Ocean acidification is the ongoing decrease in the pH of the Earth's oceans, caused by the uptake of carbon dioxide (CO
2) from the atmosphere. Seawater is slightly basic (meaning pH > 7), and ocean acidification involves a shift towards pH-neutral conditions rather than a transition to acidic conditions (pH < 7). An estimated 30–40% of the carbon dioxide from human activity released into the atmosphere dissolves into oceans, rivers and lakes. To achieve chemical equilibrium, some of it reacts with the water to form carbonic acid. Some of the resulting carbonic acid molecules dissociate into a bicarbonate ion and a hydrogen ion, thus increasing ocean acidity (H+ ion concentration). Between 1751 and 1996, surface ocean pH is estimated to have decreased from approximately 8.25 to 8.14, representing an increase of almost 30% in H+ ion concentration in the world's oceans. Earth System Models project that, by around 2008, ocean acidity exceeded historical analogues and, in combination with other ocean biogeochemical changes, could undermine the functioning of marine ecosystems and disrupt the provision of many goods and services associated with the ocean beginning as early as 2100.
Increasing acidity is thought to have a range of potentially harmful consequences for marine organisms such as depressing metabolic rates and immune responses in some organisms and causing coral bleaching. By increasing the presence of free hydrogen ions, the additional carbonic acid that forms in the oceans ultimately results in the conversion of carbonate ions into bicarbonate ions. Ocean alkalinity (roughly equal to [HCO3−] + 2[CO32−]) is not changed by the process, or may increase over long time periods due to carbonate dissolution. This net decrease in the amount of carbonate ions available may make it more difficult for marine calcifying organisms, such as coral and some plankton, to form biogenic calcium carbonate, and such structures become vulnerable to dissolution. Ongoing acidification of the oceans may threaten future food chains linked with the oceans. As members of the InterAcademy Panel, 105 science academies have issued a statement on ocean acidification recommending that by 2050, global CO
2 emissions be reduced by at least 50% compared to the 1990 level.
While ongoing ocean acidification is at least partially anthropogenic in origin, it has occurred previously in Earth's history, and the resulting ecological collapse in the oceans had long-lasting effects for global carbon cycling and climate. The most notable example is the Paleocene-Eocene Thermal Maximum (PETM), which occurred approximately 56 million years ago when massive amounts of carbon entered the ocean and atmosphere, and led to the dissolution of carbonate sediments in all ocean basins.
Ocean acidification has been compared to anthropogenic climate change and called the "evil twin of global warming" and "the other CO
2 problem". Freshwater bodies also appear to be acidifying, although this is a more complex and less obvious phenomenon.
The carbon cycle describes the fluxes of carbon dioxide (CO
2) between the oceans, terrestrial biosphere, lithosphere, and the atmosphere. Human activities such as the combustion of fossil fuels and land use changes have led to a new flux of CO
2 into the atmosphere. About 45% has remained in the atmosphere; most of the rest has been taken up by the oceans, with some taken up by terrestrial plants.
The carbon cycle involves both organic compounds such as cellulose and inorganic carbon compounds such as carbon dioxide, carbonate ion, and bicarbonate ion. The inorganic compounds are particularly relevant when discussing ocean acidification for they include many forms of dissolved CO
2 present in the Earth's oceans.
2 dissolves, it reacts with water to form a balance of ionic and non-ionic chemical species: dissolved free carbon dioxide (CO
2(aq)), carbonic acid (H
3), bicarbonate (HCO−
3) and carbonate (CO2−
3). The ratio of these species depends on factors such as seawater temperature, pressure and salinity (as shown in a Bjerrum plot). These different forms of dissolved inorganic carbon are transferred from an ocean's surface to its interior by the ocean's solubility pump.
The resistance of an area of ocean to absorbing atmospheric CO
2 is known as the Revelle factor.
2 in seawater increases the hydrogen ion (H+
) concentration in the ocean, and thus decreases ocean pH, as follows:
Caldeira and Wickett (2003) placed the rate and magnitude of modern ocean acidification changes in the context of probable historical changes during the last 300 million years.
Since the industrial revolution began, the ocean has absorbed about a third of the CO
2 we have produced since then and it is estimated that surface ocean pH has dropped by slightly more than 0.1 units on the logarithmic scale of pH, representing about a 29% increase in H+
. It is expected to drop by a further 0.3 to 0.5 pH units (an additional doubling to tripling of today's post-industrial acid concentrations) by 2100 as the oceans absorb more anthropogenic CO
2, the impacts being most severe for coral reefs and the Southern Ocean. These changes are predicted to accelerate as more anthropogenic CO
2 is released to the atmosphere and taken up by the oceans. The degree of change to ocean chemistry, including ocean pH, will depend on the mitigation and emissions pathways taken by society.
Although the largest changes are expected in the future, a report from NOAA scientists found large quantities of water undersaturated in aragonite are already upwelling close to the Pacific continental shelf area of North America. Continental shelves play an important role in marine ecosystems since most marine organisms live or are spawned there, and though the study only dealt with the area from Vancouver to Northern California, the authors suggest that other shelf areas may be experiencing similar effects.
|Time||pH||pH change relative
|Source||H+ concentration change|
relative to pre-industrial
|Pre-industrial (18th century)||8.179||analysed field|
|Recent past (1990s)||8.104||−0.075||field||+ 18.9%|
|Present levels||~8.069||−0.11||field||+ 28.8%|
2 = 560 ppm)
|2100 (IS92a)||7.824||−0.355||model||+ 126.5%|
|“||If we continue emitting CO2 at the same rate, by 2100 ocean acidity will increase by about 150 percent, a rate that has not been experienced for at least 400,000 years.||”|
|— UK Ocean Acidification Research Programme, 2015|
One of the first detailed datasets to examine how pH varied over 8 years at a specific north temperate coastal location found that acidification had strong links to in situ benthic species dynamics and that the variation in ocean pH may cause calcareous species to perform more poorly than noncalcareous species in years with low pH and predicts consequences for near-shore benthic ecosystems. Thomas Lovejoy, former chief biodiversity advisor to the World Bank, has suggested that "the acidity of the oceans will more than double in the next 40 years. He says this rate is 100 times faster than any changes in ocean acidity in the last 20 million years, making it unlikely that marine life can somehow adapt to the changes." It is predicted that, by the year 2100, If co-occurring biogeochemical changes influence the delivery of ocean goods and services, then they could also have a considerable effect on human welfare for those who rely heavily on the ocean for food, jobs, and revenues. A panel of experts who had previously participated in the IPCC reports have determined that it is not yet possible to determine a threshold for ocean acidity that should not be exceeded.
Current rates of ocean acidification have been compared with the greenhouse event at the Paleocene–Eocene boundary (about 55 million years ago) when surface ocean temperatures rose by 5–6 degrees Celsius. No catastrophe was seen in surface ecosystems, yet bottom-dwelling organisms in the deep ocean experienced a major extinction. The current acidification is on a path to reach levels higher than any seen in the last 65 million years, and the rate of increase is about ten times the rate that preceded the Paleocene–Eocene mass extinction. The current and projected acidification has been described as an almost unprecedented geological event. A National Research Council study released in April 2010 likewise concluded that "the level of acid in the oceans is increasing at an unprecedented rate". A 2012 paper in the journal Science examined the geological record in an attempt to find a historical analog for current global conditions as well as those of the future. The researchers determined that the current rate of ocean acidification is faster than at any time in the past 300 million years.
A review by climate scientists at the RealClimate blog, of a 2005 report by the Royal Society of the UK similarly highlighted the centrality of the rates of change in the present anthropogenic acidification process, writing:
"The natural pH of the ocean is determined by a need to balance the deposition and burial of CaCO
3 on the sea floor against the influx of Ca2+
3 into the ocean from dissolving rocks on land, called weathering. These processes stabilize the pH of the ocean, by a mechanism called CaCO
3 compensation...The point of bringing it up again is to note that if the CO
2 concentration of the atmosphere changes more slowly than this, as it always has throughout the Vostok record, the pH of the ocean will be relatively unaffected because CaCO
3 compensation can keep up. The [present] fossil fuel acidification is much faster than natural changes, and so the acid spike will be more intense than the earth has seen in at least 800,000 years."
In the 15-year period 1995–2010 alone, acidity has increased 6 percent in the upper 100 meters of the Pacific Ocean from Hawaii to Alaska. According to a statement in July 2012 by Jane Lubchenco, head of the U.S. National Oceanic and Atmospheric Administration "surface waters are changing much more rapidly than initial calculations have suggested. It's yet another reason to be very seriously concerned about the amount of carbon dioxide that is in the atmosphere now and the additional amount we continue to put out."
A 2013 study claimed acidity was increasing at a rate 10 times faster than in any of the evolutionary crises in Earth's history. In a synthesis report published in Science in 2015, 22 leading marine scientists stated that CO
2 from burning fossil fuels is changing the oceans' chemistry more rapidly than at any time since the Great Dying, Earth's most severe known extinction event, emphasizing that the 2 °C maximum temperature increase agreed upon by governments reflects too small a cut in emissions to prevent "dramatic impacts" on the world's oceans, with lead author Jean-Pierre Gattuso remarking that "The ocean has been minimally considered at previous climate negotiations. Our study provides compelling arguments for a radical change at the UN conference (in Paris) on climate change".
