Deep sea ‘moon launch’ solution to climate

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

Some suggest that 48 million square kilometers of ocean is suitable for seaweed farming, or 11 percent of the total ocean area.

And if nine percent of the oceans were arranged to sequester carbon from seaweed, the atmosphere could return to pre-industrial conditions within decades.

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

However, new global pressure on climate change and investor demand for large projects could dispel earlier concerns about high costs, engineering constraints and hostile growth conditions.

People were divided on the idea

“This is a killer solution,” researcher Vin Ross told the AAP.

“People either say it’s a terrible idea, we’re wasting valuable feedstock or low-carbon products, or people say the opposite, it’s a great climate solution, let’s do it, let’s start dumping seaweed.”

He says there is significant industrial interest in seaweed as a climate solution and it will need funding from the carbon markets.

“But rather than rushing into it or writing it off completely, more ocean research is needed.”

In 2021, coastal mangroves and seagrass sequester more than 14 million tons of carbon – equivalent to emissions from more than four million cars. Photo: Getty

The doctoral student published the latest findings with the head of the Deakin University Blue Carbon Laboratory, Professor Peter McCready, and Sea Green director Paddy Tarbuck.

One reason the industry is in its infancy is the challenge of dropping seaweed at least 2,000 metres.

The paper warns that there are significant research gaps on how much carbon from marine algae reaches the ocean depths and its impact on seafloor organisms.

How to grow seaweed is still in the idea stage

It’s also important to consider competition with phytoplankton for nutrients and that ends up making little difference overall.

And it should be possible to track changes in ocean carbon uptake at points in time during seaweed farming.

So far, all of the proposed ideas have been early-stage commercial projects without any supporting research, according to the paper published in the academic journal. Frontiers of Marine Science.

Concepts include growth platforms tethered in the ocean depths, linked to oil and gas infrastructure, or offshore wind farms.

Seaweed can be grown in traditional coastal operations and then disposed offshore.

Or untethered motorized platforms might rise and fall in the deep sea with ocean currents and avoid shipping.

Mangrove protected coast

Some blue carbon projects are already receiving credits on the Australian Carbon Credit Market.

But those qualified to absorb and store blue carbon — or sink it — are limited to deep mud in coastal regions where mangroves, salt marshes and seagrass beds can serve as a natural sink for carbon.

The federal environment ministry said other blue carbon activities, including seaweed creation, are not currently eligible for credits.

Mangroves protect about 18,000 km of coastline, providing protection from storms and tides for 85,000 homes and 175,000 people.

In 2021, coastal mangroves and seagrass sequester more than 14 million tons of carbon – equivalent to emissions from more than four million cars.

Pacific communities produce seaweed for food

Currently, the production of seaweed as a food crop provides income to Pacific communities and can contribute to the Sustainable Development Goals to which countries including Australia are signatories.

Planting vast swaths of ocean seaweed just to get carbon credits could be another option, as governments and industry look at new climate solutions.

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

But he said coastal projects have less scope for expansion, which decision-makers need to do.

A report on an independent review of Australian carbon credits is due by the end of the year, and how any new ways of earning credits are assessed will be part of the government’s response.


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