Anthropogenic CO2 is accumulating in the atmosphere and trapping reflected infrared radiation, resulting in warming of both terrestrial and ocean ecosystems. At the same time, the dissolution of CO2 into seawater is increasing surface ocean acidity, a process known as ocean acidification. Effects of ocean acidification on marine primary producers have been documented to be stimulative, inhibitive, or neutral. Elevated CO2 and reduced pH levels can interact with solar radiation, which fluctuates over different time scales from limiting to saturating or even stressful levels, to bring about synergistic, antagonistic, or balanced effects on marine primary producers at different depths or under changing weather conditions. However, shoaling of the upper mixed layer (enhanced stratification) due to ocean warming and freshening (rain, ice melting) can lead to additional photosynthetically active radiation (PAR) and ultraviolet (UV) exposure, which can have both benefits and costs to photosynthetic organisms. Elevated CO2 concentrations under low or moderate levels of PAR have been shown to enhance photosynthesis or growth of both phytoplankton and macroalgae; excessive levels of PAR, however, can lead to additional inhibition of photosynthesis or growth under elevated CO2, and addition of UV radiation (280 to 400 nm) can increase or down-regulate such inhibition, since solar UV-B (280 to 315 nm) radiation often harms algal cells, while UV-A (315 to 400 nm) at moderate levels stimulates photosynthetic carbon fixation in both phytoplankton and macroalgae. In view of warming effects, increased temperatures have been shown to enhance photorepair of UV-damaged molecules, though it simultaneously enhances respiratory carbon loss. The net effects of ocean acidification on marine primary producers are therefore largely dependent on the photobiological conditions (light limitation, light or UV stress), as well as interactions with rising temperature and other variables such as altered nutrient availability. Hence, feedbacks between changing carbonate chemistry and solar radiation across the entire spectrum present complications to interpret and understand ocean acidification effects based on single-factor experiments.
Posts Tagged 'review'
Responses of marine primary producers to interactions between ocean acidification, solar radiation, and warming
Published 10 December 2012 Science ClosedTags: algae, biological response, calcification, growth, light, multiple factors, photosynthesis, phytoplankton, primary production, respiration, review, temperature
Environmental controls on coccolithophore calcification
Published 10 December 2012 Science ClosedTags: biological response, calcification, light, multiple factors, phytoplankton, review, temperature
Coccolithophores are major contributors to global marine planktonic calcification, and in nature coccolithophores are invariably calcified through almost all of their life cycle. The response of calcification to environmental factors is essential in understanding the persistence of coccolithophores through at least 220 million years of changing global environments, and their prospects for current environmental change. So far the responses examined have been at the level of acclimation rather than adaptation in evolution. Variation in results of CO2 manipulation experiments can be tentatively attributed to variation among genotypes rather than differences in experimental procedure. Comparisons of methods using the same genotype, and of several genotypes using a single method, suggest significant variation among genotypes. The general response is a decreased particulate inorganic carbon (PIC) to particulate organic carbon (POC) ratio in higher than present CO2 concentrations and vice versa for lower CO2 concentrations. Fewer studies have investigated the effect of other environmental factors. Decreased availability of phosphorus and, to a lesser extent, nitrogen, as well as decreasing photosynthetically active radiation (PAR) down to a certain low value increase PIC:POC, while variable results have been found for changes in ultraviolet radiation (UVR). Many of these results can be accommodated by considering the restriction of calcification to the G1 phase of the cell cycle and the length of this phase under different growth conditions. Fewer studies have investigated the interactions among environmental factors which change with increased CO2 and increasing sea surface temperature; the shoaling of the thermocline will increase the mean PAR and UVR whilst decreasing nitrogen and phosphorus availability. More studies of these interactions, as well as of genetic adaptation in response to changed environmental factors, are needed.