The rate at which ocean acidification will occur may be influenced by the rate of surface ocean warming, because the chemical equilibria that govern seawater pH are temperature-dependent. Greater seawater warming could lead to a smaller change in pH for a given increase in CO2.
Changes in ocean chemistry can have extensive direct and indirect effects on organisms and their habitats. One of the most important repercussions of increasing ocean acidity relates to the production of shells and plates out of calcium carbonate (CaCO
3). This process is called calcification and is important to the biology and survival of a wide range of marine organisms. Calcification involves the precipitation of dissolved ions into solid CaCO
3 structures, such as coccoliths. After they are formed, such structures are vulnerable to dissolution unless the surrounding seawater contains saturating concentrations of carbonate ions (CO32−).
Of the extra carbon dioxide added into the oceans, some remains as dissolved carbon dioxide, while the rest contributes towards making additional bicarbonate (and additional carbonic acid). This also increases the concentration of hydrogen ions, and the percentage increase in hydrogen is larger than the percentage increase in bicarbonate, creating an imbalance in the reaction HCO3− ⇌ CO32− + H+. To maintain chemical equilibrium, some of the carbonate ions already in the ocean combine with some of the hydrogen ions to make further bicarbonate. Thus the ocean's concentration of carbonate ions is reduced, creating an imbalance in the reaction Ca2+ + CO32− ⇌ CaCO3, and making the dissolution of formed CaCO
3 structures more likely.
The increase in concentrations of dissolved carbon dioxide and bicarbonate, and reduction in carbonate, are shown in a Bjerrum plot.
The saturation state (known as Ω) of seawater for a mineral is a measure of the thermodynamic potential for the mineral to form or to dissolve, and for calcium carbonate is described by the following equation:
Here Ω is the product of the concentrations (or activities) of the reacting ions that form the mineral (Ca2+
3), divided by the product of the concentrations of those ions when the mineral is at equilibrium (K
sp), that is, when the mineral is neither forming nor dissolving. In seawater, a natural horizontal boundary is formed as a result of temperature, pressure, and depth, and is known as the saturation horizon. Above this saturation horizon, Ω has a value greater than 1, and CaCO
3 does not readily dissolve. Most calcifying organisms live in such waters. Below this depth, Ω has a value less than 1, and CaCO
3 will dissolve. However, if its production rate is high enough to offset dissolution, CaCO
3 can still occur where Ω is less than 1. The carbonate compensation depth occurs at the depth in the ocean where production is exceeded by dissolution.
The decrease in the concentration of CO32− decreases Ω, and hence makes CaCO
3 dissolution more likely.
Calcium carbonate occurs in two common polymorphs (crystalline forms): aragonite and calcite. Aragonite is much more soluble than calcite, so the aragonite saturation horizon is always nearer to the surface than the calcite saturation horizon. This also means that those organisms that produce aragonite may be more vulnerable to changes in ocean acidity than those that produce calcite. Increasing CO
2 levels and the resulting lower pH of seawater decreases the saturation state of CaCO
3 and raises the saturation horizons of both forms closer to the surface. This decrease in saturation state is believed to be one of the main factors leading to decreased calcification in marine organisms, as the inorganic precipitation of CaCO
3 is directly proportional to its saturation state.
Increasing acidity has possibly harmful consequences, such as depressing metabolic rates in jumbo squid, depressing the immune responses of blue mussels, and coral bleaching. However it may benefit some species, for example increasing the growth rate of the sea star, Pisaster ochraceus, while shelled plankton species may flourish in altered oceans.
The reports "Ocean Acidification Summary for Policymakers 2013" and the IPCC approved "Special Report on the Ocean and Cryosphere in a Changing Climate" from 2019 describe research findings and possible impacts.
Impacts on oceanic calcifying organisms
Although the natural absorption of CO
2 by the world's oceans helps mitigate the climatic effects of anthropogenic emissions of CO
2, it is believed that the resulting decrease in pH will have negative consequences, primarily for oceanic calcifying organisms. These span the food chain from autotrophs to heterotrophs and include organisms such as coccolithophores, corals, foraminifera, echinoderms, crustaceans and molluscs. As described above, under normal conditions, calcite and aragonite are stable in surface waters since the carbonate ion is at supersaturating concentrations. However, as ocean pH falls, the concentration of carbonate ions required for saturation to occur increases, and when carbonate becomes undersaturated, structures made of calcium carbonate are vulnerable to dissolution. Therefore, even if there is no change in the rate of calcification, the rate of dissolution of calcareous material increases.
The Royal Society published a comprehensive overview of ocean acidification, and its potential consequences, in June 2005. However, some studies have found different response to ocean acidification, with coccolithophore calcification and photosynthesis both increasing under elevated atmospheric pCO
2, an equal decline in primary production and calcification in response to elevated CO
2 or the direction of the response varying between species. A study in 2008 examining a sediment core from the North Atlantic found that while the species composition of coccolithophorids has remained unchanged for the industrial period 1780 to 2004, the calcification of coccoliths has increased by up to 40% during the same time. A 2010 study from Stony Brook University suggested that while some areas are overharvested and other fishing grounds are being restored, because of ocean acidification it may be impossible to bring back many previous shellfish populations. While the full ecological consequences of these changes in calcification are still uncertain, it appears likely that many calcifying species will be adversely affected.
When exposed in experiments to pH reduced by 0.2 to 0.4, larvae of a temperate brittlestar, a relative of the common sea star, fewer than 0.1 percent survived more than eight days. There is also a suggestion that a decline in the coccolithophores may have secondary effects on climate, contributing to global warming by decreasing the Earth's albedo via their effects on oceanic cloud cover. All marine ecosystems on Earth will be exposed to changes in acidification and several other ocean biogeochemical changes.
The fluid in the internal compartments where corals grow their exoskeleton is also extremely important for calcification growth. When the saturation rate of aragonite in the external seawater is at ambient levels, the corals will grow their aragonite crystals rapidly in their internal compartments, hence their exoskeleton grows rapidly. If the level of aragonite in the external seawater is lower than the ambient level, the corals have to work harder to maintain the right balance in the internal compartment. When that happens, the process of growing the crystals slows down, and this slows down the rate of how much their exoskeleton is growing. Depending on how much aragonite is in the surrounding water, the corals may even stop growing because the levels of aragonite are too low to pump into the internal compartment. They could even dissolve faster than they can make the crystals to their skeleton, depending on the aragonite levels in the surrounding water. Under the current progression of carbon emissions, around 70% of North Atlantic cold-water corals will be living in corrosive waters by 2050–60.
A study conducted by the Woods Hole Oceanographic Institution in January 2018 showed that the skeletal growth of corals under acidified conditions is primarily affected by a reduced capacity to build dense exoskeletons, rather than affecting the linear extension of the exoskeleton. Using Global Climate Models, they show that the density of some species of corals could be reduced by over 20% by the end of this century.
An in situ experiment on a 400 m2 patch of the Great Barrier Reef to decrease seawater CO2 level (raise pH) to close to the preindustrial value showed a 7% increase in net calcification. A similar experiment to raise in situ seawater seawater CO2 level (lower pH) to a level expected soon after the middle of this century found that net calcification decreased 34%.
In some places carbon dioxide bubbles out from the sea floor, locally changing the pH and other aspects of the chemistry of the seawater. Studies of these carbon dioxide seeps have documented a variety of responses by different organisms. Coral reef communities located near carbon dioxide seeps are of particular interest because of the sensitivity of some corals species to acidification. In Papua New Guinea, declining pH caused by carbon dioxide seeps is associated with declines in coral species diversity. However, in Palau carbon dioxide seeps are not associated with reduced species diversity of corals, although bioerosion of coral skeletons is much higher at low pH sites.
Ocean acidification may affect the ocean's biologically driven sequestration of carbon from the atmosphere to the ocean interior and seafloor sediment, weakening the so called biological pump. Seawater acidification could also see Antarctic phytoplanktons smaller and less effective at storing carbon.
Effect on reef fish
With the production of CO2 from the burning of fossil fuels, oceans are becoming more acidic since CO2 dissolves in water and forms the acidic bicarbonate ion. This results in a pH drop which then causes corals to expel their algae with which they have a symbiotic relationship with, causing the coral to eventually die due to a lack of nutrients.
Since corals reefs are one of the most diverse ecosystems on the planet, coral bleaching due to ocean acidification could result in a major loss of habitat for the many species of reef fish, resulting in increased predation and the eventual endangered classification or extinction of countless species. This will ultimately decrease the overall diversity of fish in marine environments, which will cause many predators of reef fish to die off since their normal supply of food was cut off. Food webs in coral reefs will also be greatly impacted because once a species goes extinct or is less prevalent, their natural predators will lose their primary food source causing the food web to collapse in on itself. If such an extinction event occurred in our oceans, it will greatly affect humans since much of our food supply is reliant on fish or other marine animals.
