In his book Blue Heart, Vice Admiral Mark Mellett (Rtd.), 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. He 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. Vice Admiral (Ret.) Mark Mellett is a leader whose career bridges defence, environmental stewardship, and leadership on complex global challenges. The first naval officer appointed as Ireland’s Defence Forces Chief of Staff and the country’s longest-serving defence chief in over fifty years, he has commanded at sea and ashore, with service in the North and South Atlantic, as well as in Afghanistan and Lebanon. Trained at the Royal Naval College Greenwich, the Irish Military Command and Staff College, and the US Naval War College, he has led operations at national and international levels, including Ireland’s military Covid-19 response. He was appointed a Commander of the Légion d’Honneur by the President of the French Republic and was awarded two Distinguished Service Medals by the Irish government. Holding a PhD in Ecosystem-Based Ocean Governance, he founded Green Compass, advising on climate action, ocean sustainability, and strategic risk. He chairs the boards of the Irish Maritime Area Regulatory Authority and Sage Advocacy, Ireland’s National Independent Advocacy Service for older people. He serves as Chair of the Advisory Council of the Azure Contemporary Forum on Security. He is a Life Fellow of the Irish Management Institute, and Co-Council Chair and a founding member of CaraDem, Ireland’s democracy institute.
