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Changes of Global Sea-Level Rise and Relative Sea-Level Rise in Coastal Louisiana in the 21st Century

Abstract

The rate of relative sea-level rise has been measured for approximately 200 years at ports largely in the north Atlantic and measured at sites along the Gulf of Mexico coast of Louisiana for nearly 100 years. The rate of relative sea-level rise (RSLR) has been determined to be accelerating due to global warming measured over the past 130 years. However, in the past 18 to 20 years there has been observed a pause of global warming when the temperature has remained approximately constant. Has the temperature pause impacted RSLR for Louisiana? For the Louisiana coast line RSLR was impacted more by local subsidence than global sea-level rise. A number of studies have determined Louisiana RSLR is to up to ten times greater than that due to only global RSLR. For the Louisiana coast line has a reduction in oil production during the past twenty years impacted RSLR significantly?

Values of RSLR in Louisiana and Florida were determined using U.S. Geological Survey tidal gaging stations located in those states, which were located in rivers or streams where records clearly show the daily influence of tides. This set of data includes over a dozen stations in Louisiana and Florida. The RSLR value at each station was determined by taking a linear regression of daily mean gage values. Stations records are typically 10 to 15 years in length. Florida is considered a stable area where RSLR lacks any significant impact from local subsidence. By contrast, Louisiana is an area where RSLR is dominated by local subsidence due to isostatic flexure caused by a thick pile of sediment, over 50,000 feet thick that has been dumped into this region by the Mississippi River and ancestral versions since the Jurassic. This explains the difference of average RSLR between Louisiana and Florida.