Summary

Sea-level rise is one of the most certain and costly consequences of a warming world with potentially hazardous impacts on coastal infrastructure, property, and the livelihoods of coastal communities (Nicholls and Cazenave, 2010). Since 1992, radar altimeters on board of satellites have been continuously monitoring sea-level changes with high accuracy and nearly global coverage, providing essential information on the behavior of regional and (near-) global mean sea level (GMSL) (Ablain et al., 2015). However, placing this valuable record into historical context is challenging, since estimates of GMSL before the altimetry era rely on a spatially and temporally sparse set of either tide gauge or proxy-records along the coast. In addition, these in-situ records are affected by regionally varying geoid and solid earth processes such as vertical land motion (VLM) caused by glacial isostatic adjustment (GIA) or other local processes, which may mask the global information in the records. Uncertainties in geoid and solid earth corrections in combination with different processing schemes (manifesting itself in a different weighting of the tide gauges) cause current estimates of 20th century GMSL change based on tide gauges to vary widely between ~1 and 2 mm/yr (Church and White, 2011; Jevrejeva et al., 2014; Hay et al., 2015; Dangendorf et al., 2017). Furthermore, pre-industrial reconstructions of GMSL based on sea level proxies are limited to one single study (Kopp et al., 2016). The approaches and datasets used in the different published estimates of past GMSL change differ considerably, and there has been no consistent assessment of the differences between the individual reconstructions.
This ISSI team aims to (i) objectively assess the performance of pre-altimetric sea level reconstructions using a consistent and reproducible framework of common datasets, (ii) understand and reduce the wide range of past estimates, and (iii) put the high contemporary GMSL rates obtained from satellite altimeters (~3.4 mm/yr) into a better constrained historical context.

References:

  • Ablain M., et al. (2015) Improved sea level record over the satellite altimetry era (1993–2010) from the Climate Change Initiative project. Ocean Sci 11:67–82. doi:10.5194/os-11-67-2015
  • Church JA, White NJ (2011) Sea-level rise from the late 19th to the early 21st Century. Surveys in Geophysics, 32, 585-602.
  • Dangendorf, S., et al. (2017) Reassessment of 20th century global mean sea-level rise, PNAS, 114, 5946–5951, doi: 10.1073/pnas.1616007114.
  • Hay C. H., et al.. (2015) Probabilistic reanalysis of twentieth-century sea level rise. Nature, 517, 481–484
  • Jevrejeva S, Moore JC, Grinsted A, Matthews AP, Spada G (2014) Trends and acceleration in global and regional sea levels since 1807. Global and Planetary Change, 113, 11-22.
  • Kopp, R. E., et al. (2016) Temperature-driven global sea-level variability in the Common Era. Proceedings of the National Academy of Sciences, doi:10.1073/pnas.1517056113.
  • Nicholls, R. J., Cazenave, A. (2010) Sea-level rise and its impacts on coastal zones, Science, 328(5985), 1517-20.