Habitat suitability can also be reduced by moderate RSLR, due to its impact on light attenuation (IPCC AR6_WGII, confidence: medium)
Overall, warming will drive range shifts in wetland species (medium to high confidence), but SLR poses the greatest risk for mangroves and salt marshes, with significant losses projected under all future scenarios by mid-century (IPCC AR6_WGII, confidence: medium)
Observations Projections AR5 (Wong et al., 2014) ‘Globally, beaches and dunes have in general undergone net erosion over the past century or longer.’ ‘Attributing shoreline changes to climate change is still difficult owing to the multiple natural and anthropogenic drivers contributing to coastal erosion.’‘In the absence of adaptation, beaches, sand dunes and cliffs currently eroding will continue to do so under increasing sea level (IPCC AR6_WGII, confidence: high)
In many locations, finding sufficient sand to rebuild beaches and dunes artificially will become increasingly difficult and expensive as present supplies near project sites are depleted (high confidence).’ ‘In the absence of adaptation measures, beaches and sand dunes currently affected by erosion will continue to be affected under increasing sea levels (high confidence).’ SROCC (Bindoff et al., 2019a) Coastal ecosystems are already impacted by the combination of SLR, other climate-related ocean changes and adverse effects from human activities on ocean and land (IPCC AR6_WGII, confidence: high)
Attributing such impacts to SLR, however, remains challenging due to the influence of other climate-related and non-climate drivers such as infrastructure development and human-induced habitat degradation (IPCC AR6_WGII, confidence: high)
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)
Coastal ecosystems also progressively lose their ability to adapt to climate-induced changes and provide ecosystem services, including acting as protective barriers (IPCC AR6_WGII, confidence: high)
This will be especially important in low-lying coastal areas with high population and building densities (medium confidence).’ ‘Assuming that the physiological underpinning of the relationship between body size and temperature can be applied to warming (medium confidence), the body size of sandy beach crustaceans is expected to decrease under warming (low evidence, medium agreement).’ Sandy beaches transition from undetectable to moderate risk between 0.9°C and 1.8°C (medium confidence) of global sea surface warming and from moderate to high risk at 2.3°C–3.0°C of global sea surface warming (IPCC AR6_WGII, confidence: medium)
However, pervasive coastal urbanisation lowers the buffering capacity and recovery potential of sandy beach ecosystems to impacts from SLR and warming, and thus is expected to limit their resilience to climate change (high confidence).’ ‘Coastal squeeze and human-driven habitat deterioration will reduce the natural capacity of these ecosystems to adapt to climate impacts (high confidence).’ by 2100 under all scenarios except SSP1-1.9 (IPCC AR6_WGII, confidence: high)
MHWs pose the greatest risk to seagrasses (IPCC AR6_WGII, confidence: high)
In all cases, losses will be greatest where accommodation space is constrained or where other non-climate drivers exacerbate risk from climate-induced drivers (IPCC AR6_WGII, confidence: very high)
Nevertheless, RSLR, increases in wave energy and/or changes in wave direction, disruptions to sediment supplies (including sand mining) and other anthropogenic modifications of the coast have driven localised beach erosion (IPCC AR6_WGII, confidence: very high)
Corresponding analyses of coarse-scale (30-m resolution) global data estimate that 15% of tidal flats (including beaches) have been lost since 1984 (medium confidence) (Mentaschi et al., 2018; Murray et al., 2019) but with a corresponding number of the world’s beaches accreting (28%) as eroding (24%) (IPCC AR6_WGII, confidence: medium)
None of these local studies, however, considered high-energy storm events, which are known to also impact sandy coasts (IPCC AR6_WGII, confidence: high)
Nevertheless, the most- advanced available models, which incorporate multiple coastal processes, including SLR, project that without anthropogenic barriers to erosion, 13.6–15.2% and 35.7–49.5% of the world’s beaches likely risk undergoing at least 100 m of shoreline retreat (relative to 2010) by 2050 and 2100, respectively (IPCC AR6_WGII, confidence: low)
Aggregating these trends regionally suggests that relative rates of shoreline change under RCP4.5 and RCP8.5 diverge strongly after mid-century, with trends towards erosion escalating under RCP8.5 by 2100 (IPCC AR6_WGII, confidence: medium)
