Presented by: Richard Bailey (Associate Professor, University of Oxford) and Andreas Merkl (CEO, Ocean Conservancy)

We have known for years that  multiple simultaneous stressors affect elements of ocean systems. It is also recognized that pressures on ocean systems from anthropogenic impacts are mounting. Our present inability to calculate the consequences of novel collections of stresses poses a significant potential risk: underestimation of the probabilities of serious declines in ocean function and the various ‘services’ upon which human societies variously depend.  

Two obstacles to progress exist: (i) uncertainty in the specific effects of stressors and the nature of interactions between them; (ii) the lack of an efficient analytical framework within which to explore the probabilities of reaching persistent degraded ocean states, specifically over the coming decades. The OSIRIS model is an attempt at such a framework, providing a relatively coarse and light-weight approximation of networks of interactions between multiple system elements and relevant external forcings. Model simplicity and computational efficiency allow uncertainties to be propagated numerically, and relevant parameter spaces to be explored, in the search for problematic combinations of forcings and synergistic interactions, and an assessment of the associated risks.