The Urban Coast Under Climate Change and Sea Level Rise: A Potential Hazard to the Ocean and an Ethical Challenge to Humanity

Human presence in the coastal environment is rapidly growing, resulting in an equally rapid growth in construction, built environment, and consumer goods in the coastal zones. The coastal urban areas are receiving a growing fraction of the population migrating from rural into urban areas. As a result, most of today’s megacities are in the coastal zone or in flood plains of major rivers. This urbanization of the coastal zone is expected to continue for the foreseeable future. At the same time, the coastal zone is exposed to a changing spectrum of natural hazards originating in the atmosphere-ocean and terrestrial systems, including coastal flooding, storms and storm surges, river floods, tsunamis, and sea level rise. While considerable efforts are being made to increase resilience of the urban coast with respect to these hazards, little attention has been paid to future threats posed to the ocean and the marine biosphere by the human presence in the coastal zone. Large efforts are being made to reduce present impacts of human activities on the ocean and the marine biosphere. However, the future risks to the ocean associated with marine debris emerging from the urban coast built in the coastal zone at present is to a large extent overlooked. The way coastal urban areas are developed today creates a risk with potentially large harmful impacts on future generation. Efforts to transform the way urban coasts are developed so that the built environment is adapted to sea level rise and a changing hazard spectrum would help to bring present-day actions in line with our normative ethics. Developing internationally accepted rules for the abandonment of urban coasts that can not longer be defended against encroaching seas would ensure that the threats to the ocean, the marine biosphere and future generations are reduced.