As global temperatures increase, the growth of microbes is predicted to increase, creating a positive feedback between metabolism, atmospheric CO2 concentration, and warming. Responses of microbial metabolism to increasing global temperatures will depend on ecological and evolutionary changes in microbial communities. Yet, the contributions of chance and contingency (dependence on previous steps) in the ecology and evolution of microbial communities often hinders our ability to make predictive models. I argue that not all contingency is created equal; sometimes previous evolutionary changes (like conserved metabolic architectures) limit the space of what is possible, allowing for high predictability of community changes.
