FACT BRIEF

Do ice core records showing that warming preceded CO2 rise cast doubt on greenhouse warming?

Tuesday, June 29, 2021

By John Cook

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Antarctic ice core records dating back 800,000 years suggest that increases in carbon dioxide lagged behind increases in temperature by a couple of hundred years. This observation has been used by some to incorrectly claim that modern CO2 emissions cannot be causing a rise in temperature. This misconception is based on the false dichotomy that warming is either driven by CO2 or CO2 is driven by warming. In reality, both are true.

In the past, warming was driven by variations in Earth’s orbit and tilt, resulting in changes in solar energy reaching Earth which caused some initial warming. This triggered the release of CO2 from oceans which caused additional warming. Thus, while CO2 first increased due to warming, the extra CO2 also caused additional warming.

Recent anthropogenic global warming cannot be explained by natural cycles, which are in their cooling phase.

See a full discussion of this at Skeptical Science

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Sources

Science Synchronous Change of Atmospheric CO2 and Antarctic Temperature During the Last Deglacial Warming

NASA Milankovitch (Orbital) Cycles and Their Role in Earth's Climate

American Institute of Physics The Carbon Dioxide Greenhouse Effect

NASA Why Milankovitch (Orbital) Cycles Can't Explain Earth's Current Warming

NASA Carbon Dioxide

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Skeptical Science

Skeptical Science is a non-profit science education organization. Our goal is to remove a roadblock to climate action by building public resilience against climate misinformation. We achieve this by publishing debunking of climate myths as well as providing resources for educators, communicators, scientists, and the general public. Skeptical Science was founded and is led by John Cook, a Senior Research Fellow with the Melbourne Centre for Behaviour Change at the University of Melbourne.

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