Ocean acidification is rapidly changing the carbonate system of the world oceans. Past mass extinction events have been linked to ocean acidification, and the current rate of change in seawater chemistry is unprecedented. Evidence suggests that these changes will have significant consequences for marine taxa, particularly those that build skeletons, shells, and tests of biogenic calcium carbonate. Potential changes in species distributions and abundances could propagate through multiple trophic levels of marine food webs, though research into the long-term ecosystem impacts of ocean acidification is in its infancy. This review attempts to provide a general synthesis of known and/or hypothesized biological and ecosystem responses to increasing ocean acidification. Marine taxa covered in this review include tropical reef-building corals, cold-water corals, crustose coralline algae, Halimeda, benthic mollusks, echinoderms, coccolithophores, foraminifera, pteropods, seagrasses, jellyfishes, and fishes. The risk of irreversible ecosystem changes due to ocean acidification should enlighten the ongoing CO(2) emissions debate and make it clear that the human dependence on fossil fuels must end quickly. Political will and significant large-scale investment in clean-energy technologies are essential if we are to avoid the most damaging effects of human-induced climate change, including ocean acidification.

Abstract Future ocean acidification mainly depends on the continuous ocean uptake of CO 2 from the atmosphere. The trajectory of future atmospheric CO 2 is prescribed in traditional climate projections with Earth system models, leading to a small model spread and apparently low uncertainties for projected acidification, but a large spread in global warming. However, climate policies such as the Paris Agreement define climate targets in terms of global warming levels and as traditional simulations do not converge to a given warming level, they cannot be used to assess uncertainties in projected acidification. Here, we perform climate simulations that converge to given temperature levels using the Adaptive Emission Reduction Algorithm (AERA) with the Earth system model Bern3D-LPX at different setups with different Transient Climate Response to cumulative carbon Emissions (TCRE) and choices between reductions in CO 2 and non-CO 2 forcing agents. With these simulations, we demonstrate that uncertainties in surface ocean acidification are an order of magnitude larger than the usually reported inter-model uncertainties from simulations with prescribed atmospheric CO 2 . Uncertainties in acidification at a given stabilized temperature are dominated by TCRE and the choice of emission reductions of non-CO 2 greenhouse gases (GHGs). High TCRE and relatively low reductions of non-CO 2 GHGs, for example, necessitate relatively strong reductions in CO 2 emissions and lead to relatively little ocean acidification at a given temperature level. The results suggest that choices between reducing emissions of CO 2 versus non-CO 2 agents should consider the economic costs and ecosystem damage of ocean acidification.

Abstract:The acid–base relations of plant (including algal) environments are complex, comprising geological processes as modified by biology including, especially over the last 200 years, man. Some habitats (e.g. high intertidal rockpools and some freshwater bodies) have pH variations of up to three units over a diel cycle as a result of photosynthesis and respiration. Other habitats, e.g. nutrient-poor open ocean habitats, have diel variations that are more than an order of magnitude smaller. Anthropogenic influences on acid–base relations of different habitats include the input to the atmosphere of gases that dissolve to produce acidic solutions. The quantitatively predominant gas is CO2, but SO2, NOx and NHy (via nitrification) can also be significant. The influence of the acidic gases in aquatic habitats (including the upper layers of peat bogs) and on terrestrial photosynthetic organisms alters the inorganic carbon speciation and pH around the photosynthetic cells. The calcified coralline marine red macroalgae, with benthic and unattached (maerl) life forms, have extracellular calcification; their calcification rate will decline in the future, with a more CO2-rich ocean and decreasing CO32- concentrations. The marine planktonic coccolithophores have intracellular calcification, though the coccoliths themselves occur externally. While many coccolithophores show decreased calcification with increasing external CO2 and the attendant decrease in external CO32-, this is not universal. For both coralline red algae and coccolithophores the external CaCO3 will dissolve when seawater becomes undersaturated with respect to the relevant crystal form of CaCO3. Overall, the effects of increased CO2 alone are negligible or result in increased growth of non-calcified algae, while there is most generally a decreased growth of calcified algae.

We synthesize and review the impacts of climate change on the physical, chemical, and biological environments of the Indian Ocean and discuss mitigating actions and knowledge gaps. The most recent climate scenarios identify with high certainty that the Indian Ocean (IO) is experiencing one of the fastest surface warming among the world's oceans. The area of surface waters of >28 °C (IO Warm Pool) has significantly increased during 2012-2021 by expanding into the northern-central basins. A significant decrease in pH and aragonite (building blocks of calcified organisms) levels in the IO was observed from 1981 to 2020 due to an increase in atmospheric CO2 concentrations. There are also signals of decreasing trends in primary productivity in the north, likely related to enhanced stratification and nutrient depletion. Further, the rapid warming of the IO will manifest more extreme weather conditions along its adjacent continents and oceans, including marine heat waves that are likely to reshape biodiversity. However, the impact of climate change beyond the unprecedented warming, increase in marine heat waves, expansion of the IO Warm Pool, and decrease in pH, remains uncertain for many other key variables in the IO including changes in salinity, oxygen, and net primary production. Understanding the response of these physical, chemical, and biological variables to climate change is vital to project future changes in regional fisheries and identify mitigation actions. We accordingly conclude by identifying knowledge gaps and recommending directions for sustainable fisheries and climate impact studies.

