Editing IPCC:AR6/SROCC/Chapter-5 (section)

== Box 5.6 Policy Responses to Ocean Acidification: Is there an International Governance Gap? ==

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Ocean acidification is not specifically mentioned in the Paris Agreement on climate change (UNFCCC, 2015 <sup>[[#fn:r2481|2481]]</sup> ) and has only been given limited attention to date in other UNFCCC discussions. Nevertheless, ocean acidification is widely considered to be part of the climate system: it is one of seven state-of-the-climate indicators used by the World Meteorological Organization (WMO, 2019); it featured strongly in AR5, being covered by both WGI and WGII; its impacts are assessed in many sections of this Chapter; and concerns regarding ocean acidification have been raised through many international governance structures, including the United Nations Convention on the Law of the Sea (UNCLOS), the Convention on Biological Diversity (CBD), the United Nations Environment Programme (UNEP), and the Intergovernmental Oceanographic Commission of the United Nations Educational, Scientific and Cultural Organization (IOC-UNESCO).

Although many bodies have interests in ocean acidification, no unifying treaty or single instrument has been developed (Herr et al., 2014 <sup>[[#fn:r2482|2482]]</sup> ; Harrould-Kolieb and Hoegh-Guldberg, 2019 <sup>[[#fn:r2483|2483]]</sup> ) and there has been only limited governance action that is specific to the problem (Fennel and VanderZwaag, 2016 <sup>[[#fn:r2484|2484]]</sup> ; Jagers et al., 2018 <sup>[[#fn:r2485|2485]]</sup> ). Exceptions to this generalisation are the development of coordinated monitoring through the Global Ocean Acidification Observing Network (Newton et al., 2015 <sup>[[#fn:r2486|2486]]</sup> ), with associated scientific support through the International Atomic Energy Agency (IAEA) (Osborn et al., 2017 <sup>[[#fn:r2487|2487]]</sup> ; Watson-Wright and Valdés, 2018 <sup>[[#fn:r2488|2488]]</sup> ); and SDG14.3, with its non-binding, and relatively general, commitment to ‘minimise and address the impacts of ocean acidification, including through enhanced scientific cooperation at all levels’.

One possible response to the fragmented responsibilities for ocean acidification governance would be the development of a new UN mechanism specifically to address ocean acidification (Kim, 2012). This option would take time and political will, and has not been widely supported (Harrould-Kolieb and Herr, 2012 <sup>[[#fn:r2489|2489]]</sup> ). One pragmatic approach could be enhancing the involvement of UNFCCC with acidification governance (Herr et al., 2014 <sup>[[#fn:r2490|2490]]</sup> ) together with increased use of multilateral environment agreements (Harrould-Kolieb and Herr, 2012 <sup>[[#fn:r2491|2491]]</sup> ) ( ''medium confidence'' ).

UNFCCC action to stabilise the climate by reducing CO 2 emissions also necessarily addresses the problem of ocean acidification, which is primarily caused by anthropogenic CO 2 dissolving in seawater and lowering pH. Nevertheless, there are also distinct ocean acidification mitigation and adaptation issues, including:

* Climate mitigation measures that might be focused on greenhouse gases other than CO 2
* pH-associated thresholds or tipping-points (Hughes et al., 2013 <sup>[[#fn:r2492|2492]]</sup> ; Good et al., 2018 <sup>[[#fn:r2493|2493]]</sup> ) that have implications for scenario-modelling of emission reductions (Steinacher et al., 2013 <sup>[[#fn:r2494|2494]]</sup> )
* The large-scale use of bioenergy with carbon capture and storage (BECCS) as a mitigation option, if this involved sub-seafloor CO 2 storage, with risk of leakage and hence ocean acidification impacts (Blackford et al., 2014 <sup>[[#fn:r2495|2495]]</sup> )
* The use of other CO 2 removal techniques (negative emissions) such as ocean fertilisation (Section 5.5.1.3), or solar radiation management, without CO 2 emission reductions; both approaches would worsen ocean acidification (Williamson and Turley, 2012 <sup>[[#fn:r2496|2496]]</sup> ; Keller et al., 2014a <sup>[[#fn:r2497|2497]]</sup> ).

Adaptation to climate change could also include a more integrated approach to reduce ocean acidification impacts (Section 5.5.2). Proposed adaptation actions for ocean acidification (Kelly et al., 2011 <sup>[[#fn:r2498|2498]]</sup> ; Billé et al., 2013 <sup>[[#fn:r2499|2499]]</sup> ; Strong et al., 2014 <sup>[[#fn:r2500|2500]]</sup> ; Albright et al., 2016a <sup>[[#fn:r2501|2501]]</sup> ) include reduction of pollution and other stressors (thereby strengthening resilience); water treatment (e.g., for high value aquaculture); and the use of seaweed cultivation and seagrass restoration to slow longterm pH changes (although short-term variability may be increased) (Sabine, 2018 <sup>[[#fn:r2502|2502]]</sup> ). These measures are generally applicable to relatively limited spatial scales; whilst they may succeed in ‘buying time’, their future effectiveness will decrease unless underlying global drivers are also addressed ( ''high confidence'' ).

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