In Indonesia, climate change is already a pernicious threat. More than 30 million people across northern Java suffer from coastal flooding and erosion related to more severe storms and sea level rise. In some places, entire villages and more than a mile of coastline have been lost to the sea.

The flooding and erosion are exacerbated by the destruction of natural mangrove forests. These forests absorb the brunt of waves’ impact, significantly reducing both the height and speed of waves reaching shore. And mature mangroves can store nearly 1,000 tons of carbon per hectare, thus mitigating climate change while also helping communities adapt.

Without mangroves, 18 million more people worldwide would suffer from coastal flooding each year (an increase of 39%). That’s why in Demak, Java, a diverse group of residents, NGOs, universities and the Indonesian government are working together on the “Building with Nature” project to restore a 12-mile belt of mangroves. The project, managed by Wetlands International, has already improved the district’s climate resilience, protecting communities from coastal flooding and absorbing carbon dioxide from the atmosphere.

Meanwhile, off the shores of Virginia, vast meadows of seagrass sway in the shallow waters. Over the past two decades, conservation scientists have spread more than 70 million seeds in the bays there, restoring 3,600 hectares of an ecosystem devastated by disease in the 1930s. The work has brought back eelgrass (Zostera marina) — a keystone species that supports crustaceans, fish, and scallops, and is now absorbing the equivalent of nearly half a metric ton of CO2 per hectare per year.

Now, the Virginia Nature Conservancy is aiming to turn those tons into carbon credits that it can sell for cash.

The collaborative project — with planting done by the Virginia Institute of Marine Science (VIMS) and the Nature Conservancy, and long-term carbon data provided by the University of Virginia — is the first seagrass project in the world to apply for carbon credit certification with the carbon standard not-for-profit Verra, the world’s largest overseer of voluntary carbon credit projects. “It’s proof of concept — that’s the important part here,” says Christopher Patrick, director of the VIMS seagrass restoration and monitoring program. “We’re not going to change global climate with this one project. But we can show it’s a viable approach.”

If successful, it will join a handful of other blue carbon credit projects around the world, the vast majority of which are mangrove restoration efforts — a trickle of blue that many anticipate will soon become a flood. So far, Verra has issued a grand total of just under 970,000 credits (representing 970,000 metric tons of CO2 equivalents) to blue carbon projects. But mangrove projects are now ramping up dramatically in scope, with one alone aiming to soak up millions of tons of CO2 equivalents a year. And scientists are working hard to account for the carbon in other ecosystem types — seagrasses, salt marshes, seaweeds, and seafloor sediments — so they, too, can enter the market.

The rules to allow these other ecosystems to claim credits are new. In 2015, Verra published its first methodology to give credits to tidal wetland and seagrass restoration, but only last September did Verra expand its rules to cover wetland conservation. That was “a very big deal,” says Jennifer Howard, marine climate change director for Conservation International. “I know of at least 20 different projects right now that are all trying to get developed and on the market in the next two years. I think we’re going to see a big explosion.”

Corporations, including Apple, have been very vocal about their blue carbon purchases and projects.

“The market is small but growing exponentially,” agrees marine ecologist Oscar Serrano at Edith Cowan University in Perth, who has helped to catalogue the capacity for Australia’s blue carbon reserves in mitigating climate change.

Amy Schmid, ecologist and manager of natural climate solutions development for Verra, says, “there’s a lot of demand for blue carbon credits.” Companies in shipping and tourism are keen to put money back into conserving the landscapes they have an impact on, she says, while offsetting their own emissions. And many of these projects offer win-win-win stories for people, biodiversity, and carbon, which boosts the price that organizations can get for their credits on the open market. Corporations, including Geneva-based MSC Cruises and Apple, have been very vocal about their blue carbon purchases and projects.