Could Europe's coastal wetlands address our climate change concerns?

euronews (in English)

From Ireland's salt marshes to the Netherlands' peatlands and Italy's underwater seagrass; Ocean investigates whether Europe's coasts could hold the answer to our carbon questions.

Transcript

00:00 When it comes to fighting climate change, we often think about planting more trees.

00:10 But coastal wetlands, like these salt marshes here in South Western Ireland, capture and

00:15 store carbon even better than tropical forests.

00:19 Are we overlooking a climate change solution that's right under our feet?

00:30 With every high tide, the waves of the Atlantic wash over Derrymore Island marshes.

00:37 It's more than a scenic view, it's a natural carbon sink.

00:41 A team from University College Dublin is here to study just how well these marshes help

00:46 remove carbon from the air.

00:50 Salt marshes are tidally inundated habitats, so they're low-lying.

00:54 And the plants that live here, they need to be able to tolerate the salty conditions and

00:59 also the water-louse conditions that actually make salt marshes good at storing carbon.

01:05 All plants capture CO2 to grow, but on dry land, they release most of that carbon back

01:10 into the air when they decompose.

01:14 Marsh grasses are different.

01:16 Saturated by salty water, they're less likely to break down, keeping their captured carbon

01:21 in the soil.

01:23 We dig half a metre down to find roots and stems that have been holding onto their carbon

01:28 for a century.

01:31 We're trying to really get a sense of exactly how much carbon is being stored in this habitat

01:37 and then we can propose different ways of managing these habitats so that they can continue

01:41 to store carbon.

01:43 Another key tool for this research is the eddy covariance tower, a sensitive instrument

01:48 that tracks the exchange of gases between the soil and the atmosphere, indicating the

01:53 actual amount of carbon the marsh is capable of storing.

01:57 What we calculate here is the fluxes of carbon dioxide and water vapour.

02:02 We are seeing CO2 uptake during the daytime because of photosynthesis and then carbon

02:07 dioxide emissions at night time because of plant respiration.

02:12 This thriving wetland is capturing more carbon than it's letting go.

02:16 But this only happens when conditions strike a balance - not too wet and not too dry.

02:23 When the systems get flooded, they really struggle to continue to work properly.

02:28 In the other extreme, if we drain the ecosystem for, say, agricultural use, that really detrimentally

02:33 affects the system and releases a lot of carbon.

02:37 If coastal wetlands deteriorate, they can turn from a carbon sink into a carbon source,

02:44 thus exacerbating climate change.

02:47 Coastal wetlands around the world are under threat by development, agriculture and also

02:53 sea level rise.

02:55 Within Ireland particularly, we have lost a lot of salt marsh habitat over the last

03:00 number of years, but also globally.

03:03 That's true as well, and it's true for mangrove forests and it's true for seagrasses as well.

03:08 Draining a wetland triggers the decomposition of organic matter stored over the centuries.

03:15 The Dutch polders are a good example.

03:18 Underneath these green fields in northern Holland is peatland, a type of wetland where

03:23 conditions stop plant material from fully decomposing.

03:27 At nearly five metres below sea level, water has to be pumped out continuously to keep

03:32 the land dry for dairy cows.

03:36 But this patch has to be re-wetted, and now typho plants, also known as cattails, are

03:42 sprouting from peatland submerged in about 15 centimetres of water.

03:47 Because the soil is no longer exposed to oxygen, it's not releasing nearly as much CO2 from

03:52 decomposing peat.

03:54 Aldert van Vieren, who's running this experiment, thinks this could be a greener alternative

03:59 to traditional dairy farming in the area.

04:04 Amount of carbon which is attached on one litre of milk produced on these meadows is

04:10 about the same emission as burning two litres of benzene, petrol, in your car.

04:16 The moment you re-wet, there is no carbon emissions coming from this area anymore.

04:21 But then you can't have cows running around and grass, so you see a different crop.

04:26 And instead of being a dairy farmer, I am now a fibre farmer.

04:33 The plant is naturally strong, flexible and resistant to rot.

04:37 Aldert van Vieren sees big potential for its fibres, from non-woven fabrics to greener

04:43 construction and packaging materials.

04:47 It's almost impossible to crank it like this.

04:49 You can try what you like, you can even stand on it.

04:52 So it has a very stable structure because of these cells and a sponge system in there.

04:58 And that makes it a good building material and a perfect insulation material.

05:02 And that's what we think will be the future of farming, these kind of things, making nice

05:08 building material for the city of Amsterdam in the background.

05:12 Possible financial incentives for cutting down emissions and restoring natural habitats

05:17 could help make this land use financially viable in the long term.

05:21 Plus new lightweight machines could propel wetland farming to a larger scale, turning

05:27 captured carbon into sustainable building materials.

05:31 This is made of just chopped kettle, layers on top of each other and as a binder we use

05:37 magnesium oxide.

05:38 It's not burning, it's self-supporting and it's an insulator.

05:42 And those cellulose fibres mixed with water gave you this kind of boards, just made from

05:48 pure plant fibres without any binder.

05:51 This is a hydromechanical binding.

05:54 People don't believe it, but it's true, it works.

05:58 But coastal carbon capture isn't limited to land, it's also happening underwater.

06:05 This lagoon in Italy's Emilia-Romagna region is a natural fish habitat used for extensive

06:11 aquaculture.

06:12 The patches of seagrass provide more than just an ideal nursery for fish.

06:17 Globally these underwater plants capture 10% of all carbon buried in ocean sediment.

06:24 Half a century ago all local lagoons were carpeted with seagrasses.

06:29 Most of these plants have since been wiped out, likely due to pollution.

06:34 Now the European funded project Life Transfer is replanting surviving grasses in nearby

06:39 lagoons, inspired by promising results from a pilot site near Venice.

06:45 You have to reverse the process, to get to a stage where there is an expansion, like

06:52 happened with the Venice lagoon, because we have a good example of success that we want

06:58 to export to the Mediterranean, and not just to Europe.

07:03 Led by Graziano Caramori, the research team has come up with a method to give seagrasses

07:08 a new home.

07:10 They lift patches from a donor site and swiftly move them to another spot with similar characteristics.

07:15 Their aim is to boost the odds that these underwater plants turn into lush seabed meadows.

07:22 In the long term this should result in cleaner water, less coastal erosion and new safe havens

07:28 for aquatic wildlife.

07:31 We will certainly make a huge contribution to the environment, because it improves biodiversity,

07:37 but we will also make a contribution to ourselves, because we increase the ability to kidnap

07:42 carbon dioxide, which can contribute to the fight against climate change.

07:48 From salt marshes to seagrasses, some of the best solutions to the climate challenge are

07:54 right at our shorelines.

07:56 (music fades)

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