Mainstreaming climate change adaptation and mitigation into marine and coastal governance regimes) Coordinated measures are needed to combat climate-related stressors on marine biodiversity, e.g., ocean acidification, ocean warming and deoxygenation (Bijma et al., 2013; Pörtner, 2014; Levin et al., 2018), as these stressors have sectoral effects, such as on stable fisheries agreements (Brandt & Kronbak, 2010; Galaz et al., 2012). In fact, the Paris Agreement is now the first climate agreement to explicitly consider the ocean. International and regional legal instruments and mechanisms for climate change, oceans, fisheries and the environment are relevant for these challenges, but they remain inadequate (Galland et al., 2012; Herr et al., 2014; IPCC, 2017). At the least, sectoral and general ocean governance will have to mainstream major climate issues in governance regimes at international, regional and national levels. This mainstreaming will help sectoral management adapt and mitigate emissions. If linked to climate actions, this may also help reduce some of the knowledge gaps on climate and the ocean, and gaps between scientific and government attention to climate change (Magnan et al., 2016; Gallo et al., 2017). Achieving policy coherence over such complex issues also requires significant new knowledge on the oceans and climate which can feed back into climate science. In the case of proposed climate solutions such as geoengineering to capture carbon from the atmosphere, the IPCC warns that the impacts on marine ecosystems “remain unresolved and are not, therefore, ready for near-term application” (http://www.ipcc.ch/ipccreports/tar/wg3/index.php?idp=25).