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Sea surface temperature (around Japan)

Updated on 24 Apr. 2017
Global Environment and Marine Department

The annual average sea surface temperature (SST) around Japan has risen by +1.09°C over the last 100 years, which exceeds the corresponding figure for the global ocean (+0.53°C) and is similar to that for surface air temperature in Japan (+1.19°C). The rates of increase in Areas I, II, III, V, VII and XIII (see the table below) are also similar to those for surface air temperature in Japan, while those for Areas IV, VI, VIII, IX and X are lower and that for Area XII is higher.

Rates of area averaged SST increase around Japan
Area
number
Area name
IYellow Sea
IINorthern part of the East China Sea
IIISouthern part of the East China Sea
IVSea around the Sakishima Islands
VSea off Shikoku and Tokai
VIEast of Okinawa
VIISea off Kushiro
VIIISea off Sanriku
IXEastern part of the sea off Kanto
XSouthern part of the sea off Kanto
XINortheastern part of the Sea of Japan
XIICentral part of the Sea of Japan
XIIISouthwestern part of the Sea of Japan

Increase rates of area-averaged annual mean SSTs around Japan from 1900 to 2016 (°C per century)
Areas with no symbol and those marked with [∗] have statistically significant trend at the confidence levels of 99 % and 95 %, respectively. Areas marked with [#] are those where no discernible trend is seen due to large SST variability factors such as decadal oscillation.

Commentary

The annual average SST around Japan has risen by +1.09°C over the last 100 years, which exceeds the corresponding figure for the global ocean and the North Pacific (+0.53 and +0.50°C, respectively) and is similar to that for surface air temperature in Japan (+1.19°C). The rates of increase in regional annual mean SSTs in Areas I, II, III, V, VII and XIII (see the table above) are similar to those for surface air temperature in Japan, while those for Areas IV, VI, VIII, IX and X are lower and that for Area XII is higher. The SST in Area XI exhibits no statistical long-term trend.

According to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC AR5) Working Group I, warming of the climate system is unequivocal and it is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century. As detailed in the IPCC AR5 Working Group I Report, observed changes in surface temperatures during the period from 1901 to 2012 show significant variations among regions. The inland of Asia has exhibited particularly marked warming. The global warming is considered to have contributed to the SST increase around Japan. In addition to that, natural fluctuations such as Pacific Decadal Oscillation (PDO) and variations in the Kuroshio Extension are also thought to have contributed to the rising SST trend observed around Japan.