Preprints
https://doi.org/10.5194/egusphere-2022-1028
https://doi.org/10.5194/egusphere-2022-1028
20 Oct 2022
 | 20 Oct 2022

Impacts and uncertainties of climate-induced changes in watershed inputs on estuarine hypoxia

Kyle E. Hinson, Marjorie A. M. Friedrichs, Raymond G. Najjar, Maria Herrmann, Zihao Bian, Gopal Bhatt, Pierre St-Laurent, Hanqin Tian, and Gary Shenk

Abstract. Multiple climate-driven stressors, including warming and increased nutrient delivery, are exacerbating hypoxia in coastal marine environments. Within coastal watersheds, environmental managers are particularly interested in climate impacts on terrestrial processes, which may undermine the efficacy of management actions designed to reduce eutrophication and consequent low-oxygen conditions in receiving coastal waters. However, substantial uncertainty accompanies the application of Earth System Model (ESM) projections to a regional modeling framework when quantifying future changes to estuarine hypoxia due to climate change. In this study, two downscaling methods are applied to multiple ESMs and used to force two independent watershed models for Chesapeake Bay, a large coastal-plain estuary of the eastern United States. The projected watershed changes are then used to force a coupled 3-D hydrodynamic-biogeochemical estuarine model to project climate impacts on hypoxia, with particular emphasis on projection uncertainties. Results indicate that all three factors (ESM, downscaling method, and watershed model) are found to contribute significantly to the uncertainty associated with future hypoxia, with the choice of ESM being the largest contributor. Overall, in the absence of management actions, there is a high likelihood that climate change impacts on the watershed will expand low-oxygen conditions by 2050, relative to a 1990s baseline period; however, the projected increase in hypoxia is quite small (4 %) because only climate-induced changes in watershed inputs are considered and not those on the estuary itself. Results also demonstrate that the attainment of established nutrient reduction targets will reduce annual hypoxia by about 50 % compared to the 1990s. Given these estimates, it is virtually certain that fully implemented management actions reducing excess nutrient loadings will outweigh hypoxia increases driven by climate-induced changes in terrestrial runoff.

Journal article(s) based on this preprint

26 May 2023
Impacts and uncertainties of climate-induced changes in watershed inputs on estuarine hypoxia
Kyle E. Hinson, Marjorie A. M. Friedrichs, Raymond G. Najjar, Maria Herrmann, Zihao Bian, Gopal Bhatt, Pierre St-Laurent, Hanqin Tian, and Gary Shenk
Biogeosciences, 20, 1937–1961, https://doi.org/10.5194/bg-20-1937-2023,https://doi.org/10.5194/bg-20-1937-2023, 2023
Short summary

Kyle E. Hinson et al.

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-1028', Anonymous Referee #1, 21 Dec 2022
    • AC1: 'Reply on RC1', Kyle Hinson, 27 Feb 2023
  • RC2: 'Comment on egusphere-2022-1028', Bo Gustafsson, 21 Feb 2023
    • AC2: 'Reply on RC2', Kyle Hinson, 27 Feb 2023

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-1028', Anonymous Referee #1, 21 Dec 2022
    • AC1: 'Reply on RC1', Kyle Hinson, 27 Feb 2023
  • RC2: 'Comment on egusphere-2022-1028', Bo Gustafsson, 21 Feb 2023
    • AC2: 'Reply on RC2', Kyle Hinson, 27 Feb 2023

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload
ED: Publish subject to minor revisions (review by editor) (27 Feb 2023) by Kenneth Rose
ED: Publish subject to minor revisions (review by editor) (01 Mar 2023) by Marilaure Grégoire (Co-editor-in-chief)
AR by Kyle Hinson on behalf of the Authors (31 Mar 2023)  Author's response   Author's tracked changes   Manuscript 
ED: Publish subject to technical corrections (21 Apr 2023) by Kenneth Rose
ED: Publish subject to technical corrections (23 Apr 2023) by Marilaure Grégoire (Co-editor-in-chief)
AR by Kyle Hinson on behalf of the Authors (24 Apr 2023)  Author's response   Manuscript 

Journal article(s) based on this preprint

26 May 2023
Impacts and uncertainties of climate-induced changes in watershed inputs on estuarine hypoxia
Kyle E. Hinson, Marjorie A. M. Friedrichs, Raymond G. Najjar, Maria Herrmann, Zihao Bian, Gopal Bhatt, Pierre St-Laurent, Hanqin Tian, and Gary Shenk
Biogeosciences, 20, 1937–1961, https://doi.org/10.5194/bg-20-1937-2023,https://doi.org/10.5194/bg-20-1937-2023, 2023
Short summary

Kyle E. Hinson et al.

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Latest update: 07 Oct 2023
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.

Short summary
Climate impacts are essential for environmental managers to consider when implementing nutrient reduction plans designed to reduce hypoxia. This work highlights relative sources of uncertainty in modeling regional climate impacts on the Chesapeake Bay watershed and consequent declines in Bay oxygen levels. The results demonstrate that planned water quality improvement goals are capable of reducing hypoxia levels by half, offsetting climate-driven impacts to terrestrial runoff.