Instrumental measurements of climate variables (e.g., precipitation, temperature, ocean circulation, etc.) are only available over the past century or less. In order to quantify the rate and magnitude of natural climate variability going back in time beyond the 20th century, scientists rely on paleoclimate reconstructions.
Sediment cores collected from high-accumulation rate basins in the deep Gulf of Mexico, along with lake sediment cores from lakes in the tropics and sub-tropics, are used to develop highly-resolved records of past climate variability over the Holocene (the last 10,000 years). Analysis of microfossils, trace metal geochemistry, stable isotope geochemistry and biomarkers is performed at sub-millennial to decadal resolution to generate records of climate variability.
Paleoclimate from Lake Sediments
The hydrogen isotopic composition (δ2H) of lipids from leaf waxes and algal lipids can be used as a proxy for hydroclimatic changes in the past. One of the projects that scientists at the USGS St. Petersburg Coastal and Marine Science Center are working on is the reconstruction on precipitation variability in central Florida over the past 2000 years.
Paleoceanography from Gulf of Mexico Sediments
Scientists at the USGS SPCMC have been focused on generating high-resolution (decadal to multi-decadal) records of sea surface temperature and salinity variability from sediment cores collected throughout the northern and western Gulf of Mexico. The primary proxy used is the magnesium to calcium ratio (Mg/Ca) paried with the oxygen isotopic composition (δ18O) of the planktic foraminifer, Globigerinoides ruber.
Holocene paleoceanographic reconstructions from the Gulf of Mexico:
Pigmy Basin
Fisk Basin
Garrison Basin
Understanding Climate Forcing
The larger goal of this project is to use paleoceanographic reconstructions from the Gulf of Mexico and surrounding region to better understand what mechanisms are forcing climate variability on decadal to centennial time-scales. These reconstructions are also used to assess how phenomena like El Nino Southern Oscillation (ENSO), Atlantic Multidecadal Oscillation (AMO), Atlantic Meridional Overturning Circulation (AMOC), etc., behave in the pre-anthropogenic era.
Below are other science projects associated with this project.
Climate and Environmental Change in the Gulf of Mexico and Caribbean
Paleoceanographic Proxy Calibration
- Overview
Instrumental measurements of climate variables (e.g., precipitation, temperature, ocean circulation, etc.) are only available over the past century or less. In order to quantify the rate and magnitude of natural climate variability going back in time beyond the 20th century, scientists rely on paleoclimate reconstructions.
Sources/Usage: Public Domain.Scientists are working on a calibration study to determine how the hydrogen isotopes of lipids from the lake respond to precipitation in Florida. Lake Tulane, located in Highlands County, is and is an ideal location for paleoclimate reconstruction due to high accumulation rates and anoxic conditions at the sediment-water interface. (Public domain.) Sediment cores collected from high-accumulation rate basins in the deep Gulf of Mexico, along with lake sediment cores from lakes in the tropics and sub-tropics, are used to develop highly-resolved records of past climate variability over the Holocene (the last 10,000 years). Analysis of microfossils, trace metal geochemistry, stable isotope geochemistry and biomarkers is performed at sub-millennial to decadal resolution to generate records of climate variability.
Paleoclimate from Lake Sediments
The hydrogen isotopic composition (δ2H) of lipids from leaf waxes and algal lipids can be used as a proxy for hydroclimatic changes in the past. One of the projects that scientists at the USGS St. Petersburg Coastal and Marine Science Center are working on is the reconstruction on precipitation variability in central Florida over the past 2000 years.
Paleoceanography from Gulf of Mexico Sediments
Scientists at the USGS SPCMC have been focused on generating high-resolution (decadal to multi-decadal) records of sea surface temperature and salinity variability from sediment cores collected throughout the northern and western Gulf of Mexico. The primary proxy used is the magnesium to calcium ratio (Mg/Ca) paried with the oxygen isotopic composition (δ18O) of the planktic foraminifer, Globigerinoides ruber.
Holocene paleoceanographic reconstructions from the Gulf of Mexico:
Pigmy Basin
Fisk Basin
Garrison Basin
Sources/Usage: Public Domain.SEM image of a Globigerinoides ruber specimen from the Gulf of Mexico.
Sources/Usage: Public Domain.Multicores collected from the northern Gulf of Mexico. These cores contain roughly 1 meter of sediment from the seafloor, and represent the past ~2000 years of deposition. USGS scientists slice these cores in 5 mm increments, and analyze the chemical composition of microfossils (e.g., foraminifera) and molecular fossils (e.g., alkenones, GDGTs, leaf waxes, etc.), to generate paleoclimate records over the past 2 millennia. Understanding Climate Forcing
The larger goal of this project is to use paleoceanographic reconstructions from the Gulf of Mexico and surrounding region to better understand what mechanisms are forcing climate variability on decadal to centennial time-scales. These reconstructions are also used to assess how phenomena like El Nino Southern Oscillation (ENSO), Atlantic Multidecadal Oscillation (AMO), Atlantic Meridional Overturning Circulation (AMOC), etc., behave in the pre-anthropogenic era.
Sources/Usage: Some content may have restrictions. Visit Media to see details.Long-term correlations between observed sea-surface salinity and rainfall. Correlation map between northern Gulf of Mexico sea-surface salinity (SSS; dashed red box) and global oceanic SSS (ORA-S4 data set; red-blue scale), as well as continental precipitation (GPCC data set; brown-green scale) with locations of proxy records used in the study. Proxy locations are marked with circles (sedimentary records), triangles (speleothems), dashed boxes (tree-ring compilations), stars (circulation proxies), and squares (additional proxies) with color fill indicating sign (fresh – blue; dry/wet–brown/green; purple–weakened poleward transport) during the Little Ice Age (1450–1850 C. E.). Figure from: Thirumalai and others, 2018. - Science
Below are other science projects associated with this project.
Climate and Environmental Change in the Gulf of Mexico and Caribbean
This project documents paleoceanographic, climatic, and environmental changes in the Gulf of Mexico and adjacent land areas over the last 10,000 years. The paleoenvironmental data is used to determine rates of change in the past, and to better understand both the natural and anthropogenic factors that contribute to climate variability on inter-annual to millennial timescales.Paleoceanographic Proxy Calibration
A sediment trap time series in the northern Gulf of Mexico is used to better assess the control of environmental variables (e.g., temperature and salinity) on the flux of both microfossils and molecular fossils to the sediments. The information gained from sediment trap studies is used to develop better proxy-based estimates of past oceanographic conditions from analyses of microfossils and... - Publications