By Lee Suh-yoon
Every year, Gongji stream in Chuncheon, Gangwon Province, completely freezes over by early January.
Except it hasn't this year. There are thin sheets of ice here and there but the stream mostly flows on, says Gangwon district weather station. According to observations from previous years, the stream's surface should be completely iced over by now.
Monday was supposed to be the coldest day this winter but the long cold spells that usually arrive between December and January never came. The stream is likely to keep flowing as this mild weather continues.
Last year, the nation recorded its second-hottest average temperature since 1973 ― when the KMA started monitoring atmospheric conditions ― at 13.5 degrees Celsius. The highest figure was 13.6 degrees in 2016.
"We know ocean and atmospheric temperatures are rising due to greenhouse gases, including Siberia. This could partly explain why the high pressure cold air from Siberia is so weak this year," Yun Ki-han, a Korea Meteorological Administration (KMA) spokesperson, told The Korea Times.
With the milder climate, the oceans flanking the Korean peninsula are also warmer.
"This winter, the ocean around the Korean peninsula are about 1 to 3 degrees higher than usual," Han In-sung, a researcher at the National Institute of Fisheries Science, said. "The spike is linked to the relatively warm weather we are having this winter. "
The last temperature spike in the oceans was in 2007 and 1979. Even then, however, the rise did not exceed 1.5 degrees.
The temperatures currently range between 12 to 16 degrees Celsius in the East Sea, 12 to 18 degrees Celsius in the South Sea and four to 12 degrees in the West Sea. The highest temperature spike of three degrees was found at parts of the East Sea like Jumunjin beach at Gangwon Province.
It's a global trend. A recent study published in the journal Advances in Atmospheric Sciences reported last year's ocean temperatures were the hottest on record. Oceans are known to absorb most of the excess heat trapped in the atmosphere by greenhouse gases.
The warm weather is having repercussions for the country's fisheries and marine plant farms. In the southern tip of the peninsula, laver farms are reporting a drastic drop in production due to warmer waters. Meanwhile, East Sea fisheries up north have seen a three to five-fold increase in their catch of Yellowtail, which used to be found further south near Jeju Island.
"Over the last decades, we have seen dominant fishing stocks around the peninsula switch to species found in warmer waters, such as mackerel, squid and anchovy," Kim Jung-jin, a researcher who studies fisheries at the National Institute of Fisheries Science, said . Kim added that the correlation was inconclusive for specific fish species due to other variables like overfishing and changing currents.
Warmer oceans are also ideal for the formation of tropical typhoons. Korea experienced seven typhoons in the last year, the highest number since the KMA collected records in 1904, along with 1950 and 1959.