Either you're saying that's a very long time for a small amount, or a very short time for a large amount. Either way, it's likely to be true. Thermal expansion alone (that's the expansion of water as it is heated by the air above it) is predicted to be around 20cm over the next 100 years, as global temperatures continue to increase. While to you it might not sound like a lot, [url=http://flood.firetree.net/]why not have a look at this[/url]? Pop the levels at just 100cm and see how many low-lying areas are going to be influenced by such an increase. Particularly, look at the Outer Banks in North Carolina. Notice anything? Or, if we're going by my own work, which received a grade of 85 (95 being the highest attainable): [quote]Using prediction models of climate change and factoring in expected temperature alterations, it is possible to predict sea level change in the future. A number of sources (EPA, 2014 and IPCC, 2014) suggest that if emissions were to continue growing at the current rate, a global temperature increase of between 4 and 6.4oC could be expected by 2100. Thermal expansion of the sea would therefore result in a sea level rise of up to 2.2m, if the average depth of the sea is taken as 5km. However, during the time period, it is unlikely that the entire potential expansion will have taken place. In addition to a sea level rise due to thermal expansion, the threat of melting ice sheets adds a significant factor to the projected sea level rise by 2100. While several models exist to predict ice melt up to the end of the 21st Century, Pfeffer et al (2008) state that the current rate of ice melt outlet is only 1.2km per year from the Greenland system. However, none of these models and calculations factor in ice sheet dynamics, so any ice seen to be calving from the main ice sheets is not included. Calving would only increase the rate of glacier retreat, further increasing the rate of sea level rise. This, combined with the outlet from West and East Antarctica shows a likely maximum sea level rise of 0.8m to 2m by 2100 as a result of ice melt. Combining thermal expansion with ice melt yields a predicted maximum sea level rise of 4.2m by 2100, which poses a significant threat to low-lying coastal regions.[/quote]

My issue is with the fact that geologists can measure these types of changes in the sedimentary levels happening all the time throughout history.