ALBERT

Description: ABSTRACT The coastal China areas stretching from tropical to temperate zone represent major environmental and economic assets. However, knowledge of climate change and its impact in coastal seas, which is very critical for marine resource and risk-management issues, is relatively poor compared with that on land. Here, we show that the coastal China seas experienced a long-term surface warming with a rate of 0.015 °C year −1 and an obvious sea level rise along the coast, particularly along the East China Sea with a rate of more than 3.2 mm year −1 since the late 1950s. The Eurasian atmospheric circulation underwent clearly inter-decadal changes in the past decades due to the tropical ocean thermal changes including warming hiatus and conversely influenced the higher latitude coastal marine conditions through regional air–sea interaction. Marine climate variables including sea surface temperature, sea surface height, and atmospheric cyclonic circulation have formed a favourable condition for phytoplankton blooms such as harmful algae blooms (e.g. red tides) and Enteromorpha prolifera blooms (green tides). These algae blooms could strongly lower oxygen levels in the seawater and have been posing threats for the health of coastal and marine ecosystems since the late 1970s. The impacts and key risks of climate change risks in coastal China seas and the coastal zone are reviewed and analysed as follows: frequent occurrences of red tides and green tides, distribution shifts of marine species and changes in their seasonal behaviour, reduction of coastal habitat, decline of marine ecosystem services, flooding and coastal inundation, seawater intrusion, and threats to coastland community security and marine industries, etc. Furthermore, the accumulated effects of human activity, such as reclamation, sewage discharge, and overfishing, have led to an apparent increase in climate-related vulnerabilities. Adaptation issues and risk-management strategies in response to climate change are discussed and proposed as well.