Decline in atmospheric carbon dioxide key to ancient climate transition

University of Southampton:

A decline in atmospheric carbon dioxide (CO2) levels led to a fundamental shift in the behaviour of the Earth’s climate system around one million years ago, according to new research led by the University of Southampton.

A team of international scientists used new geochemical measurements, coupled with a model of the ‘Earth system’, to show that the growth and changing nature of continental ice sheets, approximately a million years ago, coincided with a cascade of events that ultimately lowered atmospheric CO2 during glacial intervals – periods when the Earth experienced extreme cold.

The researchers have shown this change was key in triggering what is known as the Mid-Pleistocene Transition (MPT), which lasted around 400,000 years. The MPT had long lasting effects on the frequency at which the Earth transitioned between periods of warm and cold climate, (the ‘ice age cycles’).

Findings of the study are published in the journal Proceedings of the National Academy of Sciences.

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