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POLICY BRIEF N°17/12 NOVEMBER 2012 | acidification - what can we do? Raphaël Billé (IDDRI-Sciences Po), Ryan Kelly (University of Washington and Center for Ocean Solutions), Arne Biastoch (GEOMAR), Ellycia Harrould-Kolieb (Melbourne University), Dorothée Herr (IUCN), Fortunat Joos (University of Bern), Kristy Kroeker (University of California Davis), Dan Laffoley (IUCN), Andreas Oschlies (GEOMAR), Jean-Pierre Gattuso (CNRS-INSU and UPMC)

This policy brief is based on a more comprehensive research published by Environmental Management in 2013 and available at http://link.springer.com/article/10.1007%2 Fs00267-013-0132-7. It is the second version of policy brief 17/12 published in November 2012 and replaces the previous one.

CAUSES AND CONSEQUENCES OF The have absorbed about one third of anthropogenic dioxide (CO2) emissions during the past five decades. This massive input of CO2 generates sweeping changes in the chemistry of , especially on the system. These changes are collectively referred to as “ocean acidification” because increased CO2 lowers seawater pH (i.e., increases its acidity). The basic chemistry of ocean acidification being well understood, future projections are quite straightforward for the surface open ocean for a given atmospheric CO2 trajectory. Those based on the International Panel on Change (IPCC) scenarios give reduc- tions in average global surface pH of between 0.14 and 0.35 units over the 21st century, which means surface pH may reach 7.81 in the year 2100 (Orr, 2011)—compared to 8.18 prior to the industrial era and 8.10 at present. Furthermore, impacts related to ocean acidification Institut du développement durable will continue to aggravate for centuries even if emissions are stopped (Joos et al., 2011). et des relations internationales 27, rue Saint-Guillaume www.iddri.org 75337 Paris cedex 07 France 1. On the total scale. Ocean acidification - what can we do?

Although the ocean’s uptake of atmospheric CO2 OPTIONS TO TAKE ACTION AGAINST is by far the major driver of ocean acidification OCEAN ACIDIFICATION globally, two other known or potential causes of ocean acidification have been identified: Preventing ocean acidification mm Coastal acidification due to additional pol- lutants: Nitrogen and phosphate runoff from Given the three potential causes of acidification, agricultural, industrial, urban and domestic this may be done through: sources causes acidification of coastal waters. The relative importance of each of these mecha- Limiting CO2 concentration in the atmos- nisms—as well as the importance of each rela- phere, either by reducing emissions or by remov- tive to that of global CO2—is a matter of active ing CO2 once emitted. CO2 and other GHGs have research, but it seems clear that non-CO2 inputs been the primary target of the United Nations can contribute significantly to the overall acidi- Framework Convention on (UN- fication threat in some coastal regions (Feely et FCCC) since its adoption in 1992, and of all sub- al., 2012). sequent climate talks. International climate ne- mm Release of hydrates into the ocean: gotiations, however, have failed to reach a legally Methane hydrates currently stored in the sedi- binding, long-term agreement that would include ments below the ocean represent a significant all major and emerging economies to reduce CO2 fraction of the amount of carbon globally stored. and other GHGs emissions so as to meet the target Owing to high pressure and cold of limiting global average temperature rise to less conditions, methane today remains in stable than 1.5 to 2oC above pre-industrial levels. Regard- hydrate form below 300 m. Deep oceanic war- less, this politically accepted limit chosen “to pre- ming could cause a transition from the hydrate vent dangerous anthropogenic interference with into the gas phase. Microbial aerobic oxidation the ”2 may not effectively address would then convert methane remaining in the ocean acidification for two reasons. First, it is still water column, with oxygen, into CO2, thus unclear what level of atmospheric CO2 may con- contributing to ocean acidification. Due to the stitute a “safe” level with respect to ocean acidifi- thermal inertia of the ocean and the delayed cation. Second, climate talks deal with cumulative intrusion of heat into the sediments, the process radiative effects and do not prioritize reductions of methane release would be irreversible and on any one gas (CO2 instead of others). would continue for a long time, even after glo- Removing CO2 from the once emit- bal warming has eventually stopped. However ted, on the other hand, could also prevent ocean there is no consensus, as of today, as to whether acidification. Of the methods that aim to enhance the dissolution of methane hydrates represents uptake and storage by terrestrial and oceanic bio- a real and significant threat to the oceans in the logical systems, or to use engineered (physical, course of the 21st century. chemical, biochemical) systems, “none has yet been demonstrated to be effective at an affordable Consequences of ocean acidification on societies cost, with acceptable side effects” (The Royal So- will depend on interactions among and between ciety, 2009). Their effectiveness to reduce ocean species and (all reacting at different acidification is technique specific and they hold lit- rates and magnitudes), on the interaction of ocean tle promise in terms of the maximum reduction in acidification with other ocean stressors; and on atmospheric CO2 they might realistically achieve responses of each human group affected. Never- (Williamson and Turley, 2012). However, calls to theless, it is clear that the speed and magnitude evaluate the potential, costs and benefits of geo- of acidification is threatening many marine spe- engineering solutions to ocean acidification grow cies and ecosystems. Calcifying organisms such as louder every day. reefs, and are among the first potential victims. Therefore ocean acidi- Reducing local factors of ocean acidification fication will impact various economic sectors (e.g. is another lever for mitigating acidification in the , aquaculture, and ) and coastal coastal ocean3 (Kelly et al., 2011). The potential for communities, and may also have heavy indirect effects on much broader segments of the world economy and population. It is thus an appropri- 2. UNFCCC, Article 2. ate time to review the available management and 3. For the open ocean, which is likely to experience the policy options despite the uncertainties surround- effects of coastal stressors less directly, such policy levers are probably both less important (likely to have less ing the details of acidification impacts. effect) and less feasible (given the governance issues of the high ).

