The sea level surrounding the Korean Peninsula has risen. The rate of sea level rise in the East Sea is relatively higher than that in the South and Yellow seas, and the rates of sea level rise for the South and Yellow seas are similar.

 

 Observed mean sea level fluctuations around the Korean Peninsula are 2.07 mm/yr, 2.41 mm/yr, and 3.70 mm/yr in the Yellow, South, and East seas, respectively. Mean sea level fluctuation in Jejudo is the highest at 4.44 mm/yr. Jeju recorded the highest sea level fluctuation among all the sea regions at 5.43 mm/yr, followed by Ulleungdo (5.13 mm/yr), Pohang (4.55 mm/yr), and Geomundo (0.41 cm/yr).

 

 Compared to the other seas, the sea level rise in the East Sea is remarkable. It is due to an increase in the heat transport of the Kuroshio warm current and a rise in the temperature of warm current through the East Sea as a result of global warming. If global warming is accelerated, the coastal areas are expected to suffer great damage from coastal flooding due to sea level rise.

 

 According to the Representative Concentration Pathway (RCP) 4.5 (8.5) scenario, the sea level around Korea will rise by 53 cm (65 cm) in both the South Sea and the Yellow Sea, and 74 cm (99 cm) in the East Sea within the second half of the twenty-first century (2071–2100). Meanwhile, the global average sea level is expected to rise by 70.6 cm (88.5 cm) for the same period. According to the RCP 4.5 (8.5) scenario, the sea level will rapidly increase by 2100, and the sea level around the Korean Peninsula will continue to rise by more than 65 cm (85 cm) in both the South Sea and the Yellow Sea, and 90 cm (130 cm) in the East Sea. According to the RCP 8.5 scenario, the high risk of flooding due to rising sea levels can be seen in coastal lowlands.