the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 06 Oct 2025
Evaluation of national Greenhouse Gas Removal potential under a changing climate using a process-based land surface model
Abstract. Global warming and climate change caused by greenhouse gas emissions (GHG) will have multiple impacts on forest ecosystems. As the UK’s currently planned contribution to global efforts to mitigating these impacts, the Climate Change Act has set a goal of net zero emissions of GHG by 2050. A core part of the strategy to meet this target is to use afforestation and forestry management to implement large-scale Greenhouse Gas Removal (GGR). These measures will need to be resilient to some level of climate change even if the international community successfully meets the goals of the Paris Agreement in limiting global warming. However, the effectiveness of afforestation as a GGR strategy is difficult to fully evaluate with standard empirical models due to a myriad of changing environmental conditions. Here we use the process-based land surface model, coupled to a model of large-scale forest demography (JULES-RED). We focus on a low climate change scenario, which would yield peak global warming close to 2oC. We project that widespread Sitka Forest afforestation could potentially sequester 15 MtCO2 annually by 2080 assuming a plantation rate of 30,000 ha year-1 from 2025 to 2050. If the world fails to meet the goals of the Paris Agreement, UK woodlands will need to be resilient to more severe regional climate changes and the plantation locations will need be selected more precisely.
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Status: open (until 10 Dec 2025)
- RC1: 'Comment on egusphere-2025-4536', Anonymous Referee #1, 16 Nov 2025 reply
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Review of egusphere-2025-4536 (His-Kai et al.)
His-Kai et al. address the potential of afforestations for carbon sequestration in the UK under climate change. Afforestations and other forest-based carbon storage approaches are a highly important topic in the context of climate change mitigation. The study provides an example how a dynamic, climate-sensitive model could be used to estimate the carbon sequestration potential of afforestations under different future scenarios. The paper addresses certainly a scientifically significant topic that fits with the scope of BG.
However, the manuscript suffers from multiple and severe flaws regarding its scientific and presentation quality. The four major issues that are marring the manuscript are explained below ('General comments'). Additional specific comments can be found in the attached commented PDF version of the manuscript.
Based on the review criteria, I have come to the conclusion that the current version of the manuscript clearly does not meet the quality standards of Biogeosciences. There may be potential in the manuscript, but it would need to be essentially re-written from scratch based on partly rather different simulation studies. Therefore, I don’t think it can be pursued further in the present form for Biogeosciences.
General comments:
The study makes use of the coupled JULES-RED model to simulate carbon dynamics of afforestations along a wide environmental gradient in the UK, based on 300 site-specific simulations. The simulated vegetation dynamics in the model depends heavily on the parametrisation of Sitka spruce, which was based on a generic Plant Functional Type, whose parameters were heavily calibrated to only one Sitka spruce forest. This raises the question of over-calibration because (1) tree growth at this site is highly unlikely to be representative for all other 299 sites where simulation studies are conducted, and (2) one site is not representative for the environmental gradient covered by the study. Furthermore, no model validation against independent data was performed, thus not providing any assessment of model accuracy beyond the calibration site. This is scientifically highly questionable and raises doubts about the reliability of the study results overall.
JULES was developed to simulate carbon and other fluxes between the land surface and the atmosphere. Such models are usually applied at regional, country, or global scale. However, in this study the model is used at the stand scale, but the authors provide little evidence that the coupled JULES-RED model is suitable to represent forest dynamics at this spatial scale. Examples for this are the excessively simply mortality formulation (which is not sensitive to climate, as it appears) and the simple formulation of competition for light. As a matter of fact, the statements in the manuscript that refer to the model and its suitability are based on a limited number of studies, predominantly from the same author group (e.g. Argles et al., Clark et al.). Furthermore, the introduction focuses only on the model JULES but misses any broader review of forest modelling literature which would be important to put the model into context. It is everything but clear that JULES-RED is the most appropriate approach for studying stand-scale forest dynamics across 300 sites in the UK.
The text is often not logical and quite difficult to follow. The Introduction is lacking clear research questions or hypotheses, but it already contains descriptions of the methods. The Method section is incomplete and lacks transparency (for more details, cf. annotated PDF). The Result section describes the results only poorly and contains many additional explanations of the methods. The Discussion section is largely a re-cap of things from the Results section together with the presentation of new results, whereas this section actually lacks a proper discussion (i.e. putting the results achieved in this paper in the context of the broader literature). Lastly, the Conclusions section is far too long, unfocused, and contains surprising statements that are not warranted by the substance of the paper.
The paper appears to have been put together in great haste. The writing is often sloppy and there are many grammar errors and language glitches. The layout of the presented figures is often inconsistent (e.g. axis labels, placement of legend) and the captions are often insufficient to understand the figures on their own. Figures 4 and 5 are identical (i.e. we surmise that Figure 5 was pasted twice). The list of references is in a terrible state, and not all references cited in the text can be found in the list of references. Overall, the manuscript gives the impression of a quickly assembled paper using copy-paste from multiple other sources.