For many years, mangroves were an underappreciated climate ally.

Not anymore.

For countries looking to meet their promised climate goals, mangroves have become an attractive investment. In just a single square mile, these coastal forests can hold as much climate-warming carbon as the annual emissions of 90,000 cars. One report found that every dollar spent protecting them could yield upwards of five dollars’ worth of additional benefits, such as food security and coastal protection from extreme storms.

And there’s a lot of room for growth: Since 1980, 35 percent of the world’s mangroves have been lost to coastal development, unsustainable aquaculture and sea-level rise.

But the swelling interest in mangrove restoration has raised a critical question: How much does restoring mangroves cost?

That question matters because there are limited resources to go around, said Jonah Busch, a former Conservation International fellow. And without a clear answer, targeting where to get the most bang for your buck is next to impossible.

In a new study, Busch and Dane Klinger, Conservation International mangrove and aquaculture expert, unpack this question — and how to accelerate and improve restoration projects across the globe.

Conservation News: Why did you do this research?

Jonah Busch: Mangroves have emerged in recent years as an unsung hero of the climate and biodiversity crises. They’re extremely rich in carbon, act as nurseries for fisheries and protect coasts from storms and tsunamis.

People have really woken up to their value — and as a result, there’s been a wave of restoration initiatives around the globe. This is fantastic, but now we’re entering the hard and practical work of getting this done. And one critical piece of information has been missing: How much does it cost to restore a mangrove forest?

Individual projects have estimated costs in various places around the globe, but that information hadn’t been pulled together and synthesized to give a clear picture of the costs. So that’s what we did — we created a map that estimates the cost of mangrove restoration anywhere in the world based on what it’s cost others in comparable conditions. We combined this with a map of the amount of carbon mangroves in any given location will capture.

Coastlines are extremely competitive places for land — think about all the pressure from the tourism and aquaculture industries, for example. With these maps, we can offer a clear picture of where a restoration project will get the best bang for its buck.

What did the research find?

JB: We found three key numbers: the area of mangroves that could be restored, how much carbon mangrove restoration would remove from the atmosphere, and, based on information from over 250 restoration projects, how much it would cost to do so.

The amount of mangroves that the world has lost since 1996 equals about 1 million hectares — an area about the size of Jamaica. Restoring all those mangroves would pull roughly 1 billion tons of carbon dioxide — equivalent to 212 million cars driven for one year — out of the atmosphere. And the cost to accomplish that is roughly US$ 11 billion.

Keep in mind that this cost is what we call implementation cost — essentially, everything associated with getting the trees in the ground and keeping them alive. It doesn’t include the costs of acquiring the land, which if needed, could up to triple the overall costs.

Indonesia, Brazil and Mexico have the greatest potential for restoration at a decent price point — meaning, where the costs are lowest and the carbon capture potential is highest. Several factors determine whether the costs go up or down in a location. For example, the larger the area for restoration is, the lower the per-area costs, and the richer the country — in terms of national GDP per capita — the higher the costs. What the site was used for prior also affects the cost. If it was an aquaculture pond, for example, it’s cheaper to restore than if it was eroded land.

What does this mean for mangrove restoration going forward?

Dane Klinger: Put into context, this study shows that mangrove restoration is not prohibitively expensive. On average, it costs less than US$ 10,000 per hectare, that’s US$ 11 per ton of carbon kept out of the atmosphere. When you measure that against the benefits of healthy mangroves, it’s worth it.

And while this study solely focuses on the carbon value of mangrove restoration, the monetary value of the biodiversity, storm protection and local livelihoods that mangroves support is enormous. One study estimated that mangroves provide US$ 65 billion annually in flood protection alone.

Yet globally, the resources available for mangrove restoration are currently much smaller than the need. With this research, our hope is to maximize the scarce resources for mangrove restoration by prioritizing restoration in locations where there are the greatest benefits at the least cost.

Further reading: 

• To save a dying forest, this town dug in
• Can shrimp farming restore mangroves? This scientist is making it happen
• In Ecuador, a ‘milestone’ effort to protect mangroves — and people

Mary Kate McCoy is a staff writer at Conservation International. Want to read more stories like this? Sign up for email updates. Also, please consider supporting our critical work.