Budyko-Sellers Energy Balance: Ice Line, Hysteresis and Snowball Earth Globe

What is the Budyko-Sellers Model?

The Budyko-Sellers model is a simplified yet powerful tool used to understand Earth's climate dynamics. It focuses on the global energy budget, particularly the balance between incoming solar radiation and outgoing infrared radiation. The model incorporates key factors like albedo (reflectivity) of ice and snow, which significantly affect how much solar energy is absorbed or reflected by the planet.

Originally developed in the 1950s, this model has been refined over time to include more sophisticated representations of heat transport between latitudes and feedback mechanisms that amplify small changes in climate.

Key Components of the Model

The Budyko-Sellers model considers several critical components: absorbed solar radiation, outgoing infrared radiation, poleward heat diffusion, and the ice-albedo feedback loop. Absorbed solar radiation depends on latitude and season, while outgoing infrared radiation is influenced by temperature. Poleward heat diffusion accounts for the transport of heat from equatorial to polar regions, which helps maintain a more uniform global climate.

The ice-albedo feedback is perhaps the most significant feature of this model. Ice and snow have high albedos (reflectivity), meaning they reflect much of the incoming solar radiation back into space. As temperatures drop, more ice forms, reflecting even more sunlight and further cooling the planet—a positive feedback loop that can lead to rapid changes in climate.

Hysteresis and Snowball Earth

One of the most striking features of the Budyko-Sellers model is its hysteresis behavior, which refers to the phenomenon where the system's response depends on its history. For example, if you increase solar radiation or greenhouse gases, the ice line moves northward, but when you decrease these factors, the ice line does not immediately retreat to its original position; instead, it may move further south, leading to a new equilibrium state.

This hysteresis loop is particularly evident in scenarios of extreme climate change, such as the transition from a warm Earth to a snowball Earth. A snowball Earth scenario occurs when global temperatures drop so low that ice and snow cover most of the planet's surface, reflecting more sunlight and further cooling the Earth—a vicious cycle that can be difficult to reverse.

Applications and Implications

The Budyko-Sellers model has numerous applications in climate science. It helps researchers understand past climatic changes, such as those during ice ages or the transition between glacial and interglacial periods. Additionally, it provides insights into potential future scenarios under different greenhouse gas emissions pathways.

By studying this model, scientists can better predict how small perturbations in solar radiation or atmospheric composition might lead to significant shifts in global climate patterns, including the possibility of runaway ice-albedo feedbacks that could result in a snowball Earth scenario.

Frequently asked questions

Try it live

Everything above runs in your browser — open Budyko-Sellers Energy Balance: Ice Line, Hysteresis and Snowball Earth Globe and change the parameters while it is running. Nothing is installed, nothing is uploaded, the whole model lives in one tab.