Using the Record of Sea-Level Rise Along the West Louisiana and Texas Coast to Predict Coastal Response to Accelerating Sea-Level Rise

John B. Anderson and Kristy T. Milliken
Earth Sciences, Rice University, Houston,, TX

The IPCC predictions for sea-level rise by the end of this century range upwards to 90 cm. The greatest uncertainty lies in the potential contribution from ice sheets, in particular the Greenland and West Antarctic Ice Sheets. The most recent evidence suggests that both ice sheets may indeed be decreasing in volume. Additionally, the rate of sea-level rise has increased this century. Along the Texas and Louisiana coasts, eustatic rise is amplified by subsidence, but large uncertainties about current subsidence rates limit our ability to predict coastal inundation regionally.

A new composite sea-level curve for the western Louisiana and Texas coast provides constraints on relative sea-level rise during the past few thousand years. The curve shows that variations in relative sea-level rise of the coastal plain spanning central Texas to west Louisiana are minimal. Comparison of this curve to global sea-level curves suggest that coastal subsidence within the study area over the past several thousand years has been negligible. Further comparison to the late Holocene record of sea-level rise to satellite altimetry and tide gauge records indicates that rates of rise have dramatically increased over the past century. If current rates continue longer than several decades, the changes to future shoreline and bayline configuration will be dramatic. Our results also indicate that coastal response to accelerated sea-level rise in the past has varied widely across the study area. This reflects the importance of other factors, such as sediment supply, wave climate, antecedent topography and tropical storms in regulating coastal inundation. For this reason, passive inundation models that simply submerge the landscape as sea level rises are not good for predicting future coastal change.

AAPG Search and Discover Article #90078©2008 AAPG Annual Convention, San Antonio, Texas