The role of negative carbon dioxide emissions in climate system reversibility

The current trend of rising atmospheric CO2 concentrations is likely to lead to harmful changes in Earth’s climate system. This research explores the role of artificial atmospheric CO2 removal (referred to as negative emissions) in reversing human-induced climate change. We designed a range of plausible CO2 emission scenarios, which follow a gradual transition from a fossil fuel driven economy to a zero-emission energy system, followed by a period of negative emissions. The climate system components’ responses are computed using the University of Victoria Earth System Climate Model of intermediate complexity.The results suggest that while it is possible to restore global mean temperature to a lower level after overshoot (i.e. 2°C above pre-industrial), sea level rise is not reversible for several centuries, despite implementation of large amounts of negative emissions. Outgassing of CO2 from terrestrial and marine carbon sinks offsets the artificial removal of atmospheric CO2, thereby reducing its effectiveness.