Can seaweed save the world?

Cows, sheep and goats are ruminants — named after the largest of their four stomach chambers, the "rumen". As food is broken down by fermentation, methane is a by-product. One cow produces between 250 and 500 litres a day, nearly all of which is burped out.

With over a billion sheep and 1.5 billion cows worldwide, livestock generates a significant percentage of global greenhouse gas emissions. And while methane doesn't stay in the atmosphere for as long as CO2 does, it has up to 100 times more heat-trapping potential. It's so concerning that 149 countries and the EU have joined the Global Methane Pledge to cut emissions by 30 per cent in this decade. Sea Forest, an Australian start-up, plans to fight methane with seaweed.

In Tasmania, the most southerly part of Australia, a few corrugated-iron sheds house Sea Forest's laboratory. "This seaweed has the power to radically reduce global methane emissions," CEO Sam Elsom told The Sydney Morning Herald. Asparagopsis armata is one of two seaweed species with an extraordinary ability to cut the amount of methane that comes out of animals. The effect is so dramatic, the scientists who made the discovery thought their equipment must be broken. Elsom calls it "one of the most amazing climate-change discoveries of the decade".

From clothes to climate

An unlikely eco-hero, Elsom was still a fashion designer in 2017, with his own label in Sydney. But he's also an entrepreneur, and when he learned about the seaweed-methane connection, he began investigating and was told to "call Rocky".

Rocky De Nys is a seaweed biologist at James Cook University, in North Queensland. Soon, the two were talking regularly. Elsom says: "I couldn't even speak the same language. I was scribbling like a maniac in my book, then googling the terms later. He was just so generous. He treated me like a peer." Elsom learned a lot — including that the two most important seaweed species for methane reduction are native to Australian waters.

Elsom's fashion industry connections led him to Stephen Turner, a venture capitalist with whom he founded Sea Forest in 2018. The company is growing, but Elsom and Turner choose their investors carefully. "It was always about climate change, not making huge profits," Elsom says. Today, Sea Forest is worth more than A$40 million (€25 million).

Super seaweed

With no need for land, freshwater or fertilizer, seaweed is almost a zero-input crop. It's grown on ropes that are lowered into the sea. After eight weeks, the ropes are pulled out. With a tiny seaweed supplement (of one per cent or less) in their diets, ruminants produce virtually no methane. But how do you get cows and sheep to eat seaweed? The essential compound, bromoform, is oil-soluble, so De Nys created seaweed "smoothies" with canola that are added to the feed. The animals appear to enjoy it — or at least don't seem to notice it.

With more proof-of-concept trials taking place, the early results are very promising. Elsom, however, knows they're still at the beginning: "We're on the journey but won't be there until we're feeding hundreds of thousands, even millions, of cows."