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Researchers use minerals from ancient soils to reconstruct past climate


When the Paleocene ended and the Eocene began nearly 56 million years ago, Earth’s atmospheric carbon dioxide levels ranged between 1,400 and 4,000 parts per million (ppm). These carbon dioxide levels gave rise to sauna-like conditions across the planet, which scientists can now measure using tiny minerals called siderites.

“I’ve been obsessed with siderites since I started my postdoctoral studies more than 20 years ago,” said Timothy White, research professor in Penn State’s Earth and Environmental Systems Institute. “The minerals only form in wetland soils under the right conditions — it has to be totally saturated, and the soils cannot be frozen. Siderites are not well described in geologic literature, but I noticed that when they do appear, it’s at very discreet intervals and in really warm greenhouse episodes." more


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