Skip to content


Climate change adaptation

Flood prevention

Nature based solutions

NYC and CPH: Building resilience together

26. November 2018
climate challenge partnership

Solution provider

Danish Cleantech Hub

Danish Cleantech Hub is a public-private partnership founded by State of Green and The Confederation of Danish Industries. Danish Cleantech Hub provides a single point of entry for cleantech-related activities between Denmark and New York.

More from Danish Cleantech Hub

Want to see this solution first hand?

Add the case to your visit request and let us know that you are interested in visiting Denmark

City-to-city partnerships have the potential to accelerate climate resilience and innovation. The New York City-Copenhagen (NYC-CPH) partnership is an example of such partnership.


The partnership between New York and Copenhagen had its early beginnings in 2013 when a CPH delegation visited NYC to look for opportunities for knowledge exchange, partnering and a platform for providing Nordic Solutions within the field of climate change adaptation and resiliency planning. Later in 2015, the two cities signed a 3-year Memorandum of Cooperation (MoC) for the purposes of exchanging knowledge on solutions to climate challenges. The primary aspiration was to enable the cities to learn from one another and in turn share findings with other cities around the world facing similar climate related challenges, especially flooding.

NYC-CPH collaboration

The NYC-CPH partnership had different scopes and expressions in the two cities, depending on the local challenges and opportunities.

New York City
In 2016 NYC Department of Environmental Protection (DEP) hired the CPH-based consulting firm, Ramboll, to provide insight into ways to advance climate resiliency and traditional stormwater solutions to mitigate inland flooding and accommodate future increase in rainfall intensity through integration with ongoing urban planning and development with a focus on multi-functionality.

The Cloudburst Resiliency Planning Study built upon Ramboll’s experience and the NYC-CPH partnership. It applied the methodology used to develop the CPH Cloudburst Management Masterplans to a NYC landscape. Southeast Queens was selected as study area, due to their history with chronic flooding. The Cloudburst Resiliency Planning Study analyzes best-available data related to NYC rainfall projections, recommends methodologies for incorporating findings into ongoing resiliency planning initiatives, and identifies best practices for integrating climate change projects in future neighborhood-specific planning studies.

Through the study, specific opportunities for intervention were identified within the study area to provide retention and conveyance for extreme conditions, while offering community and environmental benefits in normal conditions.

In late 2011, the City of Copenhagen started work on its Cloudburst Management Plan. The work was divided into socio-economic and technical studies consisting of calculations of systems needed to handle large amounts of water, cost benefit analyses and a definition for a new level of service required for handling stormwater on the surface. The development of the Cloudburst Management Plan was carried out in the following steps:

  1. Division of Copenhagen into water catchments based on topography and overland flows paths.
  2. Approval of the citywide Cloudburst Management. Plan and development of catchment specific cloudburst masterplans.
  3. Development of the “climate neighborhood”: Piloting of adaptation solutions with a special focus on their potential to also provide urban space improvement and neighborhood revitalization.

After the City Council’s approval of the catchment specific masterplans, the city and the utility co-developed the implementation plan, breaking each catchment masterplan into individual projects, including descriptions of the hydraulic measures and the potential for urban space improvement for each project. In terms of barriers Copenhagen was challenged by a few legislation and regulations. However, there are many similarities, both in terms of barriers and opportunities in the legislation and regulation, between the two cities. The cooperation has provided an important insight in the ways of overcoming barriers and even turning some of them into opportunities – e.g. the Legal Grade concept in NYC which can provide the basis for regulating street levels in CPH.

The lessons learned, especially in relation to maintenance and operation, of the first implemented cloudburst projects in CPH, has served as key insight for NYC to advance their work. In addition, the strong visions set out by CPH early on in their climate adaptation agendas, which have proven to be highly effective and successful, have also served to inspire NYC to think in similar approaches.

Furthermore, the City of Copenhagen started preparation of a storm surge masterplan during the collaboration period. This was issued in 2018. NYC’s post-Sandy experience from disaster relief projects and resiliency planning has served as important inspiration for CPH’s work on the Storm Surge Management Plan.


The NYC-CPH partnership is a clear example of the value of city-to-city collaboration. It has demonstrated how city officials across borders can inspire one another, exchange insights, accelerate action, and develop new trends and opportunities.
Some conclusions include:

  • Greater urban value and co-benefits for capital investments can be achieved by using BGI for stormwater management.
  • It is possible to add a buffer from extreme rain events using BGI for a similar budget as traditional stormwater infrastructure.
  • Increased cooperation across city agencies and stakeholders through integrated planning maximizes output of invested money.
  • Adaptation and mitigation must go hand in hand through integrated planning approaches.
  • City-to-city collaboration facilitate hard conversations that otherwise may not be had.
  • Peer-to-peer knowledge-sharing fosters innovation.

In this case, the partnership has even led to more detailed designs of specific construction projects that inspire and engage the public and city stakeholders. A direct bilateral city-to-city collaboration can enable more in-depth work on the unique differences between cities. By addressing cities as complex systems, the bilateral collaboration can facilitate broader engagement across city agencies and stakeholders.

City-to-city partnerships can:

  • Provide a level of technical assistance to focus expert assistance on designing specific steps and strategies for stakeholder engagement (including other city agencies, private or other non-governmental groups or partners), workshopping and planning, and overcoming implementation challenges
  • Establish convening power, where a visiting city provides an opportunity to convene various arms of the host city, creating a forum for the host city to collaborate on climate solutions – and even design iconic and inspirational projects
  • Foster a tested relationship that can allow for mutual support in other areas and sectors (e.g. begin a relationship on stormwater management exchange that evolves to build off existing relationships to also explore energy systems resilience)
  • Provide communication and messaging resources by creating living examples to showcase

Next step

The next step in the NYC-CPH partnership is to work together on specific planning and construction projects. Furthermore, the work that we have done together has inspired NYC to expand its cloudburst work citywide to study and respond to future cloudbursts. It does not take a disaster to prompt climate resilience--we can take action in our own cities by learning from other cities’ experience. Our NYC-CPH partnership can hopefully serve as a model for other cities in many ways. There is no one-size fits all, but the close collaboration of two cities can go deep into the actual solutions and thereby supplement the work of important national and international networks.