Reumo
Mangroves play a crucial role in the blue economy, providing a range of services that contribute significantly to human well-being. These ecosystems offer provisioning services (such as fishing, gathering, and extracting natural products), regulatory services (such as carbon sequestration, nutrient cycling, and climate regulation), supporting services (such as nutrient cycling and photosynthesis), and cultural services (including tourism, recreation, education, and research). These services are fundamental and hold substantial value for life on Earth. Regarding regulatory services, the mangrove forests have a higher carbon capture and storage capacity per unit area than that observed in tropical rainforests. The conservation and restoration of mangroves can yield greater benefits than their degradation, especially when considering sustainability issues. From this perspective, this research aims to estimate the carbon (CO2) prices that economically justify the conservation and restoration of mangrove areas. These prices serve as a baseline for supporting mechanisms like payments for ecosystem services, such as in the carbon market. The research was conducted in mangroves located in the state of Ceará, in Northeast Brazil, specifically in the municipalities of Acaraú and Itarema, situated on the western coast of the state. The degraded mangrove areas in these municipalities were the focus of a restoration project that sought funding for implementation. The total area of direct and indirect impact of the project, in terms of socioeconomic and environmental effects, encompasses the entirety of both municipalities, covering 1,563 km² and home to a population of 101,445 inhabitants. The total area of mangroves to be restored amounts to 805 ha, distributed across the estuaries of the Acaraú and Aracatimirim rivers, while the conserved mangrove area covers approximately 5,000 ha. Break-even prices necessary for the conservation of remaining mangroves and the restoration of degraded mangroves were estimated. To establish the break-even CO2 price for both conservation (which avoids CO2 emissions) and restoration (which removes CO2 emissions), the economic value that one ton of CO2 (US$/tCO2) would need to reach to compensate for the potential value of alternative economic use or the opportunity cost of exploiting the area (US$/ha) was estimated. The opportunity cost (US$/ha), divided by the avoided emissions (tCO2/ha), derived from the amount of carbon stored in the biomass and soil (CO2/ha), provided the break-even price for conservation. For the break-even price of restoration, both opportunity and restoration costs were considered, divided by the removed emissions (tCO2/ha). Different scenarios with levels of 25%, 50%, and 100% were analyzed for both the carbon stock lost due to deforestation and the carbon recovered through restoration, as well as the carbon emissions avoided through conservation. The value of US$ 2.30 per tCO2 represents the price necessary to ensure the conservation of the entire mangrove area, compared to the opportunity cost of alternative uses. If 50% of the CO2 stocks were lost, the price required to conserve half of the area would need to be adjusted to US$ 4.60 per tCO2. In the scenario where 25% of the area is lost due to deforestation, the necessary price would be US$ 9.20 per tCO2. A larger deforested area or a smaller conserved area would demand a higher return in terms of CO2 price. These values suggest that the conservation of the remaining mangroves could prevent the release of 2.77 to 11.09 TgCO2 into the atmosphere. For the case of restoration, Table 2 presents the estimated break-even prices for mangrove restoration. The value of US$ 2.85 per tCO2 represents the amount necessary to facilitate the restoration of degraded mangrove areas, taking into account both the opportunity cost of alternative land uses and the cost of restoration. If 50% of the CO2 stocks are recovered, the price required to restore half of the area would need to be US$ 5.71 per tCO2. For the restoration of 25% of the area, as outlined in the restoration project, the required price would be US$ 11.41 per tCO2. Restoring a smaller area or leaving a larger portion degraded would demand a higher return in terms of CO2 pricing. These figures suggest that restoring the degraded mangroves could result in the sequestration of 0.45 to 1.79 TgCO2 in the study area. ). The break-even price estimates indicate that relatively low carbon prices would be sufficient to offset the opportunity cost of using mangrove areas, even when accounting for the added cost of restoring already degraded areas. As expected, the carbon price required for restoration is higher than that for conservation, indicating that remediation efforts are more costly than preventing environmental damage. The present study aimed to assess the break-even price of CO2 that would economically justify the conservation and restoration of mangrove ecosystem areas. The estimated prices convincingly indicate the feasibility of conservation and restoration practices for these areas, highlighting the potential for resource mobilization through the carbon credit market. This suggests a significant potential for socio-environmental improvement, not only for the specific context of the Ceará coastline but also for the entire mangrove coastal zone of the North and Northeast regions of Brazil. However, the study presents certain limitations, as it relies on average parameters associated with carbon stocks and uses an average opportunity cost without detailed consideration of activity type. For future research, it is recommended to conduct a more detailed cost-benefit analysis focusing on the conservation and restoration of mangroves.