How do ice ages begin and end?
Quick Answer
Ice ages are driven mainly by changes in Earth’s orbit and tilt, which alter how much sunlight reaches different parts of the planet. Those changes are amplified by feedbacks involving ice, oceans, and greenhouse gases.
The Full Story
The main long-term rhythm behind ice ages is linked to Milankovitch cycles: variations in Earth’s orbit shape, axial tilt, and wobble. These cycles change the distribution of sunlight, especially in high northern latitudes where ice sheets can grow. Once ice expands, it reflects more sunlight, which cools the planet further and strengthens the ice age. Greenhouse gases such as carbon dioxide and methane also change during these periods, reinforcing warming or cooling. The most recent glacial period ended about 11,700 years ago, marking the start of the current Holocene epoch.
Key Facts
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"What flips Earth between ice age and warm age?"