Data on Ancient Climate Change
From the SBS world news service in Australia: Data on Ancient Climate Change
A new study has revealed that an extraordinary burst of global warming that took place around 55 million years ago dramatically reversed the world’s pattern of ocean currents, adding weight to modern concerns over climate change.
The research, produced by scientists at Scripps Institution of Oceanography at the University of California, San Diego, showed how global warming caused by greenhouse gases can quickly disrupt ocean processes and lead to drastic changes.
The Palaeocene/Eocene Thermal Maximum (PETM), which occurred 55 million years ago, saw the planet’s surface temperature rise by between five and eight degrees Celsius in a very short time, unleashing climate shifts that lasted tens of thousands of years.
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Scientists Flavia Nunes and Richard Norris found the world’s ocean current system did a U-turn during the PETM, and then reversed itself.
The unique data set they constructed for the first time showed that a monumental reversal in the circulation of deep-ocean patterns around the world has taken place, and helped researchers conclude that it was triggered by the global warming the world experienced at the time.
“The PETM example shows that anthropogenic [man-made] forcing may have lasting effects, not only in global climate but in deep-ocean circulation as well,” said the scientists.
The huge temperature rise may have occurred within just a few thousand years, but the researchers point out that the effects were enduring and the lesson for humankind today is clear.
“The earth is a system that can change very rapidly,” said Ms Nunes.
“Fifty-five million years ago, when the earth was in a period of global warmth, ocean currents rapidly changed direction and this change did not reverse to original conditions for about 20,000 years,” she said.
“What this tells us is that the changes we make to the earth today, such as anthropogenically induced global warming, could lead to dramatic changes to our planet.”
-DS
