Climate change is the most important threat to the Earth. Even if we stabilize CO₂ concentrations, the 2007 IPCC (Intergovernmental Panel on Climate Change) Assessment confirms that warming will continue for decades and sea level will continue to rise for centuries. Some direct effects of climate change in the marine environment are already visible, but others need to be defined by enhanced observations, analysis and modelling. We have a rudimentary understanding of the sensitivity and adaptability of natural and managed ecosystems to climate change. An assessment of the consequences of climate change on the World's Oceans has a high scientific and social relevance and is urgently needed.

Although we are beginning to document the local effects and consequences of climate change on the functioning of marine ecosystems, there is no comprehensive vision at the global scale, and only limited ability to forecast the effects of climate change. To close this gap, the Symposium will focus on the major issues of climate change that affect the oceans: oceanic circulation, climate modelling, cycling of carbon and other elements, acidification, oligotrophy, changes in species distributions and migratory routes, sea-level rise, coastal erosion, etc. The Symposium will bring together results from observations, analyses and model simulations, at a global scale, and will include discussion of the climate change scenarios and the possibilities for mitigating and protecting the marine environment and living marine resources.