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.