rlacombe/ClimateX huggingface dataset:
In the deep ocean, all global warming levels will cause faster movements of temperature niches by 2100 than those that have driven extensive reorganisation of marine biodiversity at the ocean surface over the past 50 years (IPCC AR6_WGII, confidence: medium)
At warming levels beyond 2°C by 2100, risks of extirpation, extinction and ecosystem collapse escalate rapidly (IPCC AR6_WGII, confidence: high)
Paleorecords indicate that at extreme global warming levels (>5.2°C), mass extinction of marine species may occur (IPCC AR6_WGII, confidence: medium)
Some habitat- forming coastal ecosystems including many coral reefs, kelp forests and seagrass meadows, will undergo irreversible phase shifts due to marine heatwaves with global warming levels >1.5°C and are at high risk this century even in <1.5°C scenarios that include periods of temperature overshoot beyond 1.5°C (IPCC AR6_WGII, confidence: high)
Under SSP1-2.6, coral reefs are at risk of widespread decline, loss of structural integrity and transitioning to net erosion by mid-century due to increasing intensity and frequency of marine heatwaves (IPCC AR6_WGII, confidence: very high)
Other coastal ecosystems, including kelp forests, mangroves and seagrasses, are vulnerable to phase shifts towards alternate states as marine heatwaves intensify (IPCC AR6_WGII, confidence: high)
Loss of kelp forests are expected to be greatest at the low-latitude warm edge of species’ ranges (IPCC AR6_WGII, confidence: high)
Modest projected declines in global phytoplankton biomass translate into larger declines of total animal biomass (by 2080–2099 relative to 1995–2014) ranging from (mean ± very likely range) −5.7 ± 4.1% to −15.5 ± 8.5% under SSP1-2.6 and SSP5-8.5, respectively (IPCC AR6_WGII, confidence: medium)
Projected declines in upper-ocean nutrient concentrations, likely associated with increases in stratification, will reduce carbon export flux to the mesopelagic and deep-sea ecosystems (IPCC AR6_WGII, confidence: medium)
By 2100, 18.8 ± 19.0% to 38.9 ± 9.4% of the ocean will very likely undergo a change of more than 20 d (advances and delays) in the start of the phytoplankton growth period under SSP1-2.6 and SSP5- 8.5, respectively (IPCC AR6_WGII, confidence: low)
This altered timing increases the risk of temporal mismatches between plankton blooms and fish spawning seasons (medium to high confidence) and increases the risk of fish- recruitment failure for species with restricted spawning locations, especially in mid-to-high latitudes of the Northern Hemisphere (IPCC AR6_WGII, confidence: low)
Projected range shifts among marine species (IPCC AR6_WGII, confidence: medium)
Sea level rise under emission scenarios that do not limit warming to 1.5°C will increase the risk of coastal erosion and submergence of coastal land (high confidence), loss of coastal habitat and ecosystems (high confidence) and worsen salinisation of groundwater (high confidence), compromising coastal ecosystems and livelihoods (IPCC AR6_WGII, confidence: high)
Under SSP1-2.6, most coral reefs (very high confidence), mangroves (likely, medium confidence) and salt marshes (likely, medium confidence) will be unable to keep up with sea level rise by 2050, with ecological impacts escalating rapidly beyond 2050, especially for scenarios coupling high emissions with aggressive coastal development (IPCC AR6_WGII, confidence: very high)
Resultant decreases in natural shoreline protection will place increasing numbers of people at risk (IPCC AR6_WGII, confidence: very high)
The ability to adapt to current coastal impacts, cope with future coastal risks and prevent further acceleration of sea level rise beyond 2050 depends on immediate implementation of mitigation and adaptation actions (IPCC AR6_WGII, confidence: very high)
Catch composition and diversity of regional fisheries will change (high confidence), and fishers who are able to move, diversify and leverage technology to sustain harvests decrease their own vulnerability (IPCC AR6_WGII, confidence: medium)
Management that eliminates overfishing facilitates successful future adaptation of fisheries to climate change (IPCC AR6_WGII, confidence: very high)
Marine-dependent communities, including Indigenous Peoples and local peoples, will be at increased risk of losing cultural heritage and traditional seafood- sourced nutrition (IPCC AR6_WGII, confidence: medium)
Without adaptation, seafood- dependent people face increased risk of exposure to toxins, pathogens and contaminants (high confidence), and coastal communities face increasing risk from salinisation of groundwater and soil (IPCC AR6_WGII, confidence: high)
Early-warning systems and public education about environmental change, developed and implemented within the local and cultural context, can decrease those risks (IPCC AR6_WGII, confidence: high)
