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3,700
AR6_WGII
435
4
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
high
2
train
3,701
AR6_WGII
435
5
Coastal ecosystems also progressively lose their ability to adapt to climate-induced changes and provide ecosystem services, including acting as protective barriers
high
2
train
3,702
AR6_WGII
435
7
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
medium
1
train
3,703
AR6_WGII
435
9
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
high
2
train
3,704
AR6_WGII
435
10
MHWs pose the greatest risk to seagrasses
high
2
train
3,705
AR6_WGII
435
11
In all cases, losses will be greatest where accommodation space is constrained or where other non-climate drivers exacerbate risk from climate-induced drivers
very high
3
train
3,706
AR6_WGII
435
17
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
very high
3
train
3,707
AR6_WGII
435
18
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%)
medium
1
train
3,708
AR6_WGII
436
2
None of these local studies, however, considered high-energy storm events, which are known to also impact sandy coasts
high
2
train
3,709
AR6_WGII
436
3
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
low
0
train
3,710
AR6_WGII
436
4
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
medium
1
train
3,711
AR6_WGII
436
5
This trend supports the WGI AR6 assessment that projected SLR will contribute to erosion of sandy beaches, especially under high-emissions futures
high
2
train
3,712
AR6_WGII
436
7
But even amongst the best-studied taxa, such as turtles, vulnerability to warming (high confidence) and SLR
medium
1
train
3,713
AR6_WGII
436
8
Moreover, although established vulnerabilities imply high projected future risk for turtles
high
2
train
3,714
AR6_WGII
437
2
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
medium
1
train
3,715
AR6_WGII
437
3
Resilience to climate change might be further enhanced by range extensions, alterations in nesting phenology and fine-scale nest-site selection
medium
1
train
3,716
AR6_WGII
437
6
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
high
2
train
3,717
AR6_WGII
437
7
These impacts will be exacerbated by coastal squeeze along urbanised coastlines
high
2
train
3,718
AR6_WGII
437
12
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
high
2
train
3,719
AR6_WGII
437
13
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
high
2
train
3,720
AR6_WGII
437
14
The SLR is accelerating faster than expected
high
2
train
3,721
AR6_WGII
437
15
The size and number of OMZs are increasing worldwide and in most SES
high
2
train
3,722
AR6_WGII
437
16
In the Persian Gulf and Red Sea, increasing nutrient loads associated with coastal activities and warming has increased the size of OMZs
high
2
train
3,723
AR6_WGII
437
19
Consequently, SES will respond faster than most other parts of the ocean
high
2
train
3,724
AR6_WGII
437
20
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
medium
1
train
3,725
AR6_WGII
437
21
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
very high
3
train
3,726
AR6_WGII
437
22
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
medium
1
train
3,727
AR6_WGII
438
1
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
medium
1
train
3,728
AR6_WGII
438
2
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
high
2
train
3,729
AR6_WGII
438
3
In the Mediterranean Sea (Cross-Chapter Paper 4), the increase in climate extremes and mass-mortality events reported in AR5 has continued
very high
3
train
3,730
AR6_WGII
438
4
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
high
2
train
3,731
AR6_WGII
438
5
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
high
2
train
3,732
AR6_WGII
438
6
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
high
2
train
3,733
AR6_WGII
438
7
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
medium
1
train
3,734
AR6_WGII
438
9
Evidence of impacts from ocean acidification is increasing, with the rates of coral calcification showing major decline in the Red Sea
medium
1
train
3,735
AR6_WGII
438
10
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
medium
1
train
3,736
AR6_WGII
438
11
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
high
2
train
3,737
AR6_WGII
438
12
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
medium
1
train
3,738
AR6_WGII
438
22
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
high
2
train
3,739
AR6_WGII
439
1
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
high
2
train
3,740
AR6_WGII
439
2
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
high
2
train
3,741
AR6_WGII
439
7
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
high
2
train
3,742
AR6_WGII
439
8
Warming has also tropicalised the pelagic and demersal fish assemblages of mid- and high-latitude shelves