The ocean, Earth's largest carbon reservoir, exerts a central role over atmospheric CO₂ through its capacity to store carbon primarily as bicarbonate ions. Direct observations indicate that the global ocean has a net carbon uptake of 2.6-3.0 petagrams of carbon annually, representing nearly 30% of anthropogenic CO₂ emissions. This review examines two principal domains of oceanic carbon cycling. The first concerns the natural uptake and storage of anthropogenic CO₂, with emphasis on the response of the marine carbonate system and the spatial distribution of absorbed carbon. The second addresses emerging marine CO₂ removal strategies, especially ocean alkalinity enhancement and macroalgae-based approaches. Ocean alkalinity enhancement aims to increase seawater buffering capacity to facilitate greater CO₂ uptake, whereas macroalgae-based strategies rely on photosynthetic fixation and the subsequent storage of organic and inorganic carbon in various reservoirs. Effective implementation of these approaches necessitates rigorous monitoring, reporting, and verification frameworks to ensure their quantifiable efficacy and environmental integrity.

Some of the carbon from plants also becomes part of the soil, where it can stay for a long time before decomposing. Another process takes CO2 out of the air. Weathering by rain washes out CO2 in the form of dilute carbonic acid. This reacts with rock, helping to dissolve and destroy it. This also ends up as sediment. - "Weathering is a large consumer of the atmospheric carbon dioxide essential for dissolving rocks".[1] Some CO2 is also dissolved in the ocean. Right now, the oceans are taking in more CO2 than they are releasing, every year. However, this is making the oceans more acidic. The store of carbon in sedimentary rock is far greater than the CO2 in the atmosphere (this is not shown in the diagram). Eventually it returns to the air as oceanic plates subduct in tectonic plates. At the margins of plate boundaries (and some other places) volcanoes form and spew out CO2. This completes the cycle. Summary The carbon cycle is a process where carbon is recycled through the ecosystem. The concentration of carbon in living matter (18%) is almost 100 times greater than its concentration in the earth (0.19%). So living things extract carbon from their nonliving environment.

AbstractIPCC AR4 reported that the emission of the anthropogenic Carbon Dioxide (CO2) increase the CO2 concentration in atmosphere after the Industrial Revolution, and increasing of CO2 concentration caused the global warming. Moreover, it is shown that CO2 dissolution into the ocean causes the acidification in the surface layer. The buffering effect of the ocean can suppress the change of the CO2 concentration in the atmosphere. However, the rise of the CO2 concentration in the ocean surface means the pH of seawater decreases. This phenomenon continues until the difference of CO2 partial pressure between the atmosphere and the ocean disappears if the emission of CO2 is stopped. But, the acidification of the ocean progresses as long as it keeps CO2 emission. It is feared that the ocean acidification has crises influence on various organisms and entire ocean ecosystem.Carbon Capture and Storage is one of the mitigation measure technologies of CO2 emission. Famous carbon storage technology of the CCS using ocean region is Sub-seabed Geological Storage and dilution type Ocean Sequestration. These CCS Technologies has been developed in RITE. Especially, Research and development project of ocean sequestration technology was established the core technologies for example CO2 injection and dilution technology, prediction of drop and diluted CO2 and evaluation methods of biological influence of CO2. These core technologies were enabled a feasibility study of Ocean Sequestration techno

Rising atmospheric carbon dioxide (CO2), primarily from human fossil fuel combustion, reduces ocean pH and causes wholesale shifts in seawater carbonate chemistry. The process of ocean acidification is well documented in field data, and the rate will accelerate over this century unless future CO2 emissions are curbed dramatically. Acidification alters seawater chemical speciation and biogeochemical cycles of many elements and compounds. One well-known effect is the lowering of calcium carbonate saturation states, which impacts shell-forming marine organisms from plankton to benthic molluscs, echinoderms, and corals. Many calcifying species exhibit reduced calcification and growth rates in laboratory experiments under high-CO2 conditions. Ocean acidification also causes an increase in carbon fixation rates in some photosynthetic organisms (both calcifying and noncalcifying). The potential for marine organisms to adapt to increasing CO2 and broader implications for ocean ecosystems are not well known; both are high priorities for future research. Although ocean pH has varied in the geological past, paleo-events may be only imperfect analogs to current conditions.

Ocean acidification is the ongoing decrease in the pH of the Earth's ocean. Between 1950 and 2020, the average pH of the ocean surface fell from approximately Ocean acidification is the ongoing decrease in the pH of the Earth's ocean. Between 1950 and 2020, the average pH of the ocean surface fell from approximately 8.15 to 8.05. Carbon dioxide emissions from human activities are the primary cause of ocean acidification, with atmospheric carbon dioxide (CO2) levels exceeding 422 ppm (as of 2024). CO2 from the atmosphere is absorbed by the oceans. This c H…

Microbial Biofilms Along a Geochemical Gradient at the Shallow-Water Hydrothermal System of Vulcano Island, Mediterranean Sea Shallow water hydrothermal vents represent highly dynamic environments where strong geochemical gradients can shape microbial communities. Recently, these systems are being widely used for investigating the effects of ocean acidification on biota as vent emissions can release high CO2 concentrations causing local pH reduction. However, other gas species, as well as trace elements and metals, are often released in association with CO2 and can potentially act as confounding factors. In this study, we evaluated the composition, diversity and inferred functional profiles of microbial biofilms in Levante Bay (Vulcano Island, Italy, Mediterranean Sea), a well-studied shallow-water hydrothermal vent system. We analyzed 16S rRNA transcripts from biofilms exposed to different intensity of hydrothermal activity, following a redox and pH gradient across the bay. We found that elevated CO2 concentrations causing low pH can affect the response of bacterial groups and taxa by either increasing or decreasing their relative abundance.