What are the key reactions driving the global carbon cycle in Earth, the only known habitableplanet in the Solar System? And how do chemical reactions govern the transformation and movementof carbon? The special collection “Earth in Five Reactions: A Deep Carbon Perspective” featuresreview articles synthesizing knowledge and findings on the role of carbon-related reactions in Earth’sdynamics and evolution. These integrative studies identify gaps in our current understanding andestablish new frontiers to motivate and guide future research in deep carbon science. The collectionalso includes original experimental and theoretical investigations of carbon-bearing phases and theimpact of chemical and polymorphic reactions on Earth’s deep carbon cycle.