Climate change into reverse gear – reversibility and legacies

Abstract As society appears determined to significantly reduce carbon emissions, the viable question arises how nature will follow. A simple model is applied to project atmospheric CO2 concentration and near-surface temperature for emissions reductions up to 3 %/year. In result for anthropogenic efforts of 1.5-3 %/year emissions reduction, nature will return to the 1970’s CO2 concentration accompanied by a final industrial-eon temperature rise of 1.4-1.8 °C. For lower emissions reductions of e.g. 1 or 0 %/year, 22 % or 78 % of emissions need be technically removed per year to confine the temperature increase at 1.8 °C. Within this temperature regime, humankind’s ocean heating is inferred to remain within natural variabilities and sea level to approximately rise by 6 m/°C at a pace of 0.2 m/century.