high
2
train
3,743
AR6_WGII
439
9
Fisheries catch composition in many shelf-sea ecosystems has become increasingly dominated by warm- water species since the 1970s
high
2
train
3,744
AR6_WGII
439
12
For example, although, most species’ range edges are tracking temperature change on the northeast shelf of the USA
medium
1
train
3,745
AR6_WGII
439
15
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
high
2
train
3,746
AR6_WGII
439
18
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
medium
1
train
3,747
AR6_WGII
439
19
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
high
2
test
3,748
AR6_WGII
440
5
Similar to the open ocean, large shifts in the phenology of phytoplankton blooms have been projected for shelf seas throughout subpolar and polar waters
medium
1
train
3,749
AR6_WGII
440
7
Trends towards tropicalisation will continue in the future
high
2
train
3,750
AR6_WGII
440
9
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
high
2
train
3,751
AR6_WGII
440
16
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
high
2
train
3,752
AR6_WGII
440
17
Models agree on general warming in the California EBUS, with concomitant declines in oxygen content
medium
1
train
3,753
AR6_WGII
441
1
More generally, changes in upwelling intensity are observed to affect organismal metabolism, population productivity and recruitment, and food-web structure
medium
1
train
3,754
AR6_WGII
441
4
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
medium
1
train
3,755
AR6_WGII
441
5
Owing to contradictory observations, there is currently uncertainty about the future trends of major upwelling systems and how their drivers will shape ecosystem characteristics
low
0
train
3,756
AR6_WGII
441
7
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
high
2
train
3,757
AR6_WGII
441
8
This is consistent with changes expected under climate change yet remains complicated by the influence of decadal-scale variability
low
0
test
3,758
AR6_WGII
441
12
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
high
2
train
3,759
AR6_WGII
441
13
However, the interaction of coastal warming and local winds may have affected upwelling strength, with the direction of changes [varying] between and within EBUS
low
0
test
3,760
AR6_WGII
441
14
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
high
2
train
3,761
AR6_WGII
441
15
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
medium
1
train
3,762
AR6_WGII
441
16
Moreover, the high natural variability of EBUS and their insufficient representation by global ESMs [Earth system models] gives low confidence that these observed changes can be attributed to anthropogenic causes.’‘Anthropogenic changes in EBUS will emerge primarily in the second half of the 21st century
medium
1
train
3,763
AR6_WGII
441
17
EBUS will be impacted by climate change in different ways, with strong regional variability with consequences for fisheries, recreation and climate regulation
medium
1
train
3,764
AR6_WGII
441
18
The Pacific EBUS are projected to have calcium carbonate undersaturation in surface waters within a few decades RCP8.5 (high confidence); combined with warming and decreasing oxygen levels, this will increase the impacts on shellfish larvae, benthic invertebrates, and demersal fishes (high confidence) and related fisheries and aquaculture (medium confidence).’ ‘The inherent natural variability of EBUS, together with uncertainties in present and future trends in the intensity and seasonality of upwelling, coastal warming and stratification, primary production and biogeochemistry of source waters poses large challenges in projecting the response of EBUS to climate change and to the adaptation of governance of biodiversity conservation and living marine resources in EBUS (high confidence).’ ‘Given the high sensitivity of the coupled human–natural EBUS to oceanographic changes, the future sustainable delivery of key ecosystem services from EBUS is at risk under climate change; those that are most at risk in the 21st century include fisheries (high confidence), aquaculture (medium confidence), coastal tourism (low confidence) and climate regulation (low confidence).’ ‘For vulnerable human communities with a strong dependence on EBUS services and low adaptive capacity, such as those along the Canary Current system, unmitigated climate-change effects on EBUS (complicated by other non-climatic stresses such as social unrest) have a high risk of altering their development pathways
high
2
train
3,765
AR6_WGII
442
1
Notwithstanding these trends, EBUS remain vulnerable both to MHWs (high confidence) (Sen Gupta et al., 2020) and to their long-lasting impacts
high
2
train
3,766
AR6_WGII
442
3
