Mangrove restoration: what costs for carbon offsets?

A CO2 price of $130/ton is needed to earn a 10% IRR on a US mangrove restoration project. c30% is the cost of labor and c30% is land leasing. But costs in the emerging world are lower, at $15-35/ton. They can be as low as $3/ton in the best cases, if restoring nature is treated as a charitable cause rather than an investment.