The coastal mangrove forest is one of the blue carbon ecosystems and most efficient carbon sink ecosystems on earth. However, these carbon-dense wetlands are currently under pressure from major land-use and land-cover changes (LULCCs), which results in large amounts of deforested and converted mangrove areas globally. Yet, little is known about the range of impacts from different LULCC types have upon mangrove blue carbon. This presentation will overview global patterns of the magnitude and direction of mangrove carbon stocks and soil GHG effluxes following land-use changes including tree removal, aquaculture, rice field, pasture, and mangrove restoration. The findings are based on systematic review and meta-analysis of 487 global datasets from 37 papers published between 1998 and 2018. In addition, field-based data collection findings from 335 sampling plots established across Indonesian Papua mangroves over the last 3 years will also be discussed. The findings of these studies will improve the current IPCC emission factor for coastal wetlands as well as national climate policy on emission reduction targets through National Determined Contributions (NDCs).