An innocuous-looking dark brown marine algae could help in the battle to solve the world’s climate crisis. Scientists believe that the seaweed’s ability to absorb vast amounts of carbon dioxide and its fast rate of growth can help tackle climate change. It can transform the way we farm both in the oceans and on land and de-acidify the oceans. In short, seaweed farming could be one of our major allies to avert the worst effects of global warming.
Seaweed Farming Is Simple But Has Immense Benefits
The figures say it all. Seaweed is believed to sequester as much as 200 million tons of CO2 each year globally. That is equal to the annual emissions of New York state.
The aborigines in Australia have been using seaweed for as many as 45,000 years, though for a different purpose. The Chinese have been cultivating seaweed for around 1,700 years. People living along the coast used the giant algae initially as animal feed and as a food source. But later, other uses were found, including nutritional supplements and industrial uses.
Today the country accounts for around 60% of global production, but other countries are waking up to a different benefit of seaweed farming; to reverse the spike in CO2 that has contributed to global warming in the seas and oceans.
The red seaweed contains nearly 47% protein by dry weight, but other varieties also have a high amount of iron, magnesium, calcium, a hefty dose of vitamin B12, and other equally high nutrients. It is a rich source of vitamins, antioxidants, and mineral salts, especially iodine.
Seaweed farming has registered the fastest growth in the aquaculture segment, and the pace shows little indication of slowing down soon. Seaweed farming registered a 200% growth rate in Alaska in 2019 since its beginning in 2017.
Seaweed farming requires small sites of a mere few acres. Farmers use suspended longlines to save space by using the total water column. The process is simple, economical, and the environmental benefits are immense.
Research has proved that seaweed farming could have essential uses beyond its traditional ones as food, and in sourcing nutrients. It could be our greatest ally in the fight to control the pollution in our oceans and reverse the effects of global warming.
Seaweed farming doesn’t require any fertilizers as the algae sources all its nutrients from those present in the oceans and through sunlight. This does away with the need for pesticides, clearing of forests, even as it provides alternate habitats for marine life while improving the quality of the surrounding water in the process.
Sequestering Carbon Efficiently Through Seaweed Farming
Seaweed farming can help in sequestering carbon more efficiently than other coastal flora such as seagrass and mangroves. While they store CO2 closer to the store by burying it in soil underwater, seaweed thrives in habitats that are more eroded and rocky, and in deep-sea sediment deposits. This distance from the shore ensures that the CO2 is not easily released back to the atmosphere.
Around 173M metric tons of carbon dioxide can be sequestered through seaweed every year, 90% of which occurs through dissemination to the open seas.
The oceans continue to absorb the maximum amount of carbon compounds to maintain a balance of CO2 in the atmosphere. But this role as the world’s greatest carbon sink is in danger of being disturbed as humans are producing more CO2 through fossil fuels than the oceans can possibly absorb. This causes the acidification of the oceans, destroying every form of ocean life from fish to coral reefs.
It is here that seaweed has a role to play. It grows rapidly and takes out a large volume of carbon from the oceans. A recent study this year in China has found that seaweed farming leads to an increase in the pH level by 0.01. The normal pH level of surface water in the oceans is about 8.2 but has declined to 8.1 in recent years, which is an alarming 26% increase in the relative acidity of ocean water.
Seaweed farming is also a clean and convenient way to remove heavy metals plus other forms of coastal pollutants that are formed from runoff. But seaweed that is exposed to heavy levels of such pollutants will not be fit for human consumption, but these could be natural and inexpensive solutions to maintain the health of the marine ecosystem.
This form of seaweed farming with rapidly growing kelp can serve another purpose of restoring the habitats of fish and other forms of ocean life and also offer a safe and clean refuge for such species.
Runoffs continue to be the largest cause of pollution, primarily as it is not easy to trace. While industrial sources such as pesticides and fertilizers form the bulk of the pollution (around 80%), vehicles and septic tanks also add to it.
Other pollutants also get added to the runoffs. It increases the levels of phosphorus, nitrogen, and nitrates that cause dead zones in the oceans where oxygen levels are too low to sustain ocean life. It also causes algae to bloom.
There Are More Benefits To Farming The Plant
Seaweed farming can help remove these nutrients and also simultaneously produce oxygen, thus contributing in two ways by both dealing with the cause plus having a positive effect on the environment.
The Gulf of Mexico continues to be among the worst affected of the oceans, with 7,829 square miles of the dead zone with low oxygen levels. While only 9% of the total area here is considered suitable for seaweed farming. But even cultivating in just 1% of this total area is enough to reach the pollution reduction targets in the area.
While there are some potential drawbacks of seaweed farming, the advantages far outweigh the downsides. For instance, there is the risk of unregulated production affecting the sunlight that seeps through, affecting the species that depend on photosynthesis.
There is also the question of transportation, drying, and transforming the seaweed into biofuel, food, or bio-plastics that could expend resources. There is also the possibility of seaweed sucking out excess nutrients.
But the positives continue to be overwhelming. The ability to deal with nutrient pollution may mitigate the cost of treating the wastewater. But the potential of seaweed cultivation to ease the pollution levels in the sea and mitigate climate change remains a huge possibility.