Modeling ocean heat content changes during the last millennium

Observational studies show a significant increase in ocean heat content over the last half century. Herein we estimate heat content changes during the last millennium with a climate model whose forcing terms have been best‐fit to surface proxy data. The model simulates the observed late 20th century ocean heat content increase and a comparable Little Ice Age minimum. When glacial advances are factored in, these results imply a sea level fall after the Middle Ages that is consistent with some geologic data. The present ocean heat content increase can be traced back to the mid‐19th century, with a near‐linear rate of change during the 20th century.