Coastal Wetlands Crank Up Carbon Storage as Seas Rise

(CN) – As rising seawater gives way to flooding, coastal wetlands will play an important role in managing carbon emissions and should be properly managed to offset atmospheric carbon emissions, according to a new study published Wednesday.

If properly maintained, tidal marshlands along the coast of southern Africa, Australia, China and South America would be able to store about 5 million tons of carbon a year – the equivalent of taking more than a million cars off the road, says the study published in the journal Nature.

The amount of carbon dioxide concentrations in the Earth’s atmosphere is higher than at any point in at least the past 800,000 years. In fact, today’s levels of CO2 in the atmosphere match those of 3 million years ago when temperatures were up to 5 degrees warmer than the pre-industrial era and sea levels were 50 to 80 feet higher than today, according to the National Oceanic and Atmospheric Administration.

The Smithsonian Environmental Research Center looked at how coastal wetlands worldwide react to rising seas and how they become effective sponges for storing carbon dioxide.

Coastal wetlands, which include marshes, mangroves and seagrasses, already store carbon more efficiently than any other natural ecosystem, including forests.

Researchers found that wetlands react to rising sea levels by storing even more carbon concentrations – at double or nearly quadruple the amount in the top 20 centimeters of soil. Digging deeper at about 50 to 100 centimeters, storage concentrations were five to nine times higher.

Lead author Kerrylee Rogers of the University of Wollongong in Australia said of wetlands, “They may be the sleeping giants of global carbon sequestration.”

North America and Europe faced the most sea-level rise over the past 6,000 years due to melting glaciers from the last ice age. And while continents in the Southern Hemisphere have not seen much of a rise in sea waters, climate change will start to bring more coastal flooding – potentially drowning the wetlands.

Preserving those coastal wetlands will be key to cutting back on the effects of climate change. According to Rogers, giving the wetlands some space is essential: As sea waters begin to move further inland, communities across the globe will have to reprioritize beachfront properties and other developments to give the wetlands the space they need away from the rising seas.

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