Coastal development and management informed by sea level rise projections will reduce the number of people and amount of property at risk (high confidence), but historical coastal development and policies impede change (IPCC AR6_WGII, confidence: high)
Current financial flows are globally uneven and overall insufficient to meet the projected costs of climate impacts on coastal and marine social–ecological systems (IPCC AR6_WGII, confidence: very high)
Inclusive governance that (a) accommodates geographically shifting marine life, (b) financially supports needed human transformations, (c) provides effective public education and (d) incorporates scientific evidence, Indigenous knowledge and local knowledge to manage resources sustainably shows greatest promise for decreasing human vulnerability to all of these projected changes in ocean and coastal ecosystem services (IPCC AR6_WGII, confidence: very high)
Low-emission scenarios permit a wider array of feasible, effective and low-risk nature-based adaptation options (e.g., restoration, revegetation, conservation, early-warning systems for extreme events and public education) (IPCC AR6_WGII, confidence: high)
Under high-emission scenarios, adaptation options (e.g., hard infrastructure for coastal protection, assisted migration or evolution, livelihood diversification, migration and relocation of people) are more uncertain and require transformative governance changes (IPCC AR6_WGII, confidence: high)
Transformative climate adaptation will reinvent institutions to overcome obstacles arising from historical precedents, reducing current barriers to climate adaptation in cultural, financial and governance sectors (IPCC AR6_WGII, confidence: high)
Without transformation, global inequities will likely increase between regions (IPCC AR6_WGII, confidence: high)
Adaptation solutions implemented at appropriate scales, when combined with ambitious and urgent mitigation measures, can meaningfully reduce impacts (IPCC AR6_WGII, confidence: high)
Increasing evidence from implemented adaptations indicates that multi-level governance, early-warning systems for climate-associated marine hazards, seasonal and dynamic forecasts, habitat restoration, ecosystem-based management, climate-adaptive management and sustainable harvesting tend to be both feasible and effective (IPCC AR6_WGII, confidence: high)
Marine protected areas (MPAs), as currently implemented, do not confer resilience against warming and heatwaves (medium confidence) and are not expected to provide substantial protection against climate impacts past 2050 (IPCC AR6_WGII, confidence: high)
However, MPAs can contribute substantially to adaptation and mitigation if they are designed to address climate change, strategically implemented and well governed (IPCC AR6_WGII, confidence: high)
Habitat restoration limits climate-change-related loss of ecosystem services, including biodiversity, coastal protection, recreational use and tourism (medium confidence), provides mitigation benefits on local to regional scales (e.g., via carbon-storing ‘blue carbon’ ecosystems) (IPCC AR6_WGII, confidence: high)
Nature-based solutions, such as ecosystem-based management, climate-smart conservation approaches (i.e., climate- adaptive fisheries and conservation) and coastal habitat restoration, can be cost-effective and generate social, economic and cultural co- benefits while contributing to the conservation of marine biodiversity and reducing cumulative anthropogenic drivers (IPCC AR6_WGII, confidence: high)
The effectiveness of nature-based solutions declines with warming; conservation and restoration alone will be insufficient to protect coral reefs beyond 2030 (high confidence) and to protect mangroves beyond the 2040s (IPCC AR6_WGII, confidence: high)
The multidimensionality of climate-change impacts and their interactions with other anthropogenic stressors calls for integrated approaches that identify trade-offs and synergies across sectors and scales in space and time to build resilience of ocean and coastal ecosystems and the services they deliver (IPCC AR6_WGII, confidence: high)
Furthermore, existing inequalities and entrenched practices limit effective and just responses to climate change in coastal communities (IPCC AR6_WGII, confidence: high)
Previous IPCC assessments have established that many marine species ‘have shifted their geographic ranges, seasonal activities, migration patterns, abundances and species interactions in response to climate change’ (high confidence) (IPCC, 2014b; IPCC, 2014c), which has had global impacts on species composition, abundance and biomass, and on ecosystem structure and function (IPCC AR6_WGII, confidence: medium)
Warming and acidification have affected coastal ecosystems in concert with non-climate drivers (high confidence), which have affected habitat area, biodiversity, ecosystem function and services (IPCC AR6_WGII, confidence: high)