This trend supports the WGI AR6 assessment that projected SLR will contribute to erosion of sandy beaches, especially under high-emissions futures (IPCC AR6_WGII, confidence: high)
But even amongst the best-studied taxa, such as turtles, vulnerability to warming (high confidence) and SLR (IPCC AR6_WGII, confidence: medium)
Moreover, although established vulnerabilities imply high projected future risk for turtles (IPCC AR6_WGII, confidence: high)
For example, although feminisation poses a significant long-term risk to turtle populations (high confidence), it might contribute to population growth in the near to mid-term (IPCC AR6_WGII, confidence: medium)
Resilience to climate change might be further enhanced by range extensions, alterations in nesting phenology and fine-scale nest-site selection (IPCC AR6_WGII, confidence: medium)
Nevertheless, theoretical sensitivity to warming (Section 3.3.2), together with the projected loss of habitat under future climate scenarios, suggest substantial impacts for populations and communities of beach fauna into the future (IPCC AR6_WGII, confidence: high)
These impacts will be exacerbated by coastal squeeze along urbanised coastlines (IPCC AR6_WGII, confidence: high)
Since AR5, there is evidence for increasing frequency and duration of MHWs, extreme-weather events and a diversity of threats across depth strata causing mass-mortality events, local extirpations and coral reef decline (IPCC AR6_WGII, confidence: high)
In most SES, non-climate drivers, including pollution, habitat destruction and especially overfishing, are decreasing the local adaptive capacity of organisms and the ability of ecosystems to cope with climate-change impacts (IPCC AR6_WGII, confidence: high)
The SLR is accelerating faster than expected (IPCC AR6_WGII, confidence: high)
The size and number of OMZs are increasing worldwide and in most SES (IPCC AR6_WGII, confidence: high)
In the Persian Gulf and Red Sea, increasing nutrient loads associated with coastal activities and warming has increased the size of OMZs (IPCC AR6_WGII, confidence: high)
Consequently, SES will respond faster than most other parts of the ocean (IPCC AR6_WGII, confidence: high)
Due to a mixture of global and local human stressors, key fisheries have undergone fundamental changes in their abundance and distribution over the past 50 years (medium confidence).’‘Projected warming increases the risk of greater thermal stratification in some regions, which can lead to reduced O 2 ventilation [of underlying waters] and the formation of additional hypoxic zones, especially in the Baltic and Black seas (IPCC AR6_WGII, confidence: medium)
These changes are likely to increase the risk of reduced bottom-water O2 levels to Baltic and Black Sea ecosystems (due to reduced solubility, increased stratification, and microbial respiration), which is very likely to affect fisheries.’ Persian Gulf, Red Sea: ‘Extreme temperature events, such as heat waves, are projected to increase (high confidence) [... and] temperatures are very likely to increase above established thresholds for mass coral bleaching and mortality (IPCC AR6_WGII, confidence: very high)
In addition, geographic barriers, such as land boundaries [...] or lower oxygen water in deeper waters, are projected to limit species range shifts in SES, resulting in a larger relative decrease in species richness (IPCC AR6_WGII, confidence: medium)
In the Baltic Sea, OMZs are affecting the extent of suitable spawning areas of cod, Gadus morhua (high confidence) (Hinrichsen et al., 2016), while in the Black Sea, the combined effect of OMZs and warming is influencing the distribution and physiology of fish species, and their migration and schooling behaviour in their overwintering grounds (IPCC AR6_WGII, confidence: medium)
Cascading effects on food webs have been reported in the Baltic, where detrimental effects of changing oxygen levels on zooplankton production, pelagic and piscivorous fish are influencing seasonal succession and species composition of phytoplankton (IPCC AR6_WGII, confidence: high)
In the Mediterranean Sea (Cross-Chapter Paper 4), the increase in climate extremes and mass-mortality events reported in AR5 has continued (IPCC AR6_WGII, confidence: very high)
Extreme- weather events (including deep convection; González-Alemán et al., 2019) and MHWs have become more frequent (Darmaraki et al., 2019) and are associated with mass mortality of benthic sessile species across the basin (IPCC AR6_WGII, confidence: high)
Since AR5, in the Persian Gulf and Red Sea, extreme temperatures, together with disease and predation, have continued to cause bleaching-induced mortality of corals, along with declines in the average coral-colony size (IPCC AR6_WGII, confidence: high)
