Written by Sharad Ghimire (GEP Class of ’16)
On January 28th, 2015 international environmental law scholar Dr. Wil Burns delivered a lecture on ocean acidification, what some scientists have called the greatest threat oceans face today. In addition to the impact of global climate change on the world’s biodiversity, rising levels of oceanic CO2 concentration have direct impacts on ocean chemistry and marine species. Dr. Burns discussed the science of ocean acidification, its impacts on marine species and expanded on potential ways to use international regimes to find solutions and on the direction of future research.
Science of ocean acidification
About 297 billion metric tons of CO2 have been released into the atmosphere since the beginning of the industrial revolution, half of which have been released since 1978. As a result, the concentration of CO2 in the atmosphere has increased from 280 parts per million (ppm) to the current level of 400 ppm. Every year about 7 gigatons of CO2 is released, with the world’s oceans absorbing about 30 percent. Although this intake is positive for the global climate system, it has profound implications for ocean chemistry. CO2 is less reactive in the atmosphere, but when it is dissolved in oceanic water, it forms a weak carbonic acid. The acid increases the number of hydrogen ions along with bicarbonate and carbonate ions in water. Such acidity is measured in terms of pH scale, where a lower pH shows higher acidity. As the concentration of hydrogen ions in water increases, pH declines. This process is called acidification. Since the closing of the industrial revolution, increases in atmospheric CO2 concentration have reduced oceanic pH by 0.12. This is a significant change — an almost 30 percent increase in hydrogen ions. The rate of change of oceanic pH in the last 100 years is equivalent to the rate of change in millions of years, meaning oceans are now acidifying 100 times more rapidly than the acidification trend in the last 300 million years. Because of increasing CO2 emissions, by 2050, atmospheric CO2 concentration may reach double pre-industrial levels and could triple or even quadruple by 2100, resulting in the decline of pH by 0.3-0.4. Unfortunately, the ocean will continue to take in CO2 even if CO2 emissions are stopped. It has been estimated that there will be decline of pH by 0.7 by 2300. The decline of pH will continue for thousands of years beyond the point when we stop releasing CO2 into the atmosphere. As a result, changes in the ocean chemistry will continue for many generations to come.
Impact on marine species
Increased numbers of hydrogen ions in the ocean react with carbonate ions to form bicarbonate ions. Already there has been a 10 percent decline of carbonate ions from pre-industrial levels; there could be a 50 percent decline by 2100 and up to 70 percent by 2300. Some marine species form limestone carbonate shells or use calcium carbonate to form their skeletons. This calcification process occurs in many marine species, including corals, echinoderms, foraminifera, mollusks and calcareous algae. Species that form coral reefs are most affected by ocean acidification because they need a significant amount of calcium carbonate to survive. Therefore, the increase in hydrogen ions hinders the calcification process. Estimated atmospheric CO2 concentrations of 450-500 ppm for 2040 to 2050 would make calcification processes virtually impossible for coral reefs, and by the end of the century there will be few, if any, areas where coral reefs can survive. Since the change is rapid, coral reefs will not be able to adapt, resulting in massive decline of coral reefs with profound environmental and socio-economic consequences.
These ecosystems are composed of many other components, including other planktonic calcifying organisms such as coccolithophores, foraminifera and pteropods. Decline in acceptable conditions for calcification and consequent loss of these species would affect other species dependent on them for food and survival. “Trophic cascade” is a serious threat caused by a change in ocean’s planktonic composition and may have implications for commercial fish species such as pacific salmon. Similarly, pteropods, or sea butterflies, will also be affected by ocean acidification because of their thin shells. These species may ultimately disappear by 2100 due to ocean acidification. Decline of calcifying species may also increase jellyfish populations, which could have serious ecological impacts.
Besides impacts on calcifying species, there are several other direct impacts of ocean acidification. Decline of ocean pH often results in acidosis, or the buildup of acid in the bodies of many marine species. Similarly, acidification also increases the intake of toxic metals like copper, which cause damage in the sensory parts of several species, impairing their abilities to protect themselves from predators. In addition to hampering calcification, changes in acid-base balance in the body fluid and intake of toxic metals have serious effects on several marine species. Therefore, the question becomes whether there are any options for potential solutions.
