The wonder of wetlands: the secret weapon in the battle against climate change

Saltmarshes can store carbon from the atmosphere fifty times faster than a tropical forest. As a part of our monthly update on the state of our planet we visit the Venice lagoon with scientists working to guard these special wetlands and ask if these environments could possibly be nature’s secret weapon against climate change.

Firstly, here is our unique monthly update on what’s really happening to our planet with the newest data from the Copernicus Climate Change Service for January 2022.

On a world level temperatures last month were 0.3 degrees Celsius above the 1991-2020 average.

Argentina feels the warmth

There have been some notable hotspots across the planet. In Argentina the continued heatwave meant the country set 75 latest extreme temperature records for January.

Eastern Canada and the US was colder than average after which across Russia all of the solution to Kamchatka peninsula it was much warmer last month.

Zooming in on Europe, in the midst of the month, Oslo hit an all time high for January of 12.5 degrees. Then in most of France and parts of Spain it was cooler.

Staying in Spain, the Iberian peninsula continues to be much drier than average. This graphic below shows the soil moisture anomaly for January, and that is the continuation of a trend over the past 4 months.

The wonder of wetlands and climate change

Saltmarshes are havens of biodiversity and act as natural barriers to storms – but they may also sequester carbon from the atmosphere 50 times faster than a tropical forest. Setting off from St Mark’s Square we went on a mission to find the salt marshes of the Venice lagoon.

Today the marsh land across the Italian city is 43 km2, which allows it to sequester around 25 percent of the CO2 emitted from boat traffic. 2 hundred years ago the wetlands stretched over 180km2, which can be enough to offset all boat traffic in Venice in the event that they were still around today. The wetlands have been degenerated by an absence of silt and sediment plus erosion, all of that are linked to natural phenomena and human actions and activities.

In accordance with Andrea d’Alpaos, a professor of Geoscience from the University of Padua, these vulnerable ecosystems have to be higher valued and guarded.

“There’s a ignorance of the potential of those systems to store organic carbon and help to combat climate change.”

That potential he’s talking about relies on a comparatively easy process. First the plants capture CO2 from the atmosphere as they grow, after which they’re usually flooded by sediment-rich tides which bury foliage and roots within the mud.

Showing us samples taken from the saltmarsh, Professor of Sedimentology Massimiliano Ghinassi, also from the University of Padua, explained which you can literally see carbon sequestration in motion on the lagoon.

“Within the uppermost a part of the core we will distinguish several elements including each small and enormous roots just like the one we’ve got just cut.

“There’s also loads of other very small plant fragments like leaves or bits of plant stays which might be what actually store carbon within the sediment.”

Back within the lab

Within the labs on the University of Padua the scientists can calculate how much carbon is stored in several wetland zones, and even determine its source. What they’ve found is there is a huge variety in carbon storage levels across the Venice lagoon:

“We see a mean value of about 270 tonnes (of carbon) per square kilometre per yr. Nevertheless, the variability is kind of high, starting from a minimum of about 50 tonnes per square kilometre per yr to a maximum of over 500 tonnes per square kilometre per yr,” said Phd Student, Alice Puppin.

The lab results will probably be used to find out exactly which sorts of plants, soils and environmental conditions are best for sequestering carbon.

Within the meantime, Professor Andrea d’Alpaos says its vital the wetlands are preserved.

“We now have to guard them from erosion of their margins. After which we’ve got to attempt to help them of their vertical growth by making sediment available that may choose the surface of the sandbanks that will help them grow vertically and at the identical time can bury organic matter within the soils for lots of of 1000’s of years.”

*this research was performed inside the Research Program Venezia 2021, with the contribution of the Provveditorato for the Public Works of Veneto, Trentino Alto Adige and Friuli Venezia Giulia, provided through the concessionary of State Consorzio Venezia Nuova and coordinated by CORILA.

Climate Now production team:

Camera: Lionel Laval


3D Graphics: Vinod Kirouchenamourty


  • Data Graphics: Domenico Spano
  • Studio Director: Mathieu Carbonell
  • Virtual Studio Manager: Antoine Renaud
  • Studio Lighting: Jérôme Souillol
  • Production Manager: Camille Cadet


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