The increasing atmospheric carbon dioxide and other greenhouse gases will cause fundamental changes to the physical and chemical biological properties of our centrally oceans.In this study,we assessed the changes of sea surface temperature (SST),salinity,dissolved oxygen (DO),sea water pH,and chlorophyll concentration in the coastal China seas over the 21st century based on the fifth phase of the coupled model inter comparison project(CMIP5).The results show that the coastal China seas will experience significant warming,deoxygenation,acidification,and reduced chlorophyll,as a consequence of increasing greenhouse gas emissions in the next few decades.Larger changes of marine environment were found in the East China Seas (ECS,including Bohai,Yellow Sea,and East China Sea) compared to the South China Sea.By the end of this century,SST (pH) in ECS will increase(decrease) by 2℃ (0.15) and 4℃ (0.30),respectively,under the high and medium concentration emission scenarios.The enhanced warming and acidification in ECS will further result in deoxygenation and decline in chlorophyll,and thus resulting impacts environmentally and ecologically.Consequently,the coastal China seas,especially the ECS,will face the risk of serious climate change.The urgent to reduce greenhouse gas emissions with relevant adaptive measures should be proposed.