Most people who find a seashell during their summer holiday on the coast will probably not be aware that they have found a unique record of the climate. For paleontologists, those hard calcium shells provide a profound insight into the history of our earth and especially into the climate of the past.
Shells are a unique climate archive. The shells have clearly delineated growth patterns that show changing nutritional conditions, temperature fluctuations and environmental pollution. Shells are found all over the world, in the polar regions and at the equator, on land and in the ocean, in deeper waters and on ocean shelves, in tidal zones and in rivers, streams and lakes. "Shells are simply everywhere and, depending on their location, they provide us with important information about climatic developments.
They serve as records of volcanic eruptions in Iceland or the occurrence of a hurricane in Florida; they can, for example, even tell us whether the early Indian tribes on the western coast of Canada collected mollusks during full moon, crescent moon or new moon periods," states Schöne. Even though many types of shell are durable and survive for thousands of years, the mollusks themselves are extremely sensitive: In the presence of environmental pollution, they respond by lowering their rate of shell growth, which is why they can also be used for longer-term monitoring of water quality.
