The Open Ocean assessment focused on a global mapping approach to metrics, indicators, and indices for several themes (shown on the previous webpages). Whilst these results communicate the environmental problems associated with each theme, they do not allow easy and direct comparison across themes of how to set priorities in management.

Consequently, a complementary integrated assessment for the open ocean was also carried out, enabling a comparison of the issues and results across each of the themes investigated for the Open Ocean Assessment. The combined analysis of the individual results helped to develop an overall picture of the state of the global ocean ecosystem health, and the cumulative human impacts on the marine environment. Providing the overall picture also helps policy-makers to set priorities for best-practice management of the ocean and its resources, and as well, appropriate interventions for reducing human impacts on marine ecosystems and services.

Any effective management of marine systems requires information on where and how much human activities are affecting the health of the systems, and these assessments need to be comprehensive not just within a single sector (for example, only fishing). A cumulative impact assessment tool represents a way for comprehensively assessing the cumulative impact of all human activities on the state of all marine ecosystems at a global scale, in turn providing an assessment of ocean health of the natural system.

The integrated assessment was conducted following this approach, led by the University of California, Santa Barbara’s Centre for Marine Assessment and Planning. The Ocean Health Index (OHI) was one of the tools used in combination with a mapping of Cumulative Human Impact (CHI). In particular, the Cumulative Human Impact mapping process focussed on stresses to the natural system caused by human stakeholder behaviour (outlined in the conceptual framework). It allowed, with caveats, the comparison of relative impacts and the development of scenarios to test governance strategies. Scenarios were also used to test different management strategies.

The approach and results to the integrated assessment are explained in the following web-pages.