Ocean carbon sequestration: The climate solution hiding in seaweed forests

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Seaweed forests may be one of the planet's
largest natural climate allies, yet

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most are invisible to climate policy,
unprotected by conservation laws and

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missing from carbon accounting entirely.

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While mangroves and seagrasses get the
spotlight, kelp forest and other seaweed

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habitat are quietly doing the work without
recognition, protection, or funding.

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So how can one of the most productive
ecosystems on earth be almost

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completely ignored in climate solutions?

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We're gonna be talking about that
on today's episode of the How

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to Protect the Ocean Podcast.

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Let's start the show.

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Hey everybody.

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Welcome back to another exciting episode
of the How to Protect the Ocean Podcast.

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I'm your host, Andrew Lewin, Marine
biologist and science communicator

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here to tell you what's happening with
the Ocean, how you can speak up for

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the Ocean, and what you can do to live
for a better Ocean by taking action.

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And you're probably wondering
right off the bat, Andrew,

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what's going on with your voice.

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If you listen to this podcast
for any number of times,

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this is not my normal voice.

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If you're new here, this
isn't my normal voice.

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I was at a hockey tournament.

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I coach hockey for my
youngest and she's in new 18.

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We had a great tournament.

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We got to the semis, and I lost my voice.

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It just happens.

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This is what happens.

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I tried to do a recording
beforehand, ran outta time, but

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now I am doing this recording
because this is an important topic.

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We're talking about seaweed,
not seagrasses, which

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I've talked about before.

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I've talked about seaweed before in terms
of kelp, but we're gonna talk about a

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number of different things of seaweed,
and I just want you to think, although I

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may not mention every species of seaweed
or really a lot of species of seaweed.

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I'm gonna be telling you just
about seaweed in general and

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how important it is in climate
solutions in blue carbon capture.

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Now, a lot of the times you're going
to hear about carbon capture in Canada,

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you're gonna be here all around the world.

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A lot of oil and gas execs and
supporters like to use the fact

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that they use carbon capture.

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Well, carbon capture can be done
well except if you're putting

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out so much greenhouse gases.

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Carbon capture does not and has not
been able to keep up with the demand.

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But we do have natural
sources of carbon capture.

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Trees and forests are one, but they
do not have the ability to take in

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as much carbon as you would think.

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When you have seagrasses, mangroves,
kelp forest is a seaweed and other

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seaweed, you would be able to
capture four to 10 times more carbon

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than any other tree on the planet.

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So.

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Why do we not focus on that?

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Why are we not focusing on rebuilding
or protecting seagrasses, mangroves

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and then the seaweeds like kelp
so that we can better protect our

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planet against climate change?

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That is the question that we're
gonna be talking about today,

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especially focusing in on seaweed.

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Kelp and other seaweed.

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The first thing we should do
is define what blue carbon is.

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Blue carbon refers to the
carbon captured and stored by

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coastal and Marine ecosystems.

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So traditionally it includes, like
I said, mangrove, salt marshes

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even, and seagrass meadows.

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These systems trap carbon in sediments for
centuries to millennia, which is great.

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They are recognized in climate frameworks
such as National Carbon Inventories.

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but there's a major carbon capturing
ecosystem that is missing from

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that list, and that is seaweed.

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Seaweeds, including kelp forest and
macroalgae grow incredibly fast, and a

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lot of times people don't like seaweed.

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We have to have a lot of problem with
seaweed when we put our feet into the

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Ocean, if we're away on a trip to a
tropical paradise, we see seaweed.

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We're like, ah, I don't
like seaweed on my feet.

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It feels gross.

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But it's a naturally occurring thing.

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It's something that
should be in the ocean.

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Now sometimes, it's a lot and sometimes
it's not so much, but it's always

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there and people don't like it.

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Oftentimes in resorts and in
anywhere where there's tropical

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areas where there's a high tourist
attraction or a high tourist usage,

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you'll see dredging of the seaweed.

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And dredging of the beach because
people don't wanna see seaweed,

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so they'll clean up the seaweed.