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nutrient controls and other local- and national- importance for ocean acidification. This includes scale control measures depends on the but is not limited to well-connected and represent- relative importance of non-CO2 inputs in driving ative networks of marine protected areas. ocean acidification, but they could be of critical The evidence for human-mediated increases in importance in areas where the chemical effects resilience is sparse, and building resilience is not of terrestrial inputs rival CO2-driven acidification. a solution to ocean acidification per se. Ultimate- Where local and national economies rely heavily ly, increasing resilience will only be effective as upon carbonate-dependent services, a harm-mitigation technique if it is accompanied for example shellfish farming and coral tourism, by a strong limitation of CO2 concentration in the reducing local acidifying factors could produce re- atmosphere. sults both faster and in a more politically feasible manner than would a global CO2 solution alone. Adapting human activities in Reducing the risks of a potential release of anticipation of or reaction methane hydrates by limiting the greenhouse to ocean acidification effect, hence ocean warming, may be done either by reducing emissions of GHGs or by managing Adaptation to ocean acidification covers a wide solar radiation. To the extent that we really have range of potential actions taken by individuals an acidification problem exacerbated in the long- or human groups, and such measures will inevi- term by the rise of global , some non- tably be necessary given the inertia of past CO2 CO2 GHG emissions reductions appear technologi- emissions’ effect on present and future ocean cally feasible and politically viable (e.g., for PFCs, acidification. SF6 or HFCs). However, any such measures would Practical examples are still scarce, but revenue- not be sufficient by themselves to significantly generating activities like fisheries or aquaculture limit warming, largely driven by CO2 during this will have opportunities to adapt to an acidified century. On the other hand, methods for manag- ocean as the knowledge improves and ing solar radiation, and therefore thermal impacts, impacts become more noticeable. The potential of have gained some attention. However, Williamson adaptation is likely to be high for certain specific and Turley (2012) conclude that their effects on activities and issues within a narrow range of pH acidification are uncertain in both their magni- variation—for example, in commercial shellfish tude and direction. operations—but limits will be met when entire ecosystems and life cycles are disrupted beyond Strengthening ecosystem a critical threshold.5 Relocation of activities will resilience to ocean acidification hence complement local adaptation strategies.

