Climate Scenario Model for an ice age

A planet warms until it radiates away exactly the sunlight it absorbs. Balancing absorbed power S(1−α)/4 against εσT⁴ gives the equilibrium temperature. An emissivity below 1 represents greenhouse gases trapping outgoing infrared, raising the surface temperature.

Carbon moves between four great reservoirs — atmosphere, surface ocean, deep ocean, and biosphere — through exchange fluxes. Add fossil emissions to the atmosphere box and watch how slowly the oceans and land can draw it back down. The deep ocean is huge but exchanges slowly.

Three slow changes in Earth's orbit — the stretch of its ellipse (eccentricity), the tilt of its axis (obliquity), and the wobble of that axis (precession) — combine to modulate summer sunlight at high latitudes. That insolation rhythm paces the glacial-interglacial cycles recorded in ice and ocean cores.

Watson and Lovelock's Daisyworld shows how life can regulate a planet. Black daisies warm a cold world by absorbing sunlight; white daisies cool a hot one by reflecting it. As the sun brightens, the daisy mix shifts to hold the temperature nearly constant — biological homeostasis with no foresight.