Blue Heart

In Blue Heart, Vice Admiral Mark Mellett, former Chief of Staff of the Irish Defence Forces and former Chief of the Irish Naval Service, argues that the defining crises of the twenty-first century — climate change, energy insecurity, geopolitical instability, food vulnerability and the erosion of democratic resilience — are converging at sea. Drawing on a lifetime in naval command, international security and ocean governance, Mellett examines how the ocean has quietly sustained the modern world: regulating climate, absorbing carbon, carrying global trade, supporting food systems and enabling the undersea digital networks on which economies now depend. Yet this vast living system is under mounting pressure from warming waters, biodiversity collapse, overexploitation and intensifying strategic competition. From the North Atlantic to the deep waters west of Ireland, from vulnerable undersea cables to contested energy infrastructure, Blue Heart reveals an ocean becoming both more fragile and more geopolitically significant. Mellett explores the rise of hybrid maritime conflict, the risks posed by failing governance systems, and the profound implications of climate disruption for migration, sovereignty and global security. Personal, strategic and urgent, this work is a powerful examination of humanity’s relationship with the sea. It argues that ecological security and human security can no longer be separated, and that we must recover our sense of belonging to nature if we are to protect the blue heart of the planet that keeps us alive.