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Pressures on the marine environment and the changing climate of ocean biogeochemistry
Published 16 November 2012 Science ClosedTags: review
The oceans are under pressure from human activities. Following 250 years of industrial activity, effects are being seen at the cellular through to regional and global scales. The change in atmospheric CO2 from 280 ppm in pre-industrial times to 392 ppm in 2011 has contributed to the warming of the upper 700 m of the ocean by approximately 0.1°C between 1961 and 2003, to changes in sea water chemistry, which include a pH decrease of approximately 0.1, and to significant decreases in the sea water oxygen content. In parallel with these changes, the human population has been introducing an ever-increasing level of nutrients into coastal waters, which leads to eutrophication, and by 2008 had resulted in 245 000 km2 of severely oxygen-depleted waters throughout the world. These changes are set to continue for the foreseeable future, with atmospheric CO2 predicted to reach 430 ppm by 2030 and 750 ppm by 2100. The cycling of biogeochemical elements has proved sensitive to each of these effects, and it is proposed that synergy between stressors may compound this further. The challenge, within the next few decades, for the marine science community, is to elucidate the scope and extent that biological processes can adapt or acclimatize to a changing chemical and physical marine environment.
Impacts of ocean acidification on marine seafood
Published 6 November 2012 Science ClosedTags: biological response, fish, mollusks, review
Ocean acidification is a series of chemical reactions due to increased CO2 emissions. The resulting lower pH impairs the senses of reef fishes and reduces their survival, and might similarly impact commercially targeted fishes that produce most of the seafood eaten by humans. Shelled molluscs will also be negatively affected, whereas cephalopods and crustaceans will remain largely unscathed. Habitat changes will reduce seafood production from coral reefs, but increase production from seagrass and seaweed. Overall effects of ocean acidification on primary productivity and, hence, on food webs will result in hard-to-predict winners and losers. Although adaptation, parental effects, and evolution can mitigate some effects of ocean acidification, future seafood platters will look rather different unless CO2 emissions are curbed.
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Half a century of pursuing the pervasive proton
Published 30 October 2012 Science ClosedTags: algae, biological response, physiology, review
Acid–base regulation is probably a universal attribute of life, and energy coupling via transmembrane H+ gradients is very widespread. Much of my academic career has been related to these two processes and to their interactions. Highlights from my studies of acid–base regulation are the quantitative resolution of the challenges for acid–base regulation in land plant shoots when metabolism involving net H+ production (e.g. primary assimilation of NH 4 + , NH3 or N2) occurs there, quantitation of the energy costs of acid–base regulation for different locations and mechanisms of acid–base regulation for the assimilation of a range on N sources and the interaction of CO2 concentrating mechanisms in aquatic photosynthetic organisms with acid–base regulation. Research on the significance of transmembrane H+ gradients has included a significant contribution to the early development of chemiosmotic hypothesis of polar transport of indoleacetic acid, the evolutionary significance of chemiosmotic coupling and the role of H+ leakage relative to other processes which consumed energy at an essentially constant rate regardless of the rate of light energy supply in determining the minimum photon flux density at which photolithotrophic growth can occur. On a global scale, work on the effects of anthropogenic CO2 production on ocean acid–base balance has helped to set limits on the significance of this ‘ocean acidification’ for marine algae. A final point covered in the chapter is an analysis of the continuing attempts to determine precisely what is being regulated, e.g. the pH of the intracellular compartment or the ionisation state of one or more of weak electrolytes in the compartment.
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Impact of global warming and rising CO2 levels on coral reef fishes: what hope for the future?
Published 30 October 2012 Science ClosedTags: biological response, multiple factors, performance, review, temperature
Average sea-surface temperature and the amount of CO2 dissolved in the ocean are rising as a result of increasing concentrations of atmospheric CO2. Many coral reef fishes appear to be living close to their thermal optimum, and for some of them, even relatively moderate increases in temperature (2–4°C) lead to significant reductions in aerobic scope. Reduced aerobic capacity could affect population sustainability because less energy can be devoted to feeding and reproduction. Coral reef fishes seem to have limited capacity to acclimate to elevated temperature as adults, but recent research shows that developmental and transgenerational plasticity occur, which might enable some species to adjust to rising ocean temperatures. Predicted increases in PCO2, and associated ocean acidification, can also influence the aerobic scope of coral reef fishes, although there is considerable interspecific variation, with some species exhibiting a decline and others an increase in aerobic scope at near-future CO2 levels. As with thermal effects, there are transgenerational changes in response to elevated CO2 that could mitigate impacts of high CO2 on the growth and survival of reef fishes. An unexpected discovery is that elevated CO2 has a dramatic effect on a wide range of behaviours and sensory responses of reef fishes, with consequences for the timing of settlement, habitat selection, predator avoidance and individual fitness. The underlying physiological mechanism appears to be the interference of acid–base regulatory processes with brain neurotransmitter function. Differences in the sensitivity of species and populations to global warming and rising CO2 have been identified that will lead to changes in fish community structure as the oceans warm and becomes more acidic; however, the prospect for acclimation and adaptation of populations to these threats also needs to be considered. Ultimately, it will be the capacity for species to adjust to environmental change over coming decades that will determine the impact of climate change on marine ecosystems.
