Posted on August 19, 2021
OPINION: What if I told you that we could absorb carbon over millions of hectares by simply doing nothing? What if I said that doing nothing would also restore a range of biodiverse habitats in these areas? Would you believe me if I mentioned that doing nothing would protect massive carbon stores?
Could I persuade you that the science journal Nature recently called for this to happen globally? Could you imagine that an area greater than all the country’s land, could recover by doing nothing? Why would ‘do nothing’ be so important when we are asking everyone to do ‘something’ about carbon?
The Marine Sciences Society of New Zealand/Te Hunga Mātai Moana o Aotearoa recently wrote to the Climate Change Commission/He Pou a Rangi on the ocean’s ability to capture and store carbon.
It advised the commission that it had an oceanic-size hole in its draft advice, and asked it to urgently identify ways to improve carbon-storage capacity and reduce disturbance to existing carbon stores.
Research over the last few years globally is beginning to unpick the critical role of the ocean in helping to regulate carbon, and the extensive damage to this capacity from extractive impacts.
The ocean has absorbed heat and carbon dioxide as global temperatures and carbon dioxide emissions have risen, which has buffered somewhat the collective effects of our carbon-hungry activities.
Carbon is captured and stored (sequestered) in the seabed over time scales ranging from tens to millions of years.
It is estimated that as much carbon is stored in coastal shelf sediments (those less than 200 metres deep) as in the world’s tropical forests.
However, this ability to sequester carbon is being directly affected by the way we currently use our marine environment.
This is because carbon-rich sediments are frequently and repeatedly disturbed over significant areas.
When organic material settles on the seabed some of it is buried and stored. When we physically disturb the seafloor and mix those surface sediments and organic matter back into the water column we increase the rates of consumption that turn the organic matter back into carbon dioxide rather than storing it.
So what can we do to stem and reverse this in our huge expanse of marine waters? One of the key causes is bottom-trawling, which Nature recently called on all nations to significantly reduce.
Here in Aotearoa New Zealand, bottom-trawling over our shelf seas and inshore waters is, and has, been releasing carbon and damaging important living, biodiverse habitats for over 100 years.
Niwa calculated from over a million trawl records, that 33.6 million hectares was the estimated trawl footprint from 1990 to 2016 – with heavy gear contacting the seabed in many areas more than once.
To put that into context, the landmass of our country is only 26.8m hectares.
But we don’t see it. So imagine if all the native forests were bulldozed in at least part of them, and in all wetlands, dunes, and alpine areas – the public reaction would be swift and visceral.
The fishing industry acknowledges the impacts in saying it is only about 10 per cent of our marine waters, but as the map below shows, much of the trawl footprint is in the shallower shelf seas around the coast, which are highly productive, biodiverse, and therefore contain significant amounts of carbon.
Confining bottom-trawling to its existing footprint as Oceans and Fisheries Minister David Parker recently suggested, will continue to release carbon and damage the recovery of carbon-capturing habitats.
The Climate Change Commission has now acknowledged the gap in its final advice, and agreed with the NZ Marine Sciences Society that the ocean’s carbon stocks and flows needed to be modelled.
But before we can model it, we need to urgently understand the ecological and biogeochemical processes in different parts of our shelf seas.
However, there is a lack of urgency in the Commission’s report, which is at odds with a number of recent UN reports calling for transformative actions to address biodiversity loss and climate change.
Simply calling for more research is also tantamount to enabling the climate crisis to worsen.
This is because around 9m hectares are trawled each year (equivalent to a third of NZ’s landmass), according to Dame Juliet Gerard’s recent report on the future of commercial fishing.
The Prime Minister’s Chief Science Advisor imagined a future without bottom-trawling damaging the seabed within her aspirational vision for commercial fishing in 2040.
Many other scientists also recognise that the climate and habitat crises cannot be solved in isolation.
Farmers and car owners are being required to make sacrifices, yet these efforts may be undermined if the government continues to allow damage to the seabed’s ability to capture and store carbon.
Simply doing nothing to the ocean by drastically reducing bottom-trawling will help the planet and most of us, particularly our children and their kids.
Dr Steve Urlich is a senior lecturer in Environmental Management at Lincoln University.
