Milankovitch Cycles

Orbital Forcing, Ice Cores & the 100 kyr Problem

Eccentricity: T≈100 kyr
Obliquity: T≈41 kyr
Precession: T≈23 kyr

Q(t) = Q₀[1+f(e,ε,ψ,t)]
Ice model: dV/dt = −αQ − βV

Feedback: CO₂, albedo

Eccentricity amplitude 1.0

Obliquity amplitude 1.0

Precession amplitude 0.5

Ice model nonlinearity 1.0

Milankovitch (1941) proposed Earth's orbital variations drive ice ages. The 100 kyr problem: eccentricity signal is weak yet dominates the late Pleistocene glacial cycles. Explanations invoke nonlinear resonance, CO₂ feedback, and ice sheet hysteresis. Obliquity dominated before ~800 kyr ago ("mid-Pleistocene transition").