Can scientists define a “safe” or “tolerable” level of ocean acidification that must not be exceeded?
Some decision makers are asking scientists if it is possible to begin defining thresholds beyond which ecosystems will not recover. This is a complex challenge.
The combined effects of changing ocean physics, chemistry and biology vary from ecosystem to ecosystem. Impacts are also dependent on geographic location and variable local characteristics. Ecosystem impacts depend on policy decisions made now in relation to future carbon dioxide emissions and policies relating to other marine issues. Moreover, there are complex ethical and economic considerations on issues relating to “safe” or “tolerable” levels of ocean acidification.
Science cannot answer these questions but can provide some information on possible consequences of policy options. A dialogue between scientists, policymakers and stakeholders is necessary to explore what questions require answers and what options are available.
A first step towards identifying thresholds and indicators will be a concerted global research effort. This should combine experiments, models and observations to attempt to untangle the complexity of the response of marine ecosystems to ocean acidification and other stressors and will be led by the newly established International Coordination Centre.
[This text is from the Ocean Acidification Summary for Policy Makers, 2013, and is available online as a PDF with full references.]