In addition to tackling the root causes of ocean Repairing damages when the acidification, there is an increasing interest in ocean has already acidified boosting resilience in marine ecosystems to better tolerate its impacts. It is especially important Acidity may be reduced using additives other given that acidification is already happening and than iron. The addition of powdered alkaline is expected to continue even if CO2 emissions are rocks such as (“liming”), has rapidly mitigated. As of 2013, empirical studies been used to counteract lake acidification for examining population or ecosystem resilience to many years (Weatherley 1988). Similar ocean- ocean acidification are not available. However, based techniques aim at accelerating the natural many of the concepts regarding ecosystem resil- process of rock weathering that supplies alkaline ience to other stressors, including global warming, substances through rivers and run-off. , and habitat altera- There is limited experimental evidence that alka- tions, are applicable to ocean acidification.4 It is linisation could be useful in coastal environments likely that these other stressors decrease ecosystem such as mud flats (Green et al., 2009). Chemical resilience to acidification, and reciprocally, acidifi- buffering seems unlikely to scale up, however. cation will decrease ecosystem resilience to these Global models suggest that ocean alkalinisation other stressors. Therefore the tools commonly has the potential to mitigate atmospheric CO2 and used to increase resilience and alleviate the pres- ocean acidification but requires large-scale, long- sure from various stressors are also of primary term, “ intensive” additions. Much work

4. For example, ecosystems with higher diversity are 5. Hoegh-Guldberg et al. (2007) for instance find that expected to be more resilient to environmental stress consequences on coral reefs become unmanageable for (Folke et al., 2004). [CO2]atm above 500 ppm.

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remains to be done on the biogeochemical and more extreme climate events in densely populated ecological impacts of the chemical additions, cost- deltas and low-lying coastal areas, or the drive of ing, as well as on the development of methods for hundreds million people towards food insecurity verification and monitoring. because of , have so far been insuf- Another potential response to the threat of ocean ficient arguments for the international community acidification is to use opportunities for ecological to take appropriate coordinated action on GHG restoration, going beyond the current focus on re- emissions. There are therefore few reasons to be storing species, populations or habitat condition, optimistic that ocean acidification will fare better to approaches that anticipate future acidification. as an argument. Estuaries provide such an opportunity as they are No geoengineering method seems to provide an local hot spots of acidification in which substan- easy or readily acceptable alternative solution to tial economies are reliant on healthy functioning ocean acidification, in contrast to low-carbon tech- ecosystems. They have been acidifying for decades nologies (Joos et al., 2011). However, methods to due to nutrient enrichment, changes in river flows remove CO2 from the atmosphere may become a with greater freshwater input reducing buffering necessity in light of the present trajectory of CO2 rates, and inputs of other “acidifying” chemicals emissions. They involve fewer uncertainties and from the air and run-off, such as nitrogen and sul- risks than solar radiation management techniques, phur. Shellfish industries are already experiencing and are much more effective against acidification. increased mortality of larval and juvenile oysters In the same vein, reducing non-CO2 GHG emis- in estuaries (Green et al., 2009), which has forged sions will not make a big difference in the short new collaborations between scientists, conserva- to medium term as far as global acidification is tion groups and industry. Ecological restoration concerned, but it may prove opportune in the long projects now employ strategies of placing cultch term to prevent release of methane hydrates and (shell material) to speed up recovery of previously acidification in specific areas. depleted shellfish beds (Beck et al., 2009). Reducing coastal pollution sources is important for many reasons other than acidification. How- ever—and probably more efficiently than in the WEIGHING POTENTIAL ACTIONS case of the global climate talks—acidification can AGAINST OCEAN ACIDIFICATION stimulate more effective and ambitious action to- wards local pollution reduction. It can help build Not all options presented here are equally effective new strategic alliances with powerful stakeholders or feasible. They also interact and therefore need like the fisheries and shellfish industries. To this to be considered as a bundle. For instance: building end, a spatially explicit evaluation of the relative ecosystem resilience will be all the more efficient importance of different causes of acidification is as acidification is limited; locally reducing acidity necessary to maximize the utility of smaller-scale could become a regular management measure policy recommendations. for marine protected areas; local action against Strengthening ecosystems resilience and restor- coastal acidification could stimulate more ambi- ing the ones that have suffered from ocean acidi- tious efforts on CO2; having techniques available fication should be another cornerstone of action. to manage solar radiation may be a disincentive to The benefits of such action are manifold: these cut GHG emissions, including CO2. techniques address many stressors simultaneous- Any of the alternatives discussed here merely ly; much can be done within single jurisdictions, buys time to reduce CO2 emissions, which remains thus minimizing transaction costs; and many years vital whatever other action is taken. The first key of research have generated extensive experience question is therefore whether and how ocean in conservation and restoration. In addition, it ap- acidification can make a difference in the complex pears that easy and low-tech actions like returning and difficult UNFCCC talks. Incorporating ocean crushed shell material to coastal habitats can in acidification into the negotiations would aim both some cases substantially increase pH and mitigate at encouraging drastic CO2 emissions reductions localized acidification impacts. and at ensuring that mitigation policies take non- In an attempt to synthesize the discussion, Fig- thermal effects of CO2 into account—hence differ- ure 1 qualitatively compares the various options entiating CO2 from other GHGs. We can speculate discussed. “Potential” refers to how effective each that ocean acidification might be able to provide option may be with regard to fighting ocean acidi- additional urgency to act, as the chemical under- fication, and “feasibility” is understood as reflect- standing is clear and impacts are very likely irre- ing the ratio between the technological, political, versible on a human time scale. At the same time, and economic opportunities and barriers. This the possible disappearance of some island States, diagram is intended to be heuristic, rather than a

