The hope and hype of seaweed farming for carbon removal

This article is from The Spark, MIT Technology Review’s weekly climate newsletter. To receive it in your inbox every Wednesday, sign up here. Say, theoretically, that a pipe in your bathroom springs a leak. Bad situation, right? The good news is that there are pretty much only two things you need to do: turn the…
The hope and hype of seaweed farming for carbon removal

In the same way, there are two major things we need to do to address climate change. We need to cut emissions—for example, by slowing down our use of fossil fuels. That’s akin to turning off the water tap. Then we’ll need to mop up the spill—that’s carbon removal, processes that aim to pull carbon pollution out of the atmosphere. 

There’s a problem with the second part of this plan: our box of cleaning supplies is a bit bare. Researchers and startups are working on it, building demonstration projects for direct air capture and planting trees all over the world. In addition, a growing number of ventures are turning to the oceans that cover two-thirds of our planet. There’s huge potential to store carbon there. 

But there are questions too, and a new study lays out some problems with seaweed farming, one commonly-suggested technique for ocean-based carbon removal. So for the newsletter this week, let’s dive into carbon removal in the ocean: what is it, why are so many people so interested in it, and what’s standing in the way of us using a bunch of seaweed in the ocean as a giant carbon sponge?

The seascape

Carbon removal has become an essential piece of our response to climate change, as the UN’s climate change committee pointed out in a report last year. Estimates of exactly how much carbon we’ll need to remove vary, but the consensus is that it will need to top a billion tons annually within the next few decades if we’re going to keep warming below 2 °C over preindustrial levels and avoid the worst effects of climate change.