University of Otago senior research fellow Dr Rebecca McLeod said emissions reduction remained an urgent priority.
But even if carbon emissions stopped overnight, the problem remained there was too much carbon dioxide in the atmosphere — and land-based strategies to remove it were not enough, she said.
Along with five other researchers Dr McLeod has formally asked the government to establish an Aotearoa Marine Carbon Forum.
The purpose of the forum would be to provide the government with independent evidence-based advice as policy is developed alongside scientists’ understanding of marine carbon dioxide removal techniques.
"We are an island nation and we are absolutely intrinsically linked to our marine environment — and it is suffering," Dr McLeod said.
"We can’t reduce the amount of atmospheric carbon [required] just by planting trees alone.
"It’s not going to work, there’s just not enough space, and it’s not going to happen for long enough, there’s not enough permanence involved.
"The oceans are bearing the brunt, but they’re also potentially going to provide us a lifeline here."
The ocean had absorbed one-third of all the carbon dioxide emitted to date and there was now serious international interest in developing ways to increase its role as a carbon sink.
While there was a chance to do something quite innovative, in some cases involving quite a high level of intervention, some of the proposed techniques would sit uncomfortably with some people, Dr McLeod said.
Protecting areas such as Fiordland and restoring coastal wetlands had a role to play, but there were experimental biological and chemical processes being put forward that were attracting attention because there was an opportunity to considerably "scale up" the size of the intervention.
Techniques such as ocean fertilisation, to stimulate big phytoplankton blooms, or alkalinity enhancement, to alter the acidity of the ocean, held appeal for some.
"We don’t understand fully the risks involved in these options.
"We also haven’t yet determined ways to monitor and measure, firstly, how much carbon these measures are actually managing to pull out of the atmosphere, but, secondly, what the environmental impacts could be."
The proposed forum would provide the government with information on which it could base a strategy for protecting important carbon stores and bringing new techniques into New Zealand’s emissions reduction plan and broader climate change response.
A forum had formed informally last year with a goal of developing a robust assessment of the potential role of New Zealand’s coastal seas and oceans (including a mātauranga Māori approach) in the country’s climate change response.
The group met Climate Change Minister Simon Watts in June who urged the group to submit its proposal formally to New Zealand’s second emissions reduction plan.
Last month, the group did.
"Our oceans are changing in front of us, because of climate change," Dr McLeod said.
"We’re seeing these huge heatwaves all around New Zealand, which are happening really fast and having dramatic impacts.
"We’ve got ocean acidification, and we’ve got species turning up in places where they aren’t usually, and that’s disrupting our marine communities and our fisheries.
"It’s real, and it’s happening right in front of us, and that change is going to keep happening if we do nothing."