AR5 and SROCC assessed how physiological sensitivity to climate-induced drivers is the underlying cause of most marine organisms’ vulnerability to climate (IPCC AR6_WGII, confidence: high)
MHWs became more frequent over the 20th century (high confidence) and into the beginning of the 21st century, approximately doubling in frequency (high confidence) and becoming more intense and longer since the 1980s (IPCC AR6_WGII, confidence: medium)
RSL rise is driving a global increase in the frequency of extreme sea levels (IPCC AR6_WGII, confidence: high)
The expected frequency of the current 1-in-100-year extreme sea level is projected to increase by a median of 20–30 times across tide-gauge sites by 2050, regardless of emission scenario (IPCC AR6_WGII, confidence: medium)
In addition, extreme-sea-level frequency may be affected by changes in tropical cyclone climatology (low confidence), wave climatology (low confidence) and tides (IPCC AR6_WGII, confidence: high)
Recent evidence has strengthened estimates of the rate of change (Yamaguchi and Suga, 2019; Li et al., 2020a; Sallée et al., 2021), with an estimated increase of 1.0 ± 0.3% (very likely range) per decade over the period 1970–2018 (IPCC AR6_WGII, confidence: high)
WGI AR6 assessed that only the California Current system has undergone large-scale upwelling-favourable wind intensification since the 1980s (IPCC AR6_WGII, confidence: medium)
While no consistent pattern of contemporary changes in upwelling- favourable winds emerges from observation-based studies, numerical and theoretical work projects that summertime winds near poleward boundaries of upwelling zones will intensify, while winds near equatorward boundaries will weaken (IPCC AR6_WGII, confidence: high)
Nevertheless, projected future annual cumulative upwelling wind changes at most locations and seasons remain within ±10–20% of present-day values (IPCC AR6_WGII, confidence: medium)
Direct observational records since the mid-2000s remain too short to determine the relative contributions of internal variability, natural forcing and anthropogenic forcing to AMOC change (IPCC AR6_WGII, confidence: high)
Ocean acidification is also developing in the ocean interior (IPCC AR6_WGII, confidence: very high)
There, it leads to the shoaling of saturation horizons of aragonite and calcite (IPCC AR6_WGII, confidence: high)
SROCC concluded that a loss of oxygen had occurred in the upper 1000 m of the ocean (IPCC AR6_WGII, confidence: medium)
New findings since SROCC also confirm that the volume of oxygen minimum zones (OMZs) are expanding at many locations (IPCC AR6_WGII, confidence: high)
Based on these CMIP6 projections, WGI AR6 concludes that the oxygen content of the subsurface ocean is projected to decline to historically unprecedented conditions over the 21st century (IPCC AR6_WGII, confidence: medium)
Nitrogen availability tends to limit phytoplankton productivity throughout most of the low-latitude ocean, whereas dissolved iron availability limits productivity in high-nutrient, low- chlorophyll regions, such as in the main upwelling region of the Southern Ocean and the Eastern Equatorial Pacific (IPCC AR6_WGII, confidence: high)
It is concluded that the surface ocean will encounter reduced nitrate concentrations in the 21st century (IPCC AR6_WGII, confidence: medium)
The rates and magnitudes of these changes largely depend on the extent of future emissions (IPCC AR6_WGII, confidence: very high)
The Arctic Ocean is characterised by the highest rates of acidification and warming, strong nutrient depletion, and it will likely become practically sea ice free in the September mean for the first time before the year 2050 in all SSP scenarios (IPCC AR6_WGII, confidence: high)
In general, the projected changes in climate-induced drivers are less in absolute terms in the deep-sea (mesopelagic and bathypelagic domains and deep-sea habitats) than in the surface ocean and in shallow-water habitats (e.g., kelp ecosystems, warm-water corals) (IPCC AR6_WGII, confidence: very high)
Significant differences in projected trends between the SSPs show that mitigation strategies will limit exposure of deep-sea ecosystems to potential warming, acidification and deoxygenation during the 21st century (IPCC AR6_WGII, confidence: very high)
Ancient intervals of rapid climate warming that occurred between 300 and 50 million years ago (Ma) were triggered by the release of greenhouse gases (IPCC AR6_WGII, confidence: high)
Warming and deoxygenation in the oceans were closely associated in hyperthermal events (high confidence), with anoxia reaching the photic zone and abyssal depths (Kaiho et al., 2014; Müller et al., 2017; Penn et al., 2018; Weissert, 2019), whereas ocean acidification has not been demonstrated consistently (IPCC AR6_WGII, confidence: medium)
