Aim To provide high-resolution local, regional, national and global estimates of annual mangrove forest area from 2000 through to 2012 with the goal of driving mangrove research questions pertaining to biodiversity, carbon stocks, climate change, functionality, food security, livelihoods, fisheries support and conservation that have been impeded until now by a lack of suitable data.Location Global, covering 99% of all mangrove forests.Methods We synthesized the Global Forest Change database, the Terrestrial Ecosystems of the World database and the Mangrove Forests of the World database to extract mangrove forest cover at high spatial and temporal resolutions. We then used the new database to monitor mangrove cover at the global, national and protected area scales.Results Countries showing relatively high amounts of mangrove loss include Myanmar, Malaysia, Cambodia, Indonesia and Guatemala. Indonesia remains by far the largest mangrove-holding nation, containing between 26% and 29% of the global mangrove inventory with a deforestation rate of between 0.26% and 0.66% per year. We have made our new database, CGMFC-21, freely available.Main conclusions Global mangrove deforestation continues but at a much reduced rate of between 0.16% and 0.39% per year. Southeast Asia is a region of concern with mangrove deforestation rates between 3.58% and 8.08%, this in a region containing half of the entire global mangrove forest inventory. The global mangrove deforestation pattern from 2000 to 2012 is one of decreasing rates of deforestation, with many nations essentially stable, with the exception of the largest mangrove-holding region of Southeast Asia. We provide a standardized spatial dataset that monitors mangrove deforestation globally at high spatio-temporal resolutions. These data can be used to drive the mangrove research agenda, particularly as it pertains to monitoring of mangrove carbon stocks and the establishment of baseline local mangrove forest inventories required for payment for ecosystem service initiatives.

Intertidal mangrove forests are a dynamic ecosystem experiencing rapid changes in extent and habitat quality over geological history, today and into the future. Climate and sea level have drastically altered mangrove distribution since their appearance in the geological record ∼75 million years ago (Mya), through to the Holocene. In contrast, contemporary mangrove dynamics are driven primarily by anthropogenic threats, including pollution, overextraction, and conversion to aquaculture and agriculture. Deforestation rates have declined in the past decade, but the future of mangroves is uncertain; new deforestation frontiers are opening, particularly in Southeast Asia and West Africa, despite international conservation policies and ambitious global targets for rehabilitation. In addition, geological and climatic processes such as sea-level rise that were important over geological history will continue to influence global mangrove distribution in the future. Recommendations are given to reframe mangrove conservation, with a view to improving the state of mangroves in the future.

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Mangrove forests store high densities of organic carbon compared to other forested ecosystems. High carbon storage coupled with high rates of deforestation means that mangroves contribute substantially to carbon emissions. Thus, mangroves are candidates for inclusion in Intended Nationally Determined Contributions (INDCs) to the UNFCC Payments for Ecosystem Services (PES) program. This study quantifies two datasets required for INDCs and PES reporting. These are annual mangrove carbon stocks from 2000 to 2012 at the global, national, and sub-national levels and global carbon emissions resulting from deforestation. Mangroves stored 4.19 Pg of carbon in 2012, with Indonesia, Brazil, Malaysia, and Papua New Guinea accounting for greater than 50% of this 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 CO 2 emissions.Forestry, agriculture, and other land use changes account for almost 25% (up to 12 Pg CO 2 -e yr -1 ) of anthropogenic greenhouse gas emissions, due to factors such as deforestation, forest degradation and biomass burning 1 . The deforestation of tropical coastal wetlands such as mangrove forests contributes disproportionately to anthropogenic greenhouse gas emissions, as they mangrove forests can hold up to four times as much organic carbon per unit area when compared to other terrestrial forested ecosystems 2 and are undergoing deforestation across the tropics 3, 4 . Recent estimates have put global mangrove deforestation rates at up to 0.39% per year since 2000 4 , driven primarily by large-scale agricultural and aquacultural commodity production, 3, 5, 6, 7 coastal development 3, 5, 6, 7 , and sea level rise 8 . High carbon densities per unit area coupled with high deforestation rates mean that globally mangrove deforestation may be contributing as much as 0.21 Pg CO 2 -e yr -1 or 0.45 Pg CO 2 -e yr -1 to the atmosphere 2, 9 . Mangrove deforestation is so high in particular countries such as Indonesia that halting deforestation has been estimated to reduce its national land use sector emissions by between 10% and 31% 10 . As a result, carbon stored in coastal wetlands such as mangroves has recently been placed on the international policy agenda by the service provider for payment to be made. Thus, financial transactions under PES require robust information on variables such as carbon storage and rates of habitat loss, to allow the accurate quantification of carbon credits and carbon saved through avoided deforestation. We particularly need to know baselines of deforestation and carbon storage at varying spatiotemporal scales, from the site to the national level. However, we currently lack robust baselines of mangrove deforestation in many countries across the tropics 17 . We also require robust estimates of mangrove carbon stocks and emissions due to deforestation at multiple scales. Our lack of information on these parame...

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