Evidence and Causes of Sea Level Rise
EVIDENCE AND CAUSES OF SEA LEVEL RISE
In spite of the scientific criticism that has been levelled at the pseudo-science and exaggerations of the Gore movie, there remains in the public mind an indelible picture of its computer imaging of the slowly flooding continents.
Even to many Kyoto adherents, Gore’s extrapolations are pure hype. He assumes 20 feet (seven metres) per hundred years sea level rise, while even the IPCC only expects something in the order of 20 to 40 centimetres, roughly eight to sixteen inches. But propaganda movies are very effective tools to influence the public mind, as Hitler’s Leni Riefenstahl showed us first.
- What is Average Global Sea Level and how do we measure it?
Those who are familiar with the criticism of the concept of “Global Mean Temperature”, which depends on questionable observation stations, uneven coverage (desert and ocean gaps) and computer massaging to produce a statistic called Global Mean Temperature, will not be surprised to learn that there is no more an Average Global Sea Level than there is a Mean Global Temperature. Currents, persistent or changing wind patterns, vertical upwelling/downflows, El Niño events and the like are constantly affecting sea levels.
Current Sea Levels are mainly measured through Tide Gauges and by a satellite system. Both have their problems.
To the extent that we are worried about the ocean/land boundary, let’s look first at Tide Gauges. They are located predominantly in ports. Ports are often situated at river mouths and in deltas. Deltas are subject to compaction of the river sediments and therefore “land” is often not a proper reference point. Other favourite gauge locations are subject to tectonic movements which (with or without the benefit of continental drift) affects many oceanic coasts. Some of these are on islands and many papers have written about the gauge records pf the Pacific Islands and groups like the Indian Ocean’s Maldives.
Many of the Pacific islands are volcanoes that slowly subside into the thin ocean crust on which they were built. Only the corals that ring them keep them above water, as they can outgrow the subsidence.
The Maldives are located on one of the planet’s main transform faults along which India travelled northward from its origin in Gondwana to its collision with Asia, throwing up the Himalayas. It’s a still active tectonic alignment. Not a stable reference point.
Isostatic adjustments of the land surface as in formerly ice-covered areas can occur, as evident on the shores of Hudson Bay.
On the low end of the SL rise spectrum is the work by Nils-Axel Mörner who showed that sea level on the Maldives has been dropping, or at least steady, in recent decennia.
Just as the Temperature of the Lower Troposphere is more accurately measured by satellites than by surface thermometers in populated areas, so one would expect that the TOPEX/Poseidon satellite should be able to provide us with an accurate sea level measurement.
This is a very sophisticated US/French radar–based system which tries to solve the difficult job of measuring the choppy, swelling, moving surface of various sea states. Its readings are limited to areas outside the reflector disturbances of ships, land and oil rigs.
The best evaluation of the limitations were given by the late John Daly (SEE: ). He questions in particular the unwarranted appearance of accuracy, as is evident from these paragraphs:
The total sea level rise as represented by the trend line in the above graph is around 2 centimetres covering a period of 9 years, not even enough time for the 18.5-year tidal cycle to work itself through. When we consider that the basic measurement of sea level by means of radar only has a claimed accuracy of +/- 1.2 metres, or 1,200 millimetres, to now claim that the accuracy of the sea level trend is accurate to within a tenth of a millimetre, (i.e. 24,000 times greater than the basic resolution) can only be the result of relentless statistical processing and averaging, giving an illusory result rather than a real one, similar to the kind of result one would
get if an average were taken of tens of thousands of people measuring the distance between New York and London on a map.
Merely expressing a final averaged number to many decimal places does not mean the number itself is accurate to that many decimal places.
In Conclusion he says:
But while T/P has proved successful in these other areas, its use as a global sea level monitor is highly restrained by the limitations on its accuracy once millimetric scales are sought. To suggest that changes in the global level of the heaving oceans can be determined to a resolution of tenths of a millimetre, or even a centimetre, is to make unsustainable claims about the inherent capabilities of the technology itself. Statistics cannot compensate for the limitations imposed by the electronics and by radiation physics and claims to the contrary are simply not credible.
This excursion into the reality of measuring sea level in the first place will show the uncertainty of basic data, which should make one refrain from making far-going alarmist statements.
