Global warming of the future is projected by ancient carbon emissions

However, what has not been clear is how much carbon was responsible for the temperature increase and where it came from. Scientists have speculated that it might have come from massive fires from burning coal and other ancient plant material, or from ‘burps’ of methane from the continental shelves that rapidly became atmospheric carbon dioxide.

"According to this work, if the PETM was caused by the burning of plant material then climate sensitivity to carbon dioxide is more than 4.5°F (2.5°C) per carbon dioxide doubling. And if methane was the culprit, then Earth’s climate must be extremely sensitive to carbon dioxide — increasing, over 10°F (5.6°C) per carbon dioxide doubling," noted Pagani.

This finding contradicts the position held by many climate-change skeptics that the Earth’s climate is resilient to such carbon dioxide emissions and suggests that Earth’s temperature will rise substantially with atmospheric carbon dioxide concentrations that are expected to double around mid-century.

"The last time carbon was emitted to the atmosphere on the scale of what we are doing today, there were winners and losers," remarked Ken Caldeira, a co-author from the Carnegie Institution’s Department of Global Ecology. "There was ecological devastation, but new species rose from the ashes. Our work provides even more incentive to develop the clean energy sources that can provide for economic growth and development without risking the natural world that is our endowment."

Other authors on the paper include David Archer in the Department of Geophysical Sciences, University of Chicago, and James C. Zachos in the Earth Sciences Department, University of California, Santa Cruz.

Citation: Science: (December 8, 2006).