The long-term legacy of fossil fuels

Fossil fuels will have large impacts on ocean chemistry and climate during the period while they are being burnt (and carbon dioxide emitted) in large amounts. It is frequently assumed that these impacts will fade away soon thereafter. Recent model results, by contrast, suggest that significant impacts will persist for hundreds of thousands of years after emissions cease. We present a new analysis that supports these model findings by elucidating the cause of this ‘fossil fuel hangover’ phenomenon. We explain why the carbonate compensation feedback is atypical, compared to other feedbacks, in the sense that convergence is back towards a new steady-state that is distinct from the starting state. We also calculate in greater detail the predicted implications for the future ocean and atmosphere. The post-fossil fuel longterm equilibrium state could differ from the pre-anthropogenic state by as much as 50% for total dissolved inorganic carbon and alkalinity and 100% for atmospheric pCO2, depending on the total amount of future emissions.