South Korea's seas had second-warmest summer on record at 26.95C, fisheries institute says
In short
The National Institute of Fisheries Science said on 20 October that the average sea surface temperature around Korea in July to September was 26.95 degrees, 1.49 degrees above the 1991-2020 norm. It was the second-highest summer reading after last year's 27.75 degrees.
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South Korea's seas had their second-warmest summer on record this year, according to the National Institute of Fisheries Science. The institute said on 20 October that its analysis of satellite observation data put the average sea surface temperature for July to September at 26.95 degrees. That was 1.49 degrees above the 1991-2020 norm. [ 1 , 2 , 3 ]
The reading ranks behind last year's 27.75 degrees. Using its real-time observation system for coastal waters, the institute also reported that the August average temperature along the East Sea and South Sea coasts was 25.87 degrees. That was 1.69 degrees above the average of the past 10 years and 3.42 degrees above the previous year. [ 1 , 2 , 3 ]
The institute said the higher coastal temperatures this summer appear to result from a heat dome and marine heat waves that strengthened heating of the sea surface. Yonhap said the heat dome was linked to the position of a high-pressure air mass. Yonhap and Maeil Business defined a marine heat wave as sea surface temperature in the top 10 percent of the climate norm lasting five days or more. [ 1 , 2 , 3 ]
Cold water mass formation in the East Sea and South Sea was weaker, and relatively warm offshore water kept flowing toward the coast, which the outlets reported as another factor. Newsis said this continuous supply of warm offshore water kept coastal temperatures high. [ 1 , 2 , 3 ]
Kwon Sun-wook (권순욱), head of the institute, said: "Sea temperature variability and uncertainty are increasing because of recent climate change." He said the institute would respond ahead of time to changes in the marine environment through precise temperature observation and forecasting. Maeil Business, citing Yonhap, added that high temperatures continuing from last year have increased concern about marine environment changes linked to climate change. [ 1 , 2 , 3 ]
Why it matters
The figures come from the National Institute of Fisheries Science's satellite and coastal observations. Its head said sea temperature variability and uncertainty are rising with climate change, and that the institute will step up observation and forecasting.
Key facts
- The National Institute of Fisheries Science said the average sea surface temperature in July to September was 26.95 degrees, based on satellite observation data. [ 1 , 2 , 3 ]
- That was 1.49 degrees above the 1991-2020 norm and the second highest after last year's 27.75 degrees. [ 1 , 2 , 3 ]
- In August, the average coastal temperature in the East Sea and South Sea was 25.87 degrees, 1.69 degrees above the 10-year average and 3.42 degrees above the previous year. [ 1 , 2 , 3 ]
- The institute attributed the warmth to a heat dome and marine heat waves that strengthened sea surface heating. [ 1 , 2 , 3 ]
- Weaker cold water mass formation in the East Sea and South Sea and a continuous supply of relatively warm offshore water to the coast were also cited. [ 1 , 2 , 3 ]
Confirmed by several sources
- The summer 2026 average sea surface temperature was 26.95 degrees, 1.49 degrees above the 1991-2020 norm and second only to last year's 27.75 degrees, according to the National Institute of Fisheries Science. [ 1 , 2 , 3 ]
- August coastal temperatures in the East Sea and South Sea averaged 25.87 degrees, 1.69 degrees above the 10-year average and 3.42 degrees above the previous year. [ 1 , 2 , 3 ]
Still unclear
- What the 1.49-degree difference is measured against Newsis and Yonhap say it is against the 1991-2020 norm, but one passage in the Maeil Business text says it is higher than last year, which conflicts with the other two outlets and with last year's stated 27.75 degrees.