Ocean acidification due to global warming will also change the reproductive cycles of reef fish who normally spawn during late spring and fall. On top of this, there will be increased mortality rates among the larvae of coral reef fish since the acidic environment slows down their development. The hypothalamo-pituitary-gonadal (HPG) axis is one of the regulatory sequences in fish for reproduction, which is mainly controlled by surrounding water temperature. Once a minimum temperature threshold is reached, the production of hormone synthesis increases significantly, causing the fish to produce mature egg and sperm cells. Spawning in the spring will have a shortened period, while fall spawning will be delayed substantially. Because of the increased CO2 levels in the ocean from coral bleaching, there will be a substantial decrease in the number of young reef fish that survive to maturity. There is also evidence that shows that embryo and larval stage fish have not matured enough to express the appropriate levels of acid/base regulation that is present in adults. These will ultimately lead to hypoxia due to the Bohr effect driving oxygen off of hemoglobin. This will lead to increased mortality as well as impaired growth performance for fish in slightly acidic conditions relative to the normal proportion of acid dissolved in marine water.
In addition, ocean acidification will make fish larvae more sensitive to the surrounding pH since they are more sensitive to environmental fluctuations than adults. In addition, larvae of common prey species will have lower survival rates, which in turn will eventually cause the species to become endangered or extinct. Also, elevated CO2 in marine environments can lead to neurotransmitter interference in both predator and prey fish which increases their mortality rate. It has also been shown that when fish spend considerable time in high concentrations of dissolved CO2 up to 50,000 micro-atmospheres (μatm) of CO2 in marine environments, cardiac failure leading to death is much more common than in normal CO2 environments. In addition, fish that live in high CO2 environments are required to spend more of their energy to keep their acid/base regulation in check. This diverts precious energy resources from important parts of their life cycle such as feeding and mating to keep their osmoregulatory functions in check.
Another important consequence of ocean acidification is that endangered species will have fewer places where their eggs are laid. For species with poor larval dispersal, it puts them at a greater risk of extinction because natural egg predators will find their nests or hiding places and eat the next generation.
Other biological impacts
Aside from the slowing and/or reversing of calcification, organisms may suffer other adverse effects, either indirectly through negative impacts on food resources, or directly as reproductive or physiological effects. For example, the elevated oceanic levels of CO
2 may produce CO
2-induced acidification of body fluids, known as hypercapnia. Also, increasing ocean acidity is believed to have a range of direct consequences. For example, increasing acidity has been observed to: reduce metabolic rates in jumbo squid; depress the immune responses of blue mussels; and make it harder for juvenile clownfish to tell apart the smells of non-predators and predators, or hear the sounds of their predators. This is possibly because ocean acidification may alter the acoustic properties of seawater, allowing sound to propagate further, and increasing ocean noise. This impacts all animals that use sound for echolocation or communication. Atlantic longfin squid eggs took longer to hatch in acidified water, and the squid's statolith was smaller and malformed in animals placed in sea water with a lower pH. The lower PH was simulated with 20–30 times the normal amount of CO
2. However, as with calcification, as yet there is not a full understanding of these processes in marine organisms or ecosystems.
Another possible effect would be an increase in red tide events, which could contribute to the accumulation of toxins (domoic acid, brevetoxin, saxitoxin) in small organisms such as anchovies and shellfish, in turn increasing occurrences of amnesic shellfish poisoning, neurotoxic shellfish poisoning and paralytic shellfish poisoning.
Although red tide is harmful, other beneficial photosynthetic organisms may benefit from increased levels of carbon dioxide. Most importantly, seagrasses will benefit. An experiment done in 2018 concluded that as seagrasses increased their photosynthetic activity, calcifying algae's calcification rates rose. This could be a potential mitigation technique in the face of increasing acidity.
Ecosystem impacts amplified by ocean warming and deoxygenation
While the full implications of elevated CO2 on marine ecosystems are still being documented, there is a substantial body of research showing that a combination of ocean acidification and elevated ocean temperature, driven mainly by CO2 and other greenhouse gas emissions, have a compounded effect on marine life and the ocean environment. This effect far exceeds the individual harmful impact of either. In addition, ocean warming exacerbates ocean deoxygenation, which is an additional stressor on marine organisms, by increasing ocean stratification, through density and solubility effects, thus limiting nutrients, while at the same time increasing metabolic demand.
Meta analyses have quantified the direction and magnitude of the harmful effects of ocean acidification, warming and deoxygenation on the ocean. These meta-analyses have been further tested by mesocosm studies that simulated the interaction of these stressors and found a catastrophic effect on the marine food web, i.e. that the increases in consumption from thermal stress more than negates any primary producer to herbivore increase from elevated CO2.
Leaving aside direct biological effects, it is expected that ocean acidification in the future will lead to a significant decrease in the burial of carbonate sediments for several centuries, and even the dissolution of existing carbonate sediments. This will cause an elevation of ocean alkalinity, leading to the enhancement of the ocean as a reservoir for CO
2 with implications for climate change as more CO
2 leaves the atmosphere for the ocean.
Impact on human industry
The threat of acidification includes a decline in commercial fisheries and in the Arctic tourism industry and economy. Commercial fisheries are threatened because acidification harms calcifying organisms which form the base of the Arctic food webs.
Pteropods and brittle stars both form the base of the Arctic food webs and are both seriously damaged from acidification. Pteropods shells dissolve with increasing acidification and the brittle stars lose muscle mass when re-growing appendages. For pteropods to create shells they require aragonite which is produced through carbonate ions and dissolved calcium. Pteropods are severely affected because increasing acidification levels have steadily decreased the amount of water supersaturated with carbonate which is needed for aragonite creation. Arctic waters are changing so rapidly that they will become undersaturated with aragonite as early as 2016. Additionally the brittle star's eggs die within a few days when exposed to expected conditions resulting from Arctic acidification. Acidification threatens to destroy Arctic food webs from the base up. Arctic food webs are considered simple, meaning there are few steps in the food chain from small organisms to larger predators. For example, pteropods are "a key prey item of a number of higher predators – larger plankton, fish, seabirds, whales". Both pteropods and sea stars serve as a substantial food source and their removal from the simple food web would pose a serious threat to the whole ecosystem. The effects on the calcifying organisms at the base of the food webs could potentially destroy fisheries. The value of fish caught from US commercial fisheries in 2007 was valued at $3.8 billion and of that 73% was derived from calcifiers and their direct predators. Other organisms are directly harmed as a result of acidification. For example, decrease in the growth of marine calcifiers such as the American lobster, ocean quahog, and scallops means there is less shellfish meat available for sale and consumption. Red king crab fisheries are also at a serious threat because crabs are calcifiers and rely on carbonate ions for shell development. Baby red king crab when exposed to increased acidification levels experienced 100% mortality after 95 days. In 2006, red king crab accounted for 23% of the total guideline harvest levels and a serious decline in red crab population would threaten the crab harvesting industry. Several ocean goods and services are likely to be undermined by future ocean acidification potentially affecting the livelihoods of some 400 to 800 million people depending upon the emission scenario.
Impact on indigenous peoples
Acidification could damage the Arctic tourism economy and affect the way of life of indigenous peoples. A major pillar of Arctic tourism is the sport fishing and hunting industry. The sport fishing industry is threatened by collapsing food webs which provide food for the prized fish. A decline in tourism lowers revenue input in the area, and threatens the economies that are increasingly dependent on tourism. The rapid decrease or disappearance of marine life could also affect the diet of Indigenous peoples.
Members of the InterAcademy Panel recommended that by 2050, global anthropogenic CO
2 emissions be reduced less than 50% of the 1990 level. The 2009 statement also called on world leaders to:
- Acknowledge that ocean acidification is a direct and real consequence of increasing atmospheric CO
2 concentrations, is already having an effect at current concentrations, and is likely to cause grave harm to important marine ecosystems as CO
2 concentrations reach 450 [parts-per-million (ppm)] and above;
- ... Recognize that reducing the build up of CO
2 in the atmosphere is the only practicable solution to mitigating ocean acidification;
- ... Reinvigorate action to reduce stressors, such as overfishing and pollution, on marine ecosystems to increase resilience to ocean acidification.
Stabilizing atmospheric CO
2 concentrations at 450 ppm would require near-term emissions reductions, with steeper reductions over time.
The German Advisory Council on Global Change stated:
In order to prevent disruption of the calcification of marine organisms and the resultant risk of fundamentally altering marine food webs, the following guard rail should be obeyed: the pH of near surface waters should not drop more than 0.2 units below the pre-industrial average value in any larger ocean region (nor in the global mean).
One policy target related to ocean acidity is the magnitude of future global warming. Parties to the United Nations Framework Convention on Climate Change (UNFCCC) adopted a target of limiting warming to below 2 °C, relative to the pre-industrial level. Meeting this target would require substantial reductions in anthropogenic CO
On 25 September 2015, USEPA denied a 30 June 2015, citizens petition that asked EPA to regulate CO
2 under TSCA in order to mitigate ocean acidification. In the denial, EPA said that risks from ocean acidification were being "more efficiently and effectively addressed" under domestic actions, e.g., under the Presidential Climate Action Plan, and that multiple avenues are being pursued to work with and in other nations to reduce emissions and deforestation and promote clean energy and energy efficiency.
