Articles | Volume 29, issue 2
Nonlin. Processes Geophys., 29, 219–239, 2022
https://doi.org/10.5194/npg-29-219-2022
Nonlin. Processes Geophys., 29, 219–239, 2022
https://doi.org/10.5194/npg-29-219-2022
Research article
 | Highlight paper
15 Jun 2022
Research article  | Highlight paper | 15 Jun 2022

Climate bifurcations in a Schwarzschild equation model of the Arctic atmosphere

Kolja L. Kypke et al.

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Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on npg-2022-2', Anonymous Referee #1, 17 Feb 2022
  • RC2: 'Comment on npg-2022-2', Marek Stastna, 31 Mar 2022
  • AC1: 'Comment on npg-2022-2', Allan Willms, 20 Apr 2022

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision
AR by Allan Willms on behalf of the Authors (09 May 2022)  Author's response    Author's tracked changes    Manuscript
ED: Publish as is (18 May 2022) by Vicente Perez-Munuzuri
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Executive editor
Climate change is causing rapid temperature increases in the polar regions. A fundamental question is whether these temperature increases are reversible. If we control carbon dioxide emissions will the temperatures revert, or will we have passed a tipping point beyond which return to the present state is impossible? We address this question with a column model of the Arctic atmosphere based on mathematical representations of the primary physical features, including the Schwarzschild two-stream equations for the long wave radiation, the Clausius-Clapeyron equation for water vapour concentrations, atmosphere absorption characteristics dependent on carbon dioxide and water vapour concentration levels, and nonlinear albedo response to surface temperature. We analyzed solutions of our model under four representative carbon pathways (RCPs) extending into the future. Under the strongest mitigation pathway (which represents far swifter carbon emission reductions than presently seen), the Arctic shows a mild increase in temperature that is reversible. Under the highest carbon pathway (which represents a continuation of the status quo with regard to emissions), the Arctic climate undergoes an irreversible bifurcation to a warm steady state, corresponding to annually ice-free conditions, prior to the end of this century. Under the two intermediate pathways, temperatures increase substantially and the system enters a state of bi-stability where an external perturbation could possible cause an irreversible switch to warm, ice-free state.
Short summary
Climate change is causing rapid temperature increases in the polar regions. A fundamental question is whether these temperature increases are reversible. If we control carbon dioxide emissions, will the temperatures revert or will we have passed a tipping point beyond which return to the present state is impossible? Our mathematical model of the Arctic climate indicates that under present emissions the Arctic climate will change irreversibly to a warm climate before the end of the century.