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A History and Projection of Global Sea Level
Reference
Morner, N.-A. 2004. Estimating future sea level changes from past records. Global and Planetary Change 40: 49-54.

What was done
The author, who has devoted his entire professional life to the study of the topic, applies all "observational material[s] and theoretical consideration[s] for a sound estimation of the sea level changes to be expected in the near future," noting that his analysis "is a contribution of the INQUA Commission on Sea level Changes and Coastal Evolution, and can be regarded as the commission's official evaluation of the sea level changes that are to be expected in the near-future."

What was learned
Morner remarks that "prior to 5000-6000 BP, all sea level curves are dominated by a general rise in sea level in true glacial eustatic response to the melting of continental ice caps," but that "sea level records are now dominated by the irregular redistribution of water masses over the globe ... primarily driven by variations in ocean current intensity and in the atmospheric circulation system and maybe even in some deformation of the gravitational potential surface."

With respect to the last 150 years, Morner notes that "the mean eustatic rise in sea level for the period 1850-1930 was [o]n the order of 1.0-1.1 mm/year," but that "after 1930-40, this rise seems to have stopped (Pirazzoli et al., 1989; Morner, 1973, 2000)." This stasis, in his words, "lasted, at least, up to the mid-60s." Thereafter, with the advent of the TOPEX/POSEIDON mission, Morner notes that "the record can be divided into three parts: (1) 1993-1996 with a clear trend of stability, (2) 1997-1998 with a high-amplitude rise and fall recording the ENSO event of these years and (3) 1998-2000 with an irregular record of no clear tendency." Most important of all, in his words, "there is a total absence of any recent 'acceleration in sea level rise' as often claimed by IPCC and related groups."

What it means
Writing on behalf of the INQUA Commission on Sea Level Changes and Coastal Evolution, Morner says that "when we consider past records, recorded variability, causational processes involved and the last centuries' data, our best estimate of possible future sea level changes is +10 10 cm in a century or, maybe, even +5 15 cm." Hence, in his words, "we have to discard the model output of IPCC (2001) as untenable, not to say impossible (Morner, 1995; INQUA, 2000), and we cite the Gilgamesh Epos from about 5000 BP saying: Lay upon the sinner his sin. Lay upon the transgressioner his transgression." Or to put it more bluntly, as Morner does in the final sentence of his abstract, "there is no fear of any massive future flooding as claimed in most global warming scenarios."

References
INQUA. 2000. Homepage of the commission on sea level changes and coastal evolution, http://www.pog.su.se/sea. Sea Level Changes, News and Views, The Maldives Project.

IPCC. 2001. Climate Change. Cambridge University Press, Oxford, UK.

Morner, N.-A. 1973. Eustatic changes during the last 300 years. Palaeogeography, Palaeoclimatology, Palaeoecology 9: 153-181.

Morner, N.-A. 1995. Recorded sea level variability in the Holocene and expected future changes. In: Eisma, D. (Ed.), Climate Change. Impact on Coastal Habitation. CRC Press, Boca Raton, FL, pp. 17-28.

Morner, N.-A. 2000. Sea level changes along Western Europe. In: Integrated Coastal Zone Management, 2nd ed. IPC Publ., London-Hong Kong, pp. 33-37.

Pirazzoli, P.A., Grant, D.R. and Woodworth, P. 1989. Trends of relative sea-level changes: past, present, future. Quaternary International 2: 63-71.


Reviewed 4 February 2004