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But it's a natural occurring It's
required to be there in the ecosystems

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because part of the ecosystem, and it does
a really good job at capturing carbon.

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The only thing is, is like even though
they capture massive amounts of carbon

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dioxide through photosynthesis, much
of their carbon isn't staying in that

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same area like seagrasses or mangroves.

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When seagrasses or mangroves take
in carbon through photosynthesis,

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they actually put it into the
sediments right below where they are.

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With algae, algae can break off and
it can float across oceans through

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circulation patterns and so forth.

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And so the fact that they don't
stay there is very difficult to

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measure how much carbon is actually
being captured in that one area.

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That carbon can sink as it floats away.

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A carbon can sink into the deep sea and
it can be stored for hundreds of years

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in the deep sea, which is fantastic
to have as it's naturally occurring.

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Seaweed does not store the carbon
place like mangroves, but it exports

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carbon across the ocean, which
challenges how we measure and value it.

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Why do seaweed meadows
matter beyond carbon?

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We'll seaweed habitats like
kelp forests, they support fish

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invertebrates and juvenile fish and
all different types of life stages.

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They act as a coastal buffer
against waves and erosion.

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They improve local water quality.

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Many of the coastal fisheries
depend on kelp associated species

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as another seaweed species.

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So this is something that is huge.

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If kelp forests disappear, entire food
webs unravel, not just carbon pathways.

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Entire food webs unravel.

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So the central problem that the recent
scientists have uncovered is that most

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seaweed ecosystems lack formal protection.

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Marine protected areas often
don't consider kelp specifically.

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Seaweed is excluded from many
blue carbon policies because it

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does not store carbon locally.

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So it's very difficult to measure the
local carbon storage effect because

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seaweed is transported across oceans.

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So climate finance mechanisms rarely
apply to macroalgae because even though we

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know the science of seaweed, it matters,
but the policy hasn't caught up to what

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seaweed could do for the climate system.

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So climate is only now uncovering the way
that carbon is stored in seaweed and how

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much of it is actually stored in seaweed.

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And that's through improved
tracking of carbon export pathways.

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So the fact is we start to be able to
see how carbon is stored within seaweed

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and how it's traveled across the way.

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Now it's a number of different ways
that we can see what's happening.

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Like we better model deep
sea carbon sequestration.

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We better model ocean currents.

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We recognize that ignoring seaweed
underestimates ocean carbon uptake,

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and of course, growing calls to
expand the definition of blue carbon

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helps include different pathways
such as seaweed in this carbon.

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Now, some of the ways that we can
track carbon is very interesting.

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So we have better ocean centers
and autonomous platforms.

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So autonomous gliders, floats
and underwater vehicles now

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carry biogeochemical sensors.

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So we can see where carbon is
stored and we can also track

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where that carbon is coming from.

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So it's not just, this is Marine carbon.

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It's coming from, this is a
carbon that was coming from

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specific species of seaweed.

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That's how good we've got it.

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So these instruments that we have,
like these autonomous gliders, the

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floats, the underwater vehicles,
these instruments continually measure

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dissolved carbon, oxygen, nutrients.

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They operate for months, even
years, in some cases across

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coastal and offshore water.

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So these are huge, huge things.

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So seaweed carbon does not
just stay where it grows.

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These platforms let researchers detect
carbon rich water masses moving offshore.

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Something that ships alone
could not track this reliably.

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So you have to have something like
this, some sort of improved systems

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like we do, like I just mentioned.

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Now of course we can use stable isotopes
to better help distinguish seaweed

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derived from phytoplankton carbon.

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Biomarker compounds unique to
macroalgae can now be traced

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in sediments and deep waters.

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So scientists can now say with far more
confidence that this carbon came from kelp

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and not that just this carbon is Marine.

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Huge, huge aspect of that.

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Now of course we can also use
particle tracking and ocean balls.

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This is something that I was
going to be doing for my PhD. If

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I was gonna go through with it.

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We were gonna be tracking particles within
a network of Marine protected areas to

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see how these biological systems are
connected within the marine protected area

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network to make sure that all the biology,
all the larval stages will actually go

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to another part of the Marine protected
area to ensure that is protected.

