Breakthrough fills the knowledge gap for mathematical and computer modeling of carbon dioxide (CO2) elimination in underwater breathing apparatus (UBA). The intended audience is every UBA designer or diver interested in a better understanding of scrubber canisters and metabolic CO2 elimination. It introduces the reader to a new form of stochastic modeling using cellular automata to quantify and visualize the complex thermokinetics of the carbon dioxide absorption reactions that keep divers alive during rebreather diving. This technical monograph provides insights into the hidden chemical and mechanical machinery of rebreather scrubbers, a primary Underwater Life Support System component. The topic is most relevant to the categories of Life Support Systems, Technical Diving, and Rebreather Diving. It also pertains to the categories of Mathematical Modeling and Computer Modeling.