Despite low confidence in detailed projections for ecological changes in EBUS, the WGI assessment (WGI AR6 Chapter 9; Fox-Kemper et al., 2021) that upwelling-favourable winds will weaken (or be present for shorter durations) at low latitude but intensify at high latitude (high confidence), albeit by no more than 20% in either case
medium
1
train
3,767
AR6_WGII
442
11
Over the past two decades, Arctic Ocean surface temperature has increased in line with the global average, while there has been no uniform warming across the Antarctic
high
2
train
3,768
AR6_WGII
442
12
Thus, the rate of change due to warming, and associated sea ice loss, is greater in the Arctic than in the Antarctic
high
2
train
3,769
AR6_WGII
442
15
Previous assessments of polar seas (Table 3.14) concluded that climate change has already profoundly influenced polar ecosystems, through changing species distributions and abundances from primary producers to top predators, including both ecologically and economically important species (high confidence), and that it will continue to do so (Table 3.14).Since SROCC, evidence demonstrates that warmer oceans, less sea ice and increased advection results in increasing primary production in the Arctic, albeit with regional variation (high confidence), while trends remain spatially heterogeneous and less clear in the Antarctic
medium
1
train
3,770
AR6_WGII
442
17
Major community shifts, both gradual and abrupt, are observed in polar oceans in response to warming trends and MHWs (Arctic only)
high
2
train
3,771
AR6_WGII
442
18
In general, abundances and ranges of Arctic fish species are declining and contracting, while ranges of boreal fish species are expanding, both geographically and in terms of feeding interactions and ecological roles
high
2
train
3,772
AR6_WGII
442
21
Phenological, behavioural, physiological and distributional changes are observed in marine mammals and birds in response to altered ecological interactions and habitat degradation, especially to loss of sea ice
high
2
train
3,773
AR6_WGII
442
22
Reproductive failures and declining abundances attributed to warmer polar oceans and less sea ice cover are observed in populations of polar bears, Ursus maritimus, seals, whales and marine birds
high
2
train
3,774
AR6_WGII
442
24
Calcareous polar organisms are among the groups most sensitive to ocean acidification
high
2
train
3,775
AR6_WGII
443
23
Impacts of shifts in ocean conditions affect fish and shellfish abundances in the Arctic
high
2
train
3,776
AR6_WGII
443
24
Changes in sea ice and the physical environment to the west of the Antarctic Peninsula are altering phytoplankton stocks and productivity, and krill (high confidence).Some marine species will shift their ranges in response to changing ocean and sea ice conditions in the polar regions
medium
1
train
3,777
AR6_WGII
443
25
Loss of sea ice in summer and increased ocean temperatures are expected to impact secondary pelagic production in some regions of the Arctic Ocean, with associated changes in the energy pathways within the marine ecosystem
medium
1
train
3,778
AR6_WGII
443
26
Ocean acidification has the potential to inhibit embryo development and shell formation of some zooplankton and krill in the polar regions, with potentially far-reaching consequences to food webs in these regions
medium
1
train
3,779
AR6_WGII
443
27
Shifts in the timing and magnitude of seasonal biomass production could disrupt coupled phenologies in the food webs, leading to decreased survival of dependent species
medium
1
train
3,780
AR6_WGII
443
28
SR15 (Hoegh-Guldberg et al., 2018a) ‘A fundamental transformation is occurring in polar organisms and ecosystems, driven by climate change
high
2
train
3,781
AR6_WGII
443
29
There is high agreement and robust evidence that phytoplankton species will change because of sea ice retreat and related changes in temperature and radiation, and this is very likely to benefit fisheries productivity [in the Arctic spring bloom system].’ ‘‘Unique and threatened systems’ (RFC1), [including Arctic and coral reefs], display a transition from high to very high risk of transition at temperatures between 1.5°C and 2°C of global warming, as opposed to at 2.6°C of global warming in AR5 (high confidence).’ SROCC (Bindoff et al., 2019a) Climate-induced changes in seasonal sea ice extent and thickness as well as ocean stratification are altering marine primary production (high confidence), with impacts on ecosystems
medium
1
train
3,782
AR6_WGII
443
30
Changes in the timing, duration and magnitude of primary production have occurred in both polar oceans, with marked regional or local variability
high
2
train
3,783
AR6_WGII
443
31
In both polar regions, climate-induced changes in ocean and sea ice conditions have expanded the range of temperate species and contracted the range of polar fish and ice-associated species
