Future climate change has been the subject of considerable speculation with scientists called upon to predict timing, magnitude, and impact of these changes. The Pliocene Warm Period serves as the best-available, pre-modern analog to predicted climate changes, and Pliocene climate anomalies are examined as possible scenarios for future climate change. Comparing modern conditions to the mean climate state of the Pliocene is essential for better constrained predictions of future climate change, and seasonal paleoenvironmental records provide a data set more analogous to instrumental observations and thereby reducing the uncertainty in modeled climate changes. This study first examines the potential of large gastropod shells as a paleoclimate proxy. Specimens of Busycon sinistrum, active in winter, and Fasciolaria tulipa , active in the summer, were collected alive from Tampa Bay and St. Joseph Bay in the hope of establishing a multi-year record of seasonality. The δ18O time series of each shell were compared with predicted δ18O, based on local marine temperature variations, and both species cease shell growth during the winter months, despite opposing seasons of feeding activity. As none of the profiles provide information on winter environmental parameters, this sclerochronological system was replaced by work on pristine specimens of the scleractinian coral Siderastrea spp.  Seasonal δ18O and Sr/Ca time series from two Pliocene corals, collected from the Lower Pinecrest Member of the Tamiami Formation in southwest Florida, were used to calculate seawater δ18O variations. Inferred salinity in the Pliocene has a reversed seasonal pattern from that of modern annual salinity variations, and is interpreted to be a response to an increase in winter precipitation, a teleconnection of the Pliocene “Super El Niño.” Concentrations of variance in the typical ENSO frequency band are not apparent above the 95% confidence interval, suggesting that the Pliocene was dominated by a perennial, rather than an intermittent, El Niño-like state.  Further geochemical analyses from both Pliocene and Pleistocene Siderastrea spp. corals indicate a high nutrient nearshore marine environment in south Florida. Marine phosphates, inferred from P/Ca analyses, were significantly higher in the Pliocene Tamiami Fm. than in the Early Pleistocene Caloosahatchee and Bermont Fms, and the decline in nutrients preceded local extinction by > 0.5 Ma. Additionally, high-resolution P/Ca analyses of an individual coral reveal no evidence of seasonality required by a previously hypothesized upwelling-based nutrient delivery mechanism The Pliocene nearshore marine environment in southwest Florida was characterized by higher nutrients than in the Pleistocene and precipitation patterns similar to modern El Niño teleconnections.

Florida's Plio-Pleistocene strata record episodes of sea-level highstands. The age of the strata is often ambiguous as there are no consistently reliable dating techniques that can be unequivocally applied to many of the units. The lack of preservation of continuous Plio-Pleistocene sedimentary sequences is a consequence of Pleistocene mean sea-levels not flooding peninsular Florida, the low volume of sedimentary supply, and the lack of new accommodation space. This study investigates a 6 m cyclothem-type set of six shallow-marine shell beds separated by five subaerially exposed packstone beds. These strata are part of the biostratigraphically-defined early Pleistocene (1.1 -- 1.6 Ma) Bermont formation and were likely deposited during a 160 kyr interval between 1.3 and 1.1 Ma. The shell beds are mollusk-rich and contain moderately well-sorted fine sands. The packstones contain sparry calcite cements and show evidence of subaerial weathering, such as an irregular upper solution surface, root molds, and sparry freshwater calcite cements. The upper surfaces of the packstones are unconformities that separate five episodes of highstand deposition. A grain-size analysis shows an upward-coarsening trend between depositional episodes, which most likely indicates a progressively decreasing water depth. The bivalve assemblages suggest a mean paleodepth during the deposition of the shell beds of approximately 7.5 m; alternatively, in situ Anodontia alba, which colonized these units after deposition, point to a depth of 1 m. A subsidence rate of 6 m/Ma is inferred from the thickness of deposits near the locality. Based on a comparison of the height of the strata with ex isting eustatic curves, the early Pleistocene age of the formation, and the 6 m/Ma subsidence rate, the most parsimonious duration for the interval between the cyclothems is 41 kyr, dominantly forced by obliquity orbital variability. Combining the data indicates that the early Pleistocene sea level was between 11.2 and 14.4 m above sea level (asl); previous estimates of early Pleistocene highstands have shown an elevation approximately 15 m asl. If the 1 m depth of Anodontia alba is used, the depth was likely 6.3 m asl.

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