As extreme weather intensifies globally, governments are seeking nature-based solutions that deliver both climate and economic benefits.

The restoration of wetlands is an often overlooked opportunity. As our recent study shows, wetlands have long been treated as environmental “add-ons” but are in fact rising economic assets, delivering more value as they mature.

Restored coastal wetlands, particularly mangroves and saltmarshes, offer growing returns in the form of carbon sequestration, biodiversity protection and storm buffering. These benefits build up gradually, sometimes exponentially, over time.

But planning frameworks treat restorations as static costs, rather than compounding investments.

Using international data and economic modelling, we developed a framework to capture how wetland benefits evolve over decades. While we draw on global datasets, this approach can be applied in New Zealand to understand the value of local restoration projects.

Traditional cost-benefit analyses treat wetland restoration as a one-off expense with fixed returns. Our research shows this misses the bigger, long-term picture.

For example, coastal mangroves initially store a modest amount of carbon while seedlings develop. But as root systems establish and capture sediment, there is a critical threshold when carbon sequestration accelerates dramatically. Mature restored mangroves can store three times more carbon annually than during early years.

Saltmarshes follow a similar pattern. They develop from basic habitat into complex networks that buffer storm surges,........

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