Schwinger, J., Asaadi, A., Goris, N., & Lee, H. (2022). Possibility for strong northern hemisphere high-latitude cooling under negative emissions. Nature Communications, 13(1), 1095. https://doi.org/10.1038/s41467-022-28573-5
It is well established that a collapse or strong reduction of the Atlantic meridional overturning circulation (AMOC) would substantially cool the northern high latitudes. In this study the authors show that there is a possibility that such cooling could be amplified under deliberate CO2 removal and result in a temporary undershoot of a targeted temperature level. This behaviour was found in Earth system models that show a strong AMOC decline in response to anthropogenic forcing. Idealised simulations of CO2 removal with one of these models indicate that the timing of negative emissions relative to AMOC decline and recovery is key in setting the strength of the temporary cooling. This study shows that the pronounced temperature-fluctuations at high northern latitudes found in these simulations would entail considerable consequences for sea-ice and permafrost extent as well as for high latitude ecosystems.
Policy relevant message:
Cooling of the northern hemisphere as a result of a collapse or strong reduction of the Atlantic meridional overturning circulation (AMOC) can be amplified by Carbon dioxide removal (CDR) techniques. Therefore, not emitting CO2 into the atmosphere is a preferable action over post emission CO2 removal.