APPROACH (APplying Proxy-based Reconstruction Of Atlantic Climate CHange)
USGS scientists use marine geological archives to investigate how ocean temperature, salinity and circulation patterns changed over the past few centuries to millennia. This is done by analyzing the geochemical and physical clues about past environments that are preserved in fossil coral skeletons, clam shells, foraminifera and marine sediments.
The major Atlantic surface currents like the Gulf Stream, the Florida Current, and the Loop Current are part of a larger circulation system known as the Atlantic Meridional Overturning Circulation, or AMOC. This system is an important feature of global climate, and can influence things like rainfall patterns, hurricane intensification, and fisheries in North America. By reconstructing past variability in these Atlantic surface currents, we can start to build a clearer picture of how ocean circulation has changed in the past. This will help us to better predict and prepare for future changes in North American climate.
Sediment Traps
Sediment trap studies help scientists better understand the environmental factors (for example, temperature, salinity, ocean circulation, and nutrient supply) that influence the modern chemistry, ecology, and life history of planktic organisms living in the water column. Scientists at the USGS are using long-running sediment traps that have been deployed (2008–2025+) in the northern Gulf of America to calibrate foraminifera, biomarker, and other micropaleontological proxies to improve the accuracy of climate reconstructions. The present is the key to the past.
Sediment cores
Marine and lake sediment cores give USGS scientists the ability to develop long-term climate records spanning thousands of years. Using the preserved shells of microscopic planktic organisms called foraminifera, micropaleontologists can reconstruct the temperature and salinity of the surface water they lived in. These reconstructions help us understand natural patterns of climate variability in the past so that we can better predict future climate change.
Coral Cores
Corals have been growing in south Florida and the Caribbean for several thousands of years and they record information about the surrounding ocean water in their skeletons as they grow. This means a long-dead coral may be used as a snapshot of the marine environment during which it was alive. USGS scientists use the chemistry of fossil coral skeletons (from the last 10,000 years) to reconstruct past climate variability and to determine how climate influenced the development of Atlantic coral reefs in the past.
Shells
Bivalve shells are a common object found along coastlines worldwide. Some species’ lives may extend from decades to centuries, making them another valuable data archive of marine paleoenvironmental conditions. USGS scientists use well-established shell proxy archives like the ocean quahog to reconstruct changes in high latitude North Atlantic Ocean currents, while developing new bivalve proxies in the low-latitude North Atlantic Ocean. This work expands the toolbox available to paleoclimate scientists to solve mysteries of changing marine climate in recent centuries.
Developing a USGS Digital Coral Growth Archive using Rotating X-Ray Computerized Tomography - The ACTS Project
Reconstructing Ocean Circulation & Hydroclimate in the Subtropical Atlantic
Coral Reef Ecosystem Studies (CREST)
Holocene Coral-Reef Development
USGS scientists use marine geological archives to investigate how ocean temperature, salinity and circulation patterns changed over the past few centuries to millennia. This is done by analyzing the geochemical and physical clues about past environments that are preserved in fossil coral skeletons, clam shells, foraminifera and marine sediments.
The major Atlantic surface currents like the Gulf Stream, the Florida Current, and the Loop Current are part of a larger circulation system known as the Atlantic Meridional Overturning Circulation, or AMOC. This system is an important feature of global climate, and can influence things like rainfall patterns, hurricane intensification, and fisheries in North America. By reconstructing past variability in these Atlantic surface currents, we can start to build a clearer picture of how ocean circulation has changed in the past. This will help us to better predict and prepare for future changes in North American climate.
Sediment Traps
Sediment trap studies help scientists better understand the environmental factors (for example, temperature, salinity, ocean circulation, and nutrient supply) that influence the modern chemistry, ecology, and life history of planktic organisms living in the water column. Scientists at the USGS are using long-running sediment traps that have been deployed (2008–2025+) in the northern Gulf of America to calibrate foraminifera, biomarker, and other micropaleontological proxies to improve the accuracy of climate reconstructions. The present is the key to the past.
Sediment cores
Marine and lake sediment cores give USGS scientists the ability to develop long-term climate records spanning thousands of years. Using the preserved shells of microscopic planktic organisms called foraminifera, micropaleontologists can reconstruct the temperature and salinity of the surface water they lived in. These reconstructions help us understand natural patterns of climate variability in the past so that we can better predict future climate change.
Coral Cores
Corals have been growing in south Florida and the Caribbean for several thousands of years and they record information about the surrounding ocean water in their skeletons as they grow. This means a long-dead coral may be used as a snapshot of the marine environment during which it was alive. USGS scientists use the chemistry of fossil coral skeletons (from the last 10,000 years) to reconstruct past climate variability and to determine how climate influenced the development of Atlantic coral reefs in the past.
Shells
Bivalve shells are a common object found along coastlines worldwide. Some species’ lives may extend from decades to centuries, making them another valuable data archive of marine paleoenvironmental conditions. USGS scientists use well-established shell proxy archives like the ocean quahog to reconstruct changes in high latitude North Atlantic Ocean currents, while developing new bivalve proxies in the low-latitude North Atlantic Ocean. This work expands the toolbox available to paleoclimate scientists to solve mysteries of changing marine climate in recent centuries.