Reversing climate warming by artificial atmospheric carbon-dioxide removal: Can a Holocene-like climate be restored?


Corresponding author: A. H. MacDougall, School of Earth and Ocean Science, University of Victoria, Victoria, BC V8W 3V6, Canada. (


[1] Most climate modeling studies of future climate have focused on the effects of carbon emissions in the present century or the long-term fate of anthropogenically emitted carbon. However, after carbon emissions cease, there may be a desire to return to a “safe” CO2 concentration within this millennium. Realistically, this implies artificially removing CO2 from the atmosphere. In this study, experiments are conducted using the University of Victoria Earth system-climate model forced with novel future scenarios to explore the reversibility of climate warming as a response to a gradual return to preindustrial radiative forcing. Due to hysteresis in the permafrost carbon pool, the quantity of carbon that must be removed from the atmosphere is larger than the quantity that was originally emitted (115–180% of original emissions). In all the reversibility simulations with a moderate climate sensitivity, a climate resembling that of the Holocene can be restored by 3000 CE.