The Carbon Cost of Coastal Adaptation:
A Performance Evaluation Methodology for Nature-based Solutions
North America
Client
The Salata Institute for Climate and Sustainability at Harvard University
CPD Members
Pamela Conrad
Greg Barger
Project Team
Charles Waldheim, Office for Urbanization
Date
2025
If left unchecked, the carbon emissions from coastal adaptation efforts could potentially contribute more than two gigatons of greenhouse gases (carbon dioxide equivalent/CO2e) to global warming by 2050, equivalent to adding the annual emissions of New York City for the next forty years.
According to this study’s findings, 45%-64% of those embodied carbon emissions can be avoided now to meet the global 1.5oC goals, primarily through informed decisions made by the design team regarding sourcing and specifying materials, as well as collaborating with contractors and manufacturers.
However, complete nature-based adaptations, with up to 91% improved carbon impacts and 30% less cost, will not be fully realized without support from clients, owners, and municipalities. Carbon limitation requirements are emerging for buildings but do not yet exist for site infrastructure.
Sixty-two percent of coastal adaptations within this study exceed the established upper carbon emission limits for buildings, a largely overlooked pattern that will persist without intervention. When fully implemented, Nature-based Solutions (NbS) can course-correct coastal adaptations from contributing to climate change to becoming net positive solutions.
These benefits are not only through adaptation—preventing 173 million lives impacted globally by 2050—but also from mitigation through carbon sequestration, the avoidance of future emissions, and a myriad of ecological benefits.
This case study methodology examines thirteen coastal adaptations from twelve notable U.S. projects, revealing ways to shift from business-as-usual, largely high-emitting site infrastructure to solutions that can fully address both the climate and biodiversity crises.
