뜨거워지는 대한민국 남쪽 바다, 이어도가 보내는 경고음 > K-wave Trends

As a result of the research team's detailed analysis of observational data accumulated over 20 years from 2004 to 2023, it was calculated that the surface water temperature in the waters around Ieodo Island increased by 1.1 degrees. This is more than twice the average rise of the world's oceans, excluding polar regions, of 0.48 degrees during the same period. In particular, in May of this year, the water temperature reached 17 degrees, significantly exceeding the May average of 15 degrees over the past 20 years, and the air temperature also broke the all-time high at 19.1 degrees. This phenomenon goes beyond simple seasonal fluctuations and is objective evidence suggesting that our waters are at the forefront of climate change and are most directly affected by it.

This rapid warming of the Ieodo sea area is the result of complex environmental changes rather than a single factor. First, as the influence of the Kuroshio Warm Current strengthens, warm seawater continues to flow in, and as the force of the high pressure in the Northwestern Pacific becomes stronger in the summer, surface heating is further intensifying. In addition, the ‘heat trapping phenomenon’ occurs, where low-salt water flowing from the Yangtze River stays in the surface layer and prevents heat from dissipating into the deep sea. These complex mechanisms resulted in abnormally high surface water temperatures, demonstrating the unique value of field data from Ieo Island, which is difficult to determine through satellite observations or simulations alone.

The rapid rise in water temperature is not just a change in ocean temperature, but also portends a serious domino effect throughout the marine ecosystem and fisheries industry. In general, coral bleaching begins when the water temperature rises by just 0.5 degrees, and when the temperature rises by 1 degree, the energy of typhoons and hurricanes increases dramatically, causing a rapid increase in the frequency of super typhoons. In fact, Ieo Island is located on the main path of typhoons heading to the Korean Peninsula, so the high temperature phenomenon here is very threatening in that it can serve as an energy source that strengthens the power of typhoons. In addition, due to changes in the distribution of fish species, the production of squid, which was once a major fish species on the southern coast, has decreased sharply and the proportion of warm-water fish species such as mackerel is changing, causing a real blow to the industry.

The biggest achievement of this study is that it secured the reliability of field observation data accumulated by the Ieodo Marine Science Station over 20 years and made it public to researchers around the world. This dataset, built jointly with the National Oceanic and Atmospheric Survey, was processed precisely enough to eliminate errors in the massive raw data, standardize it on an hourly basis, and allow direct comparison with computer simulations. It has already been recognized for its academic value enough to be published in ‘Scientific Data’, a sister journal of Nature, and will be used as key basic data for monitoring climate change and predicting marine disasters in the future. This once again confirms the pivotal role that Ieodo has played as an outpost for marine observation in Korea since its completion in 2003.