Deep sea ‘moonshot’ solution for climate

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Deep sea kelp forests could be the answer to climate change by absorbing carbon and pumping out credits. It is also in demand as a sustainable miracle crop for biofuel or food.

Some suggest that 48 million square kilometers of ocean are suitable for algal aquaculture, or 11% of the total ocean area.

And if nine percent of the oceans were engineered for carbon sequestration by algae, the atmosphere could return to pre-industrial conditions within decades.

Carbon sequestration involves the permanent removal of carbon from the atmosphere in a “sink” site, but growing algae for the sole purpose of carbon offsets or carbon credits has its detractors.

However, new global pressure on climate change and investor demand for large projects may ease past concerns about high costs, engineering constraints and hostile growing conditions.

“It’s a lunar solution,” researcher Finn Ross told AAP.

“Either people say it’s a terrible idea, we’re wasting precious raw materials or low carbon products, or people say otherwise, it’s an amazing climate solution, let’s do it, let’s start flowing the seaweeds.”

He says industry is taking a keen interest in algae as a climate solution and will need to be funded through carbon markets.

“But rather than rush it or cancel it altogether, there needs to be more ocean research.”

The PhD student released the latest findings with Deakin University’s Blue Carbon Lab Director, Professor Peter Macreadie, and Sea Green Director, Paddy Tarbuck.

One of the reasons the industry is in its infancy is the challenge of knocking down algae from at least 2000 meters.

The paper warns of major research gaps on the amount of algal carbon entering the deep ocean and the impact on seabed organisms.

It is also important to consider competition with phytoplankton for nutrients and make little difference overall.

And it must be possible to track changes in ocean carbon uptake at specific times during algae cultivation.

So far, all of the proposed ideas have been early-stage commercial ventures with no supporting research, according to the paper published in the academic journal Frontiers of Marine Science.

Concepts include cultivation platforms tethered in the deep ocean or attached to oil and gas infrastructure or offshore wind farms.

Seaweed could be grown in traditional coastal farms and then dumped offshore.

Or untethered automated platforms on the high seas could rise and fall with ocean currents and avoid shipping.

Some blue carbon projects are already earning credits on the Australian carbon credit market.

But those eligible to absorb and store — or sink — blue carbon are limited to the deep mud of coastal areas where mangroves, salt marshes and sea grasses can act as a natural carbon sink.

Other blue carbon activities, including the establishment of algae, are not currently eligible for credits, the federal environment department said.

Some 18,000 kilometers of coastline are protected by mangroves, providing protection from storms and tidal waves for 85,000 homes and 175,000 people.

In 2021, coastal mangroves and seagrasses sequestered more than 14 million tons of carbon, equivalent to the emissions of more than four million cars.

Currently, the production of seaweed as a food crop provides Pacific communities with an income and could contribute to the Sustainable Development Goals to which countries, including Australia, have signed up.

Planting vast swathes of ocean algae just for carbon credits could be another option, as governments and industry consider new climate solutions.

“It’s difficult because they’re politically unpopular…other blue carbon projects are much more popular,” Ross said.

But coastal projects have fewer opportunities for scaling, which is the trade-off policymakers have to make, he said.

An independent review of Australia’s carbon credits is due to be published by the end of the year, and how to assess any new method of earning credits will be part of the government’s response.

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