Paper No. 12
Presentation Time: 5:05 PM
EVIDENCE OF INTENSE HURRICANE ACTIVITY COUPLED WITH ELEVATED SEA SURFACE TEMPERATURES AND DECREASED EL NIÑO ACTIVITY OVER THE PAST ~1,500 YR B.P
There is now evidence that suggests that the effects of anthropogenic global change will increase hurricane frequency and magnitude in the near future. Major factors influencing hurricane activity include changing sea surface temperatures (SST) and the El Niño/Southern Oscillation (ENSO) dynamics in the North Atlantic and surrounding basins. However, statistical trends observed from the historic record have come into question, as technological advances through time have provided more reliable data regarding storm frequency and magnitude. Field-based geologic studies can bridge this gap by providing hurricane activity over centennial to millennial timescales that significantly expand the historic record. From these types of analyses, more robust statistical conclusions can be drawn. Here we show that intense hurricane landfalls in the western Gulf of Mexico appear to correlate with higher SST and decreased El Niño activity in the past. A carefully selected sediment core from the inner shelf offshore Matagorda Island, Texas yields a ~4,500 year record of coarse-grained hurricane derived deposition that correlates well with the long-term intense hurricane frequency previously established from published sites around the Gulf of Mexico. Between ~1,000 and ~1,500 yr B.P., intense hurricane strikes were frequent, and coincide with a time where a nearby Gulf of Mexico SST record suggests similar or possibly slightly higher SST than modern. This same time interval also coincides with decreased El Niño activity based on a published proxy from Ecuador. Between ~1,000 yr B.P. to modern times (i.e. ~150 years ago), as SST became cooler in addition to increased El Niño activity, intense hurricane impacts were reduced. The last ~150 years shows frequent intense hurricane strikes again coinciding with high SST and lower El Niño activity. Analysis of the geologic record therefore suggests that if SST increase and El Niño events decrease, Gulf of Mexico intense hurricane activity becomes elevated.