Two teams of researchers taking a harder look at air trapped in ancient ice say greenhouse gases could make the planet much warmer than previously projected.
Scientists have known for more than a decade that as temperature rises on Earth, concentrations of carbon dioxide rise as well.
Most scientists suspect the reason is because feedback mechanism is at work, so that warmer temperatures spur the planet to release carbon dioxide — a heat-trapping gas — in turn causing higher temperatures and more releases of carbon dioxide.
The new studies, to be published Friday in a prominent earth sciences journal, attempt to size up these increases from past warming periods and apply them to the 21st century.
The two teams, a Dutch-German-British team and a Berkeley team, were unable to explain the exact mechanism at work, which limits the value of the findings for other scientists seeking to project greenhouse effects from fossil fuel burning.
But the size of the effect could be significant — as much as 2 degrees Celsius (3.6 degrees Fahrenheit) more warming by the end of the century than previously forecast, raising
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