Preprints
https://doi.org/10.5194/bg-2022-227
https://doi.org/10.5194/bg-2022-227
 
06 Dec 2022
06 Dec 2022
Status: this preprint is currently under review for the journal BG.

A comparison of the climate and carbon cycle effects of carbon removal by Afforestation and an equivalent reduction in Fossil fuel emissions

Koramanghat Unnikrishnan Jayakrishnan and Govindasamy Bala Koramanghat Unnikrishnan Jayakrishnan and Govindasamy Bala
  • Centre for Atmospheric and Oceanic Sciences, Indian Institute of Science, Bangalore-560012, India

Abstract. Afforestation and reduction of fossil fuel emissions are two major components of climate mitigation policies. However, their effects on the earth’s climate are different because reduction of fossil fuel emissions directly alters the biogeochemical cycle of the climate system, while afforestation causes biophysical changes in addition to changes in the biogeochemical cycle. In this paper, we compare the climate and carbon cycle consequences of carbon removal by afforestation and an equivalent fossil fuel emission reduction using simulations from an intermediate complexity Earth system model. Our simulations show that the climate is cooler by 0.36 °C, 0.47 °C, and 0.42 °C in the long term (2471–2500) in the case of reduced fossil fuel emissions compared to the case with afforestation when the emissions follow the SSP2-4.5, SSP3-7.0, and SSP5-8.5 scenarios, respectively. Though afforestation results in a lower atmospheric CO2, the cooling from the reduced atmospheric CO2 is partly offset by the warming from surface albedo decrease associated with the regrowth of forests. Since this warming effect from surface albedo decrease is nearly absent in the reduced fossil fuel emission case, the climate is relatively cooler, even though the atmospheric CO2 levels are similar to the afforestation case. Thus, in terms of climate benefits, reducing fossil fuel emissions is relatively more beneficial than afforestation for the same amount of carbon removed from the atmosphere. Nevertheless, fossil fuel emission reduction and afforestation efforts should be pursued simultaneously as both lead to a decrease in global mean warming and reduced ocean acidification.

Koramanghat Unnikrishnan Jayakrishnan and Govindasamy Bala

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on bg-2022-227', Anonymous Referee #1, 20 Dec 2022
  • RC2: 'Comment on bg-2022-227', Anonymous Referee #2, 05 Jan 2023
  • RC3: 'Comment on bg-2022-227', Anonymous Referee #3, 05 Jan 2023
  • RC4: 'Comment on bg-2022-227', Anonymous Referee #4, 05 Jan 2023

Koramanghat Unnikrishnan Jayakrishnan and Govindasamy Bala

Koramanghat Unnikrishnan Jayakrishnan and Govindasamy Bala

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Short summary
Afforestation and reducing fossil fuel emissions are two important mitigation strategies to reduce the amount of global warming. Our work shows that reducing fossil fuel emissions is relatively more effective than afforestation for the same amount of carbon removed from the atmosphere. However, both afforestation and reduction in fossil fuel emission should be pursued simultaneously to mitigate climate change and reduce ocean acidification.
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