Longterm sealevel change revisited the role of salinity

Long-term sea-level change revisited: the role of salinity Objective • Evaluate observed and simulated halosteric (salinitydriven) sea level changes since 1950 and contrast them with the better understood thermosteric (warming-driven) changes Research • Regionally and on short timescales, halosteric sea level changes are known to be important to the column-integrated steric total, however the importance of this effect on larger space and longer time scales has not been investigated to date • Using observed and modeled estimates of long-term (1950 -2008) steric changes, assess the role of halosteric changes on basin-scale sea level totals • Contrast observed (in-situ) and modeled sea level change estimates to test for pattern consistency, and investigate the role of forcing in models Impact • This analysis provides evidence that the role of salinity on basin-scale sea level changes has been substantially underestimated. These results have important implications for future sea level assessments and suggest that salinity-driven changes should no longer be ignored 1 BER Climate Research How do observed and simulated halosteric sea level changes compare? There is a general basinscale agreement between the patterns of halosteric sea level changes – the Pacific shows a halosteric expansion (freshening) and the Atlantic shows a contraction (enhanced salinity). Units are mm yr -1 It is possible to contrast model simulations which include and exclude anthropogenic effects in their 20 th and early 21 st century halosteric patterns Result: Anthropogenic CO 2 forcing is required to replicate the observed basin -scale halosteric patterns in models Reference: P. J. Durack, S. E. Wijffels and P. J. Gleckler (2014): Long-term sea-level change revisited: the role of salinity. Environmental Research Letters, 9 (11), 114017. doi: 10. 1088/1748 -9326/9/11/114017 Department of Energy • Office of Science • Biological and Environmental Research