Ocean Acidification guide
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| Shrimp catch, southern India © Roger Grace / Greenpeace International |
Ocean acidification is one of the nine planetary boundaries that we transgress at our peril, according to the influential report by the Stockholm Resilience Centre. The threat posed to the marine food chain by a more acidic ocean has fast-forwarded into our lifetimes, redoubling calls for decisive cuts in carbon dioxide emissions. The environmental movement carries the urgent responsibility of rescuing ocean acidification from the fringes of international negotiations on climate change.
updated August 2011
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Chemistry
Ocean acidification describes how the marine ecosystem is being destabilised by interaction with anthropogenic carbon dioxide emissions, with potentially devastating consequences.
Approximately 30% of atmospheric carbon dioxide dissolves in the surface waters of the ocean, forming a solution of carbonic acid. This counters the natural alkaline properties of saltwater. The rapid growth of carbon dioxide emissions during the modern era of industrialisation increases the natural incidence of this chemical reaction.
The consequent rise in acidity is measured by the inverse “pH” scale. The global average pH at the surface of the ocean has dropped from 8.2 to 8.1 since the 18th century. This is a logarithmic scale which means that ocean acidity has increased by about 30% in that period.
The construction of shells and skeletons of many marine organisms occurs through “calcification”. This is a process which involves interaction with carbonate and calcium ions that are present in sea water. Increasing acidity reduces the availability of carbonate ions so that calcification becomes less efficient.
A 2009 report prepared for the UN Convention on Biological Diversity described the increase in ocean acidification as “100 times faster than any change in acidity experienced in the marine environment over the last 20 million years, giving little time for evolutionary adaptation within biological systems.”
Ocean acidification in a nutshell, from Greenpeace
Marine Impact
Species dependent on calcification experience the stress of acidification in varying degrees, depending on the type of shell and the depth of habitat. However, all are ultimately exposed to a tipping point beyond which the chemical process reverses and shells become liable to corrosion.
The 2007 4th Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) expressed concern about this threshold at which “marine organisms can no longer form calcium carbonate shells”, warning that “conditions detrimental to high-latitude ecosystems will be reached in a few decades, not centuries as suggested previously.”
More recent studies have endorsed this conclusion, predicting that the tipping point will be reached first in cold polar waters where atmospheric carbon dioxide most readily dissolves. If emissions continue unabated, 10% of the Arctic Ocean could cross the threshold by 2018, and 50% by 2050.
If tiny Arctic plankton and shellfish species are unable to thrive, the marine food chain is threatened. Scientists identify herring, salmon and whales as particularly dependent on these small creatures. More species will become affected as acidification eventually takes hold in other oceans.
Coral skeletons, the foundation on which coral reefs are formed, also depend on calcification. Weaker development of these skeletons in an acidifying ocean increases the vulnerability of the reef to storm and bio-erosion. Vulnerable cold water corals are less well known than their tropical cousins but many important fish species depend on them for food, shelter and nurseries.
The impact of acidification on marine life is not entirely negative. Sea grasses and some algae are expected to flourish, to the benefit of a number of fish species. The predicted boost to jellyfish populations is of particular concern due to their predatory impact.
Ocean Acidification: Changing Planet – marine organisms are struggling to adjust to higher levels of carbon dioxide. From National Science Foundation.
Human Impact
The planet’s top predator must register alarm at the prospect of chronic interference with the marine food chain and habitat. Human food security and economic prosperity are too closely entwined with the ocean’s abundance.
Over 150 million people are believed to be dependent on livelihoods which are linked with fisheries. Seafood is the primary source of protein for one billion people, many of them located in regions with high incidence of poverty, such as West Africa.
The impact on human society is likely to be the exacerbation of existing shortages. Overfishing already threatens our fish stocks whilst coral reefs are in serious trouble from bleaching caused by warmer waters.
Our experience of resource scarcity is that richer countries can spend their way out of trouble whilst the poor have no such remedy. Nonetheless, some studies have suggested that ocean acidification will have its greatest economic impact on rich countries such as Japan, due to their dependence on fisheries and the appeal of coral biodiversity to tourists.
Indeed, the natural orientation of coastal communities to rich fishing grounds may compound the impact of ocean acidification. These locations tend to be estuarine or continental shelf regions where marine nutrients are drawn from deep ocean upwellings. But these are cold waters prone to greater acidification.
Ocean upwellings rich in dissolved carbon dioxide provide the most likely explanation for the poor survival rate of oyster larvae and other shellfish farmed along the US Pacific Coast, one of the world’s most prosperous fishing economies. Political lobbying for action to reduce carbon dioxide emissions is therefore growing in regions not normally associated with concern about consumption of fossil fuels.