high
2
train
3,784
AR6_WGII
443
32
Ocean acidification will affect several key Arctic species (medium confidence).Future climate-induced changes in the polar oceans, sea ice, snow and permafrost will drive habitat and biome shifts, with associated changes in the ranges and abundance of ecologically important species
medium
1
train
3,785
AR6_WGII
443
33
Projected range expansion of sub-Arctic marine species will increase pressure for high-Arctic species
medium
1
train
3,786
AR6_WGII
443
34
Both polar oceans will be increasingly affected by CO 2 uptake, causing corrosive conditions for calcium carbonate shell-producing organisms (high confidence), with associated impacts on marine organisms and ecosystems
medium
1
train
3,787
AR6_WGII
443
35
The projected effects of climate-induced stressors on polar marine ecosystems present risks for commercial and subsistence fisheries, with implications for regional economies, cultures and the global supply of fish, shellfish, and Antarctic krill
high
2
train
3,788
AR6_WGII
444
4
While levels of pollutants in biota (e.g., persistent organic pollutants, mercury) have generally declined over the past decades, recent increasing levels are associated with release from reservoirs in ice, snow and permafrost, and through changing food webs and pathways for trophic amplification
medium
1
test
3,789
AR6_WGII
444
5
Also, a warmer climate, altered ocean currents and increased human activities elevate the risk of invasive species in the Arctic (medium confidence), potentially changing ecosystems in this region
high
2
train
3,790
AR6_WGII
444
7
Fisheries are largely sustainably managed yet are expanding polewards following sea ice melt in the Arctic
high
2
train
3,791
AR6_WGII
444
8
Tourism is increasing and expanding in both polar regions, while shipping and hydrocarbon exploration are growing in the Arctic, increasing the risks of compound effects on vulnerable and already stressed populations and ecosystems
high
2
train
3,792
AR6_WGII
444
14
Nevertheless, increasing evidence supports that sustainable and adaptive ecosystem-based fisheries practices can reduce detrimental impacts of climate change on harvested populations
medium
1
train
3,793
AR6_WGII
445
1
On average, species’ distributions have shifted poleward by 72.0 ± 0.35 km per decade (high confidence).Spatial shifts of marine species due to projected warming will cause high-latitude invasions and high local-extinction rates in the tropics and semi-enclosed seas
medium
1
train
3,794
AR6_WGII
445
2
SROCC (Bindoff et al., 2019a) ‘Ocean warming has contributed to observed changes in biogeography of organisms ranging from phytoplankton to marine mammals (high confidence).’ ‘The direction of the majority of the shifts of epipelagic organisms are consistent with a response to warming (high confidence)’ but are also shaped by oxygen concentrations and ocean currents across depth, latitudinal and longitudinal gradients
high
2
train
3,795
AR6_WGII
445
3
Geographic ranges have shifted since the 1950s by 51.5 ± 33.3 km per decade (mean and very likely range) and 29.0 ± 15.5 km per decade for organisms in the epipelagic and seafloor ecosystems, respectively.‘Recent model projections since AR5 and SR15 continue to support global-scale range shifts of marine fishes at rates of tens to hundreds of km per decade in the 21st century, with rate of shifts being substantially higher under RCP8.5 than RCP2.6.’ range shifts consistent with climate change) estimates that marine species are moving poleward at a rate of 59.2 km per decade (very likely range: 43.7–74.7 km per decade), closely matching the local climate velocity
high
2
train
3,796
AR6_WGII
445
5
Biogeographic shifts lead to novel communities and biotic interactions (high confidence) (Zarco-Perello et al., 2017; Pecuchet et al., 2020b), with concomitant changes in ecosystem functioning and servicing
high
2
train
3,797
AR6_WGII
447
1
These changes subsequently affect biogenic carbon cycling through alteration of microbial remineralisation and carbon sequestration in deep water
medium
1
train
3,798
AR6_WGII
447
9
Although vertical redistribution of thermal niches is three to four orders of magnitude slower than horizontal displacement, maximum depth limits imposed by the seafloor and photic layer (both of which are projected to be reached in this century) will likely vertically compress suitable habitat for most marine organisms
medium
1
train
3,799
AR6_WGII
447
11
The volume of OMZs have been expanding at many locations (high confidence), and the oxygen content of the subsurface ocean is projected to decline to historically unprecedented conditions over the 21st century
medium
1
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