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Millimeters That Matter: The Sea Level Rise Threshold Coastal Wetlands Can't Survive · How To Protect The Ocean

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  Sea level rise. It's a term that we all hear and we're supposed to be afraid of it,
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  but we don't really see it on a regular basis.
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  It's really hard to believe somebody who's saying,
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  hey, you know what? Sea level's rising and it's a real problem.
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  And I'll be like, well, how much is it rising?
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  And they're like, you know, a couple of millimeters every year.
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  What? A couple of millimeters?
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  That doesn't make sense. Why should I be worried about a couple of millimeters?
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  And today's episode, we're going to talk about the effects of those couple
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  of millimeters.
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  per year increase and how that's increased over time,
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  the rate of the those millimeters,
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  how it's increased over time, and why we should be worried about it
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  and how habitats are adapting to it in an era of climate change.
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  That's what we're gonna talking about on today's episode of the How
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  to Protect the Ocean podcast. This is the podcast where you find out what
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  you want to know about the ocean,
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  ocean news, ocean updates, ocean science,
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  ocean conservation, all these wonderful topics that we can talk about.
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  I'm your host, Andrew Lewin. I'm a marine biologist and a science communicator.
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  I love to talk about the ocean.
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  I've made a my life's mission to be able to talk to you about things that happen
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  in the ocean so that you can understand the people,
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  like and get to know the people and the projects that they're working
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  on to really find out, you know,
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  how we're doing with ocean. And sometimes it's just to calm that ocean anxiety,
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  sometimes and the climate anxiety,
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  once we know.
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  People are working on something and we can talk about it to our friends and family.
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  So that's what we're here to do.
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  So hit that follow button on your favorite podcast app that you're listening
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  to this to and and enjoy the show.
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  So today we're going to be talking about sea level rise because sea level rise
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  has an effect on coastal habitats.
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  And all week we've been talking about coastal habitats,
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  in particular mangroves and marshes.
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  And you're probably wondering like why these two sp specific areas,
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  these coastal habitats, is because
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  We had Adam Langley, who's a who's a professor and he focuses on nutrients
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  and he focuses on how habits, coastal habitats,
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  in particular mangroves and and marshes in Florida and the southern East
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  US perform and adapt to how things are happening with nutrients and
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  how things are happening with the environment in terms and especially within
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  sea level rise. And because you know these all these areas they
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  They are able to adapt to their systems a lot of times,
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  right? So the way these animals work is,
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  or the way these habitats work is that they build up on their soil.
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  So a tree will grow, like say a mangrove tree or a marsh will grow.
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  And then those plants eventually die.
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  They go into the soil, they break down into the soil,
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  they create more soil, and then that gets compacted on top of each other.
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  And the soil just builds and builds and builds.
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  And it'll solidify.
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  that area the nutrients get get up taken into those those trees or
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  the marshes and then everything else is kind of like packed in like this waterlogg
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  soil because it's along the coastline and so they can handle
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  the the salinity because that's what they're doing.
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  Marshes are also called salt marshes and mangroves are known to
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  be coastal coastal plants and coastal habitats that can handle this type
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  of this type of environment and they will just build on top and on top
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  of each other now with
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  Rising seas, they will build that that rising sea will build millimeter
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  by millimeter by millimeter. Now in 1990,
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  the rate was around two and two point three millimeters per year.
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  That's how much the the sea was rising.
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  Three decades later, now we're looking at about four and a half millimeters
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  per year. So that's increasing the rate by almost double or more than double,
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  or actually almost double. And so we're getting to a point where,
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  at some point.
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  the rate at which the soil is gonna pack on and these mangroves can keep
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  up with sea level rise is going to get even and and the sea level
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  is gonna take over. It's predicted by 2050,
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  I believe, to go over the amount,
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  the six point one millimeters of rate,
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  which is more than what a mangrove and salt marshes can compact the soil,
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  that that rate.
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  The rate of sea level rise is going to outpace the rate of building up that soil.
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  So they can't avoid sea level rise by going up.
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  So what do you do? There's another mechanism,
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  the way these animals or the way these habitats will move,
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  these plants will move. They will move horizontally.
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  So if you can't move vertically,
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  they'll move horizontally. And if they can't move vertically,
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  they're eventually going to start dying in areas where this rate is going up.
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  But where they can move is they can move vertically,
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  they can move over.
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  And I think that's where it it becomes a really important thing to look
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  at because once you start moving over,
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  now you you're like, well, how can they move over?
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  How come they haven't moved over before?
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  So mangroves and salt marshes have a limit,
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  a latitudinal limit. It means they can only go to certain that they're usually
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  in warmer environments. So when they go north,
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  they're gonna die based on the freezes.
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  But as those freezes let up,
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  those mangroves will continue to move forward.
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  They're always trying to push.
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  They're always trying to make way to build a bigger habitat.
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  But they're they're limited by the amount like by the freezing that happens
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  and by the weather. So if that temperature in a warmer environment is
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  not going to kill them, then they're going to just continue to to move over.
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  So I think there's a couple of things within here to really understand.
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  i when we when we're talking about this stuff.