Adaptation and the physiology of ocean acidification
Published 22 October 2012 Science ClosedTags: adaptation, physiology, review
- Ocean acidification, caused by the uptake of atmospheric CO2, is a threat to marine biodiversity, potentially rivalling the threat imposed by rising temperatures in some marine ecosystems. Although a growing body of literature documents negative effects of acidification on marine organisms, the majority of this work has focused on the effects of future conditions on modern populations, ignoring the potential effects of adaptation and physiological acclimatization.
- We review current literature on the potential for adaptation to elevated pCO2 in marine organisms. Although this body of work is currently quite small, we argue that data on the physiological effects of acidification, natural variation in pH and lessons learned from previous work on thermal adaptation can all inform predictions and priorities for future research.
- Spatially varying selection is one of the most important forces maintaining intraspecific genetic variation. Unlike temperature, pH lacks a strong and persistent global gradient, and so selection may maintain less adaptive variation for pH than for temperature. On the other hand, we are only beginning to amass long-term data sets for pH variation in natural habitats, and thus, pH gradients may be more common than previously observed.
- Two of the most important effects of elevated pCO2 are reduced calcification and changes in metabolism. We discuss the ways that a detailed understanding of the physiological mechanisms underlying these effects is key to predicting the capacity for acclimatization and adaptation.
- Important priorities for future research will be to assess local adaptation to pH conditions and to measure the capacity for adaptation to future acidified conditions in natural populations. Tools for this work include traditional quantitative genetics, transcriptomics and the adaptation of ion-sensitive field-effect transistor (ISFET) technology for use in continuous seawater pH monitoring in the field.
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The ecosystem impacts of global warming and related ecological crises
Published 11 October 2012 Science ClosedTags: review
The geophysical and biophysical impacts of human actions on the Earth’s systems during the Anthropocene epoch are increasingly dangerous, ubiquitous, and well documented. The loss of biodiversity, ocean acidification, declining fresh water, more frequent extreme weather events, stratospheric ozone depletion, expanding threats to human health, altered nitrogen and phosphorus cycles, rising sea levels and coastal zone impacts, aerosol pollution, chemical pollution, and the disruption of agriculture and food supplies comprise a partial list of the impacts of human action that threaten the viability of human societies and the survival of millions of species on Earth.
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5 – Impact of climate change on fishes in complex Antarctic ecosystems
Published 10 October 2012 Science ClosedTags: Antarctic, biological response, fish, physiology, review
Antarctic marine ecosystems are increasingly threatened by climate change and are considered to be particularly sensitive because of the adaptation of most organisms to cold and stable environmental conditions. Fishes play a central role in the Antarctic marine food web and might be affected by climate change in different ways: (i) directly by increasing water temperatures, decreasing seawater salinity and/or increasing concentrations of CO2; (ii) indirectly by alterations in the food web, in particular by changes in prey composition, and (iii) by alterations and loss of habitat due to sea ice retreat and increased ice scouring on the sea floor. Based on new data and data collected from the literature, we analyzed the vulnerability of the fish community to these threats.
The potential vulnerability and acting mechanisms differ among species, developmental stages and habitats. The icefishes (family Channichthyidae) are one group that are especially vulnerable to a changing South Polar Sea, as are the pelagic shoal fish species Pleuragramma antarcticum. Both will almost certainly be negatively affected by abiotic alterations and changes in food web structure associated with climate change, the latter additionally by habitat loss. The major bottleneck for the persistence of the majority of populations appears to be the survival of early developmental stages, which are apparently highly sensitive to many types of alterations. In the long term, if climate projections are realized, species loss seems inevitable: within the demersal fish community, the loss or decline of one species might be compensated by others, whereas the pelagic fish community in contrast is extremely poor in species and dominated by P. antarcticum. The loss of this key species could therefore have especially severe consequences for food web structure and the functioning of the entire ecosystem.
