The South China Sea (SCS) is an important marginal land sea in China. Coral reefs are abundant in resources and are more susceptible to ocean acidification. According to the IPCC report, the rapid growth of global atmospheric carbon dioxide concentration is mainly due to anthropogenic carbon dioxide emissions. Therefore, it is particularly important to distinguish between anthropogenic carbon dioxide emissions and natural carbon dioxide emissions in China's offshore atmosphere for grasping the carbon dioxide emissions of China and its surrounding countries, formulating China's energy saving and emission reduction policies, and formulating nature-based solutions.