By Mary Kate McCoy
July 18, 2023
New study reveals seaweed’s hidden climate benefits
5 min
To learn why, Conservation News sat down with the study’s lead author Albert Pessarrodona, a post-doctoral researcher at Conservation International.
Conservation News: What did your research find?
Albert Pessarrodona: For years, we’ve suspected that seaweed is an underappreciated ally in the fight against climate change. Our research set out to examine that potential. We looked closely at seaweed forests, like those made up of fast-growing kelp, and found that the conservation and restoration of those forests around the world could help keep roughly 36 million metric tons of carbon out of the atmosphere. That’s roughly the same amount of carbon captured by between 1.1 and 1.6 billion trees.
But not all seaweed forests play an equal part in sequestering carbon. Location makes a big difference. Seaweed forests in temperate and polar regions absorb more carbon than those in warmer, tropical waters. That’s because cool, nutrient-rich waters support the tallest forests, which are better at absorbing carbon.
Given the right conditions, could seaweed be a climate game-changer?
AP: It’s complicated. We know seaweed forests absorb large amounts of carbon, but to make a difference in terms of climate change that carbon needs to be kept out of the atmosphere for a long time.
Again, location matters. Like most plants, seaweed absorbs carbon as it grows. Then, when it dies, some of it can drop to the bottom of the ocean or be buried into layers of sediment. That’s where the carbon can be sequestered for up to hundreds of years. Seaweed forests growing near the deep ocean, such as in oceanic islands and canyons, or near fjords, where lots of sedimentation occurs, have greater potential for carbon sequestration.
Until now, it has been difficult to quantify the amount of carbon seaweed forests lock away because of the challenge of measuring carbon in hard-to-reach deep sea areas. To help, we created a framework as part of this study that categorizes coastlines based on their carbon sequestration potential — and identifies areas that are among the most critical for conservation. For example, Chile’s coastline, which has many fjords, cool water and prolific seaweed forests, is going to have greater carbon sequestration potential than a coastline in the tropics that doesn’t have the same conditions.
How can these findings be applied to marine conservation?
We hope that this research will bring attention to the importance of seaweed forests — from storing carbon to increasing biodiversity to supporting fish habitats worldwide. There’s no silver bullet when it comes to curbing climate change — it’s an all-hands-on-deck effort that needs as many solutions as possible. Our research proves that protecting and restoring seaweed forests belongs in the world’s climate toolkit.
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