EVIDENCE OF A SIMILAR FREQUENCY OF INTENSE STORMS FOR THE GULF OF MEXICO OVER THE LAST 4,000 YEARS

The anthropogenic contribution to hurricane formation, intensity, and track have been heavily debated in recent years. Hurricane magnitude and frequency has been linked to numerous mechanisms, including the steady rise in annual sea surface temperatures, ENSO variations, and atmospheric changes. In order to better understand and predict future hurricane activity for the entire Gulf coast, a robust sampling strategy spanning the geologic past must be achieved. Here, we present a detailed record from ~4,000-900 yr BP of past intense hurricane impacts for 4 cores collected from Laguna Madre, South Padre Island, TX. From sediment dynamics equations, we calculate storm surges associated with these deposits to be between ~2 and 3.8m. We determine an approximate landfall probability of ~.45% for storms of these intensities over this time interval. Comparison of our data to previous studies in Western Lake, FL and Lake Shelby, AL reveals similar hurricane frequency trends and suggests relatively constant intense hurricane strikes for the Gulf of Mexico from ~4,000-500 yr BP. Western Lake, FL shows probabilities of intense storm strikes of .36%, while Lake Shelby, AL shows .34%. Intense hurricane impacts in the Gulf were likely regulated by shifting warm, dry air masses in southwestern North America. The intervals of intense hurricane strikes presented in this study all coincide with centennial length periods of warm, dry air masses centered over Texas. During warmer, drier periods, hurricanes are less likely to impact the Gulf Coast than during cooler, wetter periods. For the past 500 yrs, a cool, wet climate regime has prevailed.