On 28 March 2017 the US by executive order rescinded the Climate Action Plan. On 1 June 2017 it was announced the US would withdraw from the Paris accords, and on 12 June 2017 that the US would abstain from the G7 Climate Change Pledge, two major international efforts to reduce CO
Geoengineering has been proposed as a possible response to ocean acidification. The IAP (2009) statement said more research is needed to prove that this would be safe, affordable and worthwhile:
Mitigation approaches such as adding chemicals to counter the effects of acidification are likely to be expensive, only partly effective and only at a very local scale, and may pose additional unanticipated risks to the marine environment. There has been very little research on the feasibility and impacts of these approaches. Substantial research is needed before these techniques could be applied.
Iron fertilization of the ocean could stimulate photosynthesis in phytoplankton (see Iron hypothesis). The phytoplankton would convert the ocean's dissolved carbon dioxide into carbohydrate and oxygen gas, some of which would sink into the deeper ocean before oxidizing. More than a dozen open-sea experiments confirmed that adding iron to the ocean increases photosynthesis in phytoplankton by up to 30 times. While this approach has been proposed as a potential solution to the ocean acidification problem, mitigation of surface ocean acidification might increase acidification in the less-inhabited deep ocean.
A report by the UK's Royal Society (2009) reviewed the approach for effectiveness, affordability, timeliness and safety. The rating for affordability was "medium", or "not expected to be very cost-effective". For the other three criteria, the ratings ranged from "low" to "very low" (i.e., not good). For example, in regards to safety, the report found a "[high] potential for undesirable ecological side effects", and that ocean fertilization "may increase anoxic regions of ocean ('dead zones')".
- Feely, R. A.; Sabine, C. L.; Hernandez-Ayon, J. M.; Ianson, D.; Hales, B. (June 2008). "Evidence for upwelling of corrosive "acidified" water onto the continental shelf". Science. 320 (5882): 1490–2. Bibcode:2008Sci...320.1490F. CiteSeerX 10.1.1.328.3181. doi:10.1126/science.1155676. PMID 18497259. Retrieved 25 January 2014 – via Pacific Marine Environmental Laboratory (PMEL).
- Caldeira, K.; Wickett, M. E. (2003). "Anthropogenic carbon and ocean pH". Nature. 425 (6956): 365. Bibcode:2001AGUFMOS11C0385C. doi:10.1038/425365a. PMID 14508477.
- The ocean would not become acidic even if it were to absorb the CO2 produced from the combustion of all fossil fuel resources.
- Millero, Frank J. (1995). "Thermodynamics of the carbon dioxide system in the oceans". Geochimica et Cosmochimica Acta. 59 (4): 661–677. Bibcode:1995GeCoA..59..661M. doi:10.1016/0016-7037(94)00354-O.
- Feely, R. A.; Sabine, C. L.; Lee, K.; Berelson, W.; Kleypas, J.; Fabry, V. J.; Millero, F. J. (July 2004). "Impact of Anthropogenic CO2 on the CaCO3 System in the Oceans". Science. 305 (5682): 362–366. Bibcode:2004Sci...305..362F. doi:10.1126/science.1097329. PMID 15256664. Retrieved 25 January 2014 – via Pacific Marine Environmental Laboratory (PMEL).
- Jacobson, M. Z. (2005). "Studying ocean acidification with conservative, stable numerical schemes for nonequilibrium air-ocean exchange and ocean equilibrium chemistry". Journal of Geophysical Research: Atmospheres. 110: D07302. Bibcode:2005JGRD..11007302J. doi:10.1029/2004JD005220.
- Hall-Spencer, J. M.; Rodolfo-Metalpa, R.; Martin, S.; et al. (July 2008). "Volcanic carbon dioxide vents show ecosystem effects of ocean acidification". Nature. 454 (7200): 96–9. Bibcode:2008Natur.454...96H. doi:10.1038/nature07051. hdl:10026.1/1345. PMID 18536730.
- "Report of the Ocean Acidification and Oxygen Working Group, International Council for Science's Scientific Committee on Ocean Research (SCOR) Biological Observatories Workshop" (PDF).
- Mora, C (2013). "The projected timing of climate departure from recent variability". Nature. 502 (7470): 183–187. Bibcode:2013Natur.502..183M. doi:10.1038/nature12540. PMID 24108050.
Global mean ocean pH moved outside its historical variability by 2008 (±3 years s.d.), regardless of the emissions scenario analysed
- Mora, C.; et al. (2013). "Biotic and Human Vulnerability to Projected Changes in Ocean Biogeochemistry over the 21st Century". PLoS Biology. 11 (10): e1001682. doi:10.1371/journal.pbio.1001682. PMC 3797030. PMID 24143135.
- Anthony, KRN; et al. (2008). "Ocean acidification causes bleaching and productivity loss in coral reef builders". Proceedings of the National Academy of Sciences. 105 (45): 17442–17446. Bibcode:2008PNAS..10517442A. doi:10.1073/pnas.0804478105. PMC 2580748. PMID 18988740.
- Kump, L.R.; Bralower, T.J.; Ridgwell, A. (2009). "Ocean acidification in deep time". Oceanography. 22: 94–107. doi:10.5670/oceanog.2009.10. Retrieved 16 May 2016.
- Orr, James C.; et al. (2005). "Anthropogenic ocean acidification over the twenty-first century and its impact on calcifying organisms" (PDF). Nature. 437 (7059): 681–686. Bibcode:2005Natur.437..681O. doi:10.1038/nature04095. PMID 16193043. Archived from the original (PDF) on 25 June 2008.
- Cornelia Dean (30 January 2009). "Rising Acidity Is Threatening Food Web of Oceans, Science Panel Says". New York Times.
- Robert E. Service (13 July 2012). "Rising Acidity Brings and Ocean Of Trouble". Science. 337 (6091): 146–148. Bibcode:2012Sci...337..146S. doi:10.1126/science.337.6091.146. PMID 22798578.
- IAP (June 2009). "Interacademy Panel (IAP) Member Academies Statement on Ocean Acidification"., Secretariat: TWAS (the Academy of Sciences for the Developing World), Trieste, Italy.
- Zeebe, R.E. (2012). "History of Seawater Carbonate Chemistry, Atmospheric CO
2, and Ocean Acidification". Annual Review of Earth and Planetary Sciences. 40 (1): 141–165. Bibcode:2012AREPS..40..141Z. doi:10.1146/annurev-earth-042711-105521.
- Henehan, Michael J.; Ridgwell, Andy; Thomas, Ellen; Zhang, Shuang; Alegret, Laia; Schmidt, Daniela N.; Rae, James W. B.; Witts, James D.; Landman, Neil H.; Greene, Sarah E.; Huber, Brian T. (17 October 2019). "Rapid ocean acidification and protracted Earth system recovery followed the end-Cretaceous Chicxulub impact". Proceedings of the National Academy of Sciences. 116 (45): 22500–22504. doi:10.1073/pnas.1905989116. ISSN 0027-8424. PMC 6842625. PMID 31636204.
- Carrington, Damian (21 October 2019). "Ocean acidification can cause mass extinctions, fossils reveal". The Guardian. ISSN 0261-3077. Retrieved 22 October 2019.
- Zachos, J.C.; Röhl, U.; Schellenberg, S.A.; Sluijs, A.; Hodell, D.A.; Kelly, D.C.; Thomas, E.; Nicolo, M.; Raffi, I.; Lourens, L. J.; McCarren, H.; Kroon, D. (2005). "Rapid acidification of the ocean during the Paleocene-Eocene thermal maximum". Science. 308 (5728): 1611–1615. Bibcode:2005Sci...308.1611Z. doi:10.1126/science.1109004. PMID 15947184.
- "Ocean Acidification Is Climate Change's 'Equally Evil Twin,' NOAA Chief Says". Huffington Post. 9 July 2012. Archived from the original on 12 July 2012. Retrieved 9 July 2012.
- Nina Notman (29 July 2014). "The other carbon dioxide problem". Chemistry World.
- Alex Rogers (9 October 2013). "Global warming's evil twin: ocean acidification". The Conversation.
- Hennige, S.J. (2014). "Short-term metabolic and growth responses of the cold-water coral Lophelia pertusa to ocean acidification". Deep-Sea Research Part II. 99: 27–35. Bibcode:2014DSRII..99...27H. doi:10.1016/j.dsr2.2013.07.005.
- Pelejero, C. (2010). "Paleo-perspectives on ocean acidification". Trends in Ecology and Evolution. 25 (6): 332–344. doi:10.1016/j.tree.2010.02.002. PMID 20356649.
- Doney, S.C. (2009). "Ocean Acidification: The Other CO
2 Problem". Annual Review of Marine Science. 1: 169–192. Bibcode:2009ARMS....1..169D. doi:10.1146/annurev.marine.010908.163834. PMID 21141034.
- Gies, E. (11 January 2018). "Like Oceans, Freshwater Is Also Acidifying". Scientific American. Retrieved 13 January 2018.
