Biotic Proxies

Climate proxies allow multiple independent pieces of a complex puzzle to be put together to create a master picture of the Earth's past climates. Each piece, no matter how small, makes an important contribution in the effort not only to understand when and where climate change occurred but also how and why. Knowing the answers to these questions is important because it strengthens the community's understanding of the sensitivity of the Earth's climate, how it responds to global warming, and the effect human behavior is having on natural systems. Another major group of proxies that scientists use to study past climate change are the biotic proxies. These include items once alive on Earth, such as life-forms, trees, coral, and plants. This chapter first looks at how the presence of fossils and other evidence of once-living creatures tell a story about the climate of the past. By examining them and the associations of environmental conditions today in which their modern-day descendants live, climatologists can gain clues as to what the past environment was like. Next, it looks at trees and the science of dendrochronology and examines how far back into the historical time line this technique can reliably take scientists when they attempt to reconstruct past climates. The use of corals is presented next, including the environment they need in order to survive and why ancient coral formations are found today in some of the most unexpected places. Finally, the paleoclimatic story told by plants and how they relate directly to climate change is examined.

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