There is little evidence for ocean acidification in the past 2.6 Ma (low confidence) (Hönisch et al., 2012), but ocean ventilation was highly sensitive to even modest warming such as observed in the past 10,000 years (IPCC AR6_WGII, confidence: medium)
Temperature affects the movement and transport of molecules and, thereby, the rates of all biochemical reactions; thus, ongoing and projected warming that remains below an organism’s physiological optimum will generally raise metabolic rates (IPCC AR6_WGII, confidence: very high)
For example, organisms adapted to thermally stable environments (e.g., tropical, polar, deep sea) are often more sensitive to warming than those from thermally variable environments (e.g., estuaries) (IPCC AR6_WGII, confidence: very high)
Heat tolerance also decreases with increasing organisational complexity (Storch et al., 2014; Pörtner and Gutt, 2016) and is lower in eggs, embryos and spawning fish than for their larval stages or adults outside the spawning season (IPCC AR6_WGII, confidence: high)
By altering physiological responses, projected changes in ocean warming (Section 3.2.2.1) will modify growth, migration, distribution, competition, survival and reproduction (IPCC AR6_WGII, confidence: very high)
Detrimental impacts of acidification include decreased growth and survival, and altered development, especially in early life stages (IPCC AR6_WGII, confidence: high)
Calcifiers are generally more sensitive to acidification (e.g., for growth and survival) than non-calcifying groups (IPCC AR6_WGII, confidence: high)
For calcifying primary producers, including phytoplankton and coralline algae, ocean acidification has different, often opposing effects, for example, decreasing calcification while photosynthetic rates increase (IPCC AR6_WGII, confidence: high)
Under hypoxia (oxygen concentrations ≤2 mg l–1; Limburg et al., 2020), physiological and ecological processes are impaired and communities undergo species migration, replacement and loss, transforming community composition (IPCC AR6_WGII, confidence: very high)
Hypoxia can lead to expanding OMZs, which will favour specialised microbes and hypoxia-tolerant organisms (IPCC AR6_WGII, confidence: medium)
As respiration consumes oxygen and produces CO 2, lowered oxygen levels are often interlinked with acidification in coastal and tropical habitats (Rosa et al., 2013; Gobler and Baumann, 2016; Feely et al., 2018) and is an example of a compound hazard (Sections 3.2.4.1, 3.4.2.4).Increased density stratification and mixed-layer shallowing, caused by warming, freshening and sea ice decline, can alter light climate and nutrient availability within the surface mixed layer (IPCC AR6_WGII, confidence: high)
Decreased upward nutrient supply is expected to decrease primary production in the low-latitude ocean (IPCC AR6_WGII, confidence: medium)
Alternatively, higher mean underwater light levels resulting from changes in sea ice and/or mixed layer shallowing can increase primary production in high-latitude offshore regions, provided nutrient levels remain sufficiently high (IPCC AR6_WGII, confidence: medium)
In some parts of the open Southern Ocean, where iron limitation largely controls primary productivity (Tagliabue et al., 2017), changes in wind fields will deepen the summer mixed-layer depth (Panassa et al., 2018), entrain more nutrients, and raise primary productivity in the future (IPCC AR6_WGII, confidence: medium)
Marine heatwaves exacerbate the impacts of rising mean temperatures, with major ecological consequences (IPCC AR6_WGII, confidence: very high)
The amplitude of diel and seasonal pH and CO 2 changes are projected to increase in the future due to lowered CO 2 seawater buffering capacity (IPCC AR6_WGII, confidence: very high)
Non-climate drivers (Section 3.1) can dominate outcomes or amplify vulnerability to climate- induced drivers, with mostly detrimental effects such as extirpation (IPCC AR6_WGII, confidence: very high)
Co-occurring environmental drivers often cause complex organismal responses (IPCC AR6_WGII, confidence: high)
Ocean acidification poses a large risk for coralline algae that is further amplified by warming (IPCC AR6_WGII, confidence: medium)
For seagrass, warming beyond a species’ thermal tolerance will limit growth and impact germination, but ocean acidification appears to increase thermal tolerance of some eelgrass species by increasing the photosynthesis-to-respiration ratio (IPCC AR6_WGII, confidence: medium)
Thermal sensitivity of pelagic primary producers changes with nutrient supply (IPCC AR6_WGII, confidence: high)
This trend may hold for open-ocean phytoplankton, which are often iron- limited (IPCC AR6_WGII, confidence: medium)
Rising metabolic rates due to warming will be restricted to primary producers in high- nutrient regions (IPCC AR6_WGII, confidence: medium)
