The city of Baltimore is transforming brownfields in underserved areas into trails and parks that will build natural resilience to the impacts of climate change. The city and its partner, the Parks & People Foundation, are engaging hundreds of community members to bring about an inclusive vision—the Middle Branch Waterfront Restoration Project. By enhancing wildlife habitat, adapting to sea level rise, and improving water quality, this project serves as a model of a nature-based solution at work for communities.

It’s happening in the Cherry Hill neighborhood, which is bounded by the Patapsco River and railroad tracks, has limited road access, and is home to one of the city’s largest public housing projects. The project is also at work in Westport, a predominantly Black community that has in recent years struggled with crime, housing abandonment, and unemployment.

Nature-based solutions can lessen climate impacts, like extreme heat, heightened flood risks and others, that threaten both economic development and livability in U.S. cities. Many cities address climate resilience by defaulting to gray infrastructure, such as dams and seawalls. Despite their high cost, the return on investment for gray infrastructure is often easier to quantify and thus easier to secure funding for. Yet nature-based solutions can build resilience as well, often at a lower cost, while promoting social equity, especially in communities where climate impacts are disproportionately high.

Nature-based solutions include green infrastructure, such as green roofs, bioswales, rain gardens, urban tree canopies, and permeable pavements. Other nature-based solutions focus on rebuilding natural infrastructure, such as restoring wetlands, mangroves, marshes, or oyster reefs, and other natural landscapes.

Nature-based solutions have a variety of benefits complementing the overarching goal of protecting cities against physical climate impacts, which also protects their economies. Notable benefits include reducing wave impacts during floods, mitigating the effects of sea level rise, preventing erosion, improving water quality, reducing extreme heat, reducing air pollution, improving public health, promoting livability and tourism, and even sequestering carbon. For example, the San Francisco Bay Living Shoreline protects against shoreline erosion by reducing wave energy by 30-50 percent. Elsewhere, Kansas City is on track to install 700,000 square feet of green roofs by the end of 2020, an initiative the EPA predicts will reduce runoff by retaining up to 29 inches of stormwater, cut sensible heat exchange by 64 percent compared to conventional roofs, decrease building energy consumption, and ultimately reduce annual carbon dioxide emissions by 269 tons.

Additionally, nature-based solutions can save cities billions in damage, repair, and maintenance costs compared to traditional gray infrastructure, and can offer comparable flood protection benefits. For instance, Philadelphia stands to save up to $8 billion over the next 25 years through its 2011 Green City Clean Waters plan, which uses rain gardens, tree trenches, and green roofs to prevent stormwater runoff. The program will cost about $2.1 billion over the next 25 years; by comparison, a gray infrastructure plan prioritizing tunnels and treatment systems could cost four to five times as much. In Los Angeles, a green infrastructure storm drainage project will likely cost $2.8 billion to $7.4 billion, as opposed to the traditional gray infrastructure project costing $44 billion. Savings from these solutions could free up capital to invest in additional protections for the community.

However, not everyone receives the same access to nature’s flood protection and other benefits. For instance, communities of color are three times more likely than white communities to be located in nature-deprived places. When this disadvantage is combined with additional risk factors, such as health and socioeconomic status, some communities are disproportionately impacted by the climate crisis. Two U.S. cities, Baltimore and Providence, Rhode Island, exemplify how nature-based resilience initiatives that incorporate diversity from local communities at every step can begin to address these historic inequalities.

• Baltimore is prioritizing equity and addressing systemic racism throughout its planning processes. The city’s 2018 Equity Assessment Program ordinance mandates that all agencies assess and proactively address policies for racial, gender, or income inequities. Additionally, Baltimore aims to refresh its Climate Action Plan and DP3 disaster plan with a social equity lens, engaging communities in a similar fashion to the development of its 2019 Sustainability Plan. This approach can be seen in city initiatives like the Middle Branch Waterfront Restoration Project, and also in Critical Area Management Program grants. These grants prioritize afforestation, stormwater management, and environmental education in underserved areas, funding projects such as “pocket parks” in neighborhoods with high vacancy rates.
• In Providence, the Woonasquatucket River Watershed Council (WRWC), with the support of the Rhode Island Infrastructure Bank, is pouring its energy into the Greening the Woonasquatucket River Greenway This project serves the Olneyville neighborhood, an underserved area scoring in the 94^th percentile for low-income populations within the state and representing the highest density of Spanish speakers in the city. By installing bioretention cells, rain gardens, green roofs, bioswales, and “storm trees,” the city strives to build resilience against sea level rise and flooding and foster community wellbeing. The WRWC uses its own River Ranger team, composed of Olneyville residents, to build and maintain these projects. River Rangers developed and maintained the Farm Fresh Rhode Island Food Hub, which installed enough green infrastructure to capture and treat 100 percent of stormwater. The WRWC also plans to educate Olneyville residents about climate resilience. These community voices will be central in the prioritization, planning, and implementation of future nature-based projects.

Cities must look toward nature-based solutions to build true resilience and address a long history of systemic inequalities in the distribution of natural and built climate change adaptations. Nature-based initiatives are strongest when co-created with the local community and designed for equitable distribution, especially toward historically disadvantaged populations. In coastal communities, sand dunes and coral reefs can supplant seawalls. Upstream watersheds can be restored to replace advanced water filtration systems.

Nature-based solutions can be highly effective in mitigating climate impacts, provide significant cost savings, and offer unique opportunities to provide equitable benefits. Moreover, unlike gray infrastructure, these projects can help people connect to nature, engage their communities, and celebrate local culture. Cities adding nature-based strategies to their toolkit can cultivate a resilient foundation, even enhancing economic competitiveness along the way.