Bangkok's coastal location makes it particularly vulnerable to rising sea levels due to global warming and climate change. A study by the OECD has estimated that 5.138 million people in Bangkok may be exposed to coastal flooding by 2070, the seventh highest figure among the world's port cities. There are fears that the city may be submerged by 2030. A study published in October 2019 in ''Nature Communications'' corrected earlier models of coastal elevations and concluded that up to 12 million Thais—mostly in the greater Bangkok metropolitan area—face the prospect of annual flooding events. This is compounded by coastal erosion, which is an issue in the gulf coastal area, a small length of which lies within Bangkok's Bang Khun Thian District. Tidal flat ecosystems existed on the coast, however, many have been reclaimed for agriculture, aquaculture, and salt works. 