The Sun Conducts Ice Ages express
For 800,000 years, ice ages have occurred every 100,000 years. The rhythm matches the elongation of Earth's orbit. But the orbit changes the flow of solar heat so subtly — as if the conductor barely moved the baton, yet the orchestra thundered. It remained a mystery how this weak signal controls the ice sheets.
Previously, it was thought that the climate itself amplifies the nudges: melting ice and carbon dioxide act like a megaphone. But new research shows that a model of the Sun's direct effect on ice — without amplifiers — reproduces the data over 800,000 years.
The model refutes the need for complex chemistry. It also explained an anomaly from 400,000 years ago — a prolonged interglacial — by random heat from the ocean. Nature is conducted from space: simply and without a chemical score.
The ocean's mute: The 400,000-year orbital cycle exists, but in the ice age record it is absent — the ocean dampens slow oscillations, leaving only the 100,000-year rhythm.