Coral is a useful indicator of local past climate. This piece of coral (Porites lobata) is a skeleton built of calcium carbonate extracted from seawater by coral polyps. Coral formed in the winter has a different density than that formed in the summer, creating annual bands. This piece came from a coral that grew from approximately 1740 to 1900. Because coral grows near the ocean surface, the thickness of the layers varies with changes in temperature, salinity, and cloud cover.
Topic: Earth Science
Subtopic: Climate/Climate Change
Keywords: Climate, Climatology, Ocean temperature, Porites lobata, Salinity