Ocean acidification is mentioned in paragraph 166 of the outcome document “The future we want” of the United Nations Conference on Sustainable Development (Rio+20).
Paragraph 166. We call for support to initiatives that address ocean acidification and the impacts of climate change on marine and coastal ecosystems and resources. In this regard, we reiterate the need to work collectively to prevent further ocean acidification, as well as enhance the resilience of marine ecosystems and of the communities whose livelihoods depend on them, and to support marine scientific research, monitoring and observation of ocean acidification and particularly vulnerable ecosystems, including through enhanced international cooperation in this regard.
United Nations Conference on Sustainable Development (Rio+20), 24 July 2012. Outcome document.