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Multi-partner interactions in corals in the face of climate change
Published 20 September 2012 Science ClosedTags: biological response, corals, prokaryotes, review
Recent research has explored the possibility that increased sea-surface temperatures and decreasing pH (ocean acidification) contribute to the ongoing decline of coral reef ecosystems. Within corals, a diverse microbiome exerts significant influence on biogeochemical and ecological processes, including food webs, organismal life cycles, and chemical and nutrient cycling. Microbes on coral reefs play a critical role in regulating larval recruitment, bacterial colonization, and pathogen abundance under ambient conditions, ultimately governing the overall resilience of coral reef systems. As a result, microbial processes may be involved in reef ecosystem-level responses to climate change. Developments of new molecular technologies, in addition to multidisciplinary collaborative research on coral reefs, have led to the rapid advancement in our understanding of bacterially mediated reef responses to environmental change. Here we review new discoveries regarding (1) the onset of coral-bacterial associations; (2) the functional roles that bacteria play in healthy corals; and (3) how bacteria influence coral reef response to environmental change, leading to a model describing how reef microbiota direct ecosystem-level response to a changing global climate.
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Impact of climate change in Mediterranean aquaculture
Published 13 September 2012 Science ClosedTags: review, socio-economy
The Mediterranean Sea is the biggest marginal sea of the Earth and is at the centre of the life for several millions of people. Seafood is consumed widely in this region, with an average of 16.5 kg/capita/year, and one-fourth of the seafood supply comes from aquaculture activities. The Mediterranean aquaculture sector has expanded in recent decades. Production increased by 77% over the past decade reaching about 1.3 million metric tonnes in 2009. The total value of production was around 3700 million US dollars, representing 3.4% of the value of global aquaculture production. The growth of seafood demand in the Mediterranean is expected to increase in the future, especially in southern countries. Yet, during the 21st century, the Mediterranean basin is expected to observe: (i) an increase in air temperature of between 2.2°C and 5.1°C; (ii) a decrease in rainfall of between 4% and 27%; (iii) an increase in drought periods related to a high frequency of days during which the temperature would exceed 30°C; and (iv) an increase of the sea level of around 35 cm and saline intrusion. Moreover, extreme events, such as heat waves, droughts or floods, are likely to be more frequent and violent. This paper reviews the present status of Mediterranean aquaculture (e.g. production trends, main farmed species, production systems, major producing countries), the most relevant impacts of climate change on this sector (temperature, eutrophication, harmful algae blooms, water stress, sea level rise, acidification and diseases) and proposes a wide range of adaptation and mitigation strategies that might be implemented to minimize impacts.
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How will ocean acidification affect Baltic Sea ecosystems? An assessment of plausible impacts on key functional groups
Published 4 September 2012 Science ClosedTags: Baltic, biological response, review
Increasing partial pressure of atmospheric CO2 is causing ocean pH to fall—a process known as ‘ocean acidification’. Scenario modeling suggests that ocean acidification in the Baltic Sea may cause a ≤3 times increase in acidity (reduction of 0.2–0.4 pH units) by the year 2100. The responses of most Baltic Sea organisms to ocean acidification are poorly understood. Available data suggest that most species and ecologically important groups in the Baltic Sea food web (phytoplankton, zooplankton, macrozoobenthos, cod and sprat) will be robust to the expected changes in pH. These conclusions come from (mostly) single-species and single-factor studies. Determining the emergent effects of ocean acidification on the ecosystem from such studies is problematic, yet very few studies have used multiple stressors and/or multiple trophic levels. There is an urgent need for more data from Baltic Sea populations, particularly from environmentally diverse regions and from controlled mesocosm experiments. In the absence of such information it is difficult to envision the likely effects of future ocean acidification on Baltic Sea species and ecosystems.
Biological impacts of ocean acidification: a postgraduate perspective on research priorities
Published 3 September 2012 Science ClosedTags: biological response, review
Research into the effects of ocean acidification (OA) on marine organisms has greatly increased during the past decade, as realization of the potential dramatic impacts has grown. Studies have revealed the multifarious responses of organisms to OA conditions, indicating a high level of intra- and interspecific variation in species’ ability to accommodate these alterations. If we are to provide policy makers with sound, scientific input regarding the expected consequences of OA, we need a broader understanding of these predicted changes. As a group of 20 multi-disciplinary postgraduate students from around the globe, with a study focus on OA, we are a strong representation of ‘next generation’ scientists in this field. In this unique cumulative paper, we review knowledge gaps in terms of assessing the biological impacts of OA, outlining directions for future research.
