Guides
How the cycles work
One guide for each motion, one on why northern summers decide whether ice grows, and one on how the cycles differ from today’s warming.
Five guides
What would you like to know?
Eccentricity
How the shape of Earth’s orbit changes over 100,000 years, why that barely changes yearly sunlight, and why it still matters for the ice ages.
Obliquity
Why Earth’s tilt swings between 22.1° and 24.5° every 41,000 years, and what that does to the strength of the seasons.
Precession
How the turning of Earth’s axis and of its orbit moves the seasons around the orbit every 23,000 years or so.
Sunlight at 65°N
Why scientists use midsummer sunlight at 65°N to study the ice ages, and what the number does and does not tell you.
Modern warming
No. The orbit changes over tens of thousands of years. Today’s warming comes mainly from greenhouse gases released by human activity.