Hysteresis of the Earth system under positive and negative CO2 emissions

Jeltsch-Thömmes, A., Stocker, T. F., & Joos, F. (2020). Hysteresis of the Earth system under positive and negative CO2 emissions. Environmental Research Letters, 15(12), 124026. https://doi.org/10.1088/1748-9326/abc4af

Summary:

Carbon dioxide removal (CDR) from the atmosphere is part of all emission scenarios of the IPCC that limit global warming to below 1.5 °C. In this study, hysteresis characteristics were investigated in 4 x pre-industrial atmospheric CO₂ concentration scenarios with exponentially increasing and decreasing CO₂ using the Bern3D-LPX Earth system model. Hysteresis is quantified as the difference in a variable between the up and down pathway at identical cumulative carbon emissions. Due to hysteresis, sustained negative emissions are required to return to and keep a CO₂ and warming target. The results suggest, that not emitting carbon in the first place is preferable over carbon dioxide removal, even if technologies would exist to efficiently remove CO₂ from the atmosphere and store it away safely.

Policy relevant message:

Not emitting carbon in the first place is preferable over carbon dioxide removal, even if technologies would exist to efficiently remove CO₂ from the atmosphere and store it away safely.