Global carbon stocks and potential emissions due to mangrove deforestation from 2000 to 2012

  • January 1, 2018
Marine and Coastal Mangroves

Study Number

93

Author

Stuart E. Hamilton, Daniel A. Friess

Abstract

Mangrove forests store high densities of organic carbon, which, when coupled with high rates of deforestation, means that mangroves have the potential to contribute substantially to carbon emissions. Consequently, mangroves are strong candidates for inclusion in nationally determined contributions (NDCs) to the United Nations Framework Convention on Climate Change (UNFCCC), and payments for ecosystem services (PES) programmes that financially incentivize the conservation of forested carbon stocks. This study quantifies annual mangrove carbon stocks from 2000 to 2012 at the global, national and sub-national levels, and global carbon emissions resulting from deforestation over the same time period. Globally, mangroves stored 4.19 Pg of carbon in 2012, with Indonesia, Brazil, Malaysia and Papua New Guinea accounting for more than 50% of the global stock. 2.96 Pg of the global carbon stock is contained within the soil and 1.23 Pg in the living biomass. Two percent of global mangrove carbon was lost between 2000 and 2012, equivalent to a maximum potential of 316,996,250 t of CO2 emissions.

Main Results and Conclusions

  • Almost 25% of anthropogenic greenhouse gas emissions are due to forestry, agriculture, and other land use changes.
    • “Forestry, agriculture and other land use changes account for almost 25% (up to 12 Pg CO2e yr−1) of anthropogenic greenhouse gas emissions due to factors such as deforestation, forest degradation and biomass burning.” (240)
  • Greenhouse gas emissions are in large part due to the change of land use in tropical coastal wetlands.
    • “The deforestation of tropical coastal wetlands such as mangrove forests contributes disproportionately to anthropogenic greenhouse gas emissions, as they can hold up to four times as much organic carbon per unit area than other terrestrial forested ecosystems and are undergoing deforestation across the tropics.” (240)
    • “Recent estimates have put global mangrove deforestation rates at up to 0.39% per year since 2000.” (240)
    • “Mangrove deforestation is so high in some countries, such as Indonesia, that it has been estimated that halting deforestation would reduce its national land use sector emissions by between 10% and 31%.” (240)
  • Some countries contain more mangrove carbon stocks than others.
    • “Indonesia, Brazil, Malaysia and Papua New Guinea contain more than 50% of the world’s mangrove carbon stock, with Indonesia alone accounting for more than 30% of the world’s mangrove carbon” (241)
    • “The top 10 mangrove-holding countries contain just under 70% of the world’s mangrove carbon stocks, and the top 25 countries just over 90%.” (241)
  • Large mangrove areas do not equal large carbon density.
    • “…Bangladesh ranks three places lower globally when ranked by mangrove carbon stocks than if it were ranked by actual mangrove area. Conversely, Gabon is ranked two spots higher than if it were ranked solely based on mangrove area.” (241)
    • Sub-national estimates of carbon stocks are important.
    • “…slightly over one-third of the global mangrove carbon stocks are contained within only ten level-one administrative units (Table 2). Indeed, more than 50% of the world’s mangrove carbon stocks are located within only 21 administrative level units.” (241)
    • “Many mangrove forests are managed at highly granular levels beyond commonly mapped administrative units. For example, mangrove-holding nations such as Indonesia, India, Thailand and the Philippines have highly successful community-based mangrove management programmes…” (241)
  • Carbon stock loss rates are consistent over time but vary country to country.
    • “Carbon stock loss rates are highly consistent across the 13-year analysis period, averaging 0.17% per year.” (241)
    • “Indonesia alone is responsible for almost 41,946,838 t, or 48.56% of the loss in global mangrove carbon stock during this period. Also, Myanmar has a loss rate of 7.99%, a fourfold increase over the global loss rate for the period 2000–2012, and so contributes a disproportionate volume of emissions relative to its total mangrove extent.” (241-242)
  • Some new ideas have emerged on how to conserve mangroves in international climate policy.
    • “PES schemes such as Reducing Emissions from Deforestation and Degradation (REDD+) incentivize conservation through ‘avoided deforestation’, with a service buyer paying a service provider to store carbon that would otherwise be emitted due to land cover change.” (240)
  • PES schemes require vigorous information in order to facilitate the transaction of monetary values.
    • “…on vegetated carbon stocks, and emissions due to land cover change through time.” (240)
    • “…most definitions of PES need some form of conditionality which sets rules and standards that must be met by the service provider for payment to be made.” (240)
    • “….financial transactions under PES require robust information on variables such as carbon storage and rates of habitat loss, to allow for the accurate quantification of carbon credits and carbon saved through avoided deforestation. We particularly need to know the baselines of deforestation and carbon storage at varying spatiotemporal scales, from the site to the national level.” (240)
  • Lack of information regarding mangrove deforestation and mangrove carbon stocks and emissions due to deforestation in many countries across the tropics have disrupted the ability for these potential international climate policies to develop into action. (240)
  • This study fills gaps that have existed until now.
    • “This study provides the clear and robust baseline information on carbon stocks that is required for use in national emissions reporting and PES schemes at high spatiotemporal resolutions.” (241)
    • “We report global, national and sub-national mangrove carbon stocks for the year 2012 and estimates the global carbon stock losses and potential CO2 emissions resulting from mangrove area change between 2000 and 2012.” (241)
    • “In addition to reporting global mangrove carbon stocks, we delineate the amount of global mangrove carbon in the aboveground living pool, the belowground living pool and mangrove soil, key carbon pools that must be delineated and quantified for national emissions reporting.” (241)