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  You know, as I mentioned, we're looking at a tipping point of,
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  roughly once once the sea level rise passes roughly 6.1 millimeters per year,
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  mangroves generally can't build the soil that fast,
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  Fast enough to keep up and keep their heads literally above water.
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  And NASA's own sea level data shows that the global rate has already reached four
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  and a half millimeters per year and is and it continues to climb.
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  So it's gonna get there. We're actually closer than
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  we ever have been, than we were in the 90s.
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  And of course, the second method is to is for the marsh or mangrove to move.
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  So it's to shift landward as this as the shoreline behind it floods.
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  So the the idea is that as this kind of grows,
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  as the sea level kind of overtakes those mangroves,
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  they're going to move in and they're going to move out.
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  Or they're going to move over.
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  So it really just depends on what how what like what's built behind them
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  to allow them to move and where they can go
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  in the future. And I think that's interesting.
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  the Blackwater National Wildlife Refuge is in in Maryland,
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  which is just around Chesapeake Bay,
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  has lost more than 4,000 acres of marshland,
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  nearly half of its historic wetland since it was established in
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  the the projections are pointing to as much as three feet of sea level rise
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  in Chesapeake Bay by 2100, which is to be honest,
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  it's not that far off. We're already in 2026.
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  You know, it seems far off, but it's actually not that far off to get to that level.
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  It's enough to submerge almost all the refugees remaining tidal marsh
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  if nothing changes. Now, this doesn't really necessarily mean that it's
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  not going to adapt, These habitats have adapted for you know hundreds
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  of thousands of years. And so in 2013,
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  refuge biologists Matt Wilbeck and colleagues published
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  the Blackwater 2100 strategy.
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  And it's built on it on one insight that marshes have always survived rising seas
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  by moving inland. So away from the coast and moving inland.
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  So as those the rising seas get higher and higher along the coastline,
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  the marshes are going to get taken over,
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  but they're also going to move inland,
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  towards more towards inland. And they've always survived that way.
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  So what they're what the managers were thinking during this Blackwater Hunter
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  strategy is like, how do we make sure that they can actually move inland?
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  It's been developed. There's there's a lot of development that's been going
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  on since there.
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  So they're gonna have to make sure that they can make way and clear the
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  way for this movement to happen,
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  and not have like not move in towards a fixed line,
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  And so the plan identified the migration corridors.
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  So they were gonna have specific c corridors,
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  so roughly 2,300 potential acres along the Nanticoke River
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  and roughly 3,600 potential acres along the Corsi Creek.
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  And that started using like conservation easements to keep that land open.
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  Paying landowners and farm and mostly farmers 40 to 60% of the property value
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  to keep it undeveloped rather than converting it.
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  So just part of their land, maybe not all their land.
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  And the thing is that like it's worked.
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  About 812 acres are protected along Corsi Creek and roughly 2,300 acres along
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  the Nanacoke, which is what they wanted.
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  And with about 5,000 acres still unprotected.
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  So they still have some work to do in certain areas.
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  So it's not necessarily a finished story.
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  It's not a victory right now. And scientists and conservation managers
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  are still involved in that marsh migration because that migration might
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  not always outpace the current state of sea level rise.
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  and there may not be always like these willing landowners to sell what they want,
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  or those landowners may need to develop that land at some point in time.
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  You know, they may be forced to do so.
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  So it's a real working model and it's proof that like if you give wetlands room
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  to move, that works. But it's something like the community,
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  can actually plan around and fund and not just hope for.
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  So it's one of these things where it's like,
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  yes, these animals these these habitats,
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  I keep calling the animals, these habitats can build up.
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  And they are a place for refuge for a lot of other animals in the sea as well
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  as on land.
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  So having that buildup is great.
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  But if it outpa if that sea level rise outpaces the buildup,
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  which it's going to at some point,
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  then and some point sooner than later,
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  then it's gonna move vertically.
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  And that move is gonna go move towards inland.
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  So it's up to managers and people who are looking after the coast to
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  not develop it with hard concrete pads or like a what they call hardlining coastal
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  areas. You gotta keep those soft,
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  you gotta keep those green so that these these habitats can move inward.
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  and move around and they can get away from the sea level rise,
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  which is happening more than often than not.
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  And for sea level rise, you just don't know like people often say,
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  like, how does work? Part of it is melting sea ice that that raises the water.
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  The other part is that it's so warm,
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  the water expands and it has to has nowhere to go.
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  So it goes up. And yes, it might seem like it's small in millimeters,
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  but it's having an impact right now as we speak on marshes,
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  on mangroves and other coastal habitats.
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  We just use those two as examples.
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  but if you want more information,
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  you can go to the interview I did on Monday in Monday's episode and
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  and and listen to that because that's where Adam Langley talks all about it,
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  gives you more detail. And I think it's important to understand that seal
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  of rise is a problem. It's a threat,
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  even if it's millimeters, and we need to have we need to do better with that.
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  So that's it for today's episode.
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  if you have any questions or comments,
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  you can hit me up on either Spotify has a comment section,
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  or you can go to the show notes.
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  I have all my socials in there.
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  I want to 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, Andrew, and have a great day.
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  We'll talk to you next time in happy conservation.