Bob Steneck, Professor of Marine Sciences at University of Maine, explains how the fishing economy of the State of Maine is almost entirely dependent on shellfish which are threatened by ocean acidification.
Solutions
It used to be suggested that ocean acidification was a tolerable price to pay for nature’s solution to anthropogenic global warming. Not only do the surface waters extract carbon dioxide, but the oceans also act as sinks, slowing the pace of climate change. But the impacts of both global warming and ocean acidification have become far too threatening to indulge in such wishful thinking.
There are no credible geo-engineering solutions to ocean acidification under discussion. The feasibility of adding alkaline substances to surface waters is overwhelmed by the scale of the oceans, quite apart from any adverse effects.
The retention period of carbon dioxide in the atmosphere is such that further significant rise in ocean acidity is inevitable, even if emissions stopped outright. As with climate change, we therefore have no option but to accept a degree of anthropogenic ocean acidification, seeking to confine it within acceptable limits through deep and immediate cuts in carbon dioxide emissions.
Current UN climate negotiations envisage a safe limit of two degrees for global warming. This demands an approximate concentration of atmospheric carbon dioxide (excluding other greenhouse gases) of 350 parts per million. The UN process has failed so far to identify a corresponding safe threshold for ocean acidification, nor suitable targets and indicators for monitoring progress.
If future research indicates that this threshold lies at or below 350 parts per million, then the argument that two degrees is an unacceptably high target for global warming will be strengthened. This is already the view of many developing countries who believe that cuts in emissions should be much more decisive than currently contemplated.
Ellycia Harrould-Kolieb of Oceana talked to OneClimate at the 2010 Cancun climate change conference about the impact of ocean acidification and how we should respond, from OneWorld TV.
Integrity of Science
If ocean acidification is to stimulate campaigns for a low carbon world, then its science will be exposed to public challenge of a nature familiar to climate change discourse. There will be the same demands for tangible evidence that predicted changes are happening and that the changes are adverse rather than beneficial.
Most oceanographers would attribute a very high degree of certainty to the basic premise that the chemistry of the ocean is being changed as a result of human activities which release carbon dioxide.
However, they would also admit that the science of the impact of acidification is far from complete. The deep ocean is one of the least explored territories on earth and authoritative studies of acidification have emerged only over the last decade. Even basic data gathering stations to measure acidity and monitor its impact on marine life are few and far between.
One important uncertainty stems from our awareness that results of laboratory tests on living organisms may not be reproduced in the natural environment. Marine life may prove unexpectedly resilient to change; equally, undetected vulnerabilities may emerge.
Another fundamental complexity is the interaction of ocean acidification with other destabilising influences, in particular nitrate pollution from agriculture run-off and higher sea temperatures due to global warming.
Assessing the potential feedback loops between this “deadly trio” of anthropogenic impacts, a 2011 conference of experts concluded that “acting together they have a greater impact than if they were occurring on their own.” Further research is an obvious imperative.
Dr Alex Rogers, Scientific Director of the International Programme on the State of the Ocean warns that the combination of global warming, ocean acidification and anoxia (lack of oxygen) is associated with mass extinctions in the geological record.
Political Response
Recognition of the importance of acidification is relatively advanced at national level. Many developed countries sponsor scientific research and recognise the subject in their national climate change plans.
The US government has taken the lead by legislating for action. The Federal Ocean Acidification Research and Monitoring Act, signed by President Obama in 2009, demands that a national action plan be submitted to Congress during 2011.
In a separate response, the US regulatory body, the Environmental Protection Agency, has been persuaded to exercise its powers under the Clean Water Act. By regarding carbon dioxide as a water pollutant, the EPA requires that coastal States monitor the pH level of their ocean waters.
Such steps will not in themselves lead directly to policies to reduce carbon dioxide emissions. Although ocean acidification is often described as “the other CO2 problem”, the subject has never gained a strong foothold in negotiations associated with the UN Framework Convention on Climate Change.
Ocean scientists therefore sought to influence world leaders at the Copenhagen climate conference in 2009. The Monaco Declaration, signed by 155 scientists from 26 countries, warned that ocean acidification has the potential “within decades, to severely affect marine organisms, food webs, biodiversity, and fisheries.”
Unfortunately such appeals rarely short cut the slow process of science-based input to international policy. National research programmes must be brought together into a coordinated peer-reviewed structure, such as the IPCC format for climate change.
The IPCC has indeed promised that the "carbon cycle including ocean acidification" will be a cross-cutting theme in its 5th Assessment Report. Alas, this is not due for completion until 2014. Meanwhile, the 2010 Cancun Agreements on climate change contain a single reference to ocean acidification in the small print of a footnote.
