Ocean acidification is not explicitly governed by international treaties. United Nations (UN) processes and international and regional conventions are beginning to note ocean acidification (London Convention/Protocol, UN Convention on the Law of the Sea, Convention on Biological Diversity and others). Negotiators to the UN Framework Convention on Climate Change (UNFCCC) have begun to receive regular reports from the scientific community on ocean acidification, and the issue is now covered in the assessment reports of the Intergovernmental Panel on Climate Change (IPCC).
In June 2012, the UN Conference on Sustainable Development (Rio+20) recognised ocean acidification as a threat to economically and ecologically important ecosystems and human wellbeing. However, there are still no international mechanisms or adequate funding to deal specifically with mitigation or adaptation to ocean acidification.
- The primary cause of ocean acidification is the release of atmospheric CO2 from human activities. The only known realistic mitigation option on a global scale is to limit future atmospheric CO2 levels.
- Appropriate management of land use and land-use change can enhance uptake of atmospheric CO2 by vegetation and soils through activities such as restoration of wetlands, planting new forests and reforestation.
- Geoengineering proposals that do not reduce atmospheric CO2 – for example, methods that focus solely on temperature (such as aerosol backscatter or reduction of greenhouse gases other than CO2) – will not prevent ocean acidification. Adding alkaline minerals to the ocean would be effective and economically feasible only on a very small scale in coastal regions, and the unintended environmental consequences are largely unknown2.
- The impacts of other stressors on ocean ecosystems such as higher temperatures and deoxygenation – also associated with increasing CO2 – will be reduced by limiting increases in CO2 levels.
- The shellfish aquaculture industry faces significant threats and may benefit from a risk assessment and analysis of mitigation and adaptation strategies. For example, seawater monitoring around shellfish hatcheries can identify when to limit the intake of seawater with a lower pH, hatcheries can be relocated, or managers can select larval stages or strains that are more resilient to ocean acidification for breeding.
- At local levels, the effects of ocean acidification on ecosystem resilience may be constrained by minimising other local stressors3,4,5 through the following:
• Developing sustainable fisheries management practices such as regulating catches to reduce overfishing and creating long-term bycatch reduction plans. If implemented and enforced, this type of management has been shown to sustain ecosystem resilience.
• Adopting sustainable management of habitats, increased coastal protection, reduced sediment loading and application of marine spatial planning.
• Establishing and maintaining Marine Protected Areas (MPAs) that help manage endangered and highly vulnerable ecosystems to enhance their resilience against multiple environmental stressors6.
• Monitoring and regulating localised sources of acidification from runoff and pollutants such as fertilisers.
• Reducing sulphur dioxide and nitrous oxide emissions from coal-fired power plants and ship exhausts7 that have significant acidifying effects locally.
[This text is from the Ocean Acidification Summary for Policy Makers, 2013, and is available online as a PDF with full references.]