Tectonic degassing drove global temperature trends since 20 Ma
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Updated: Sep 6, 2025

Using Generative Art to Convey Past and Future Climate Transitions
Published on: March 31, 2023
Timothy D Herbert1, Colleen A Dalton1, Zhonghui Liu2
1DEEPS, Brown University, Providence, RI 02912, USA.
Abstract:
The Miocene Climatic Optimum (MCO) from ~17 to 14 million years ago (Ma) represents an enigmatic reversal in Cenozoic cooling. A synthesis of marine paleotemperature records shows that the MCO was a local maximum in global sea surface temperature superimposed on a period from at least 19 Ma to 10 Ma, during which global temperatures were on the order of 10°C warmer than at present. Our high-resolution global reconstruction of ocean crustal production, a proxy for tectonic degassing of carbon, suggests that crustal production rates were ~35% higher than modern rates until ~14 Ma, when production began to decline steeply along with global temperatures. The magnitude and timing of the inferred changes in tectonic degassing can account for the majority of long-term ice sheet and global temperature evolution since 20 Ma.
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