- Weiss, L. C.; Pötter, L.; Steiger, A.; Kruppert, S.; Frost, U.; Tollrian, R. (2018). "Rising pCO2 in Freshwater Ecosystems Has the Potential to Negatively Affect Predator-Induced Defenses in Daphnia". Current Biology. 28 (2): 327–332.e3. doi:10.1016/j.cub.2017.12.022. PMID 29337079.
- "carbon cycle". Encyclopædia Britannica Online. Retrieved 11 February 2010.
- Raven, J. A.; Falkowski, P. G. (1999). "Oceanic sinks for atmospheric CO
2". Plant, Cell & Environment. 22 (6): 741–755. doi:10.1046/j.1365-3040.1999.00419.x.
- Cramer, W.; et al. (2001). "Global response of terrestrial ecosystem structure and function to CO
2 and climate change: results from six dynamic global vegetation models". Global Change Biology. 7 (4): 357–373. Bibcode:2001GCBio...7..357C. doi:10.1046/j.1365-2486.2001.00383.x.
- Woods Hole Oceanographic Institution (August 2016). "Changes in Aragonite Saturation of the World's Oceans, 1880–2015". epa.gov.
- Kump, Lee R.; Kasting, James F.; Crane, Robert G. (2003). The Earth System (2nd ed.). Upper Saddle River: Prentice Hall. pp. 162–164. ISBN 978-0-613-91814-5.
- IPCC (2005). "IPCC Special Report on Carbon Dioxide Capture and Storage" (PDF): 390. Cite journal requires
- "Ocean Acidification". www.oceanscientists.org. Retrieved 11 December 2018.
- Raven, JA, et al. (2005) "Ocean acidification due to increasing atmospheric carbon dioxide". Royal Society, London, UK.
- Bows, Kevin; Bows, Alice (2011). "Beyond 'dangerous' climate change: emission scenarios for a new world". Philosophical Transactions of the Royal Society A. 369 (1934): 20–44. Bibcode:2011RSPTA.369...20A. doi:10.1098/rsta.2010.0290. PMID 21115511.
- Turley, C. (2008). "Impacts of changing ocean chemistry in a high-CO
2 world". Mineralogical Magazine. 72 (1): 359–362. Bibcode:2008MinM...72..359T. doi:10.1180/minmag.2008.072.1.359.
- Key, R. M.; Kozyr, A.; Sabine, C. L.; Lee, K.; Wanninkhof, R.; Bullister, J.; Feely, R. A.; Millero, F.; Mordy, C.; Peng, T.-H. (2004). "A global ocean carbon climatology: Results from GLODAP". Global Biogeochemical Cycles. 18 (4): GB4031. Bibcode:2004GBioC..18.4031K. doi:10.1029/2004GB002247.
- "Ocean acidification and the Southern Ocean". Australian Antarctic Division — Australia in Antarctica.
- "EPA weighs action on ocean acidification". 4 February 2009.
- Review of Past IPCC Emissions Scenarios, IPCC Special Report on Emissions Scenarios (ISBN 0521804930).
- Cited in Tim Flannery, Atmosphere of Hope. Solutions to the Climate Crisis, Penguin Books, 2015, page 47 (ISBN 9780141981048).
- Wootton, J. T.; Pfister, C. A.; Forester, J. D. (2008). "Dynamic patterns and ecological impacts of declining ocean pH in a high-resolution multi-year dataset". Proceedings of the National Academy of Sciences. 105 (48): 18848–18853. Bibcode:2008PNAS..10518848W. doi:10.1073/pnas.0810079105. PMC 2596240. PMID 19033205.
- "Ocean Growing More Acidic Faster Than Once Thought; Increasing Acidity Threatens Sea Life". Science Daily. 26 November 2008. Retrieved 26 November 2008.
- "UN: Oceans are 30 percent more acidic than before fossil fuels". Archived from the original on 3 January 2011.
- "What is Ocean Acidification". NOAA. Retrieved 24 August 2013.
- Gattuso, Jean-Pierre; Mach, Katharine J.; Morgan, Granger (April 2013). "Ocean acidification and its impacts: an expert survey". Climatic Change. 117 (4): 725–738. doi:10.1007/s10584-012-0591-5. ISSN 0165-0009.
- "Rate of ocean acidification the fastest in 65 million years". Physorg.com. 14 February 2010. Retrieved 29 August 2013.
- Joel, Lucas (21 October 2019). "The Dinosaur-Killing Asteroid Acidified the Ocean in a Flash - The Chicxulub event was as damaging to life in the oceans as it was to creatures on land, a study shows". The New York Times. Retrieved 22 October 2019.
- Henehan, Michael J.; et al. (21 October 2019). "Rapid ocean acidification and protracted Earth system recovery followed the end-Cretaceous Chicxulub impact". Proceedings of the National Academy of Sciences of the United States of America. 116 (45): 22500–22504. doi:10.1073/pnas.1905989116. PMC 6842625. PMID 31636204.
- "An Ominous Warning on the Effects of Ocean Acidification by Carl Zimmer: Yale Environment 360". e360.yale.edu. Archived from the original on 16 February 2014. Retrieved 25 January 2014.
- Newspapers, Les Blumenthal-McClatchy (22 April 2010). "Report: Ocean acidification rising at unprecedented rate". mcclatchydc.
- United States National Research Council, 2010. Ocean Acidification: A National Strategy to Meet the Challenges of a Changing Ocean
- "The Geological Record of Ocean Acidification". JournalistsResource.org, retrieved 14 March 2012
- Hönisch, Bärbel; Ridgwell, Andy; Schmidt, Daniela N.; Thomas, E.; Gibbs, S. J.; Sluijs, A.; Zeebe, R.; Kump, L.; Martindale, R. C.; Greene, S. E.; Kiessling, W.; Ries, J.; Zachos, J. C.; Royer, D. L.; Barker, S.; Marchitto, T. M.; Moyer, R.; Pelejero, C.; Ziveri, P.; Foster, G. L.; Williams, B. (2012). "The Geological Record of Ocean Acidification". Science. 335 (6072): 1058–1063. Bibcode:2012Sci...335.1058H. doi:10.1126/science.1208277. hdl:1983/24fe327a-c509-4b6a-aa9a-a22616c42d49. PMID 22383840.
- David (2 July 2005). "The Acid Ocean – the Other Problem with CO2 Emission". Real Climate.
- Marah J. Hardt; Carl Safina (9 August 2010). "How Acidification Threatens Oceans from the Inside Out". Scientific American. Archived from the original on 26 December 2010.
- Fiona Harvey (25 August 2013). "Rising levels of acids in seas may endanger marine life, says study". The Guardian. Retrieved 29 August 2013.
- Harrabin, Roger (3 July 2015). "CO2 emissions threaten ocean crisis" – via www.bbc.com.
- Humphreys, M. P. (2016). "Climate sensitivity and the rate of ocean acidification: future impacts, and implications for experimental design". ICES Journal of Marine Science. 74 (4): 934–940. doi:10.1093/icesjms/fsw189.
- Mitchell, M. J.; et al. (2010). "A model of carbon dioxide dissolution and mineral carbonation kinetics". Proceedings of the Royal Society A. 466 (2117): 1265–1290. Bibcode:2010RSPSA.466.1265M. doi:10.1098/rspa.2009.0349.
- Atkinson, M.J.; Cuet, P. (2008). "Possible effects of ocean acidification on coral reef biogeochemistry: topics for research". Marine Ecology Progress Series. 373: 249–256. Bibcode:2008MEPS..373..249A. doi:10.3354/meps07867.
- Thurman, H.V.; Trujillo, A.P. (2004). Introductory Oceanography. Prentice Hall. ISBN 978-0-13-143888-0.
- The Royal Society. Ocean Acidification Due To Increasing Atmospheric Carbon Dioxide, The Clyvedon Press Ltd. (2005): 11.
- Marubini, F.; Ferrier-Pagès, C.; Furla, P.; Allemand, D. (2008). "Coral calcification responds to seawater acidification: a working hypothesis towards a physiological mechanism". Coral Reefs. 27 (3): 491–499. Bibcode:2008CorRe..27..491M. doi:10.1007/s00338-008-0375-6.
- Rosa, R.; Seibel, B. (2008). "Synergistic effects of climate-related variables suggest future physiological impairment in a top oceanic predator". PNAS. 105 (52): 20776–20780. Bibcode:2008PNAS..10520776R. doi:10.1073/pnas.0806886105. PMC 2634909. PMID 19075232.
- Bibby, R.; et al. (2008). "Effects of ocean acidification on the immune response of the blue mussel Mytilus edulis". Aquatic Biology. 2: 67–74. doi:10.3354/ab00037.
- Gooding, R.; et al. (2008). "Elevated water temperature and carbon dioxide concentration increase the growth of a keystone echinoderm". Proceedings of the National Academy of Sciences. 106 (23): 9316–21. Bibcode:2009PNAS..106.9316G. doi:10.1073/pnas.0811143106. PMC 2695056. PMID 19470464.
- Kollipara, Puneet (27 September 2013). "Some like it acidic". Science News.
