w:National Oceanic and Atmospheric Administration, Department of Commerce
Photo Credit to D. B. Scott, Centre for Marine Geology, Dalhousie University, Halifax, Nova Scotia, Canada
Microscopic shells found in sediment cores can be used as proxy data to determine past climate conditions including ocean temperatures and atmospheric chemistry. This image was acquired from NOAA Paleoclimatology Educational Slide Sets. The media is owned by NOAA and cannot be copyrighted, however the photo credit goes to D. B. Scott of the Centre for Marine Geology, Dalhousie University, Halifax, Nova Scotia, Canada.
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National Oceanic and Atmospheric Administration, Department of Commerce Photo Credit to D. B. Scott, Centre for Marine Geology, Dalhousie University, Halifax, Nova Scotia, Canada Microscopic shells found in sediment cores can be used as proxy data to determine past climate conditions including ocean temperatures and atmospheric chemistry. ~~~~
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Sediment cores from the ocean floor contain types of information that scientists use to better understand the fluctuations of global climate. Perhaps the most important information is that gleaned from the microscopic shells of animals such as this, called planktonic Foraminifera ("forams" for short). Forams provide two main types of information. First of all, different species of forams prefer different ocean temperature and nutrient conditions. . Scientists can therefore learn much about the climatic conditions of a core site in the past by looking at which species once inhabited the area. Secondly, the shells of forams effectively lock in the oxygen and carbon isotopic composition of the waters in which they formed. Because past periods of glaciation changed the relative quantities of heavy oxygen (18O) and light oxygen (16O), scientists can use the isotopic composition of foram shells as a proxy signal for past changes in global ice volume. Other chemical measures are available as well by studying the composition of the shells. Data from ocean cores about past glaciation matches Milankovitch's theory remarkably well.