Poleward migration and tropicalisation of species (Section 3.4.2.3) has also continued in the Mediterranean, and these phenomena have also become an issue in the Black Sea (IPCC AR6_WGII, confidence: high)
Climate impacts on phytoplankton production and phenology show high spatial heterogeneity across the Mediterranean Sea (medium evidence) (Marbà et al., 2015b; Salgado- Hernanz et al., 2019), with consequent effects on the diversity and abundance of zooplankton and fish species (IPCC AR6_WGII, confidence: medium)
Evidence of impacts from ocean acidification is increasing, with the rates of coral calcification showing major decline in the Red Sea (IPCC AR6_WGII, confidence: medium)
In the Mediterranean Sea, evidence of acidification events have been reported at the local scale (Hassoun et al., 2015), with impacts on bivalves and coralligenous species (IPCC AR6_WGII, confidence: medium)
Climate models project increasing frequency and intensity of MHWs (high confidence) (Section 3.2.2.1), which will exacerbate warming- driven impacts in the Red Sea and Persian Gulf regions, and erode the resilience of Red Sea coral reefs (IPCC AR6_WGII, confidence: high)
In the Persian Gulf region, extreme temperatures, >35°C (Pal and Eltahir, 2016), have been linked with high rates of extirpation and a decrease in fisheries catch potential (IPCC AR6_WGII, confidence: medium)
Seasonal bottom-water hypoxia occurs in some shelf seas (e.g., northern Gulf of Mexico, Bohai Sea, East China Sea) due to riverine inputs of freshwater and nutrients, promoting stratification, enhanced primary production and organic carbon export to bottom waters (IPCC AR6_WGII, confidence: high)
Eutrophication and seasonal bottom- water hypoxia in some shelf seas have been linked to warming (high confidence) (Wei et al., 2019; Del Giudice et al., 2020) and increased riverine nutrient loading (IPCC AR6_WGII, confidence: high)
Since SROCC, some severe HABs have been attributed to extreme events, such as MHWs (Section 14.4.2; Roberts et al., 2019; Trainer et al., 2019); however, a recent worldwide assessment of HABs attributed the increase in observed HABs to intensified monitoring associated with increased aquaculture production (IPCC AR6_WGII, confidence: high)
Changes in abundance, species composition and size of zooplankton have been detected in some shelf seas (Yellow Sea, North Sea, Celtic Sea and Tasman Sea), including a decline in stocks of larger copepods, increased abundances of gelatinous and meroplankton, and a shift to smaller species due to warming, increased river discharge, circulation change and/or extreme events (high confidence) (Wang et al., 2018a; Bedford et al., 2020; Evans et al., 2020; Shi et al., 2020; Edwards et al., 2021).Ocean warming has shifted distributions of fish (Free et al., 2019; Franco et al., 2020; Pinsky et al., 2020b; Fredston et al., 2021) and marine mammal species (Salvadeo et al., 2010; García-Aguilar et al., 2018; Davis et al., 2020) poleward (IPCC AR6_WGII, confidence: high)
Warming has also tropicalised the pelagic and demersal fish assemblages of mid- and high-latitude shelves (IPCC AR6_WGII, confidence: high)
Fisheries catch composition in many shelf-sea ecosystems has become increasingly dominated by warm- water species since the 1970s (IPCC AR6_WGII, confidence: high)
For example, although, most species’ range edges are tracking temperature change on the northeast shelf of the USA (IPCC AR6_WGII, confidence: medium)
For example, fisheries productivity Table 3.11 | Summary of past IPCC assessments of shelf seas Observations Projections AR5 (Hoegh-Guldberg et al., 2014) ‘Primary productivity, biomass yields and fish capture rates have undergone large changes within the ECS [East China Sea] over the past decades (limited evidence, medium agreement, low confidence).’ ‘Changing sea temperatures have influenced the abundance of phytoplankton, benthic biomass, cephalopod fisheries and the size of demersal trawl catches in the northern SCS [South China Sea] observed over the period 1976–2004 (limited evidence, medium agreement).’ ‘Concurrent with the retreat of the ‘cold pool’ [...] on the northern Bering Sea shelf, [...] bottom trawl surveys of fish and invertebrates show a significant community-wide northward distributional shift and a colonisation of the former cold pool areas by sub-Arctic fauna (high confidence).’ ‘Observed changes in the phenology of plankton groups in the North Sea over the past 50 years are driven by climate forcing, in particular regional warming (high confidence).’‘Global warming will result in more frequent extreme events and greater associated risks to ocean ecosystems (IPCC AR6_WGII, confidence: high)