This impasse presents an apparently compelling opportunity for the major environmental groups to breathe life into ineffective climate change campaigns. Their goal of radical cuts in carbon dioxide emissions is now in alignment with the interests of marine conservation and food security.
Fishing communities in Alaska appeal to the world to take action on carbon dioxide emissions which threaten the marine food chain, from Alaska Fisheries.
If you like this site, please make a voluntary micropayment to help OneWorld publish its educational Guides (credit/debit card or PayPal).
Ocean acidification describes how the marine ecosystem is being destabilised by interaction with anthropogenic carbon dioxide emissions, with potentially devastating consequences.
Approximately 30% of atmospheric carbon dioxide dissolves in the surface waters of the ocean, forming a solution of carbonic acid. This counters the natural alkaline properties of saltwater. The rapid growth of carbon dioxide emissions during the modern era of industrialisation increases the natural incidence of this chemical reaction.
The consequent rise in acidity is measured by the inverse “pH” scale. The global average pH at the surface of the ocean has dropped from 8.2 to 8.1 since the 18th century. This is a logarithmic scale which means that ocean acidity has increased by about 30% in that period.
The construction of shells and skeletons of many marine organisms occurs through “calcification”. This is a process which involves interaction with carbonate and calcium ions that are present in sea water. Increasing acidity reduces the availability of carbonate ions so that calcification becomes less efficient.
A 2009 report prepared for the UN Convention on Biological Diversity described the increase in ocean acidification as “100 times faster than any change in acidity experienced in the marine environment over the last 20 million years, giving little time for evolutionary adaptation within biological systems.”
Ocean acidification in a nutshell, from Greenpeace
Marine Impact
Species dependent on calcification experience the stress of acidification in varying degrees, depending on the type of shell and the depth of habitat. However, all are ultimately exposed to a tipping point beyond which the chemical process reverses and shells become liable to corrosion.
The 2007 4th Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) expressed concern about this threshold at which “marine organisms can no longer form calcium carbonate shells”, warning that “conditions detrimental to high-latitude ecosystems will be reached in a few decades, not centuries as suggested previously.”
More recent studies have endorsed this conclusion, predicting that the tipping point will be reached first in cold polar waters where atmospheric carbon dioxide most readily dissolves. If emissions continue unabated, 10% of the Arctic Ocean could cross the threshold by 2018, and 50% by 2050.
If tiny Arctic plankton and shellfish species are unable to thrive, the marine food chain is threatened. Scientists identify herring, salmon and whales as particularly dependent on these small creatures. More species will become affected as acidification eventually takes hold in other oceans.
|
| Coral life in the Belau islands © Jack Noble / Greenpeace International |
The impact of acidification on marine life is not entirely negative. Sea grasses and some algae are expected to flourish, to the benefit of a number of fish species. The predicted boost to jellyfish populations is of particular concern due to their predatory impact.
Ocean Acidification: Changing Planet – marine organisms are struggling to adjust to higher levels of carbon dioxide. From National Science Foundation.
Human Impact
The planet’s top predator must register alarm at the prospect of chronic interference with the marine food chain and habitat. Human food security and economic prosperity are too closely entwined with the ocean’s abundance.
Over 150 million people are believed to be dependent on livelihoods which are linked with fisheries. Seafood is the primary source of protein for one billion people, many of them located in regions with high incidence of poverty, such as West Africa.
|
| Pacific oyster and tiger prawn © LWY / Flickr |
Our experience of resource scarcity is that richer countries can spend their way out of trouble whilst the poor have no such remedy. Nonetheless, some studies have suggested that ocean acidification will have its greatest economic impact on rich countries such as Japan, due to their dependence on fisheries and the appeal of coral biodiversity to tourists.
Indeed, the natural orientation of coastal communities to rich fishing grounds may compound the impact of ocean acidification. These locations tend to be estuarine or continental shelf regions where marine nutrients are drawn from deep ocean upwellings. But these are cold waters prone to greater acidification.
Ocean upwellings rich in dissolved carbon dioxide provide the most likely explanation for the poor survival rate of oyster larvae and other shellfish farmed along the US Pacific Coast, one of the world’s most prosperous fishing economies. Political lobbying for action to reduce carbon dioxide emissions is therefore growing in regions not normally associated with concern about consumption of fossil fuels.
Bob Steneck, Professor of Marine Sciences at University of Maine, explains how the fishing economy of the State of Maine is almost entirely dependent on shellfish which are threatened by ocean acidification.
Solutions
It used to be suggested that ocean acidification was a tolerable price to pay for nature’s solution to anthropogenic global warming. Not only do the surface waters extract carbon dioxide, but the oceans also act as sinks, slowing the pace of climate change. But the impacts of both global warming and ocean acidification have become far too threatening to indulge in such wishful thinking.
