How reliable - and (net) beneficial - is the green in green infrastructure

The idea of green infrastructure (GI) has generated great interest and creativity in addressing a range of challenging and expensive environmental problems, from coastal resilience to control of combined sewer overflows (CSOs). The appeal of GI stems from its cost savings compared to traditional "gray" infrastructure and the multiple benefits it provides, including biodiversity, aesthetics, and carbon sequestration. For example, a "green" approach to controlling CSOs in New York City saved $1.5 billion compared to a "gray" approach. Despite these advantages, GI still does not have detailed design and reliability specifications as compared to engineered gray infrastructure, potentially hindering its adoption. In this paper, we review some of the potential applications of GI in modern environmental science and discuss how reliability and associated (un)certainty in net benefits need to be addressed to realize the potential of this new approach.