New Zealand scientists have for the first time uncovered a previously hidden asset in our fight against carbon emissions.
It's called 'blue carbon' and refers to coastal ecosystems like salt marshes, mangroves and seagrass.
Like forests, they absorb carbon from the atmosphere and we now know they hold the equivalent of 26,000 cars worth of emissions each year.
And it's prompted calls to invest in their restoration to help fight climate change.
New Zealand's emissions are trending down - but not enough to hit our international target by 2030. We need some help to get there.
That's where emissions removals come in - ie letting nature do some of the work for us.
"Blue carbon is carbon sequestered in the marine environment, so that's mostly mangroves, salt marshes and seagrasses," said PhD candidate Finn Ross.
The problem has been we haven't known how good these environments are at drawing CO2 down and banking it.
"To date we haven't understood or assessed the potential for the ocean in New Zealand to contribute to carbon sequestration, so this is the first bit of science that says 'hey this is the scale of opportunity for New Zealand, for our ocean to contribute to our climate change fight'," Ross said.
The paper Ross has just published shows that contribution is decent.
"Blue carbon ecosystems in New Zealand are currently sequestering the equivalent emissions of 26,000 cars per year, which is pretty significant," he said.
That means we can look to including them in our official emissions offsets which currently only includes forestry.
Mangroves may not look like much but they are heroes of carbon absorption and they're expanding for a not-so-good reason - sediment runoff.
National leader Christopher Luxon raised the idea of blue carbon at the end of last year and got flack for "fantasy thinking". Now he said he's keen to look at expanding the Emissions Trading Scheme (ETS) to include offsets like blue carbon.
"I haven't seen the details of that particular report of analysis but I'd like to have a look at that because we are very open to expanding the ETS," he said.
"We wouldn't commit to a politician picking a particular project, we would commit to the Emissions Trading Scheme being stable and making it profitable to do projects that sequester carbon," added ACT leader David Seymour.
But it's not going to be enough to simply add them to the ETS - Ross said politicians have to actually invest in restoring these ecosystems.
Because when they are degraded or destroyed they emit the carbon they had been storing, speeding up climate change.
So leaving them alone and restoring them may be the way to maximise an asset we've previously overlooked.
