Massive Far North wetlands fire produced 515,000 tonnes of carbon dioxide emissions

A helicopter equipped with a monsoon bucket fights the massive fire at Kaimaumau, in the Far North, in 2022.

A massive fire in the Far North’s Kaimaumau wetlands in 2022 produced 515,000 tonnes of carbon dioxide emissions - losses that would cost the country millions based on current carbon markets.

More than 600,000 tonnes of carbon were lost to the atmosphere in recent fires at two of New Zealand’s most important wetlands, highlighting the importance of keeping wetlands wet. If these losses had to be paid for, the estimated cost would be about $32 million based on current carbon markets.

The Department of Conservation, working with scientists at Manaaki Whenua - Landcare Research (MWLR), looked into carbon emissions from the 2022 fires in the Kaimaumau-Motutangi wetland on the northwest side of Rangaunu Harbour and on east side of the Aupouri Peninsula of the Far North and the Awarua wetland in Southland.

Both wetlands are peatlands which have an incredible ability to store carbon in peat, built up over tens of thousands of years, the newly published report on the research says.

In Kaimaumau the burnt area was over 2900ha, while at Awarua it was 980ha. It’s estimated to have cost more than $7 million to fight it and forced some residents to flee their homes from the advancing flames.

Both fires were caused by humans. Natural peatland fires occurred in New Zealand before human arrival but the increased frequency due to human activities is concerning.

The report was a collaboration involving DoC and Manaaki Whenua - Landcare Research scientists and supported by local iwi, in particular Ngāi Takoto and Awarua Runaka.

This research is the first detailed study on peatland fire carbon emissions completed in New Zealand.

DoC freshwater scientist Hugh Robertson said calculating carbon loss really brings home the impact of wetland fires on New Zealand’s stores of carbon.

“Carbon emissions from the 2022 fires were large, estimated at more than 515,000 tonnes of carbon dioxide emissions from Kaimaumau and more than 104,000 tonnes from Awarua. All of that carbon was released into the atmosphere.”

The fire at Kaimaumau in Northland in 2022 produced 515,000 tonnes of carbon dioxide emissions.

MWLR scientist Jack Pronger said the loss of carbon due to the two fires represents about 5% of New Zealand’s annual target for the 2026-2030 emissions reduction period.

“Year-on-year vegetation growth in peatlands removes carbon dioxide from the atmosphere and stores it as peat soil. Fire stops this process by releasing carbon back into the air, which then contributes to greenhouse gas emissions,” Pronger said.

Robertson said peat soils are highly flammable, particularly when they are dried out.

“If we reduce drainage and protect our wetlands, we’re supporting an important nature-based solution to climate change. Re-wetting our wetlands will make them less likely to burn and will reduce greenhouse gas emissions,” he said.

The fires also caused a loss of over 3000ha of native vegetation and damaged habitats of the critically threatened matuku-hūrepo/Australasian bittern and at-risk freshwater fish.

“Recovery and restoration of the Kaimaumau and Awarua wetlands will require extensive weed control, as the bare, burnt ground allows exotic plants to establish,” Robertson said.

Wetlands aren’t included in New Zealand’s emissions trading scheme, or carbon accounting, but the research highlights the significant potential of wetlands to contribute to the country’s response to climate change. This potential is also noted in New Zealand’s emissions reduction plan.