On geological time scales, evolutionary innovations in soil biota (such as
termites) have diminished C sequestration and resulted
in greenhouse periods. Conversely, evolutionary innovations
in plants, such as the acquisition of lignin and
woody tree trunks, have led to increased C sequestration
and long ice ages (Retallack 2001). The concept that
plants cool the planet whereas fauna warm it, called the
“Proserpina Principle” after the Roman goddess of
spring, underscores the fragile balance between storage
and release of soil C.