Projected climate change in the western North Pacific at the end of the 21st century from ensemble simulations with a high-resolution regional ocean model

Future climate change in the western North Pacific at the end of the 21st century (2081–2100) was examined using a high-resolution regional ocean model (10-km mesh) under the RCP2.6 and RCP8.5 scenarios. The range of uncertainty in future projections was estimated from ensemble simulations. Projected results indicated no significant change in the Kuroshio net transport and the latitude of the Kuroshio Extension under both RCP scenarios; the changes were within the range of variability associated with the present climate. Projected sea surface temperature (SST) increased by as much as several degrees Celsius, especially in SST fronts, including the subarctic frontal zone. The significant increase of SST east of Japan was attributed to the northward expansion of the northern part of the subtropical gyre in response to basin-scale atmospheric changes. The projected area of sea ice in the Sea of Okhotsk decreased in both RCP scenarios. The projected offshore sea-level rise was larger in the subtropical gyre and smaller in the subpolar gyre. The sea-level rise along the coast of Japan, in contrast, showed no significant spatial variation. The mean sea-level rise along the coast of Japan was mostly comparable to the global mean sea-level rise.