期刊名称：Journal of Advances in Modeling Earth Systems
电子版ISSN：1942-2466
出版年度：2021
卷号：13
期号：3
页码：e2020MS002323
DOI：10.1029/2020MS002323
出版社：John Wiley & Sons, Ltd.
摘要：Ocean dynamic sea level (DSL) change is a key driver of relative sea level (RSL) change. Projections of DSL change are generally obtained from simulations using atmosphere‐ocean general circulation models (GCMs). Here, we develop a two‐layer climate emulator to interpolate between emission scenarios simulated with GCMs and extend projections beyond the time horizon of available simulations. This emulator captures the evolution of DSL changes in corresponding GCMs, especially over middle and low latitudes. Compared with an emulator using univariate pattern scaling, the two‐layer emulator more accurately reflects GCM behavior and captures non‐linearities and non‐stationarity in the relationship between DSL and global‐mean warming, with a reduction in global‐averaged error during 2271–2290 of 36%, 24%, and 34% in RCP2.6, RCP4.5, and RCP8.5, respectively. Using the emulator, we develop a probabilistic ensemble of DSL projections through 2300 for four scenarios: Representative Concentration Pathway (RCP) 2.6, RCP 4.5, RCP 8.5, and Shared Socioeconomic Pathway (SSP) 3–7.0. The magnitude and uncertainty of projected DSL changes decrease from the high‐to the low‐emission scenarios, indicating a reduced DSL rise hazard in low‐ and moderate‐emission scenarios (RCP2.6 and RCP4.5) compared to the high‐emission scenarios (SSP3‐7.0 and RCP8.5). Plain Language Abstract As climate warms, sea‐level rise poses a major threat to coastal communities and ecosystems. A key driver of local sea level change is ocean dynamic sea level change, which is associated with changes in ocean density and circulation. The primary tools used to project changes in dynamic sea level are atmosphere‐ocean general circulation models, which are computationally expensive. Here we develop an emulator for dynamic sea level changes that is, built upon a two‐layer energy balance model. Considering both the rapid response of well‐mixed surface layer and the delayed response of the deep ocean to forcing, the emulator facilitates the estimation of probability distributions of future dynamic sea level change under different emission scenarios and the extension of projections beyond the time horizon of available simulations from some atmosphere‐ocean general circulation models. This emulator captures the evolution of dynamic sea level changes in the atmosphere‐ocean general circulation models to which it is tuned, including the non‐linear and non‐stationary relationship between the dynamic sea level and global warming. The emulator thus facilitates the estimation of future local sea‐level changes.
