The best carbon capture device is the ocean, and for the last 10 years or so huge amounts of free-floating sargassum seaweed have grown in warm ocean waters around the world. Nobody is certain why the sargassum has appeared in such volume lately, but it's plausible to speculate that increased CO2 in ocean water plays a role. As far as I can see the only remotely efficient way to sequester carbon at scale is to leverage the ocean by gathering the seaweed and dumping it on marginal or desert land, both to trap the carbon and fertilize the soil, thus promoting additional carbon-binding plant growth.
> Nobody is certain why the sargassum has appeared in such volume lately
For the record 2025 volumes specifically, the ABC article notes that sudden phosphorus flushes as a result of multi-year drought-hit watersheds finally being flushed out likely contributed. Ocean ecology at scale is usually highly correlated with nutrient density.
As a layman on this topic, but assuming the gathering requires fossil fuel and probably lots of it given the scale, is it feasible to do the gathering in a net negative carbon way?
I feel like anything I hear about that teases net negative sequestration at scale eventually falls apart or is found to be akin to a perpetual energy machine that eventually is debunked.
