This episode of SciShow is brought to you in partnership with Gates Notes.
If you’re a college student you can head to Gatesnotes.com 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 Gatesnotes.com 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.
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