Here’s an interesting opportunity for impact investors around the globe: Investing in “green” infrastructure. Heard of it? It’s a term the World Bank and World Resources Institute use in a new report advocating for combining “green” and “gray” infrastructure – using natural environmental structures and features together with traditional concrete, steel and other heavy materials usually associated with the term “infrastructure.”

The idea is to harness the power of nature to achieve development goals, including water security and climate resilience, according to the report, “Integrating Green and Gray – Creating Next Generation Infrastructure.” Both organizations are calling for green infrastructure, such as mangroves and wetlands, to play a bigger role in traditional infrastructure planning.

Weaving “green” natural systems, including flood plains and forests, into “gray” traditional infrastructure systems can lower costs and increase resilience, they say. Examples include forests in Brazil that “filter biological impurities to protect water sources and reduce the need for expensive water treatment plant upgrades. In Vietnam, mangroves are used as a first line of defense against typhoons and sea surges, helping to reduce investments in expensive man-made sea dikes. And in Somalia, natural river sediments are trapped behind dams, helping to recharge local aquifers, thus eliminating the need for deep and expensive groundwater pumps.”

The need for financing global infrastructure is enormous and growing. Because of the environmental and social benefits, green infrastructure “opens new finance opportunities both from public sources via grants and subsidies, or from private sources, such as mission-driven investors that can help tackle this financing gap.” These are intriguing new ways to think about impact investing.

Read the full report here.