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So these high resolution circulation
models simulate how seaweed fragments

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drift and sink particle tracking
models follow carbon pathways

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from coastlines to the deep sea.

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And models are validated with real world
sensor data that I just discussed before.

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We can also track kelp forests
and kelp through remote sensing.

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So any kind of seaweed extend or
productivity satellites can map kelp

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canopy extent and seasonal growth.

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So we can see the growth or even a
retraction of that habitat from a

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number of different disturbances.

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And then of course, long
term data sets show how much

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biomass is produced each year.

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So you can't just estimate carbon
export without knowing how much

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seaweed exists in the first place.

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So these satellite imagery are able
to close this major accounting gap.

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And of course now linking the export
to long-term storage sediment cores

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that these big long tubes that go
into the sediment, right into the

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sediment, they can get a number of
different layers depending on the

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size of the core reveals that macro
algal carbon is buried at depth.

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And then genetic and chemical
markers linked, buried carbon

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back to coastal seaweed.

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If you have the same markers, you can
track it back to, like from the depth

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in like say the middle ocean to a coastal
area that's nearby or even further.

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And it's really cool to
be able to have that.

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So the fact is, without these systems,
we didn't know how much carbon the

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seaweed was actually bearing into
the deep sea or around the ocean.

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And now that we have this, we know
that we're underestimating the carbon

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capture and we know that there's more,
and we're getting closer and closer to

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fully understanding how much the seaweed
is not only capturing carbon, but also,

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that is dispersing it across the ocean.

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So here is what really needs to
change when we talk about seaweed.

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We need to expand blue carbon definitions
to include macroalgae, which is seaweed.

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Protect seaweed habitats through
targeted marine protections, like

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marine protected areas of kelp habitats.

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And fund research into carbon
export and sequestration.

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This is something that's really
important 'cause we don't

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have a lot of knowledge in it.

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And include seaweed ecosystems in
climate and biodiversity planning.

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I can't stress enough how much
biodiversity is in like a kelp forest.

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It is something that is huge, is a part
of the ocean needs to be introduced and

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it needs to be shown how important it is.

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To be honest,

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doing this research was actually
surprising that kelp hasn't been included

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in more of these policies or seaweed
hasn't been included in more of these

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policies, I guess because of the way
it gets dispersed across the ocean.

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But I'm glad we're seeing more
progress to get it better.

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But as climate solutions become
more urgent, overlooking powerful,

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natural allies like seaweed is
a risk we can't just afford.

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The ocean is already doing the
work, but only if we let it.

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So we have to understand how the seaweed
works, how it is able to be dispersed,

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and what it could do for climate change
for us in terms of carbon sequestration.

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If we want real climate solutions,
we have to start paying attention

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to the ecosystems we have

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that we've been ignoring for a long time.

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This is something that
we've done for a while.

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We need to fund more research
in this, to understand this.

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The solutions might already be there.

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We just might not know that
they're there, and we may not

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know how we can play a role.

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So that's it for today

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talking about seaweed and climate
solutions and blue carbon.

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It's something that is very
important to fighting climate

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change, reducing climate change.

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So I encourage you to follow,
subscribe to this podcast.

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Make sure you support the podcast
not only for seaweed, but for

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seagrasses that we're trying to do.

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Go over to speak up
for blue.com/sea grass.

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We need to talk more about how these
systems are so important for blue carbon

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and for doing something for climate
change or to reduce climate change.

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And so going to speak up for
blue.com/seagrass Supporting the

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Seagrass podcast as crowdfunded.

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I'm an independent podcaster.

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I wanna bring more information to you.

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I need your help, so go to speak up
for blue.com/seagrass and hopefully my

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voice gets better when I start recording
this podcast after it gets funded.

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I'm sure it will be.

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This is temporary.

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Might be for one other episode,
but we'll be good in the long run.

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But I wanna thank you so much for
joining me on today's episode of the

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How to Protect the Ocean Podcast.

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I'm your host, angel Lewin.

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Have a great day.

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We'll talk to you next time
and happy conservation.