Friday, Dec. 20, 2024
Are we heading into an ‘ice age’?
The planet has been getting warmer since the Industrial Revolution, not colder.
Historically, ice ages have followed changes in the Earth’s relationship to the sun. Natural cycles affect the tilt of Earth’s axis and its orbit around the sun. As Earth’s axis becomes less tilted, and its orbit more elliptical, it receives less solar radiation.
These “Milankovitch” cycles occur over thousands of years. Currently, Earth’s tilt is halfway between its maximum and minimum while its orbit is nearly circular.
In the absence of human activity, Earth may have gradually cooled in the coming centuries with phases corresponding to a decreasing tilt and an increasing orbital eccentricity.
However, fossil-fuel burning and other actions have raised CO2 levels to 420 parts per million—far above the 180-280 ppm seen during past ice ages. This extra CO2 has made it harder for heat to escape the atmosphere, overpowering the natural cooling trend.
This fact brief is responsive to conversations such as this one.
Sources
- NASA Milankovitch (Orbital) Cycles and Their Role in Earth’s Climate
- Cornell University Understanding long-term climate and CO2 change
- UC San Diego The Keeling Curve Hits 420 PPM
- Woods Hole Oceanographic Institution Are we heading toward another Little Ice Age?
- NASA Global Temperature
About fact briefs
Fact briefs are bite-sized, well-sourced explanations that offer clear "yes" or "no" answers to questions, confusions, and unsupported claims circulating online. They rely on publicly available data and documents, often from the original source. Fact briefs are written and published by Gigafact contributor publications.
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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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