Reconstructing Ocean Circulation & Hydroclimate in the Subtropical Atlantic

Paleoclimate Science

Paleoclimate Science

Biological proxies such as diatoms, foraminifers, ostracodes, and pollen allow scientists to make inferences about climate conditions in the past.

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Climate and Environmental Change in the Gulf of Mexico and Caribbean

Climate and Environmental Change in the Gulf of Mexico and Caribbean

Learn more about this topic and related research at the St. Petersburg Coastal and Marine Science Center.

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Science Center Objects

Changes in rainfall patterns as a result of anthropogenic climate change are already having large ecological and socioeconomic impacts across the globe. Increases in flood damage, wildfire damage, and agricultural losses can all be attributed to anomalous rainfall events and prolonged droughts across the United States in recent years. Additionally, Atlantic Ocean circulation, which has a large influence on terrestrial temperature and precipitation patterns, has been weakening and more research is needed to understand the cause of this trend. Marine and lake sediment archives can be used to reconstruct hydroclimate (e.g., salinity, rainfall, evaporation, etc.) on long timescales, extending beyond the observational record of the last century. This project aims to reconstruct past ocean and hydroclimate patterns so that researchers can better understand the changes being seen today and relate those changes to natural and anthropogenic climate forcing.

Statement of Problem: The Gulf Stream is the surface component of the Atlantic Meridional Overturning Circulation (AMOC) that is responsible for transporting heat and salt poleward in the North Atlantic Ocean. It exerts a strong influence on rainfall patterns in North America, and other land masses surrounding the North Atlantic basin. Models suggest that the AMOC will weaken in response to increased meltwater entering the North Atlantic due to a warming climate. Observations of AMOC over the past decade show a secular trend toward weakening circulation, but due to the short record of physical oceanographic observations of this system, it is impossible to ascertain whether this trend is due to entirely to anthropogenic warming or is part of a multidecadal oscillation in AMOC strength. This research will investigate past records and modeled results to better understand the changes in precipitation and ocean circulation we are seeing today.

Why this Research is Important: This research addresses key uncertainties in our understanding of climatic extremes and how those extremes have varied throughout history. It is important to better understand these extreme events due to the direct and dire consequences they can have on people’s lives and infrastructure. Policy makers and resource managers need to have a better understanding of these changing conditions, so they can prepare for the future.

Objective(s): This project is designed to address changing ocean circulation and precipitation patterns by reconstructing oceanographic and hydrographic parameters that are sensitive to AMOC changes. These include sea surface temperature and salinity in the Gulf of Mexico/Florida Straits, and precipitation changes in the Central Florida and the Caribbean. These records, combined with model results and paleoclimate reconstructions from the high latitudes, will help to determine the magnitude and frequency of past changes in AMOC. This information will allow modelers to determine whether or not current trends are unprecedented in the historical record or whether there is natural variability in the system.

Methods: Refined techniques in carbonate geochemistry and molecular isotopic analysis will be used to quantitatively reconstruct changes in hydroclimatic patterns in the Atlantic Ocean and surrounding terrestrial environments. The researchers will then relate those changes to natural and anthropogenic climate forcing.