The protection of the mangrove forests, which are threatened worldwide, is not only affordable, it offers economic potential for climate protection. Because mangroves store large amounts of carbon. Researchers have quantified the cost and monetary value of mangrove conservation in reducing global greenhouse emissions.

Mangrove forests are among the world’s most threatened ecosystems. Every year around one percent of the area is cleared to make room for fields, aquaculture, cities and hotels. Mangroves are trees of various types that grow in tropical coastal regions and are salt-resistant. They fulfill important ecological functions: with their aerial roots, they secure bank areas. The species-rich ecosystems offer young fish, crustaceans, birds and marine mammals a protected “nursery”. They are crucial for healthy fish stocks. Mangroves also store large amounts of the greenhouse gas carbon dioxide. If the forests are destroyed, the CO2 and other greenhouse gases such as methane and nitrogen escape into the atmosphere.

The underrated climate protector

Each hectare of mangrove forest binds as much carbon as several hectares of tropical rainforest. Mangroves do not even take up one percent of the area of ​​the tropical forest worldwide. According to researchers, however, this area would be sufficient to bind around 2.5 times the fossil CO2 emissions emitted annually today, namely around 20 billion tons of carbon.

Despite this potential, mangroves have so far hardly been taken into account in programs to “reduce emissions from deforestation and destructive forest use” (UN-REDD program). REDD is a mechanism of international climate protection policy with the following basic idea: If developing countries demonstrably reduce the deforestation of forests, they receive compensation payments. Most of the costs are borne by the industrialized nations by buying emission certificates to “offset” the greenhouse gas emissions they produce.

Mangrove protection is economic climate protection

Scientists have calculated the monetary value and the costs of mangrove protection based on the CO2 storage potential of these ecosystems. They conclude that preserving mangrove forests can be an effective strategy to reduce greenhouse gas emissions worldwide. The protection of the mangroves through the sale of emission rights also makes economic sense. Their conclusion: Mangroves as CO2 storage could be easily integrated into the current REDD program.

From CO2 storage to an economic factor

With a high-resolution surface grid (9 x 9 km), the scientists recorded the area of ​​the tropical mangrove forests worldwide. For each country they estimated how much carbon dioxide the forests can store in their biomass and in the soil. Then, based on the annual deforestation rates in different countries, they calculated how much CO2 is released annually by the destruction of the mangroves. These emissions can be assessed in monetary terms according to the market prices for emission certificates and the costs of reducing emissions from other (fossil) sources – and compared with the costs of avoiding these emissions. Here, the scientists considered in particular the costs for the establishment and maintenance of protected areas as well as costs that arise from the fact that the protected areas are not available for agriculture, fishing and the construction industry. These so-called opportunity costs differ depending on the type of land use and the region. And the efficiency of public behaviour also influences these costs.

The value of mangrove forests

The researchers estimate that the mangrove forests in Asia and Oceania have the greatest potential for reducing emissions, with two thirds of the world’s CO2 storage capacity in mangroves. One sixth of the global CO2 storage potential is allocated to the two regions America / Caribbean and Africa / Middle East.

The reduction of greenhouse gas emissions through the preservation of mangroves is economically attractive if the costs for mangrove protection are not higher than the costs for other measures to reduce emissions, e.g. in industry or energy generation. According to the researchers’ calculations, conservation programs could avoid potential emissions from mangroves in most regions for a cost of less than $ 10 per ton of CO2 – significantly less than the current emissions trading price of $ 20 per tonne of carbon.

In some regions, e.g. Indonesia and Thailand, large investments are needed to stop the loss of the mangroves. In these countries the opportunity costs are very high due to the yield forecasts for other land uses such as palm oil plants and shrimp aquaculture or because of the high land costs. The establishment of large protected areas can therefore have far-reaching economic effects in the regions. Further research is necessary in order to estimate the effects and opportunity costs of the various land uses for the individual regions.

Mangrove Trees

Inefficient structures cause additional costs

The countries in which mangroves grow differ greatly in the efficiency of their government and administrative structures. For long-term protection programs, inefficient structures mean political, economic and social risks, and thus uncertainty for investments. In order to minimise risks, targeted investments could be made in such countries in more efficient structures – this would mean higher costs for the establishment of protected areas. An alternative would be to exclude these countries from trading in emissions certificates. Such an exclusion would particularly affect regions in Africa and the Middle East and greatly reduce the CO2 storage capacity available on the market. As a result, the emissions trading price per tonne of carbon would rise.

Eden Reforestation & NAYA Partnership

Biodiversity side effect

A side effect of mangrove protection is that the diverse biodiversity in these ecosystems is preserved – with all its positive effects on nature, people and e.g. fisheries. For their calculations so far, the scientists had selected mangrove areas in the individual countries that could be converted into protected areas with as little investment as possible. If, on the other hand, the areas with particularly high biodiversity were to be converted into protected areas, this would not be significantly more expensive, the researchers found. However, this strategy would be more effective for protecting biodiversity. A biodiversity-focused strategy would cost about $ 30-35 million more annually – per metric ton of CO2, this would only be a price increase of about $ 1. To verify this data, further studies should be carried out, taking into account other factors and more detailed data, the researchers say .

Adjust REDD (+)

The study shows how the benefits of climate and environmental protection measures can be quantified economically. According to the calculations, the protection of the world’s threatened mangrove forests is not only affordable. It also offers economic potential for climate protection and would have positive effects on the preservation of biodiversity.

According to the scientists, including mangrove forests in the REDD mechanism would be possible and useful. Most of the CO2 stored in mangroves is bound in the soil. So far, however, soil-stored CO2 has not been taken into account in REDD. The scientists are calling for this to change.

That is why we are so excited to announce our partnership with Eden Reforestation Project to be part of the solution.


Reference

Siikamäki, J. et al. (2012): Global economic potential for reducing carbon dioxide emissions from mangrove loss. PNAS (30. Juli 2012), doi:10.1073/pnas.1200519109.