Preprints
https://doi.org/10.5194/egusphere-2025-1262
https://doi.org/10.5194/egusphere-2025-1262
03 Apr 2025
 | 03 Apr 2025

Mechanistic insights into tropical circulation and hydroclimate responses to future forest cover change

Nora L. S. Fahrenbach, Steven J. De Hertog, and Robert C. J. Wills

Abstract. Afforestation and the prevention of deforestation are important climate mitigation strategies, alongside reductions in greenhouse gas emissions. However, the biogeophysical effects of future forest cover change on the atmospheric circulation and tropical hydroclimate remain uncertain. We address this research gap using future scenario simulations from seven multi-ensemble models participating in the Land Use Model Intercomparison Project (LUMIP). The largest afforestation and avoided deforestation areas are located in the tropics, leading to robust increases in local evapotranspiration and precipitation, but widespread decreases in net precipitation (precipitation minus evapotranspiration), especially over Africa. Our results suggest that two competing mechanisms shape the tropospheric circulation and net precipitation response over Africa: The increased surface roughness not only increases evaporation, but also surface momentum fluxes, thereby slowing near-surface winds and reducing the orographic net precipitation. Opposing this surface drag effect is an energetic effect due to increased net energy input to the atmosphere, which strengthens convection and increases net precipitation. While the surface drag effect dominates and leads to a net precipitation decrease over western and southern Africa, the energetic effect dominates and leads to a net precipitation increase over central Africa. This tropical hydroclimate response to the forest cover change is largely independent of the background climate under low- to medium-warming scenarios. Our findings contribute to an improved understanding of the mechanisms of forest cover impact on future hydroclimate changes in the tropics and highlight the importance of considering hydroclimatic feedbacks in the context of future afforestation strategies.

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this paper. While Copernicus Publications makes every effort to include appropriate place names, the final responsibility lies with the authors. Views expressed in the text are those of the authors and do not necessarily reflect the views of the publisher.
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Journal article(s) based on this preprint

18 Nov 2025
Mechanistic insights into tropical circulation and hydroclimate responses to future forest cover change
Nora L. S. Fahrenbach, Robert C. J. Wills, and Steven J. De Hertog
Weather Clim. Dynam., 6, 1461–1477, https://doi.org/10.5194/wcd-6-1461-2025,https://doi.org/10.5194/wcd-6-1461-2025, 2025
Short summary
Nora L. S. Fahrenbach, Steven J. De Hertog, and Robert C. J. Wills

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2025-1262', Anonymous Referee #1, 01 May 2025
    • AC1: 'Reply on RC1', Nora L. S. Fahrenbach, 17 Jul 2025
  • RC2: 'Comment on egusphere-2025-1262', Anonymous Referee #2, 01 Jul 2025
    • AC2: 'Reply on RC2', Nora L. S. Fahrenbach, 17 Jul 2025

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2025-1262', Anonymous Referee #1, 01 May 2025
    • AC1: 'Reply on RC1', Nora L. S. Fahrenbach, 17 Jul 2025
  • RC2: 'Comment on egusphere-2025-1262', Anonymous Referee #2, 01 Jul 2025
    • AC2: 'Reply on RC2', Nora L. S. Fahrenbach, 17 Jul 2025

Peer review completion

AR – Author's response | RR – Referee report | ED – Editor decision | EF – Editorial file upload
AR by Nora L. S. Fahrenbach on behalf of the Authors (17 Jul 2025)  Author's response   Author's tracked changes   Manuscript 
ED: Referee Nomination & Report Request started (28 Jul 2025) by Roberto Rondanelli
RR by Anonymous Referee #2 (02 Aug 2025)
RR by Anonymous Referee #1 (08 Aug 2025)
ED: Publish subject to revisions (further review by editor and referees) (02 Sep 2025) by Roberto Rondanelli
AR by Nora L. S. Fahrenbach on behalf of the Authors (08 Sep 2025)  Author's response   Author's tracked changes   Manuscript 
ED: Publish subject to revisions (further review by editor and referees) (06 Oct 2025) by Roberto Rondanelli
AR by Nora L. S. Fahrenbach on behalf of the Authors (13 Oct 2025)  Author's response   Author's tracked changes   Manuscript 
ED: Publish as is (20 Oct 2025) by Roberto Rondanelli
AR by Nora L. S. Fahrenbach on behalf of the Authors (21 Oct 2025)  Manuscript 

Journal article(s) based on this preprint

18 Nov 2025
Mechanistic insights into tropical circulation and hydroclimate responses to future forest cover change
Nora L. S. Fahrenbach, Robert C. J. Wills, and Steven J. De Hertog
Weather Clim. Dynam., 6, 1461–1477, https://doi.org/10.5194/wcd-6-1461-2025,https://doi.org/10.5194/wcd-6-1461-2025, 2025
Short summary
Nora L. S. Fahrenbach, Steven J. De Hertog, and Robert C. J. Wills
Nora L. S. Fahrenbach, Steven J. De Hertog, and Robert C. J. Wills

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Short summary
Afforestation is a key strategy for climate change mitigation, yet the impacts on tropical hydroclimate remain uncertain. We find that future afforestation would increase evaporation and precipitation in the tropics, especially over Africa. It would also reduce net precipitation (precipitation minus evaporation) in these regions, which determines water availability. This happens because trees slow near-surface winds, while their influence on the energy budget strengthens convection.
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