Byline: Willie Soon and Nils-Axel Morner, SPECIAL TO THE WASHINGTON TIMES
There is much concern over rising sea levels and disappearing coastline. Yet how are such changes really measured?
Satellites can measure tiny changes in sea levels referenced to a known baseline, but those measurements have only been available since 1993. Two other methods used for changes occurring over more than 100 years are tide gauges and efforts by the United Nations' Intergovernmental Panel on Climate Change (IPCC) in computer modeling.
A tide gauge monitors water level changes in relation to a local reference height. They are simple devices, not too different from a pingpong ball floating in a tube. Tide gauge data are available for more than 1,750 stations around the world and are the longest time series available. In the case of Delaware, records go back to the early 20th century, while in places such as Amsterdam they go back to the late 17th century.
How reliable are such data?
In Atlantic City, for example, coastal engineer Cyril Galvin says the tide gauge data may be too sensitive to local and regional activities that aren't ultimately related to natural changes in sea level - including any that might be related to greenhouse gas-induced global warming.
In examining sea-level changes for 100 years or more from stations on the Eastern Seaboard, Mr. Galvin could not find any acceleration in sea-level rise. University of Florida professor Robert Dean and Army Corps of Engineers analyst James Houston have independently reached this same conclusion.
While examining tide gauge records from Atlantic City's Steel Pier, Mr. Galvin discovered a remarkable effect apparently caused by spectators who came to watch horse-diving between 1929 and 1978. From old photographs, it was estimated that there must have been about 4,000 spectators who would come to watch. Given that this crowd probably weighed about 150 tons, the pier was subject to significant loading and unloading cycles. The initial 1912-1928 data showed the sea level rising at a rate of 0.12 inches per year. The rate tripled around 1929 when the horses began diving. When the shows were suspended from 1945 to 1953, sea level fell at a rate of 0.06 inches per year. When the diving resumed, the sea level rose again at a rate of 0.16 inches per year.
Such clear documentation of the direct influence of local weight loading and unloading activities on tide gauge reading should add a cautionary note to connecting tide gauge data series to man-made greenhouse gas global warming phenomena.
Model projections of rapid sea-level rise and acceleration caused by global warming as proposed by the IPCC's coming Fifth Assessment Report should also be subject to scrutiny. …