Earth's future could resemble its hottest ancient epoch, a new study says. Picture palm trees swaying in Canada, warm seas lapping at shorelines hundreds of feet higher than they are today—and no natural ice anywhere.
That was the scene some 50 million years ago, scientists say, and rising carbon dioxide levels could make Earth's future look much like this hothouse past.
(Related: "Global Warming Is Rapidly Raising Sea Levels, Studies Warn" [March 23, 2006].)
The study shows that the high carbon dioxide (CO2) levels found during the Eocene epoch match the CO2 levels predicted for the end of this century by many global warming models.
The Eocene occurred between 56 million and 49 million years ago. It featured the highest prolonged global temperatures of the past 65 million years.
"Some frost-sensitive plants, like palm trees, lived to about 60 degrees north [for example, as far as southern Alaska] and south latitude," said geologist Tim Lowenstein of New York's Binghampton University. Lowenstein co-authored the new study, which appears in tomorrow's issue of the journal Science.
"[Palm tree remains] were found in the basin where our work was [completed] in Colorado and Wyoming," Lowenstein continued. "That would project Florida-like climates well up into Canada."
"There was no ice on any continent as far as we know," said Daniel Schrag, professor of Earth and planetary sciences at Harvard University in Cambridge, Massachusetts.
"There were forests in the Arctic and Antarctica," added Schrag, who is unaffiliated with the study. "There were crocodilians living on Ellesmere Island in the Arctic [map of Ellesmere Island region]."
The Eocene's oceans, according to fossil records of oxygen, were the warmest of the past 60 million years. They were also much higher than today's seas.
"Sea level was about 100 meters higher [328 feet]—mostly because there was no ice in Antarctica," Harvard's Schrag said.
"That's real global warming," Lowenstein added.
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