- "Ocean Acidification Summary for Policymakers". IGBP.
- "Special Report on the Ocean and Cryosphere in a Changing Climate — Special Report on the Ocean and Cryosphere in a Changing Climate". IPCC. 25 September 2019. Retrieved 12 November 2019.
- National Research Council. Overview of Climate Changes and Illustrative Impacts. Climate Stabilization Targets: Emissions, Concentrations, and Impacts over Decades to Millennia. Washington, DC: The National Academies Press, 2011. 1. Print.
- Nienhuis, S.; Palmer, A.; Harley, C. (2010). "Elevated CO2 affects shell dissolution rate but not calcification rate in a marine snail". Proceedings of the Royal Society B. 277 (1693): 2553–2558. doi:10.1098/rspb.2010.0206. PMC 2894921. PMID 20392726.
- Gattuso, J.-P.; Frankignoulle, M.; Bourge, I.; Romaine, S.; Buddemeier, R. W. (1998). "Effect of calcium carbonate saturation of seawater on coral calcification". Global and Planetary Change. 18 (1–2): 37–46. Bibcode:1998GPC....18...37G. doi:10.1016/S0921-8181(98)00035-6.
- Gattuso, J.-P.; Allemand, D.; Frankignoulle, M. (1999). "Photosynthesis and calcification at cellular, organismal and community levels in coral reefs: a review on interactions and control by carbonate chemistry". American Zoologist. 39: 160–183. doi:10.1093/icb/39.1.160.
- Langdon, C.; Atkinson, M. J. (2005). "Effect of elevated pCO
2 on photosynthesis and calcification of corals and interactions with seasonal change in temperature/irradiance and nutrient enrichment". Journal of Geophysical Research. 110 (C09S07): C09S07. Bibcode:2005JGRC..11009S07L. doi:10.1029/2004JC002576.
- D'Olivo, Juan P.; Ellwood, George; DeCarlo, Thomas M.; McCulloch, Malcolm T. (15 November 2019). "Deconvolving the long-term impacts of ocean acidification and warming on coral biomineralisation". Earth and Planetary Science Letters. 526: 115785. doi:10.1016/j.epsl.2019.115785. ISSN 0012-821X.
- Riebesell, Ulf; Zondervan, Ingrid; Rost, Björn; Tortell, Philippe D.; Zeebe, Richard E.; Morel, François M. M. (2000). "Reduced calcification of marine plankton in response to increased atmospheric CO
2". Nature. 407 (6802): 364–367. Bibcode:2000Natur.407..364R. doi:10.1038/35030078. PMID 11014189.
- Zondervan, I.; Zeebe, R. E.; Rost, B.; Rieblesell, U. (2001). "Decreasing marine biogenic calcification: a negative feedback on rising atmospheric CO2" (PDF). Global Biogeochemical Cycles. 15 (2): 507–516. Bibcode:2001GBioC..15..507Z. doi:10.1029/2000GB001321.
- Zondervan, I.; =Rost, B.; Rieblesell, U. (2002). "Effect of CO
2 concentration on the PIC/POC ratio in the coccolithophore Emiliania huxleyi grown under light limiting conditions and different day lengths" (PDF). Journal of Experimental Marine Biology and Ecology. 272 (1): 55–70. doi:10.1016/S0022-0981(02)00037-0.
- Delille, B.; Harlay, J.; Zondervan, I.; Jacquet, S.; Chou, L.; Wollast, R.; Bellerby, R.G.J.; Frankignoulle, M.; Borges, A.V.; Riebesell, U.; Gattuso, J.-P. (2005). "Response of primary production and calcification to changes of pCO
2 during experimental blooms of the coccolithophorid Emiliania huxleyi". Global Biogeochemical Cycles. 19 (2): GB2023. Bibcode:2005GBioC..19.2023D. doi:10.1029/2004GB002318.
- Kuffner, I. B.; Andersson, A. J.; Jokiel, P. L.; Rodgers, K. S.; Mackenzie, F. T. (2007). "Decreased abundance of crustose coralline algae due to ocean acidification". Nature Geoscience. 1 (2): 114–117. Bibcode:2008NatGe...1..114K. doi:10.1038/ngeo100.
- Phillips, Graham; Chris Branagan (13 September 2007). "Ocean Acidification – The BIG global warming story". ABC TV Science: Catalyst. Australian Broadcasting Corporation. Retrieved 18 September 2007.
- Gazeau, F.; Quiblier, C.; Jansen, J. M.; Gattuso, J.-P.; Middelburg, J. J.; Heip, C. H. R. (2007). "Impact of elevated CO
2 on shellfish calcification". Geophysical Research Letters. 34 (7): L07603. Bibcode:2007GeoRL..3407603G. doi:10.1029/2006GL028554. hdl:20.500.11755/a8941c6a-6d0b-43d5-ba0d-157a7aa05668.
- Comeau, C.; Gorsky, G.; Jeffree, R.; Teyssié, J.-L.; Gattuso, J.-P. (2009). "Impact of ocean acidification on a key Arctic pelagic mollusc ("Limacina helicina")". Biogeosciences. 6 (9): 1877–1882. Bibcode:2009BGeo....6.1877C. doi:10.5194/bg-6-1877-2009.
- Buitenhuis, E. T.; de Baar, H. J. W.; Veldhuis, M. J. W. (1999). "Photosynthesis and calcification by Emiliania huxleyi (Prymnesiophyceae) as a function of inorganic carbon species". Journal of Phycology. 35 (5): 949–959. doi:10.1046/j.1529-8817.1999.3550949.x.
- Nimer, N. A.; =Merrett, M. J. (1993). "Calcification rate in Emiliania huxleyi Lohmann in response to light, nitrate and availability of inorganic carbon". New Phytologist. 123 (4): 673–677. doi:10.1111/j.1469-8137.1993.tb03776.x.
- Iglesias-Rodriguez, M.D.; Halloran, P.R.; Rickaby, R.E.M.; Hall, I.R.; Colmenero-Hidalgo, E.; Gittins, J.R.; Green, D.R.H.; Tyrrell, T.; Gibbs, S.J.; von Dassow, P.; Rehm, E.; Armbrust, E.V.; Boessenkool, K.P. (2008). "Phytoplankton Calcification in a High-CO
2 World". Science. 320 (5874): 336–340. Bibcode:2008Sci...320..336I. doi:10.1126/science.1154122. PMID 18420926.
- Sciandra, A.; Harlay, J.; Lefevre, D.; et al. (2003). "Response of coccolithophorid Emiliania huxleyi to elevated partial pressure of CO
2 under nitrogen limitation". Marine Ecology Progress Series. 261: 111–112. Bibcode:2003MEPS..261..111S. doi:10.3354/meps261111.
- Langer, G.; Geisen, M.; Baumann, K. H.; et al. (2006). "Species-specific responses of calcifying algae to changing seawater carbonate chemistry" (PDF). Geochemistry, Geophysics, Geosystems. 7 (9): Q09006. Bibcode:2006GGG.....709006L. doi:10.1029/2005GC001227.
- "Acidification Of Oceans May Contribute To Global Declines Of Shellfish, Study By Stony Brook Scientists Concludes" (Press release). School of Marine and Atmospheric Sciences at Stony Brook University. 27 September 2010. Archived from the original on 3 September 2012. Retrieved 4 June 2012.
- Ruttiman, J. (2006). "Sick Seas". Nature. 442 (7106): 978–980. Bibcode:2006Natur.442..978R. doi:10.1038/442978a. PMID 16943816.
- Cohen, A.; Holcomb, M. (2009). "Why Corals Care About Ocean Acidification: Uncovering the Mechanism" (PDF). Oceanography. 24 (4): 118–127. doi:10.5670/oceanog.2009.102. Archived from the original (PDF) on 6 November 2013.
- Pérez, F.; Fontela, M.; García-Ibañez, M.; Mercier, H.; Velo, A.; Lherminier, P.; Zunino, P.; de la Paz, M.; Alonso, F.; Guallart, E.; Padín, T. (22 February 2018). "Meridional overturning circulation conveys fast acidification to the deep Atlantic Ocean". Nature. 554 (7693): 515–518. Bibcode:2018Natur.554..515P. doi:10.1038/nature25493. PMID 29433125.
- Mollica, Nathaniel R.; Guo, Weifu; Cohen, Anne L.; Huang, Kuo-Fang; Foster, Gavin L.; Donald, Hannah K.; Solow, Andrew R. (20 February 2018). "Ocean acidification affects coral growth by reducing skeletal density". Proceedings of the National Academy of Sciences. 115 (8): 1754–1759. Bibcode:2018PNAS..115.1754M. doi:10.1073/pnas.1712806115. PMC 5828584. PMID 29378969.
- Albright, R.; Caldeira, L.; Hosfelt, J.; Kwiatkowski, L.; Maclaren, J. K.; Mason, B. M.; Nebuchina, Y.; Ninokawa, A.; Pongratz, J.; Ricke, K. L.; Rivlin, T.; Schneider, K.; Sesboüé, M.; Shamberger, K.; Silverman, J.; Wolfe, K.; Zhu, K.; Caldeira, K. (24 February 2016). "Reversal of ocean acidification enhances net coral reef calcification". Nature. 531 (7594): 362–365. Bibcode:2016Natur.531..362A. doi:10.1038/nature17155. PMID 26909578.
