Wednesday, March 11, 2009

Accelerated sea-level rise?

I mentioned a few days ago a report that sea levels are rising faster than predicted by the IPCC. There is another such report just out here.

Below is an email on the subject from Professor Dr. Nils-Axel Morner [], a leading world authority on sea levels and coastal erosion who headed the Department of Paleogeophysics &Geodynamics at Stockholm University
Misused data! Satellite altimetry 1993-2000 was horizontal - the same data set + 2000-2003 was tilted. On top of the physical corrections (giving horizontallity) they added "personal correction" to fit IPCCs claims. What do we call this? If not falsification? See my scientific papers - best: Global and Planetary Change 62 (2008) 219-220.

Excerpt from the paper concerned below -- pointing out that the raw data on sea levels shows that they have in fact been flat. It is only the addition of various "corrections" -- some of which are quite arbitrary -- that suggests rising sea levels.
Comment on comment by Nerem et al. (2007) on "Estimating future sea level changes from past records"

by Nils-Axel Moerner

First let us clear up the origin of my Fig. 2 (in Moerner, 2004). It is a product of the CLS Company printed in MEDIAS (2000, Fig. 1.2; also available on the net at Aviso, 2000). My curve was a redrawing of this graph. This curve, spanning the time from October 1992 to April 2000, does not record any sea level rise; only a variability plus one (or more) ENSO signals.

That was the point of my picture. It should be noted that this graph includes the technical adjustments (including the drift factor of Mitchum, 2000, Fig. 10) illustrated by the lower arrow in Fig. 1. Later the same graph re-appears with a strong tilt (Aviso, 2003; cf. Leuliette et al., 2004; Moerner, 2005). Why is that?

It is because of the introduction of additional calibrations (Mitchum, 2000; Leuliette et al., 2004; Cazenave & Nerem, 2004) - and those "calibrations" are subjective interpretations (Fig. 1; upper arrow); not objective readings. Consequently, they are opinion-dependent. "We adopt the rate given by Douglas (1991,1995) of 1.8~0.1mm/yr", Mitchum (2000) states. This rate, however, is widely debated and far from generally accepted. Especially not in the geological sea level community (cf. Moerner, 2004, Fig. 4), where we realize that the tide gauges quite frequently are installed in unstable local position, and I quote (from Moerner et al., 2004): "Tide gauge records, however, do not provide simple and straight-forward measures of regional eustatic sea level. They are often (not to say usually) dominated by the effects of local compaction and local loading subsidence.

With this perspective, our multiple morphological and sedimentological records appear more reliable and conclusive" (cf. Moerner, 2007). This makes the requited "correction" for land motion at the tide gauge very delicate and subjective. The nice and interesting thing with the graph under discussion (Moerner, 2004, Fig. 2) is that it represents the readings before all these interpretational "corrections".

Posted by John Ray.

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