The sea level around Jeju Island has been rising three times faster than the global average.

The Korea Hydrographic and Oceanographic Administration said Thursday that it analyzed records of the sea level around the Port of Jeju and discovered it has surged around six millimeters annually since related data began to be collected in 1978. That’s around three times higher than the world’s average annual growth rate of one-point-eight millimeters.

Meanwhile the overall sea level surrounding the nation has been growing two-and-a-half millimeters annually, which is also higher than the world’s average rate.

The administration said the sea level around the southern and eastern coasts rose due to an increase in water temperature and as the Kuroshio current flowed into the East Sea.