Damping of glacial‐interglacial cycles from anthropogenic forcing

Abstract Climate variability over the past million years shows a strong glacial‐interglacial cycle of ∼100,000 years as a combined result of Milankovitch orbital forcing and climatic resonance. It has been suggested that anthropogenic contributions to radiative forcing may extend the length of the present interglacial, but the effects of anthropogenic forcing on the periodicity of glacial‐interglacial cycles has received little attention. Here I demonstrate that moderate anthropogenic forcing can act to damp this 100,000 year cycle and reduce climate variability from orbital forcing. Future changes in solar insolation alone will continue to drive a 100,000 year climate cycle over the next million years, but the presence of anthropogenic warming can force the climate into an ice‐free state that only weakly responds to orbital forcing. Sufficiently strong anthropogenic forcing that eliminates the glacial‐interglacial cycle may serve as an indication of an epoch transition from the Pleistocene to the Anthropocene.