- Albright, R.; Takeshita, T.; Koweek, D. A.; Ninokawa, A.; Wolfe, K.; Rivlin, T.; Nebuchina, Y.; Young, J.; Caldeira, K. (14 March 2018). "Carbon dioxide addition to coral reef waters suppresses net community calcification". Nature. 555 (7697): 516–519. Bibcode:2018Natur.555..516A. doi:10.1038/nature25968. PMID 29539634.
- Hannah L. Wood; John I. Spicer; Stephen Widdicombe (2008). "Ocean acidification may increase calcification rates, but at a cost". Proceedings of the Royal Society B. 275 (1644): 1767–1773. doi:10.1098/rspb.2008.0343. PMC 2587798. PMID 18460426.
- Fabricius, Katharina (2011). "Losers and winners in coral reefs acclimatized to elevated carbon dioxide concentrations". Nature Climate Change. 1 (3): 165–169. Bibcode:2011NatCC...1..165F. doi:10.1038/nclimate1122.
- Henehan, Michael J.; Ridgwell, Andy; Thomas, Ellen; Zhang, Shuang; Alegret, Laia; Schmidt, Daniela N.; Rae, James W. B.; Witts, James D.; Landman, Neil H.; Greene, Sarah E.; Huber, Brian T. (5 November 2019). "Rapid ocean acidification and protracted Earth system recovery followed the end-Cretaceous Chicxulub impact". Proceedings of the National Academy of Sciences. 116 (45): 22500–22504. doi:10.1073/pnas.1905989116. ISSN 0027-8424. PMID 31636204.
- Petrou, Katherina; Nielsen, Daniel (27 August 2019). "Acid oceans are shrinking plankton, fueling faster climate change". phys.org. Retrieved 12 November 2019.
- Koenigstein, Stefan; Mark, Felix C; Gößling-Reisemann, Stefan; Reuter, Hauke; Poertner, Hans-Otto (6 March 2016). "Modelling climate change impacts on marine fish populations: process-based integration of ocean warming, acidification and other environmental drivers" (PDF). Fish and Fisheries. 17 (4): 972–1004. doi:10.1111/faf.12155. ISSN 1467-2960.
- Pankhurst, Ned W.; Munday, Philip L. (2011). "Effects of climate change on fish reproduction and early life history stages". Marine and Freshwater Research. 62 (9): 1015. doi:10.1071/mf10269. ISSN 1323-1650.
- Ishimatsu, A; Hayashi, M; Kikkawa, T (23 December 2008). "Fishes in high-CO2, acidified oceans". Marine Ecology Progress Series. 373: 295–302. Bibcode:2008MEPS..373..295I. doi:10.3354/meps07823. ISSN 0171-8630.
- Cripps, Ingrid L.; Munday, Philip L.; McCormick, Mark I. (28 July 2011). "Ocean Acidification Affects Prey Detection by a Predatory Reef Fish". PLoS ONE. 6 (7): e22736. Bibcode:2011PLoSO...622736C. doi:10.1371/journal.pone.0022736. ISSN 1932-6203. PMC 3145675. PMID 21829497.
- Ferrari, Maud C. O.; McCormick, Mark I.; Munday, Philip L.; Meekan, Mark G.; Dixson, Danielle L.; Lonnstedt, Öona; Chivers, Douglas P. (21 September 2011). "Putting prey and predator into the CO2 equation – qualitative and quantitative effects of ocean acidification on predator-prey interactions". Ecology Letters. 14 (11): 1143–1148. doi:10.1111/j.1461-0248.2011.01683.x. ISSN 1461-023X. PMID 21936880.
- Chivers, 2014
- Dixson, D. L.; et al. (2010). "Ocean acidification disrupts the innate ability of fish to detect predator olfactory cues". Ecology Letters. 13 (1): 68–75. doi:10.1111/j.1461-0248.2009.01400.x. PMID 19917053.
- Simpson, S. D.; et al. (2011). "Ocean acidification erodes crucial auditory behaviour in a marine fish". Biology Letters. 7 (6): 917–20. doi:10.1098/rsbl.2011.0293. PMC 3210647. PMID 21632617.
- Hester, K. C.; et al. (2008). "Unanticipated consequences of ocean acidification: A noisier ocean at lower pH" (PDF). Geophysical Research Letters. 35 (19): L19601. Bibcode:2008GeoRL..3519601H. doi:10.1029/2008GL034913. Archived from the original (PDF) on 30 October 2014.
- Acid In The Oceans: A Growing Threat To Sea Life by Richard Harris. All Things Considered, 12 August 2009.
- Kwok, Roberta. "Ocean acidification could make squid develop abnormally". University of Washington. Retrieved 24 August 2013.
- "Swiss marine researcher moving in for the krill". The Australian. 2008. Archived from the original on 11 December 2008. Retrieved 28 September 2008.
- "Ocean Acidification Promotes Disruptive and Harmful Algal Blooms on Our Coasts". 2014.
- Turley, Carol; Gattuso, Jean-Pierre (July 2012). "Future biological and ecosystem impacts of ocean acidification and their socioeconomic-policy implications". Current Opinion in Environmental Sustainability. 4 (3): 278–286. doi:10.1016/j.cosust.2012.05.007.
- Kroeker, et al. (June 2013) "Impacts of ocean acidification on marine organisms: quantifying sensitivities and interaction with warming." Glob Chang Biol. 19(6): 1884–1896
- Harvey, et al. (April 2013) "Meta-analysis reveals complex marine biological responses to the interactive effects of ocean acidification and warming." Ecol Evol. 3(4): 1016–1030
- Nagelkerken Global alteration of ocean ecosystem functioning due to increasing human CO2 emissions, PNAS vol. 112 no. 43, 2015
- Bednaršek, Nina, et al. (2002) "Pteropods on the edge: Cumulative effects of ocean acidification, warming, and deoxygenation." Progress in Oceanography 145 (2016): 1–24.
- Keeling, Ralph F., and Hernan E. Garcia. "The change in oceanic O2 inventory associated with recent global warming." Proceedings of the National Academy of Sciences. 99(12): 7848–7853.
- Harvey wt al Ecol Evol. 2013 Apr; 3(4): 1016–1030
- Gruber, Nicolas. "Warming up, turning sour, losing breath: ocean biogeochemistry under global change." Philosophical Transactions of the Royal Society of London A: Mathematical, Physical and Engineering Sciences 369.1943 (2011): 1980–1996.
- Anthony, et al. (May 2011) "Ocean acidification and warming will lower coral reef resilience." Global Change biology, Volume 17, Issue 5, Pages 1798–1808
- Goldenberg, Silvan U, et al. (2017) "Boosted food web productivity through ocean acidification collapses under warming." Global Change Biology.
- Pistevos, Jennifer CA, et al. (2015) "Ocean acidification and global warming impair shark hunting behaviour and growth." Scientific reports 5: 16293.
- Ridgwell, A.; Zondervan, I.; Hargreaves, J. C.; Bijma, J.; Lenton, T. M. (2007). "Assessing the potential long-term increase of oceanic fossil fuel CO
2 uptake due to CO
2-calcification feedback". Biogeosciences. 4 (4): 481–492. doi:10.5194/bg-4-481-2007.
- Tyrrell, T. (2008). "Calcium carbonate cycling in future oceans and its influence on future climates". Journal of Plankton Research. 30 (2): 141–156. doi:10.1093/plankt/fbm105.
- "Effects of Ocean Acidification on Marine Species & Ecosystems". Report. OCEANA. Retrieved 13 October 2013.
- Lischka, S.; Büdenbender J.; Boxhammer T.; Riebesell U. (15 April 2011). "Impact of ocean acidification and elevated temperatures on early juveniles of the polar shelled pteropod Limacina helicina : mortality, shell degradation, and shell growth" (PDF). Report. Biogeosciences. pp. 919–932. Retrieved 14 November 2013.
- "Comprehensive study of Arctic Ocean acidification". Study. CICERO. Retrieved 14 November 2013.
- "Antarctic marine wildlife is under threat, study finds". BBC Nature. Retrieved 13 October 2013.
- V. J. Fabry; C. Langdon; W. M. Balch; A. G. Dickson; R. A. Feely; B. Hales; D. A. Hutchins; J. A. Kleypas & C. L. Sabine. "Present and Future Impacts of Ocean Acidification on Marine Ecosystems and Biogeochemical Cycles" (PDF). Report of the Ocean Carbon and Biogeochemistry Scoping Workshop on Ocean Acidification Research.
- "Canada's State of the Oceans Report, 2012". Report. Fisheries and Oceans Canada. 2012. Archived from the original on 6 November 2013. Retrieved 21 October 2013.
