Online Curriculum - Ancient Climate (Unit 5)
Studying the Ancient Climate
Understanding how and why Earth's climate has varied over time is an important step toward understanding how the environment in which we live will continue to change in response to climate. Being able to predict the Earth's future climate and how ecosystems will respond to it would be an invaluable tool. Scientists use many tools to interpret ancient climates, including isotope analysis, fossil soils (paleosols), and leaf-margin analysis.
Stable Isotope Analysis
Carbon and oxygen are two of the most common elements used in stable isotope studies. Oxygen isotopes are considered to be an indicator of atmospheric temperatures and precipitation, whereas carbon isotopes are used to calculate atmospheric carbon dioxide and/or changes in the density of vegetation in certain areas.
Different environments where soils form will produce markedly differing types of soil profiles which are sometimes preserved as fossil soils, or "paleosols." Both physical and chemical characteristcs are informative. For example, large-scale mud cracks indicate an arid environment, and the presence of pyrite indicates a chemically reducing environment. Isotope analysis of precipitated minerals within the paleosol can also yield more regional climate information.
Leaf-margin analysis, a technique that can be applied to both modern and fossil leaves, uses physical characteristics of leaves to provide information about their environment. This is our most important information source about the paleoclimate of Florissant.