The Knowledge-based Sustainable Management for Europe's Seas (KnowSeas) project is supported by the European Commission under the Environment (including climate change) Theme of the 7th Framework Programme for Research and Technological Development. The four year project started in April 2009, has 32 partners from 15 countries and is coordinated by the Scottish Association for Marine Science. The KnowSeas consortium will strengthen the science base for managing Europe’s seas through the practical application of systems thinking. It will work at the two scales envisaged for emergent EU policy: the Regional Sea Scale and Member State Economic Exclusive Zones (EEZs). We have developed a new approach of Decision Space Analysis to investigate mismatches of scale. Knowledge created through the EU Framework Programme 6 project European Lifestyles and Marine Ecosystems, augmented with necessary new studies of climate effects, fisheries and maritime industries - in EEZ case studies - will provide a basis for assessing changes to natural systems and their human causes.