Biological and Environmental Research - Earth and Environmental System Sciences
Earth and Environmental System Modeling
28 February 2019

Internal Climate Variability and Projected Future Regional Steric and Dynamic Sea Level Rise


Observational evidence points to a warming global climate accompanied by rising sea levels which impose significant impacts on island and coastal communities. Studies suggest that internal climate processes can modulate projected future sea level rise (SLR) regionally. It is not clear whether this modulation depends on future climate pathways. Here, by analyzing two sets of ensemble simulations from a climate model, we investigate the potential reduction of SLR, as a result of steric and dynamic oceanographic effects alone, achieved by following a lower emission scenario instead of business-as-usual one over the twenty-first century and how it may be modulated regionally by internal climate variability.

  • Community Earth System Model version 1 (CESM1) with 1-degree resolution is our tool.
  • 30 member ensemble simulations with time-evolving 20th century all known forcings (1920-2005), and RCP8.5 forcings (2006-2080), and 15 member ensemble RCP4.5 (2006-2080).
  • Global and regional sea level rise
  • Internal climate variability – PDO, AMOC, NAO. ACC
  • Almost no statistically significant difference in steric and dynamic SLR on both global and regional scales in the near-term between the two scenarios, but statistically significant SLR reduction for the global mean and many regions later in the century.
  • There are regions where the SLR reduction is insignificant, such as the Philippines and west of Australia, that are associated with ocean dynamics and intensified internal variability due to external forcing.
Aixue Hu
National Center for Atmospheric Research (NCAR)