There are no credible geo-engineering solutions to ocean acidification under discussion. The feasibility of adding alkaline substances to surface waters is overwhelmed by the scale of the oceans, quite apart from any adverse effects.
The retention period of carbon dioxide in the atmosphere is such that further significant rise in ocean acidity is inevitable, even if emissions stopped outright. As with climate change, we therefore have no option but to accept a degree of anthropogenic ocean acidification, seeking to confine it within acceptable limits through deep and immediate cuts in carbon dioxide emissions.
Current UN climate negotiations envisage a safe limit of two degrees for global warming. This demands an approximate concentration of atmospheric carbon dioxide (excluding other greenhouse gases) of 350 parts per million. The UN process has failed so far to identify a corresponding safe threshold for ocean acidification, nor suitable targets and indicators for monitoring progress.
If future research indicates that this threshold lies at or below 350 parts per million, then the argument that two degrees is an unacceptably high target for global warming will be strengthened. This is already the view of many developing countries who believe that cuts in emissions should be much more decisive than currently contemplated.
Ellycia Harrould-Kolieb of Oceana talked to OneClimate at the 2010 Cancun climate change conference about the impact of ocean acidification and how we should respond, from OneWorld TV.
Integrity of Science
If ocean acidification is to stimulate campaigns for a low carbon world, then its science will be exposed to public challenge of a nature familiar to climate change discourse. There will be the same demands for tangible evidence that predicted changes are happening and that the changes are adverse rather than beneficial.
|
| Blue mussels in The Baltic © Sari Tolvanen / Greenpeace International |
However, they would also admit that the science of the impact of acidification is far from complete. The deep ocean is one of the least explored territories on earth and authoritative studies of acidification have emerged only over the last decade. Even basic data gathering stations to measure acidity and monitor its impact on marine life are few and far between.
One important uncertainty stems from our awareness that results of laboratory tests on living organisms may not be reproduced in the natural environment. Marine life may prove unexpectedly resilient to change; equally, undetected vulnerabilities may emerge.
Another fundamental complexity is the interaction of ocean acidification with other destabilising influences, in particular nitrate pollution from agriculture run-off and higher sea temperatures due to global warming.
Assessing the potential feedback loops between this “deadly trio” of anthropogenic impacts, a 2011 conference of experts concluded that “acting together they have a greater impact than if they were occurring on their own.” Further research is an obvious imperative.
Dr Alex Rogers, Scientific Director of the International Programme on the State of the Ocean warns that the combination of global warming, ocean acidification and anoxia (lack of oxygen) is associated with mass extinctions in the geological record.
Political Response
Recognition of the importance of acidification is relatively advanced at national level. Many developed countries sponsor scientific research and recognise the subject in their national climate change plans.
The US government has taken the lead by legislating for action. The Federal Ocean Acidification Research and Monitoring Act, signed by President Obama in 2009, demands that a national action plan be submitted to Congress during 2011.
In a separate response, the US regulatory body, the Environmental Protection Agency, has been persuaded to exercise its powers under the Clean Water Act. By regarding carbon dioxide as a water pollutant, the EPA requires that coastal States monitor the pH level of their ocean waters.
Such steps will not in themselves lead directly to policies to reduce carbon dioxide emissions. Although ocean acidification is often described as “the other CO2 problem”, the subject has never gained a strong foothold in negotiations associated with the UN Framework Convention on Climate Change.
Ocean scientists therefore sought to influence world leaders at the Copenhagen climate conference in 2009. The Monaco Declaration, signed by 155 scientists from 26 countries, warned that ocean acidification has the potential “within decades, to severely affect marine organisms, food webs, biodiversity, and fisheries.”
Unfortunately such appeals rarely short cut the slow process of science-based input to international policy. National research programmes must be brought together into a coordinated peer-reviewed structure, such as the IPCC format for climate change.
The IPCC has indeed promised that the "carbon cycle including ocean acidification" will be a cross-cutting theme in its 5th Assessment Report. Alas, this is not due for completion until 2014. Meanwhile, the 2010 Cancun Agreements on climate change contain a single reference to ocean acidification in the small print of a footnote.
This impasse presents an apparently compelling opportunity for the major environmental groups to breathe life into ineffective climate change campaigns. Their goal of radical cuts in carbon dioxide emissions is now in alignment with the interests of marine conservation and food security.
Fishing communities in Alaska appeal to the world to take action on carbon dioxide emissions which threaten the marine food chain, from Alaska Fisheries.
If you like this site, please make a voluntary micropayment to help OneWorld publish its educational Guides (credit/debit card or PayPal).
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