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Home | Tampa Bay Study | Data | Task 3: History and Prehistory > Climate History

This page is archived and is no longer being maintained. Content was last updated in 2015. For current research, visit http://coastal.er.usgs.gov/.
Tampa Bay Study > Data > Task 3: History and Prehistory > Climate History

Project Leads: Thomas Cronin (USGS) and Debra Willard (USGS)

Climate Change and Tampa Bay
Pollen, as seen through a microscope.

Scientists can identify habitat shifts in our recent and historic past by collecting data from cores on the types and numbers of pollen found within a dated core sample. The above image are examples of pollen as seen through a microscope.

Enlargement

Over the last century, changes in temperature, precipitation, and other environmental factors have been greater than those of at least the last 1,300 years (IPCC, 2007). To evaluate the relative influences of increased greenhouse gas concentrations, land-cover change, and other anthropogenic factors on these changes, it is important to document the natural variability of the climate system prior to significant human alteration.

Climate change occurs over varying time scales, and it is important to understand the impacts of both low-frequency (i.e., glacial-interglacial cycles) and high-frequency (i.e., El Niņo Southern Oscillation) patterns. Examination of ecosystem response on such scales is useful to assess how climate systems are likely respond to anticipated changes.

The geologic record provides a key to improve our understanding of the patterns and rates of community response to changes in sea level, temperature, and precipitation associated with climate change. Global sea level rose 120 to 125 meters since the last ice age (called the last glacial maximum) about 22,000 to 26,000 years ago. At this time, the emergent part of the Florida peninsula was much broader than today, and the very different climate resulted in a much different distribution of plant communities in the area. Since the last glacial maximum, melting ice sheets, rising sea level, and changes in temperature and precipitation played a large role in changing the distribution of lakes, wetlands, and associated plant communities on the Florida peninsula.

The USGS, in cooperation with Eckerd College and the University of South Florida, has studied changes in plant communities and regional paleoclimate using sediment cores collected as part of the Tampa Bay Study. The cores were collected from ships using either a vibracore or push-core system and then brought back into the lab for analysis. Fossil shells, pieces of wood, and pollen are dated by radiocarbon dating to provide accurate chronology. Pollen grains preserved in the sediments are used to reconstruct the composition of past plant communities in the region. Records from these cores indicate that climate of the last glacial maximum was much cooler and drier than today. The progressive warming of atmospheric temperatures from the last glacial maximum to the present was interrupted by periods of colder and drier climate. Continuing analysis of sediments deposited during the last few millennia provide important data to understand the relative impacts of anthropogenic and natural climatic changes on regional plant communities.

Percent abundance of pollen of major plant taxa vs depth.
A detailed record of Late Quaternary and Holocene sediments was recovered in an 11.28-m piston core (MD02-2579) from a karst-controlled basin in central Tampa Bay using a Calypso piston corer on the R/V Marion Dufresne in July 2002. Percent abundance of pollen of major plant taxa vs depth, core MD02-2579, Tampa Bay, Florida. (Enlargement)

Data Products
Calcareous Microfossil Analysis from Tampa Bay, Florida Sediment Cores (metadata)

Deglacial Climatic Variability of Central Florida Ascertained Through Pollen Analysis of Tampa Bay, Florida (metadata)

Related Publications

Willard, D.A., C.E. Bernhardt, G.R. Brooks, T.M. Cronin, T. Edgar, R. Larson. 2007. Deglacial climate variability in central Florida, USA. Palaeogeography, Palaeoclimatology, Palaeoecology 251:366-382.

Cronin, T., N.T. Edgar, G. Brooks, D. Hastings, R. Larson, A. Hine, B. Suthard, B. Flower, D. Hollander, J. Wehmiller, D. Willard, and S. Smith. 2007. Sea level rise in Tampa Bay. EOS 88: 117-118. Abstract.

Hine, A.C., Suthard, B.C., Locker, S.D., Cunningham, K.J., Duncan D.S., Evans, M., and Morton, R.A., (2007). Karst Subbasins and Their Relation to the Transport of Tertiary Siliciclastic Sediments on the Florida Platform, in Swart, P.K. and Eberli, G.P., eds. IAS Special Publication in Honor of Robert Ginsburg.

Partners
Eckerd College St. Petersburg, Florida logo and University of South Florida (USF) logo


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