The idea that civilizations will eventually overheat their planet harkens back to the work of Soviet scientist Mikhail I. Budyko. In 1969, he published a groundbreaking study titled “The effect of solar radiation variations on the climate of the Earth,” where he argued that “All the energy used by man is transformed into heat, the main portion of this energy being an additional source of heat as compared to the present radiation gain.

Simple calculations show that with the present rate of growth of using energy the heat produced by man in less than two hundred years will be comparable with the energy coming from the Sun.”

This is a simple consequence of all energy production and consumption invariably producing waste heat. While this waste heat is only a marginal contribution to global warming compared to carbon emissions, long-term projections indicate that this could change.

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The Dyson Sphere is a fitting example of waste heat resulting from the exponential growth of an advanced civilization. In his original proposal paper, “Search for Artificial Stellar Sources of Infrared Radiation,” Freeman Dyson argued how the need for more habitable space and energy could eventually drive a civilization to create an “artificial biosphere which completely surrounds its parent star.”

As he described, these megastructures would be detectable to infrared instruments due to the “large-scale conversion of starlight into far-infrared radiation,” meaning they would radiate waste heat to space.

“The heating we explore in our paper results from the conversion of any form of energy and is an unavoidable consequence of the laws of thermodynamics,” added Balbi, who was the study’s lead author. “For present-day Earth, this heating represents only a negligible fraction of the warming caused by the anthropogenic greenhouse effect. However, if global energy consumption continues to grow at its current rate, this effect could become significant within a few centuries, potentially impacting Earth’s habitability.”

To determine how long it would take for advanced civilizations to reach the point where they would render their home planet uninhabitable, Balbi and Lingam crafted theoretical models based on the Second Law of thermodynamics (as it applies to energy production). They then applied this to planetary habitability by considering the circumsolar habitable zone (CHZ) – i.e., the orbits where a planet would receive sufficient solar radiation to maintain liquid water on its surface.