CO2 Increases Responsible for Only 40% of Ancient Warming - Could the World Get Even Hotter Than Models Predict?

sun in the desert photo

photo: Alejandro Cañizares via flickr

New research published in the journal Nature Geoscience shows that during Paleocene-Eocene Thermal Maximum, a period about 55 million years ago when the planet warmed rapidly, only about 40% of that warming can be attributed to rises in CO2 in the atmosphere. In short, "theoretical models cannot explain what we observe in the geological record," report co-author Gerald Dickens says. (Science Codex) So, what else is going on and what does it mean for current climate models?What we know from sediment cores about the period is that atmospheric carbon levels and global surface temperatures rose rapidly, between 5-9°C in 10,000 years—a blink of an eye in geological terms—accompanied by carbon dioxide increasing about 70%.

However studying these samples reveals that CO2 was only responsible for part of the increase and that another mechanism had to be at work as well. "Some feedback loop or other processes that aren't accounted for" in the climate models must be responsible, according to Dickens.

"If this additional warming...was caused as a response to CO2 warming, then there's a chance that future warming could be more intense than people anticipate," report co-author Richard Zeebe said. (Reuters)

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