Gore’s seven metres can be offset by Mörner’s statement on this slide from a lecture he gave in Australia, in which he says in essence that it’s the same old water sloshing about the globe’s oceans.
It seems not unreasonable to accept the 2.5 mm/yr as our basic SL increase, agreed on as a long term historic average by many researchers. We still do not really know how to measure it, though.
- The rationale for Sea Level Rise
Arctic floating ice will not add much to the ocean volume as it is already mostly submerged. In that respect it must be mentioned that actual continuous aerial surveying of ice cover is a recent feature and that any claims like “greatest melt ever” are unwarranted., because “ever” must have been quite recent. It should also be remembered that ship traffic through the NW Passage (even with a small sailing ship) has been recorded in the past. The RCMP schooner St Roch travelled Eastbound in 1940 and westbound a few years later. Temporary ice-free water in the Arctic Ocean is not unknown and often due to prevailing wind. Also, the ice pack is continually rotating and often asymmetric within the Arctic Ocean.
Both in Greenland and in Antarctica the ice pack is increasing in thickness. Ice sheets keep breaking off as they have always done and – like with glaciers – melt at the toe while growing on the pack’s centre or in the cirque as the case may be. Some glaciers in South America are advancing, as do some others around the world. There does not seem to be anything out of the ordinary happening in terms of geologic time. For the polar ice packs to melt, they must be for substantial amounts of time at above freezing temperatures which is not happening, and the measured small rate of temperature increase is not bringing that day much closer very soon. The Greenhouse by itself does not melt ice. As for longer periods of time: this planet has been ice-free at times and has been a snow-ball at others.
Basic to the IPCC case for sea level rise and for the alarmists’ hype is the hypothesis that increasing levels of carbon dioxide will cause increasing amounts of global warming. It should be stressed that this assumption of truth is no more than a hypothesis, which is increasingly being attacked and on which any meaningful discussion has been thwarted by the IPCC’s political masters. It is a reality that, while the hypothesis has been politically adopted, it has never been proven. Its inclusion in the basic parameter input of the IPCC’s computer simulations as a dogmatic starting point, has infected all of these projections. The IPCC is a political organisation, not a scientific one.
This is not the place to delve deeply into the motives, counter arguments, IPCC methods and the economic spin-offs.
Suffice it to say that the last ten years in particular have seen the emergence of credible alternatives for the limited amount of warming that has taken place, though the long term average of warming seems still limited to the 0.6o Celsius/100 yrs with which we are still emerging from the Little Ice Age.
It should also be noted that climate changes are by their nature cyclic events. The IPCC’s projections are straight-lined into doom. Friis-Christensen has shown that correlations between CO2 concentrations and temperature do not hold up over time, while the temperature does follow levels of cyclic solar activity very well. Research into solar cycles has accelerated over the past ten years and the work by Shaviv, Veizer and – lately – Svensmark has provided the ”amplifier” needed to satisfy the need to lift direct solar irradiance from its low value as a climate driver to a major factor, because of the function of cosmic-rays in influencing cloud formation on the planet, regulated by solar “wind”. All tied to the natural electromagnetic cycles of our variable star.
As far as CO2 is concerned, basic physics has always been clear about the limitations of higher concentrations of gas to absorb equivalent amounts of heat radiation. ”Doubling of CO2 “ does none of the things the IPCC’s computer says it does. And that’s all separate from the fact that water vapour is a much greater “greenhouse” driver than carbon dioxide in any case.
As the IPCC’s commitment to AGW and the carbon dioxide driver will be emasculated by the demotion of carbon dioxide to a minor driver of greenhouse effectiveness, its dismissal of solar radiation as a direct and indirect major driver was to be expected.
Present astrophysical indications are that we are about to enter a period of lower solar activity and – consequently - cooling in the coming decades.
Anything associated with Climate Science is bugged by uncertainty.
Politicians should at most do careful risk analysis taking full account of the uncertainties involved and from the fact that climate is cyclic, not linear.
We should maintain our infrastructure and defences to deal with any eventualities that may occur. But it is not time to panic.
Albert F. Jacobs, M.Sc., P.Geol.
Calgary AB Canada 2007-09-23