Biological monitoring for carbon capture and storage – a review and potential future developments
Published 30 August 2012 Science ClosedTags: chemistry, field, mitigation, review
Effective monitoring of carbon capture and storage (CCS) projects is essential, but detection of leaks and subsequent subtle changes in the surrounding environment are difficult to assess. New tools are being developed for this purpose, yet biological monitoring methods have been under valued; this is surprising given the rapid technological expansion in the field of microbial ecology over the last decade. A review of biological monitoring for CCS shows a number of techniques such as plant surveys, bacterial counts and DNA fingerprinting that have been applied to natural analogues or shallow injection sites. The results of the monitoring potential of these methods vary, perhaps explaining the limited research and adoption of biological monitoring for CCS projects. However, new tools such as microarrays provide rapid throughput that can characterise microbial populations and functional genes that may change due to CO2 leakage and subsequent effects. These tools are not the whole answer for CCS monitoring, but they open new opportunities in this area and should lead to the development of simple biosensors and an expansion of the monitoring toolkit. Comparisons to other fields of research, such as tracing contaminants plumes of BTEX, demonstrate how the techniques reviewed can be developed and applied to CCS monitoring.
Phenotypic plasticity and evolutionary demographic responses to climate change: taking theory out to the field
Published 30 August 2012 Science ClosedTags: biological response, phytoplankton, review
- Rapid climate change both imposes strong selective pressures on natural populations – potentially reducing their growth rate and causing genetic evolution – and affects the physiology and development of individual organisms. Understanding and predicting the fates of populations under global change, including extinctions and geographical range shifts, requires analysing the interplay of these processes, which has long been a grey area in evolutionary biology.
- We review recent theory on the interaction of phenotypic plasticity, genetic evolution and demography in environments that change in time or space. We then discuss the main limitations of the models and the difficulties in testing theoretical predictions in the wild, notably regarding changes in phenotypic selection, the evolution of (co)variances of reaction norm parameters, and transient dynamics.
- We use two landmark examples of physiological responses to climate change –trees facing drier climate and extreme temperatures, and marine phytoplankton under rising CO2– to highlight relatively neglected questions and indicate the theoretical and empirical challenges that they raise. These examples illustrate notably that age-specific patterns of plasticity and selection on the one hand, and changes in community interactions and functioning on the other hand, need to be further investigated theoretically and empirically for a better understanding of evolutionary demographic responses to climate change in the wild.
A horizon scanning assessment of current and potential future threats to migratory shorebirds
Published 27 August 2012 Science ClosedTags: biological response, review
We review the conservation issues facing migratory shorebird populations that breed in temperate regions and use wetlands in the non-breeding season. Shorebirds are excellent model organisms for understanding ecological, behavioural and evolutionary processes and are often used as indicators of wetland health. A global team of experienced shorebird researchers identified 45 issues facing these shorebird populations, and divided them into three categories (natural, current anthropogenic and future issues). The natural issues included megatsunamis, volcanoes and regional climate changes, while current anthropogenic threats encompassed agricultural intensification, conversion of tidal flats and coastal wetlands by human infrastructure developments and eutrophication of coastal systems. Possible future threats to shorebirds include microplastics, new means of recreation and infectious diseases. We suggest that this review process be broadened to other taxa to aid the identification and ranking of current and future conservation actions.
Seawater-pH measurements for ocean-acidification observations
Published 27 August 2012 Science ClosedTags: chemistry, field, methods, review
The uptake of anthropogenic CO2 by the oceans since the onset of the industrial revolution is considered a serious challenge to marine ecosystems due to ensuing carbonate-chemistry changes (ocean acidification). Furthermore, the CO2 uptake is reducing the ocean’s capacity to absorb future CO2 emissions. In order to follow the changes in the ocean’s carbonate system, high-quality analytical measurements with good spatial and temporal resolution are necessary. High-precision and accurate pH measurements are now possible, and allow us to determine the progression of ocean acidification. The spectrophotometric pH technique is now widely used and capable of the required high-quality measurements. Spectrophotometric pH systems are deployed on ships and in situ on remote platforms. Smaller and more rugged instruments are nevertheless required for more widespread in situ application to allow routine high-resolution measurements, even in the most remote regions.