The effects of ocean acidification on growth, metabolic rates or elemental composition of primary producers changes with nutrient availability and light conditions (IPCC AR6_WGII, confidence: high)
Given the expected mixed-layer shallowing in some regions (Section 3.2.2.3), the exposure to overall higher mean irradiances could shift the effects of acidification from beneficial to detrimental for some primary producers, depending on species and organismal traits (IPCC AR6_WGII, confidence: medium)
The few experimental studies that have addressed three or more drivers (Xu et al., 2014; Boyd et al., 2015b; Brennan and Collins, 2015; Brennan et al., 2017; Hoppe et al., 2018b; Moreno-Marín et al., 2018) indicate that one or two drivers generally dominate the cumulative outcome, with others playing a subordinate role (IPCC AR6_WGII, confidence: medium)
Higher ocean CO 2 influences the thermal tolerance of species adapted to extreme but stable habitats in tropical and polar regions, more than that of thermally tolerant generalists (IPCC AR6_WGII, confidence: high)
As with ocean acidification, reduced oxygen availability further alters the influence of warming on metabolic rates (IPCC AR6_WGII, confidence: high)
In consequence, expansion of OMZs and other regions where warming, hypoxia and acidification combine will further reduce habitat for many fish and invertebrates (IPCC AR6_WGII, confidence: high)
It is difficult to generalise to what extent co-occurring ocean warming ameliorates or exacerbates effects of acidification on behaviour (Laubenstein et al., 2019); outcomes depend upon species and life stage (Faleiro et al., 2015; Chan et al., 2016; Tills et al., 2016; Wang et al., 2018b; Jarrold et al., 2020), interactions between species (e.g., Paula et al., 2019) along with confounding factors including food availability and salinity (IPCC AR6_WGII, confidence: medium)
Other influential drivers include ocean acidification, salinity (high confidence) (Lefevre, 2016; Whiteley et al., 2018; Reddin et al., 2020) or food availability/quality (IPCC AR6_WGII, confidence: medium)
In highly fluctuating environments (e.g., upwelling regions, coastal zones), multiple drivers can change and interact across temporal and spatial scales, generating geographic mosaics of tolerances and sensitivities to environmental and climate change in marine organisms (IPCC AR6_WGII, confidence: medium)
Some studies have documented higher phenotypic plasticity and tolerance to ocean warming and acidification in marine invertebrates (Dam, 2013; Kelly et al., 2013; Pespeni et al., 2013; Gaitán-Espitia et al., 2017a; Vargas et al., 2017; Li et al., 2018a), seaweeds (Noisette et al., 2013; Padilla-Gamiño et al., 2016; Machado Monteiro et al., 2019) and fish (IPCC AR6_WGII, confidence: medium)
For instance, transgenerational effects and/or developmental acclimation, both ‘carry-over effects’ (where the early- life environment affects the expression of traits in later life stages or generations), can influence within- and cross-generational changes in the tolerances of marine organisms (IPCC AR6_WGII, confidence: medium)
Although plasticity provides an adaptive mechanism, it is unlikely to provide a long-term solution for species undergoing sustained directional environmental change (e.g., global warming) (IPCC AR6_WGII, confidence: medium)
Experimental evolution suggests that microbial populations can rapidly adapt (i.e., over 1–2 years) to environmental changes mimicking projected effects of climate change (IPCC AR6_WGII, confidence: medium)
The evolutionary responses of microbes are conditioned by the number and characteristics of interacting drivers (IPCC AR6_WGII, confidence: low)
Specifically, associations between vulnerabilities and traits of marine ectotherms in laboratory experiments correspond with organismal responses to ancient hyperthermal events (IPCC AR6_WGII, confidence: medium)
On a global scale, ecosystem models project a −5.7 ± 4.1% (very likely range) to −15.5 ± 8.5% decline in marine animal biomass with warming under SSP1-2.6 and SSP5-8.5, respectively, by 2080–2099 relative to 1995–2014, albeit with significant regional variation in both trends and uncertainties (IPCC AR6_WGII, confidence: medium)
For instance, trophic amplification (strengthening of responses to climate-induced drivers at higher trophic levels) may result from combined direct and indirect food-web-mediated effects (IPCC AR6_WGII, confidence: medium)
Alternatively, compensatory species interactions can dampen strong impacts on species from ocean acidification, resulting in weaker responses at functional-group or community level than at species level (IPCC AR6_WGII, confidence: medium)
Globally, the projected reduction of biomass due to climate-induced drivers is relatively unaffected by fishing pressure, indicating additive responses of fisheries and climate change (IPCC AR6_WGII, confidence: low)