In recent years, coastal regions around the Caribbean, Gulf of Mexico, and West Africa have been grappling with an environmental menace invasive Sargassum seaweed. Once a vital part of marine ecosystems, providing a floating habitat for fish and other marine species, Sargassum is now overwhelming beaches, marine habitats, and communities in record amounts. This brown seaweed has transformed from an ecological boon into a serious threat to the environment, human health, and the local economy.
However, there's an even bigger global issue linked to Sargassum — it can release methane, a powerful greenhouse gas that speeds up climate change.
The Methane Emissions Link: Sargassum’s Decomposing Danger
While Sargassum is naturally occurring in the ocean, the seaweed’s uncontrolled growth and massive blooms have become increasingly frequent due to warmer ocean temperatures and excess nutrients from agricultural runoff. As the Sargassum washes ashore in overwhelming quantities, it creates a host of environmental and social problems. Beaches, once pristine, are now clogged with decaying mats of brown seaweed, which brings not only a foul odor but also a hidden climate threat: methane.
Sargassum’s rapid decomposition on beaches, particularly in anaerobic conditions (environments lacking oxygen), leads to the release of methane (CH₄). Methane is a greenhouse gas 28 times more potent than carbon dioxide (CO₂) in terms of its impact on global warming. As the seaweed rots in massive piles, it generates not just methane, but also hydrogen sulfide (H₂S), a gas that creates significant health hazards for local communities, contributing to respiratory issues and public health concerns.
The numbers are stark: 1,000 kilograms of wet Sargassum (which is up to 85% water) emits methane equivalent to 302 kilograms of CO₂, a significant contribution to greenhouse gas emissions. Considering the Caribbean alone sees millions of tons of Sargassum wash ashore each year, this translates into a serious methane emissions problem that most people are unaware of.
The Broader Impact of Sargassum
Methane emissions are just one part of the story. As Sargassum decomposes onshore, it also wreaks havoc on marine and coastal ecosystems. The seaweed smothers beaches, destroying important nesting sites for turtles and shorebirds. Underwater, dense mats block sunlight, choking coral reefs and seagrass beds, and creating low-oxygen “dead zones” that devastate marine life.
For the tourism-dependent economies of the Caribbean and Gulf of Mexico, the influx of Sargassum is catastrophic. Tourists are driven away by foul-smelling beaches covered in decaying seaweed, causing losses estimated at $120 million to $150 million annually. In places like Mexico’s Quintana Roo, governments are spending millions of dollars on removal efforts, only to see the seaweed return in greater amounts the following season.
Local fishing industries are also hit hard, as the seaweed entangles fishing nets, damages boats, and depletes fish populations. Overall, the combined cost of tourism losses, cleanup efforts, and damage to fishing industries could top $300 million annually.
Turning the environmental challenge into a circular economy opportunity
Harvesting Sargassum before it starts to rot, can stop methane from being released, and become a valuable resource instead of a climate problem.
Origin by Ocean is tackling the Sargassum problem by developing a sustainable solution that not only prevents harmful decomposition but transforms Sargassum into valuable products through a biorefining process.
“By harvesting Sargassum and other harmful algae, we can help to reduce methane emissions and clean coastal areas and also create sustainable, value-added products that contribute to the bioeconomy. Our approach is to turn this crisis into an opportunity, aligning with global climate goals while helping coastal communities", summarizes Heikki Heiskanen, COO of Origin by Ocean.
Origin by Ocean is tackling the Sargassum problem by developing a sustainable solution that not only prevents harmful decomposition but transforms Sargassum into valuable products through a biorefining process.
“By harvesting Sargassum and other harmful algae, we can help to reduce methane emissions and clean coastal areas and also create sustainable, value-added products that contribute to the bioeconomy. Our approach is to turn this crisis into an opportunity, aligning with global climate goals while helping coastal communities", summarizes Heikki Heiskanen, COO of Origin by Ocean.
Calculations indicate that Origin by Oceans planned facility in the Caribbean, designed to collect 100,000 tons of Sargassum annually, would prevent the release of 30,000 tons of CO₂-equivalent emissions. This reduction is greater than the emissions from burning 46,000 barrels of oil.
Origin by Ocean’s process extracts valuable compounds from Sargassum, such as biopolymers, antioxidants, and minerals. The compounds have broad commercial applications and the sustainable business model supports local economies while reducing the environmental impact of the seaweed blooms.
The economic and environmental benefits of this approach are clear: reducing methane emissions while also tackling the environmental damage Sargassum inflicts on coastal ecosystems.
Each ton of Sargassum harvested prevents the release of significant amounts of nitrogen and phosphorus back into the oceans, further protecting marine biodiversity.
Addressing the Sargassum crisis and its connection to methane emissions requires innovative, large-scale solutions. It is clear that this invasive seaweed isn’t just a local nuisance but a contributor to global climate change.
Sargassum, a seemingly small and local issue, is revealing itself to be a key part of the global conversation about climate change.