Over the weekend the New York Times ran an article on sea level rise, which for the seasoned TreeHugger reader may not add tons new to the discussion (Climate Progress has some analysis of it and gives it mostly a thumbs up, rare for mainstream media reporting on climate), but check it out if you need a refresher course. But what caught my eye was a really interesting companion article, highlighting research on Roman seaside ruins which indicate that for the past two millennia or so that sea levels have been comparatively steady, and that the level of increase we witness today really started with industrialization.Though there's no doubt that sea levels around the globe have fluctuated widely, as in hundreds of foot differences--at the end of last ice age when ice sheets melted sea level rose almost 400 feet. Since the Industrial Revolution sea levels have risen about eight inches, with current rates increasing to about twelve inches in 100 years and still increasing. By the end of this century projections, assuming emissions are reduced, are in the 3-7 foot range.
What this research shows is that rather than very slowly increasing for thousands of years, only to be spurred on by recent increases in greenhouse gases and warming, sea levels have been more or less steady since the Roman era right up through the 19th century--and that's even taking into account any land movements in relation to the sea that have occurred.
This conclusion was arrived at by a team of scientists (Australian and Italian) working in Italy, examining the ruins of Roman fish tanks constructed along the edge of the sea. The tanks were used either for decoration or for storing live fish so that banquets at nearby villas could be supplied with freshly killed fish.
The tanks were usually carved into rock at the edge of the shore and constructed in such a way that some of their features bore precise relationships to sea level at the time. For instance, walls and sluice gates had to be built to let water into the tanks while keeping fish from escaping at high tide. A few years ago, Dr. Lambeck, of the Australian National University, and his team realized that these features could be used to arrive at an estimate of sea level in the time of the Romans.
Dr. Lambeck's team used the Roman fish tanks to reach the conclusion that global ocean volume had not changed much from the Roman era to the 19th century. That means, in essence, that human civilization reached its present size and complexity during a period when shorelines were reasonably stable in much of the world.
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