Energy balance bistability, hysteresis, and catastrophic transitions
T = — K | State: — | S = 1.00 S₀
Earth's energy balance: Q_in = S₀S(1−α(T))/4, Q_out = σT⁴ − F. The albedo α(T) is high (ice, α≈0.6) when T < 263K, low (ocean, α≈0.15) when T > 293K, with a smooth transition. This creates bistability: warm Earth and snowball Earth can coexist for the same solar forcing, separated by tipping points. Hysteresis means recovery from snowball state requires much higher solar input than the forward tipping threshold.