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Cretaceous Climate Study
Global warming. Rising sea levels. Massive volcanic activity around the
world. Widespread erosion.
Its not a scene from the latest Hollywood disaster film, The Day After
Tomorrow, but the Earth as it appeared during the mid- to late-Cretaceous
geological period, 135 million to 65 million years ago, when the largest
dinosaurs ruled the planet.
Scientists have long sought clues to the Earths ancient climate from ice
cores that go back hundreds of thousands of years. Now, chemists at the
University of California, San Diego and Stanford University report in the
June 11 issue of Science that they have extended their glimpse of Earths
oceanic and atmospheric past to 130 million years, during one of its
greatest upheavals of climatic change.
Their results, the first high-resolution record of changes in seawater
sulfate, provide a portrait of the interactions between the Earth and its
atmosphere during the Cretaceous that should help scientists improve their
predictions of how our climate might change as the accumulation of carbon
dioxide and other greenhouse gases from human activities warm the planet.
The planet during the Cretaceous was very different than it is today, says
Adina Paytan, an assistant professor of geological and environmental
sciences at Stanford and the first author of the paper. Not only were
dinosaurs present, but the climate was extremely warm and global sea
levels were significantly higher than they are today. Understanding how
the atmosphere, land and ocean system interacted while in this global
greenhouse mode is very relevant if we want to understand the fate of our
This was a time when there were no glaciers in either the Arctic or
Antarctic, says Miriam Kastner, a professor of earth sciences at UCSDs
Scripps Institution of Oceanography and a co-principal investigator of the
study. So the record that we have obtained is an unusual portrait of an
extreme climate in the Earths past that will help us develop better
predictive models in the future.