Climate scientists study evidence in the geologic record, such as fossils, to figure out what climate was like over hundreds of thousands of years (“paleoclimate”). One fossil they use is pollen, a part of a flowering plant that helps make a seed. Pollen can be blown into lakes, where it is preserved in sediment. Pollen from spruces, which do well in cold climates, can suggest what climate was like when spruce pollen was deposited.
Archaeological remains include artifacts (portable) and features (non-portable) made and used by humans. Archaeologists use these objects to understand how ancient people lived. How well archaeological remains survive depends on the materials they were made of, the ways they were used, the manner in which they were discarded, and the environment in which they were deposited. Organic remains generally decay in a short time unless preserved in special conditions.