This paper describes the importance of coastal marine ecosystem-based regulatory policy development to address biodiversity loss in two Mediterranean-type ecosystem or MTES - the coastal marine areas of California and the Mediterranean Basin. The paper first provides an introduction to the importance of cultural adaptation to a dynamic Mediterranean climate, and characterizes the major pressures and threats to coastal marine biodiversity, including anthropogenic climate change, associated with MTEs. Evidence of coastal marine ecosystem-disturbance is provided for the California MTE and Mediterranean Basin. Scientists have documented a decline in primary and secondary levels of ecological productivity in these regions. Second, the paper includes a review and analysis of recent policy development in the U.S., California and the Euro-Mediterranean Basin that focus on biodiversity protection in accordance to a coastal marine ecosystem-based approach to planning and management. Two national marine sanctuaries off California are compared - the Channel Islands National Marine Sanctuary and the Monterey Bay National Marine Sanctuary - with respect to the designation of marine protected areas as an important regulatory tool that can curb the over-use of resources and mitigate the expected impacts from climate disturbance. With respect to the Euro-Mediterranean Basin, the paper includes a review of recent EU programs that support "integrated marine policy", marine protected area designation, and Integrated Coastal Zone Management. The final section of the paper offers a number of recommendations to strengthen coastal marine ecosystem-based regulatory policy across MTEs, and focuses on the need to develop bioregional zoning strategies that include the designation of a large network of marine reserves, and new social alliances and partnerships between the U.S., California and the EU.