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Figure 1. Comparing potential and feasibility of management options

Feasibility

High Strengthening Reducing ecosystem coastal resilience pollution Reducing CO2 emissions

Using Adaptation additives Removing Reducing Restoring atmospheric CO2 non-CO2 GHG degraded emissions ecosystems

Solar radiation management Potential

Low High

formal accounting; what is important is the rela- mm 3. Then comes a cluster of four options (adap- tive position of options along the two axes. Four ting, restoring degraded ecosystems, using ad- clusters arise: ditives, reducing non-CO2 GHG emissions) that mm 1. The two options targeting CO2 concentration have a lower potential than clusters 1 and 2, and in the atmosphere clearly have the greatest po- rank somewhere in the middle in terms of fea- tential, and cannot be compared with others— sibility. They still deserve significant attention at least not on the same scale. The political and either because they are effective in the short social feasibility of immediate reductions in CO2 term or because they have important co-bene- emissions raises concerns while technology is fits. Their respective potential and feasibility largely available: depending on the viewpoint, cannot be compared with the current state of feasibility can hence be considered relatively knowledge. low or high. CO2 removal may be politically ea- mm 4. Last, solar radiation management appears to sier but there are high uncertainties regarding be of little potential with respect to counterac- technologies as no large-scale demonstration ting ocean acidification in the short-to-medium has been undertaken. term, although reducing warming via radiation mm 2. Strengthening ecosystem resilience and redu- management may be more relevant at time cing coastal pollution have both high potential scales of a few centuries, depending on the pro- and feasibility. They are no-regret strategies (i.e. jected risk of methane hydrate dissolution. justified under all plausible future scenarios) and offer massive co-benefits: they are probably the two options offering the greatest combina- tion of political and biochemical advantage as of today.

