Local Sea-Level Rise Caused by Climate Change in the Northwest Pacific Marginal Seas Using Dynamical Downscaling

Yong-Yub Kim,Yang-Ki Cho,Eunil Lee,Bong-Gwan Kim,Kwang Young Jeong,Do-Seong Byun

doi:10.3389/fmars.2021.620570

Abstract

Global climate models (GCMs) have limited capacity in simulating spatially non-uniform sea-level rise owing to their coarse resolutions and absence of tides in the marginal seas. Here, regional ocean climate models (RCMs) that consider tides were used to address these limitations in the Northwest Pacific marginal seas through dynamical downscaling. Four GCMs that drive the RCMs were selected based on a performance evaluation along the RCM boundaries, and the latter were validated by comparing historical results with observations. High-resolution (1/20°) RCMs were used to project non-uniform changes in the sea-level under intermediate (RCP 4.5) and high-end emissions (RCP 8.5) scenarios from 2006 to 2100. The predicted local sea-level rise was higher in the East/Japan Sea (EJS), where the currents and eddy motions were active. The tidal amplitude changes in response to sea-level rise were significant in the shallow areas of the Yellow Sea (YS). Dynamically downscaled simulations enabled the determination of practical sea-level rise (PSLR), including changes in tidal amplitude and natural variability. Under RCP 8.5 scenario, the maximum PSLR was ∼85 cm in the YS and East China Sea (ECS), and ∼78 cm in the EJS. The contribution of natural sea-level variability changes in the EJS was greater than that in the YS and ECS, whereas changes in the tidal contribution were higher in the YS and ECS. Accordingly, high-resolution RCMs provided spatially different PSLR estimates, indicating the importance of improving model resolution for local sea-level projections in marginal seas.

Highlights

Global mean sea-level has risen over past decades (WCRP Global Sea Level Budget Group, 2018), with a significant acceleration in sea-level rise [SLR; (Chen et al, 2017; Dangendorf et al, 2019)]
We projected the SLR including barystatic and sterodynamic components considered in lateral boundary sealevel
Climate change signals of the Global climate models (GCMs) were directly applied at the lateral model boundaries, and the results showed significant predictive improvements in sea surface temperature (SST), currents, and sea surface heights (SSHs) compared with coarser resolution GCMs

Summary

INTRODUCTION

Global mean sea-level has risen over past decades (WCRP Global Sea Level Budget Group, 2018), with a significant acceleration in sea-level rise [SLR; (Chen et al, 2017; Dangendorf et al, 2019)]. The oversimplified topography of the GCM-MPI (Figure 2D), which fails to resolve the Taiwan Strait and allocates a single cell to the Korea Strait, may be causing a weak circulation and high sea-level in the YS-ECS, as these estimates were improved with the more accurate topographic conditions of the RCMs. Satellite-derived SSHs in the EJS were higher in the southern warm waters along the paths of the TC and EKWC, and lower in the northern cold-waters (Figure 5A). Timeseries of the mean annual data showed the projected SLR according to the warming signal under future climate scenarios for both the GCMs and RCMs (Figure 8). 73 (46) cm near the EKWC path (near 39◦N, 130◦E), ∼5 (2) cm higher than SLR in the same region

CONCLUSION AND DISCUSSION

DATA AVAILABILITY STATEMENT