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This episode of SciShow is brought to you in partnership with Gates Notes. If you’re a college student, you can head to to download a free e-book of “How to Avoid a Climate Disaster” by Bill Gates from October 24-31, 2021.

Although plants are great carbon-removing tools, plant agriculture produces a significant carbon footprint. So, some researchers think we could turn to the oceans (specifically, seaweed) to help reverse some of the effects of climate change.

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Gates, B. (2021). How to avoid a climate disaster: the solutions we have and the breakthroughs we need. First large print edition. New York: Random House Large Print.

This episode of SciShow is brought to  you in partnership with Gates Notes.

If you’re a college student you can head  to or click the link in the description to download a free ebook  of How to Avoid a Climate Disaster by Bill Gates from October 24th to Oct 31st, 2021. [♪ INTRO]. Carbon dioxide did not create  the climate crisis on its own.

Humans have been releasing it and other  greenhouse gases into the atmosphere way faster than Earth’s natural  cycles can pull them out again. And a lot of those natural cycles depend  on plants to remove carbon from the air. But even though plants are some of our  best carbon-removing tools, the way we’ve been growing them for food produces a  pretty significant carbon footprint.

So some researchers have turned to  the oceans. Introducing seaweed as a staple in our agricultural  industry could help reverse some of the effects of climate change. And while no one solution  is likely to save the world, these little ocean organisms have big potential.

The thought of agriculture might  lead you to picture some beautiful farms with rows of green,  carbon dioxide-consuming crops. But agriculture is a significant  contributor to the climate disaster. The US Environmental Protection  Agency estimates that in 2019, 10% of US emissions originated in agriculture.

Making fertilizer and managing  soil quality requires energy. And livestock cattle burp up  methane, which is a more potent greenhouse gas than CO2. Not to  mention, farm equipment needs fuel.

Now, I like eating, and I bet that you do too. So eliminating agriculture  isn’t really on the table. But there are some creative ideas out there  for how to improve its climate impact.

One of them is growing in the ocean as we speak. Seaweed-based food systems have the  potential to leave a much smaller carbon footprint than the land-based  food systems we rely on today. Now seaweed can refer to a huge  array of different organisms, including plants and algae,  but they’re all ocean-based photosynthesizers that use  carbon dioxide to produce energy.

In general, seaweed and  seagrasses can take in more carbon compared to land plants. And they can store two times as much carbon  per square mile as a tropical forest. And there’s extra advantages to these  marine organisms growing in the ocean.

CO2 dissolves in seawater leading to  the formation of carbonic acid, which decreases the ocean’s pH. This ocean acidification is  a huge threat to marine life, particularly corals and shelled animals. But seaweed uses that CO2 for photosynthesis, and can pull it from the water, not just the air.

Several studies have shown that  growing seaweed can raise the pH of the surrounding water during the day,  when photosynthesis is taking place. By preserving the organisms that  would otherwise be more susceptible to acidification, seaweed helps  maintain ocean biodiversity. All this adds up to seaweed  being a pretty sustainable crop.

So the question becomes what  are we gonna do with all of it? Sushi rolls are great. But some researchers envision seaweed  taking a central role in our diets, maybe one day becoming a staple  crop alongside wheat or maize.

To that end, seaweed farms  are the fastest growing area of food production in the world. But it doesn’t have to be food for us. Because a lot of our crops go  into feeding our livestock.

In a 2015 study, researchers fed  cows a seaweed-based supplement which reduced the methane in  their burps by 99 percent! So we could cut emissions from cattle production just by feeding them a little seaweed. But seaweed’s agriculture uses go beyond  just growing and eating the seaweed.

We could use it as a better  substitute for synthetic fertilizers. Seaweed can be heat-treated to make  carbon-rich additives for soil. This seaweed biochar, short  for biological charcoal, is rich in nutrients and can  increase crop productivity.

And the process of making biochar releases  some gases that can be collected and used to make fuel, and  others that can be burned to produce the heat needed to make more biochar. That means components of seaweed  could be used to make biofuel, at least on a small scale, but also help  sustain itself as a source of fertilizer. Now, seaweed is not going to  replace all of our fuel supplies.

A 2017 analysis reported that we may  only be able to grow enough seaweed to produce 10 percent as much energy as  what we currently get from wind farms. That’s because we can’t just build as many seaweed farms as we want, wherever we want. They need specific temperatures and nutrients  that aren’t found all over the ocean.

Even if we could, the seaweed  probably wouldn’t grow as well in colder waters, so it  wouldn’t take in CO2 as efficiently. This means it’s more reasonable  to limit seaweed farms to specific locations where they’re going to thrive. So no, seaweed can’t save  the world.

Not by itself. But the odds of finding a  single solution to all of our climate change problems are not good. Seaweed is one of the many very promising tools that we can use together to make  a dent in cleaning up our mess.

Thank you for watching! If  you’re interested in learning more about climate change  and you’re a college student, you can head to  or click the link in the description to download a free ebook  of How to Avoid a Climate Disaster. It’ll be available from October 24th to 31st 2021.

The ebook explains how we could reduce  and eliminate greenhouse gas emissions from changing the ways we grow things  to the ways we make things and travel. Thank you again to Gatesnotes for  sponsoring this episode of SciShow. [♪ OUTRO].