Nova Scotia

Blue carbon is the billion-dollar resource you've never heard of

Early indications show the mud and plants surrounding the Bay of Fundy could contain enough carbon to offset the emissions of thousands of vehicles.

Mud and plants along the Bay of Fundy soak up 3-5 times more carbon than trees

"Blue carbon" is the term coined by scientists to describe carbon dioxide that is stored in coastal vegetation and soil. (Brett Ruskin/CBC News)

The Bay of Fundy may soon be known for more than its powerful tides.

Instead, the plants and mud in the coastal ecosystem have the potential to hold hundreds of millions of dollars worth of carbon-offset credits.

Environment and Climate Change Canada is studying how much "blue carbon" is stored along the Bay of Fundy coastline. It has hired a team to measure the bay's potential for carbon sequestration.

"Blue carbon" is a term coined by scientists to describe carbon dioxide stored in coastal plants and soil.

On land, forests capture carbon dioxide and produce oxygen. Coastal ecosystems do the same — but they're much better at it. 

Anything trees can do, 'blue' can do better

"Coastal ecosystems can hold three to five times more carbon than the equivalent area of forest," said a federal government document published online in February.

Carbon dioxide and other greenhouse gases have been linked to global warming and climate change.

The marsh near Dipper Harbour, N.B., is an example of a blue carbon sink. It's an area where carbon dioxide has been sequestered for more than 3,000 years, with more captured every day. (Brett Ruskin/CBC News)

Forests release their carbon every few hundred years, due to fire, tree mortality or human harvesting. By comparison, coastal marshes maintain their carbon for thousands of years.

"It just stays there and gets buried," said Gail Chmura, one of North America's foremost experts in blue carbon research. She is an associate professor in the geography department at McGill University.

Gail Chmura is one of North America's leading blue carbon researchers. (Brett Ruskin/CBC News)

She's studying a marsh in Dipper Harbour, N.B., that has been soaking up and locking in carbon dioxide for 3,000 years. Many others are even older than that.

Making green off blue carbon

The financial value of blue carbon comes from its potential for carbon emission credits.

The Canadian government is gradually introducing a carbon levy. Various industries will have to pay a fee based on their carbon emissions.

That fee will increase annually until 2022, when it will be $50 per emitted tonne of carbon dioxide.

On the other hand, if a company removes carbon from the atmosphere, it could generate revenue by selling offset credits. 

According to government documents, "carbon stored in tidal salt marshes in the Bay of Fundy could have an estimated value of $202 million." That would equal $1 billion in 2022.

Tourists walk the ocean floor at the Hopewell Rocks on the Bay of Fundy, N.B. (Jonathan Hayward/Canadian Press)

It's not clear how blue carbon will fit into the national carbon emissions strategy. It could be used as an offset to meet international targets.

Coastal communities could also be allowed to protect or rehabilitate wetlands to generate carbon credits.

"So, for example, you take a flight and you feel guilty, you can buy those offset credits," said Chmura. "You could offset your flight. But no one has yet taken advantage of that to restore a salt marsh in Canada."

Officials with Environment and Climate Change Canada declined an interview request until the work to calculate the Bay of Fundy's blue carbon potential is complete. That is expected to be later this year.

Blue carbon recipe: just add water

An experiment that began in 2010 has proven how easy it is to generate blue carbon.

Two sections of drained farmland in Aulac, N.B., were allowed to flood. The sections totalled approximately the size of three CFL-sized football fields.

Scientists, including Chmura, monitored the site to see if vegetation would grow and carbon-rich mud would accumulate.

Cells A and B were once used as dry farmland, protected by dykes. Once holes were cut in the dykes, scientists monitored the plants and soil to see if they would automatically start collecting carbon from the atmosphere. (Wollenberg JT, Ollerhead J, Chmura GL (2018) Plos One)

"Within six years, up to a metre of mud accumulated in that area that was opened up," Chmura said. "That's an astounding amount of mud and that mud is very carbon rich."

These are the two flooded cells at the Aulac, N.B., marsh that were part of the experiment. (Brett Ruskin/CBC News)

The newly created marshland captured 2,493 tonnes of carbon, according to a scientific report published in the online journal Plos One. That carbon sequestration could be valued at up to $124,650 under Canada's new carbon levy regime.

This type of land is also available for a bargain. The study estimated the marsh would have cost approximately $25,700 to purchase.

While regulations aren't in place for communities to make money on blue carbon projects like these, the Aulac experiment shows the potential for this type of work.

"You can make money off it, you get all the ecosystem services, you get the habitat that salt marshes have been cherished for, and you get the carbon storage out of the atmosphere," said Chmura.

"I call it a win-win-win."


Brett Ruskin


Brett Ruskin is a reporter and videojournalist covering everything from local breaking news to national issues. He's based in Halifax.