- Robert J. Foy; Mark Carls; Michael Dalton; Tom Hurst; W. Christopher Long; Dusanka Poljak; André E. Punt; Michael F. Sigler; Robert P. Stone; Katherine M. Swiney (Winter 2013). "CO 2 , pH, and Anticipating a Future under Ocean Acidification" (PDF). ONCORHYNCHUS. Vol. XXXIII no. 1. Retrieved 14 November 2013.
- "Bering Sea Crab Fishery". Report. Seafood Market Bulletin. November 2005. Archived from the original on 11 December 2013. Retrieved 10 November 2013.
- Snyder, John. "Tourism in the Polar Regions: The Sustainability Challenge" (PDF). Report. UNEP, The International Ecotourism Society. Retrieved 13 October 2013.
- Harvey, Fiona (4 December 2019). "Tackling degraded oceans could mitigate climate crisis - report". The Guardian. ISSN 0261-3077. Retrieved 7 December 2019.
- Clarke & others (2007), Technical Summary, Table TS.2 (p. 9) and Figure TS.10 (p. 20).
- WBGU (2006), Summary for Policymakers, Halting ocean acidification in time, p. 3
- UNFCCC (15 March 2011). "Report of the Conference of the Parties on its sixteenth session, held in Cancun from 29 November to 10 December 2010. Addendum. Part two: Action taken by the Conference of the Parties at its sixteenth session" (PDF). Framework Convention on Climate Change. Geneva, Switzerland: United Nations. p. 3, paragraph 4. Document available in UN languages and text format.
- UNEP (2010), Ch 2: Which emission pathways are consistent with a 2 °C or 1.5 °C temperature limit?, pp. 28–29.
- Good & others (2010), Executive Summary.
- "Carbon Dioxide Emissions and Ocean Acidification; TSCA Section 21 Petition; Reasons for Agency Response". Environmental Protection Agency (EPA). 7 October 2015.
- Center for Biological Diversity; Donn J. Viviani. "TSCA Section 21 Petition Requesting EPA to Regulate Anthropogenic Emissions Carbon Dioxide" (PDF). US EPA.
- "The President's Climate Action Plan" (PDF). Retrieved 27 June 2017.
- Dan Merica. "Trump dramatically changes US approach to climate change". CNN Politics. CNN.
- Shear, Michael D. (1 June 2017). "Trump Will Withdraw U.S. From Paris Climate Agreement". The New York Times.
- "US opts out of G7 pledge stating Paris climate accord is 'irreversible'". The Guardian. Associated Press, Bologna. 12 June 2017.
- UK Royal Society (2009), Summary, pp. ix–xii.
- US NRC (2011), Ch 5: Key Elements of America's Climate Choices, Box 5.1: Geoengineering, pp. 52–53.
- Trujillo, Alan (2011). Essentials of Oceanography. Pearson Education, Inc. p. 157. ISBN 9780321668127.
- Cao, L.; Caldeira, K. (2010). "Can ocean iron fertilization mitigate ocean acidification?". Climatic Change. 99 (1–2): 303–311. Bibcode:2010ClCh...99..303C. doi:10.1007/s10584-010-9799-4.
- UK Royal Society (2009), Ch 2: Carbon dioxide removal techniques,Sec 2.3.1 Ocean fertilisation methods, pp. 16–19.
- UK Royal Society (2009), Ch 2: Carbon dioxide removal techniques, Sec 2.3.1 Ocean fertilisation methods, Table 2.8, p. 18.
- Clarke, L.; Edmonds, J.; Jacoby, H.; Pitcher, H.; Reilly, J.; Richels, R. (July 2007). "Scenarios of Greenhouse Gas Emissions and Atmospheric Concentrations. Sub-report 2.1A" (PDF). In U.S. Climate Change Science Program and the Subcommittee on Global Change Research (ed.). Synthesis and Assessment Product 2.1. Washington, DC., USA: Department of Energy, Office of Biological & Environmental Research. Archived from the original (PDF) on 16 June 2013.
- Good, P.; Gosling, S. N.; Bernie, D.; Caesar1, J.; Warren, R.; Arnell, N. W.; Lowe, J. A. (2010). An updated review of developments in climate science research since IPCC Fourth Assessment Report (PDF) (Report). London, UK: AVOID Consortium. Report website.
- UK Royal Society (September 2009). Geoengineering the climate: science, governance and uncertainty (PDF). London: UK Royal Society. ISBN 978-0-85403-773-5, RS Policy document 10/09. Report website.
- UNEP (November 2010). The Emissions Gap Report: Are the Copenhagen Accord pledges sufficient to limit global warming to 2°C or 1.5°C? A preliminary assessment. Nairobi, Kenya: United Nations Environment Programme (UNEP). ISBN 978-92-807-3134-7.
- US National Research Council (US NRC) (2011). America's Climate Choices. Washington, DC, USA: National Academies Press. doi:10.17226/12781. ISBN 978-0-309-14585-5.
- WBGU (2006). Special Report: The Future Oceans – Warming Up, Rising High, Turning Sour (PDF). Berlin, Germany: German Advisory Council on Global Change (WBGU). ISBN 978-3-936191-14-1. Report website.
- Antarctic Climate and Ecosystems Cooperative Research Centre (ACE CRC) (2008). Position analysis: CO2 emissions and climate change: Ocean impacts and adaptation issues. ISSN 1835-7911. Hobart, Tasmania.
- Cicerone, R.; J. Orr; P. Brewer; et al. (2004). "The Ocean in a High CO
2 World" (PDF). Eos, Transactions, American Geophysical Union. American Geophysical Union. 85 (37): 351–353. Bibcode:2004EOSTr..85R.351C. doi:10.1029/2004EO370007. Archived from the original (PDF) on 5 March 2007.
- Doney, S. C. (2006). "The Dangers of Ocean Acidification". Scientific American. 294 (3): 58–65. Bibcode:2006SciAm.294c..58D. doi:10.1038/scientificamerican0306-58. ISSN 0036-8733. PMID 16502612., (Article preview only).
- Drake, J.L.; Mass, T.; Falkowski, P. G. (2014). "The evolution and future of carbonate precipitation in marine invertebrates: Witnessing extinction or documenting resilience in the Anthropocene?". Elementa. 2: 000026. doi:10.12952/journal.elementa.000026. ISSN 2325-1026.
- Feely, R. A.; Sabine, Christopher L.; Lee, Kitack; Berelson, Will; Kleypas, Joanie; Fabry, Victoria J.; Millero, Frank J. (2004). "Impact of Anthropogenic CO
2 on the CaCO
3 System in the Oceans". Science. 305 (5682): 362–366. Bibcode:2004Sci...305..362F. doi:10.1126/science.1097329. PMID 15256664.
- Hand, Eric (2015). "Acid oceans cited in Earth's worst die-off". Science. 348 (6231): 165–166. Bibcode:2015Sci...348..165H. doi:10.1126/science.348.6231.165. PMID 25859021.
- Harrould-Kolieb, E.; Savitz, J. (2008). Acid Test: Can We Save Our Oceans From CO2?. Oceana.
- Henderson, Caspar (5 August 2006). "Ocean acidification: the other CO2 problem". New Scientist.com news service. Archived from the original on 12 May 2008.
- Jacobson, M. Z. (2005). "Studying ocean acidification with conservative, stable numerical schemes for nonequilibrium air-ocean exchange and ocean equilibrium chemistry". Journal of Geophysical Research: Atmospheres. 110: D07302. Bibcode:2005JGRD..11007302J. doi:10.1029/2004JD005220.
- Kim, Rakhyun E. (2012). "Is a New Multilateral Environmental Agreement on Ocean Acidification Necessary?" (PDF). Review of European Community & International Environmental Law. 21 (3): 243–258. doi:10.1111/reel.12000.x.
- Kleypas, J. A., R. A. Feely, V. J. Fabry, C. Langdon, C. L. Sabine, and L. L. Robbins. (2006). Impacts of Ocean Acidification on Coral Reefs and Other Marine Calcifiers: A Guide for Further Research, report of a workshop held 18–20 April 2005, St. Petersburg, FL, sponsored by National Science Foundation, NOAA and the U.S. Geological Survey, 88pp.
- Kolbert, E. (20 November 2006). "The Darkening Sea: Carbon emissions and the ocean". The New Yorker.
- Mathis, J.T.; Feely, R. A. (2014). "Building an integrated coastal ocean acidification monitoring network in the U.S.". Elementa. 1: 000007. doi:10.12952/journal.elementa.000007. ISSN 2325-1026.
- Riebesell, U., V. J. Fabry, L. Hansson and J.-P. Gattuso (Eds.). (2010). Guide to best practices for ocean acidification research and data reporting, 260 p. Luxembourg: Publications Office of the European Union.
- Sabine, C. L.; Feely, Richard A.; Gruber, Nicolas; Key, Robert M.; Lee, Kitack; Bullister, John L.; et al. (2004). "The Oceanic Sink for Anthropogenic CO
2". Science. 305 (5682): 367–371. Bibcode:2004Sci...305..367S. doi:10.1126/science.1097403. hdl:10261/52596. PMID 15256665.
- Stone, R. (2007). "A World Without Corals?". Science. 316 (5825): 678–681. doi:10.1126/science.316.5825.678. PMID 17478692.