Global economic potential for reducing carbon dioxide emissions from mangrove loss
Year Published:
2012
Study Number:

42

Author:

J. Siikamäki, J. N. Sanchirico & S. L. Jardine

Abstract:

Mangroves are among the most threatened and rapidly disappearing natural environments worldwide (extinction). In addition to supporting a wide range of other ecological and economic functions, mangroves store considerable carbon. Here, we consider the global economic potential for protecting mangroves based exclusively on their carbon. We develop unique high-resolution global estimates (5′ grid, about 9 Å~ 9 km) of the projected carbon emissions from mangrove loss and the cost of avoiding the emissions. Using these spatial estimates, we derive global and regional supply curves (marginal cost curves) for avoided emissions. Under a broad range of assumptions, we find that the majority of potential emissions from mangroves could be avoided at less than $10 per ton of CO2. Given the recent range of market price for carbon offsets and the cost of reducing emissions from other sources, this finding suggests that protecting mangroves for their carbon is an economically viable proposition. Political-economy considerations related to the ability of doing business in developing countries, however, can severely limit the supply of offsets and increases their price per ton. We also find that although a carbon focused conservation strategy does not automatically target areas most valuable for biodiversity, implementing a biodiversity-focused strategy would only slightly increase the costs.

 

Main Results and Conclusions:
  • The estimated cost for avoided carbon emission is as follows: “According to our results, preventing mangrove loss has the potential of reducing global emissions for a cost of roughly $4 to $10 ton−1 CO2 (Figure 24)”(14369-70).
  • Three global regions were identified as having the greatest potential carbon storage: Asia and Oceania region having the greatest potential, followed by the Americans and Caribbean and Africa and the Middle East (14370).
  • Monetized estimates of damage caused by green house gas emissions is greater than the estimated cost of avoiding emissions from mangrove loss (14372):
    • “In all three cases considered (low, central, and high supply), we project that the majority of available carbon offsets could be generated at less than $10 ton−1 CO2 (in 2005 US$). This estimate is below the recent EU ETS offset credit prices, which have remained between roughly $10 and $20 ton−1 CO2, even in the current economic downturn (European Energy Exchange, 2011)”(14371).
  • The ability of mangroves to store carbon is extensive, with data from the study indicating that: “if left undisturbed, uninterrupted carbon sequestration and burial annually expand mangrove carbon stock by about 16 million t C per year (60 million t CO2e) (Table 1)”(14373).
  • Estimates of carbon emission after land conversion: “We consider that 75% of carbon in the above-ground and below-ground biomass is emitted after land conversion (Donato et al., 2011; Murray et al., 2011). We also assume that land conversion affects soil carbon down to 1 m and approximate a range of emissions to correspond to the range of assumptions in the literature. At the lower bound (Donato et al., 2011), a total of 27.25% of the soil carbon is released. At the upper bound (Murray et al., 2011), 90% of soil carbon is released. The midpoint of the lower and upper bounds serves as our central estimate of the soil carbon emitted after land conversion (SI Appendix). Our low, central, and high estimates of annual global emissions because of mangrove loss are about 84 million, 122 million, and 159 million tons CO2”(14373).
  • In addition to the impact of CO2 emissions from land conversion, N2O and CH4 emissions would also increase due to their natural storage in mangroves (14371).
  • Efforts could be enacted to acknowledge various types of ecosystem services that mangroves provide to justify their protection. By combing carbon-credit and biodiversity-focused programs, more progress could be seen in mangrove conservation (14372-73).
  • In conclusion: “In most areas of the world, we find that preventing a ton of carbon emissions from mangrove deforestation is competitive (less costly) relative to reducing a ton of carbon emissions from currently regulated GHG sources in developed countries (14372).
     
Works Cited:

Donato DC, et al. (2011) Mangroves among the most carbon-rich forests in the tropics. Nat Geosci 4:293–297.

Murray BC, Pendelton L, Jenkins AW, Sifleet S (2011) Green Payments for Blue Carbon: Economic Incentives for Protecting Threatened Coastal Habitats (Nicholas Institute, Duke Univ, Durham, NC).

European Energy Exchange (2011) Market Data January 2011–June 2011 (European Energy Exchange) http://www.eex.com/en/Market%20Data/. Accessed May 12, 2012.