Potential response through the international regimes
International climate regimes aim to address CO2 emissions as the main source of potential threat to global climate. The United Nations Framework Convention on Climate Change (UNFCCC) and the Kyoto Protocol focus on stabilization of greenhouse gas concentration to prevent dangerous interference with the climate system. Both attempt to limit anthropogenic emissions of greenhouse gases, including CO2, methane, nitrous oxide and others. Because gases other than CO2 have higher global warming potential, there is little focus on CO2. Unfortunately ocean acidification cannot be addressed without reducing CO2, therefore ocean acidification should be included under global climate regimes.
There are other potentially relevant regimes, for example the UN Convention for the Law of the Sea (UNCLOS). The United States is not party to UNCLOS, although it recognizes many of its principles as customary international law. Some provisions of UNCLOS could be useful in addressing ocean acidification. For example, Article 194 gives a mandate to reduce pollution: reducing and controlling pollution from any source with an objective to protect rare or fragile ecosystems, as well as the habitat of depleted, threatened or endangered species or other forms of marine lives. Article 1 defines pollution of the marine environment as “the introduction by man, directly or indirectly, of substances or energy into the marine environment which result or likely result deleterious impact.” By this definition, CO2 is indirectly introduced into the marine environment, creating a deleterious effect. Therefore, the mandate to reduce pollution under UNCLOS should apply. More directly under article 2.12, there is mention of adopting laws and regulations to control pollution in marine environments from the atmosphere.
There are several leverage points to address ocean acidification through UNCLOS. For example, countries relying on fish harvest as a source of revenue or sustenance could bring an action through UNCLOS against major CO2 emitting countries. UNCLOS is unique because of its binding dispute resolution mechanism. Therefore a country affected by ocean acidification or pollution could use UNCLOS to address issues with offending countries. This could be a potentially a powerful mechanism to highlight the impact of ocean acidification and place pressure on countries to reduce greenhouse gas emissions associated with it.
The UN Fish Stock Agreements, established under the UNCLOS focuses on straddling fish stocks, or stocks that migrate from one country’s Exclusive Economic Zone to another. Many species dependent on coral reefs are highly migratory, opening the possibility of protection through this agreement. Article 5 requires adapting to ensure long term sustainability of the fish species, assessing impacts on fish and other species for environmental factors, and minimizing pollution and protecting biodiversity in the marine environment. Many of the species being affected by ocean acidification fall under the category of migratory species or straddling stocks, such as salmon. Again, this agreement would provide a mandate for countries to challenge rising levels of CO2 and the impact on those kinds of species.
Another potentially useful treaty is the Convention on Biological Diversity (CBD). Since ocean acidification causes trophic cascade and loss of species in the food chain, the CBD could be applicable. Article 3 asks that countries refrain from activities that damage biodiversity outside their territory. Since increases of CO2 in the atmosphere and related ocean acidification impacts biodiversity, the CBD could be instrumental. Moreover, the Nagoya Strategic Plan within the CBD has a mandate specifically to address ocean acidification. The issue has already been incorporated into the CBD. The CBD has some limitations: it doesn’t have a binding dispute resolution mechanism and it has poor record in terms of protecting biodiversity. However it has the ability to exert pressure on countries and advance its mandate to focus on impacts of ocean acidification.
Finally, there are other potential regimes such as many fishery regimes that include options to protect threatened areas. The scope of marine protected areas can be expanded to acknowledge the threats of ocean acidification. Ocean acidification from pollutants, such as SO2, can be addressed through LORTAP (Long Range Transboundary Air Pollution) regime.
We have studied only 1-2 percent of world’s ocean species in term of impacts of ocean acidification, creating a huge opportunity for more research. Most current research is lab-based, limiting the scope of real-world application. More information is needed relating to synergism and interactive impacts, as well as multi species impacts in the real world. Such research might be expensive, but is critical to determining several related questions.
Ocean acidification is rapidly emerging as a serious threat to the world’s ocean species. It is also an appealing topic to address from a political standpoint as it is easily understandable to the public and lacks the ideological baggage attached to climate change debates. It is an issue that easily could be a tool for reducing CO2 emissions, and ideally should be emphasized at the same level as the climate impact from greenhouse gases.
The Global Environmental Politics program in the School of International Service at American University is a diverse and inclusive community. The program does not necessarily endorse the ideas contained in this or any other guest post. Please understand that our aim is to provide a space for the expression of a range of perspectives on global environmental concerns.