You would think that the inexorable rise in sea level since the end of the last ice age, approximately 14,000 years ago, would be a relatively simple calculation. Land ice melts; water runs into sea, sea rises, end of story.
Nice and simple, that is, if you want to get across a simple message that human caused global warming is resulting in the melting of that ice and the subsequent rise in sea levels. So as a global warming alarmist what you don’t want is nasty facts and complicated variables muddying the water of some ‘settled science’.
For instance? Well tidal gauges in the port of Turku (near the gulf of Finland) appear to show that the sea level is falling at 1cm per year (E. Niskanen Isostatic Institution International Association of Geodesy Pub. 6, Helsinki). Stockholm used to be an island, but the sea level here also appears to be falling also at 1cm per year. But even more extreme, the city of Ephesus was a port city in biblical times. Now it is 24km inland and 5 metre above sea level. (Heaven & Earth: Global Warming the Missing Science by Ian Plimer). How can this be possible? We know from high school science that water finds its own level. It can’t be higher in one place and lower in another. But then anyone with a fleeting knowledge of geology would know that this is nothing at all to do with sea level rise or fall but the rise of the land itself. In the case of Scandinavia, the earth is rebounding after the retreat of ice from the last ice age. There are many other possible reasons for these apparently anomalous readings. There could be volcanic uplift, Techtronic uplift.
Other things that enter the equation are things like gravity. Large mountains near the sea will create a locally higher level of sea. The coriolis effect will show a higher sea level on one side of a continent than it will on the other due the earth’s spin.
My point is that sea level rise is very difficult to measure accurately. In some parts of the world tidal gauges are sinking, registering a false sea level rise. Those that claim a sea level rise over and above the background rise due to the current interglacial (if they are alarmists) will point to the 3mm rise per year over the last 20 years which if extrapolated gives a somewhat alarming trend – how satisfying for them. On the other hand since the end of the last ice age sea level rise has moved in fits and starts as a result of surges of land ice into the sea. You might note that these two competing articles use the same graph. But come one, trying to extrapolate what will happen to sea levels when using a time scale of 20 years and with all the potential inaccuracies and variables. That’s pushing it even for these dyed in the wool warmists.
If the sea level rise argument shows nothing else it is that ‘The Science is not Settled’.