SROCC (Bindoff et al., 2019a) ‘Species composition of fisheries catches since the 1970s in many shelf seas ecosystems of the world is increasingly dominated by warm-water species (IPCC AR6_WGII, confidence: medium)
Estuaries, shelf seas and a wide range of other intertidal and shallow-water habitats play an important role in the global carbon cycle through their primary production by rooted plants, seaweeds (macroalgae) and phytoplankton, and also by processing riverine organic carbon. The natural carbon dynamics of these systems have been greatly changed by human activities (IPCC AR6_WGII, confidence: high)
Similar to the open ocean, large shifts in the phenology of phytoplankton blooms have been projected for shelf seas throughout subpolar and polar waters (IPCC AR6_WGII, confidence: medium)
Trends towards tropicalisation will continue in the future (IPCC AR6_WGII, confidence: high)
Under future climate change marked by more frequent and intense extreme events and the influences of multiple drivers, more flexible and adaptive management approaches could reduce climate impacts on species while also supporting industry adaptation (IPCC AR6_WGII, confidence: high)
For example, trends in outputs from high-resolution, downscaled models in the California EBUS generally reflect those from underlying coarser-scale ESMs, but projections for physical variables are more convergent among modelling approaches than are those for biogeochemical variables (IPCC AR6_WGII, confidence: high)
Models agree on general warming in the California EBUS, with concomitant declines in oxygen content (IPCC AR6_WGII, confidence: medium)
More generally, changes in upwelling intensity are observed to affect organismal metabolism, population productivity and recruitment, and food-web structure (IPCC AR6_WGII, confidence: medium)
Finally, although MHWs are an important emerging hazard in the global ocean, with intensity, Table 3.13 | Summary of previous IPCC assessments of eastern boundary upwelling systems (EBUS) Observations Projections AR5 (Hoegh-Guldberg et al., 2014; Lluch-Cota et al., 2014) ‘[EBUS] are vulnerable to changes that influence the intensity of currents, upwelling and mixing (and hence changes in sea surface temperature, wind strength and direction), as well as O 2 content, carbonate chemistry, nutrient content and the supply of organic carbon to deep offshore locations (high confidence).’ Climate-change-induced intensification of ocean upwelling in some EBUS, as observed in past decades, may lead to regional cooling, rather than warming, of surface waters and cause enhanced productivity (IPCC AR6_WGII, confidence: medium)
Owing to contradictory observations, there is currently uncertainty about the future trends of major upwelling systems and how their drivers will shape ecosystem characteristics (IPCC AR6_WGII, confidence: low)
These risks and uncertainties are likely to involve significant challenges for fisheries and associated livelihoods along the west coasts of South America, Africa and North America (low to medium confidence).’ ‘There is robust evidence and medium agreement that the California Current has experienced [...] an increase of the overall magnitude of upwelling events from 1967 to 2010 (IPCC AR6_WGII, confidence: high)
This is consistent with changes expected under climate change yet remains complicated by the influence of decadal-scale variability (IPCC AR6_WGII, confidence: low)
Ocean acidification and decrease in oxygen level in the California Current upwelling system have altered ecosystem structure, with direct negative impacts on biomass production and species composition (medium confidence).’ ‘Three out of the four major Eastern Boundary Upwelling Systems (EBUS) have shown large-scale wind intensification in the past 60 years (IPCC AR6_WGII, confidence: high)
However, the interaction of coastal warming and local winds may have affected upwelling strength, with the direction of changes [varying] between and within EBUS (IPCC AR6_WGII, confidence: low)
Increasing trends in ocean acidification in the California Current EBUS and deoxygenation in California Current and Humboldt Current EBUS are observed in the last few decades (IPCC AR6_WGII, confidence: high)
The expanding California EBUS OMZ [oxygen minimum zone] has altered ecosystem structure and fisheries catches (medium confidence).’ ‘Overall, EBUS have been changing with intensification of winds that drives the upwelling, leading to changes in water temperature and other ocean biogeochemistry (IPCC AR6_WGII, confidence: medium)