A new treaty to protect oceans, now close to taking effect, would make it harder to remove greenhouse gases from the atmosphere through controversial geoengineering techniques like sinking seaweed and iron filings into the sea or storing carbon dioxide in seabed rocks, experts told Climate Home.
After a spate of approvals at a UN ocean summit in the French city of Nice this week, 50 countries and the European Union have now ratified a pact known as Biodiversity Beyond National Jurisdiction or the High Seas Treaty. Once ratified by 10 more states, it will come into force 120 days later.
The treaty would give governments the power to create protected areas in international waters – the parts of the ocean more than 370 km from land which make up the majority of the world’s sea. These Marine Protected Areas could restrict environmentally damaging activities like fishing boats dragging nets for their catches.
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Ralph Regenvanu, climate minister for the Pacific island nation of Vanuatu, told Climate Home from Nice that protecting biodiversity in the sea would “reduce the effects of climate change on the oceans” by making them healthier and more resilient. This would also help the oceans absorb carbon, he said.
Tom Pickerell, a marine biologist and global director of the World Resources Institute’s ocean programme, compared this treaty to the 2015 Paris climate agreement in its importance. “This will be the ocean moment,” he said.
Marine CO2 removal
The treaty would also establish a framework requiring governments to conduct impact assessments for activities on the high seas that “may cause substantial pollution of or significant and harmful changes to the marine environment”.
These assessments would likely be required for activities designed to remove carbon dioxide (CO2) from the atmosphere and slow down climate change. Such geoengineering techniques – whose ethics and feasibility are still being hotly debated – include the storage of captured CO2 in sea rocks and the sinking of carbon-absorbing seaweed to the seabed.
Other methods include putting iron filings or alkalis into the water. The iron stimulates phytoplankton which captures CO2 and the alkalis are chemical compounds that make the ocean less acidic, allowing it to absorb more greenhouse gases.
“As you can imagine, there’s a lot of questions, a lot of uncertainty” about these techniques, Pickerell said. “What would happen if we have a phytoplankton boom? Would it be possible that there are unintended consequences? These are all the things we’ve got to be aware of before we… rush headlong into it.”
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Pickerell said that if a separate regulatory regime for these kind of activities is not set up, then the treaty could “act as a brake” on them and may help stimulate regulation.
According to analysis by researchers from Columbia and Northwestern Universities, if the treaty comes into force, it would still be up to the government with jurisdiction over a certain project whether it proceeds – but other governments would have to be notified and consulted.
Real-world experiments rare
Outside of laboratories, marine carbon dioxide removal is rare. But on the south coast of England, a UK government-funded programme is sucking CO2 out of seawater to make room for it to absorb more and, off the coast of Iceland, US-based startup Running Tide sank wood chips into the sea last year.
Over 20 countries used the UN Ocean Conference in Nice as an opportunity to ratify the High Seas Treaty. Others like French Polynesia, the UK, Colombia, Brunei and France announced new restrictions on damaging fishing practices like bottom-trawling in their national waters, which are shallower and outside the scope of the treaty.
Bottom-trawling is when fishing vessels drag a net along the floor of the ocean to scoop up fish. This process disturbs the carbon stored in sediment, releasing it as carbon dioxide and acidifying the ocean.
The Spanish government recently challenged a European Union ban on bottom-trawling in certain areas of the northeast Atlantic. But the EU’s general court rejected the challenge this month – a move welcomed by environmental campaigners.
ClientEarth ocean lawyer Francesco Maletto said “there is now too much evidence about the damage wrought by wide-scale, repeat bottom-trawling to ignore”.