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LEGAL AND POLITICAL is the absence of a clear legal framework to estab- BASIS FOR ACTION lish marine protected areas in areas beyond na- tional jurisdiction. As to regulating CO2 removal The review of options to combat ocean acidification methods, the international legal framework seems raises the question of whether new legal instru- sufficient for most techniques7 but will have to be ments (multilateral environmental agreements strengthened for others as they become operation- such as conventions and protocols, or domestic al. Ocean alkalinisation would fall under the scope statutes) are needed, or whether the legal basis for of the 1996 Protocol to the London Convention on action already exists while policies (i.e. implemen- the prevention of by dumping of tation efforts) are the limit. The answer appears wastes and other matter, but further discussions to be the latter: although it is a recently emerged will be needed on the various additives, the appli- global environmental concern, ocean acidification cable regime under the Protocol and their poten- does not require significant changes in existing tial environmental impacts—whether positive or legal frameworks. Reducing CO2 and other GHG negative. Solar radiation management is not cov- emissions, reducing local nutrient , ered by any international governance framework, protecting and restoring ecosystems, adapting but it remains marginal in the ocean acidification human activities, or introducing additives: the debate. frameworks to take action are already in place to The regional level has seen the development of a large extent at the global, regional, national and many legal instruments and policies to fight land- local levels. What is lacking is implementation. based pollutions over the past decades. Many of At the global level, GHG emissions are handled these efforts used the impetus of the 1992 under the UNFCCC, and as Harrould-Kolieb and Summit, the 1995 Global Programme of Action for Herr (2011) affirm, “although the UNFCCC was the Protection of the Marine Environment from not originally designed to address ocean acidifica- Land-based Activities and the 2002 Johannes- tion, it does provide one framework within which burg Plan of Implementation which called States both ocean acidification and climate change can be to “make every effort to achieve substantial pro- tackled. Setting up a second international mecha- gress (…) to protect the marine environment from nism to deal solely with CO2 reductions would be land-based activities”. For example, the European superfluous, confusing and unrealistic”. Howev- Union adopted the Water Framework Directive er, many domestic policies have, so far, failed to (2000) and the EU Marine Strategy Framework Di- match the Convention’s objectives. rective (2008), and specific protocols were adopt- Besides the UNFCCC, CO2 uptake by the ocean ed within several UNEP regional seas frameworks. easily fits the definition of a “pollution of the ma- Yet such protocols have not received the political rine environment” under Article 1 of the United attention they deserve. Nations Convention on the Law of the (UN- At the national level, a systematic review is out CLOS): “the introduction by man, directly or in- of reach but we can illustrate a number of applica- directly, of substances or energy into the marine ble legal instruments with the U.S. example. The environment, including estuaries, which results U.S., who ratified the UNFCCC but are not Party to or is likely to result in such deleterious effects as the UNCLOS and CBD, are relatively well equipped harm to living resources and , hazards to contribute to combat acidification. Kelly and to human health, hindrance to marine activities, Caldwell (2012) relate that “the United States gov- including fishing and other legitimate uses of the ernment has begun to take notice of the acidifying sea, impairment of quality for use of sea water and ocean in small but important ways. In 2009, Con- reduction of amenities”. The 10th Conference of the gress passed legislation focused squarely on ocean Parties to the Convention on Biological Diversity acidification,8 establishing a federal interagency (CBD’s COP 10, Nagoya, Japan) made ample refer- ence to ocean acidification, and several of the 2020 7. Ocean e.g. is regulated by a resolution Aichi targets adopted under its new Strategic Plan (LC-LP.1 (2008)) adopted under the London Convention are also relevant to acidification.6 Whether these and Protocol in which Contracting Parties declared that crucial objectives will be met is, again, a matter of given the present state of knowledge, ocean fertilization activities other than legitimate scientific research should designing and implementing appropriate policies not be allowed. at the domestic level. 8. On March 30, 2009, President Obama signed the As of today, one important global regulatory gap Federal Ocean Acidification Research and Monitoring that may hamper responses to ocean acidification (FOARAM) Act, 33 U.S.C. § 3701 et seq. (authorizing funding, developing interagency plan on ocean acidification, and establishing an acidification program 6. Such as those on pollution, including excess nutrient, or within the National Oceanographic and Atmospheric on ecosystem restoration. Administration).

