Paleoclimatology is the study of climate records from hundreds to millions of years ago. Paleoclimate data come from climate records found in nature. They are known as proxy records or indirect records of climatic conditions. Most of our ‘base’ records go back a hundred or so years ago, not that great of an example to justify global warming in my mind. As I have said before we have many thousands of years to figure in climate cycles.
How Do Scientists Interpret Natural Records?
While we don’t often think about it, weather is constantly shaping our environment. Everything in nature, from river sediments to plant growth and distribution, is influenced by weather and climate. The most easily recognized type of paleoclimate record is tree ring data. Other common sources of proxy data for climate include lake and ocean sediments, layers of ice (cored from ice sheets), corals, fossils, and historical records from ship logs and early weather observers.
Paleoclimate records come from all around the world – from the tops of mountains, to the bottom of the ocean, from the tropics to the poles. [insert map of data record locations from NOAA maps and data integrated map app]
Scientists use a variety of methods to access and analyze climate proxies. The most familiar methods involve taking a core sample of tree rings, corals, sediments, and ice. By measuring the width, chemical composition, and physical structure of each layer, scientists can deduce the conditions present when each layer formed.
Another way to learn about past climate is to take the temperature of rocks at different depths via boreholes drilled directly into the Earth’s crust. Rocks respond very slowly to different temperature conditions, and deeper rocks change temperatures more slowly than shallower rocks. Precise measurements of the rate of temperature change of rocks at various depths can be correlated to past temperatures at the surface.
Because trees are sensitive to local climate conditions, such as rain and temperature, they give scientists some information about that area’s local climate in the past. For example, tree rings usually grow wider in warm, wet years and they are thinner in years when it is cold and dry.
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