Rising Sea levels: Preparing Coastal Cities with Managed Retreat

over the coming hundreds if not thousands of years. Faced with the inevitability of this phenomenon, certain areas will become uninhabitable and the relocation of people, buildings, infrastructures and activities will sometimes be inevitable.

As underlined by the Special Report of the Intergovernmental Panel on Climate Change (IPCC) on the Ocean and Cryosphere in a Changing Climate (SROCC), managed retreat is an adaptation solution to sea level rise. Unlike emergency management, managed retreat is defined as a planned effort to permanently relocate people, assets, and infrastructure away from areas at risk.

The notion of “managed retreat” in fact covers a wide range of measures that can be developed and coordinated according to the current or future situation of a locality. Managed retreat includes public policies such as: compensation and buyouts of private properties, mandatory resettlements, and revision of urban planning to provide setback
zones, restrictions on rebuilding, and downzoning to encourage decreases in asset and population exposure over time in hazardous areas.

Managed retreat policies affect small communities, individual assets, and large populations in equal measure. Hence, they must be coordinated at every level, from local to national, and draw on international cooperation. This necessity for coordination was recognised as early as 2010 at the COP16 of the United Nations Framework Convention on Climate Change (UNFCCC), encouraging States to take “measures to enhance understanding, coordination and cooperation with regard to climate change induced [...] planned relocation, where appropriate, at national, regional and international levels”. A measure, moreover, that the Sendai Framework 2015-2030 identified as a tool for achieving disaster risk reduction objectives.

Because of its complexity, managed retreat is a topic which attracts much debate and resistance among both the populations concerned and policy and decision makers. To better anticipate, design, and implement this adaptation strategy, it is essential to bring about changes in narratives and to work towards a shared understanding of the issues and the methodologies that can accompany its deployment. Why? Because managed retreat is more than just a response to sea level rise: it is an opportunity to profoundly and
sustainably transform coastlines, to the benefit of both societies and biodiversity.

With this in mind, the Ocean & Climate Platform has designed this special report to be a practical, accessible and illustrated tool, exploring four major questions:

1. Why choose managed retreat as an adaptation solution?

2. At what spatial scales should managed retreat policies be carried out?

3. Why and how to implement this adaptation strategy in a dynamic way?

4. How to ensure that managed retreat is fair and sustainable?