Only 10% of Aotearoa’s original wetlands remain intact – yet these diverse habitats may hold the key to protecting our coastal communities from climate change.

Mangroves, tidal marshes and seagrasses act as natural flood protection, soaking up water and reducing wave energy while also filtering pollutants and preventing sediment from reaching our oceans. According to international research, they’re also thought to be capable of storing up to four times more carbon than forests, and have a much faster rate of carbon sequestration.

But there is little data to prove just how effective these wetland ecosystems are in New Zealand at locking away carbon or protecting low-lying land from storm surges and coastal inundation.

That’s why a special project is now underway at Waihī Estuary to measure the ‘blue carbon’ storage (the carbon stored in coastal and marine ecosystems) and resilience potential of wetlands. The Nature Conservancy Aotearoa New Zealand (TNC NZ) is the New Zealand arm of a global non-profit organisation that is developing a methodology to measure the resilience benefits of wetlands.

TNC NZ’s Nature-based Solutions Project Manager, Olya Albot, says the ultimate goal is to develop the world’s first ‘resilience credit’, similar to a carbon credit, that encourages action to restore wetlands, and could be traded by organisations or individuals to help offset their carbon footprint and to fund adaptation to the impacts of climate change.

“We’re investigating coastal resilience because these environments are becoming more exposed to the impacts of climate change, such as increased storm surge, cyclones and sea level rise,” Olya says. “Coastal land is becoming more vulnerable as time goes on. Restoring coastal wetlands can create buffers against storm surges. We know they provide protection, but we want to find out how much.”

Potentially, money earned from trading resilience credits in a possible future international market could be put towards creating or restoring more wetlands, enabling Kiwi land-owners to move economic activities away from vulnerable land, earn ongoing income, and protect land from climate change impacts.

Spotlight On BOP

TNC NZ is currently gathering data on blue carbon while also measuring how resilient a 30ha site is between the Pongakawa River and Pukehina Canal, on the edge of the Waihī Estuary.

For the data collection aspect, they are partnering with Toi Moana Bay of Plenty Regional Council and iwi collective Te Wahapū o Waihī who jointly own the 30ha of low-lying farmland. The regional council and iwi collective aim to improve the ecological health of Waihī Estuary by redeveloping the wetland area, enabling it to treat agricultural drainage water from the adjacent dairy farms, as well as improve indigenous wetland habitat and biodiversity.

A new wetland has yet to be created but Olya and the TNC team are using 2D hydrological models to investigate how water would potentially flow over the area with or without salt marshes and mangroves. “We’re trying to quantify exactly how much water wetlands could hold back in the event of a storm surge, as well as how many hectares of land, how many people, and the value of infrastructure that could be protected by wetlands,” she says.

A $35,000 grant from BayTrust will allow Olya to expand this resilience research to take into account different types of coastline and assess TNC’s global resilience methodology against New Zealand’s unique conditions. 

“The methodology has been developed internationally and it’s important to test how well we can apply it in New Zealand. Do we need to modify it for our unique environment? We are extremely grateful to BayTrust for their support which will help us undertake this coastal resilience modelling and show Bay of Plenty communities what the coastal resilience benefits of these wetland projects might be in the future,” Olya says.

Great Potential

Bay of Plenty provides an ideal case study environment because there is almost 4000ha of land that sits below the mean high water spring inundation levels – meaning there’s lots of land suitable for wetland restoration in future.

“In New Zealand over 90% of freshwater and coastal wetlands have disappeared due to urban expansion and conversion to agriculture. Restoring wetlands will benefit people, the climate, biodiversity, and provide positive social and cultural outcomes as well,” Olya says.

Next Steps

TNC is continuing to work around the globe to develop its resilience credit methodology, with hopes of generating the first blue carbon resilience credits for a potential international market in the near future.

Olya and her team are also working with the Ministry for the Environment in New Zealand to assess the legal, policy and market considerations required to establish a national blue carbon credit scheme, so people can potentially buy blue carbon and/or resilience credits in future to offset their carbon footprint. 

“We should have something in the middle of the year with the Ministry for the Environment in terms of potential next steps for a blue carbon scheme in New Zealand. We also expect to have results from the Waihī Estuary resilience mapping by the end of this year. It’s very exciting.”

Photo credit: Andy Belcher