We critically review oceanic pH measurements, and focus on state-of-the-art spectrophotometric pH measurement techniques and instrumentation. We present a simple microfluidic design integrated in a shipboard instrument featuring high accuracy and precision as a key step towards a targeted pH microsensor system.
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Coral reefs of the turbid inner-shelf of the Great Barrier Reef, Australia: an environmental and geomorphic perspective on their occurrence, composition and growth
Published 17 August 2012 Science ClosedTags: biological response, corals, review
Investigations of the geomorphic and sedimentary context in which turbid zone reefs exist, both in the modern and fossil reef record, can inform key ecological debates regarding species tolerances and adaptability to elevated turbidity and sedimentation. Furthermore, these investigations can address critical geological and palaeoecological questions surrounding longer-term coral-sediment interactions and reef growth histories. Here we review current knowledge about turbid zone reefs from the inner-shelf regions of the Great Barrier Reef (GBR) in Australia to consider these issues and to evaluate reef growth in the period prior to and post European settlement. We also consider the future prospects of these reefs under reported changing water quality regimes. Turbid zone reefs on the GBR are relatively well known compared to those in other reef regions. They occur within 20 km of the mainland coast where reef development may be influenced by continual or episodic terrigenous sediment inputs, fluctuating salinities (24-36 ppt), and reduced water quality through increased nutrient and pollutant delivery from urban and agricultural runoff. Individually, and in synergy, these environmental conditions are widely viewed as unfavourable for sustained and vigorous coral reef growth, and thus these reefs are widely perceived as marginal compared to clear water reef systems. However, recent research has revealed that this view is misleading, and that in fact many turbid zone reefs in this region are resilient, exhibit relatively high live coral cover (> 30%) and have distinctive community assemblages dominated by fast growing (Acropora, Montipora) and/or sediment tolerant species (Turbinaria, Goniopora, Galaxea, Porites). Palaeoecological reconstructions based on the analysis of reef cores show that community assemblages are relatively stable at millennial timescales, and that many reefs are actively accreting (average 2-7 mm/year) where accommodation space is available, despite recent anthropogenic pressures. These turbid zone reefs challenge traditional views on the environmental conditions required for active reef growth, but given their proximity to land and associated stresses, current knowledge on these less well understood reefs should be synthesised to aid coastal management directives. Terrigenous sediments are a dominant influence on turbid zone reef occurrence, composition and growth, and, therefore, the assessment of their future prospects will require a detailed understanding of the sedimentary regimes under which they occur and of their differential response modes.
In the coming century, life in the ocean will be confronted with a suite of environmental conditions that have no analog in human history. Thus, there is an urgent need to determine which marine species will adapt and which will go extinct. Here, we review the growing literature on marine extinctions and extinction risk in the fossil, historical, and modern records to compare the patterns, drivers, and biological correlates of marine extinctions at different times in the past. Characterized by markedly different environmental states, some past periods share common features with predicted future scenarios. We highlight how the different records can be integrated to better understand and predict the impact of current and projected future environmental changes on extinction risk in the ocean.
Ocean acidification in a geoengineering context
Published 13 August 2012 Science ClosedTags: mitigation, review
Fundamental changes to marine chemistry are occurring because of increasing carbon dioxide (CO2) in the atmosphere. Ocean acidity (H+ concentration) and bicarbonate ion concentrations are increasing, whereas carbonate ion concentrations are decreasing. There has already been an average pH decrease of 0.1 in the upper ocean, and continued unconstrained carbon emissions would further reduce average upper ocean pH by approximately 0.3 by 2100. Laboratory experiments, observations and projections indicate that such ocean acidification may have ecological and biogeochemical impacts that last for many thousands of years. The future magnitude of such effects will be very closely linked to atmospheric CO2; they will, therefore, depend on the success of emission reduction, and could also be constrained by geoengineering based on most carbon dioxide removal (CDR) techniques. However, some ocean-based CDR approaches would (if deployed on a climatically significant scale) re-locate acidification from the upper ocean to the seafloor or elsewhere in the ocean interior. If solar radiation management were to be the main policy response to counteract global warming, ocean acidification would continue to be driven by increases in atmospheric CO2, although with additional temperature-related effects on CO2 and CaCO3 solubility and terrestrial carbon sequestration.
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