Accelerated ocean acidification in the Tsugaru Strait by an intensified
Tsugaru Warm Current
The oceanic uptake of anthropogenic CO2 has resulted in
acidification in surface and subsurface waters throughout the global
ocean. We initiated acidification monitoring in the eastern part of the
Tsugaru Strait, which connects the Sea of Japan and the North Pacific.
Annual mean pH and CaCO3 saturation state decreased
considerably throughout all depths at rates of 0.0030−0.0051
yr−1 and 0.017−0.036 yr−1 during
2012-2019, respectively. These rates of decrease are faster than those
caused by increasing atmospheric CO2, and faster than
those observed during previous research in the Sea of Japan and the
North Pacific. The accelerated acidification is attributed to enhanced
increase in dissolved inorganic carbon caused by elevated mixing of the
upper and deeper waters from the Sea of Japan at the western part of the
strait by the strengthening of the Tsugaru Warm Current.