SEA-LEVEL CHANGE IN THE GULF OF MEXICO

Sea level has been changing since the origin of the Gulf of Mexico about 150 million years ago when the Gulf was formed. During the Quaternary Period there have been 100 cycles of rising and falling sea level. The most recent high stand of sea level was oxygen isotope stage 5e which was 120,000 years ago when sea level was about three meters above the present level.

We are now in a period of climate change when eustatic rise in sea level is three millimeters per year and seems to be rising. There are many locations on the Gulf of Mexico coast where the rate of rise is much high than the global rate. In addition to additional water from melting glaciers, the compaction of fine sediment and withdrawl of fluids from the ground have contributed to the relative increase in sea level. The highest rates are more than a centimeter per year in the area of the Mississippi Delta where there is very thick mud and considerable oil and gas is taken from numerous wells. Other places where the rate is quite high include the Houston area where the development associated with a city of four million people has caused sediment compaction and fluid withdrawl is also a factor. There are several other local areas where higher than global rates are occurring. The lowest rates along the Gulf are on the Florida peninsula which is a carbonate platform where there is essentially no sediment compaction.