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working group on the issue, and a research pro- on forests, for example); (iii) ocean acidification gramme within the National Oceanographic and is a (i.e. it is happening in the entire Atmospheric Administration. An ocean acidifica- ocean and needs to be addressed globally) but will tion task force consisting of a collection of inde- impact societies and ecosystems very unevenly pendent scientists and policymakers was convened and with different time scales. Hence motivation to provide advice to the interagency working to take action will be uneven as well. Another group”. Legally, the U.S. Clean Water Act regulates handicap of a different is that most options marine pH, and the Clean Air Act allows the U.S. to reviewed here have already been identified in the regulate CO2 as a . context of other environmental problems; one Finally, at the local and subnational levels, must admit that we have not been very successful still with the U.S. example, Kelly and Caldwell in implementing them with adequate intensity at (2012) highlight the legal authority of state and the appropriate scale—beyond the many circum- local jurisdictions to control coastal scribed success stories. that may make those habitats more vulnerable to These are all reasons why one should not acidification. expect an easy solution to ocean acidification. A fundamental characteristic of the ocean acidi- The foregoing discussion means we have to fication issue is therefore the current discrepancy succeed where we have failed to a large extent so between essentially appropriate legal frameworks far: reducing CO2 emissions, protecting marine at all scales, and insufficient or inefficient policies ecosystems from various stressors, restoring the to translate them into action. ones that have been degraded, and developing last-resort technologies to cope in the worst-case scenario. Given the uncertain future outcome of A STRONG ARGUMENT TO CO2 emissions reductions efforts, any action that SUCCEED WHERE WE FAILED can be taken will have to be, however marginal its effect may seem—especially the actions Reviewing available options should not obscure which have important subsidiary environmental a number of handicaps that will undoubtedly benefits. In any case, ocean acidification is one hamper action against ocean acidification. Three more reason why climate change talks must of these handicaps stem from the nature of succeed. Admittedly it is one in an already impacts: (i) these impacts are still poorly defined long list, but it also has aspects (rapid time and hardly quantified; (ii) they are largely “invis- scales, economic and social impacts, potential ible”, both because they are difficult to isolate irreversibility) that may help make a difference from those of other stressors, and because they in the larger push to control our ever-rising CO2 occur underwater (unlike the effects of rain emissions.❚

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REFERENCES Beck, MW et al. (2009). Shellfish reefs at risk: a global Kelly, RP et al. (2011). “Mitigating Local Causes of Ocean analysis of problems and solutions. The Nature Conservancy, Acidification with Existing Laws”. 332:1036-1037. Arlington, VA, 52 p. Kelly, RP, Caldwell, MR (2012). Why Ocean Acidification Feely, RA et al. (2012). Scientific Summary of Ocean Matters to California, and What California Can Do About Acidification in Washington State Marine Waters. NOAA It: A Report on the Power of California’s State Government OAR Special Report. to Address Ocean Acidification in State Waters. Center for Ocean Solutions, Stanford Woods Institute for the Folke, C et al. (2004). “Regime shifts, resilience, and Environment, Stanford University, California. biodiversity in ecosystem management”. Annual Review of Ecology, Evolution and Systematics 35:557-581. Orr, JC (2011). “Recent and future changes in ocean carbonate chemistry”. In: Gattuso J-P, Hansson, L (eds), Green, MA et al. (2009). “Death by dissolution: Sediment Ocean acidification, Oxford University Press, Oxford, pp saturation state as a mortality factor for juvenile bivalves”. 41-66. Limnology and 54:1037-1047. The Royal Society (2009). Geoengineering the climate. Harrould-Kolieb, ER, Herr, D (2011). “Ocean acidification Science, governance and uncertainty. September, 83 p. and climate change: synergies and challenges of addressing both under the UNFCCC”. Climate Policy 12(3):378-389. Weatherley, NS (1988). “Liming to mitigate acidification in fresh-water ecosystems - A review of the biological Hoegh-Guldberg, O. et al. (2007). “Coral Reefs Under consequences”. Water, Air, and Soil Pollution 39:421-437. Rapid Climate Change and Ocean Acidification”. Science 318:1737-1742. Williamson, P, Turley, C (2012). “Ocean acidification in a geoengineering context”. Philosophical Transactions of the Joos, F. et al. (2011). « Impact of climate change mitigation Royal Society A 370:4317-4342. on ocean acidification projections ». In: Gattuso J-P, Hansson L (eds), Ocean Acidification, Oxford University Press, Oxford, pp 273-289.

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