This study investigates how human-driven land cover changes impact atmospheric chemistry and radiative forcing. The research found that compared to natural vegetation, present-day land use reduces global biogenic volatile organic compound (BVOC) emissions, leading to a decrease in global surface OH concentrations and CO mixing ratios, while increasing NOx. These shifts seem to cause regionally significant changes in ozone production with regionally varying VOC-sensitive ozone formation regimes. Ultimately simulations show a surprisingly large net cooling effect due to reduced tropospheric ozone and methane lifetimes, partially offset by warming from decreased biogenic SOA. The study highlights the critical need to understand land-use change impacts on the Earth system.

Overall, I find the study to be sound, robust, interesting and relevant, increasing our understanding of how ES-processes can work together on a fundamental level. The text is very well written and shows a high degree of consistency with minor slips here and there that are easy to remedy. I have no major concerns and only some minor comments which can be found in the attached file. I think this manuscript fits well within the scope of ACP and should be published after the comments have been addressed.

I found Code Availability to potentially contravene EGU/Copernicus requirements because reviewers have not been given access to the entire model (EMAC, etc.) and would have to reveal their identity if they would like to do so (by joining the consortium). This policy has previously lead to papers being rejected. I want the editor to be aware of this issue.

Summary

This study investigates how deforestation- and afforestation-induced changes in BVOC and NOx emissions influence OH reactivity, trace gas lifetimes, ozone production sensitivity, and radiative effects from ozone and methane changes. The authors employ a coupled climate-chemistry model (EMAC) with a dynamical vegetation model (LPJ-GUESS). Simulations were conducted for 2000-2011 under three scenarios: 1) a hypothetical no-deforestation case (PNV), 2) a present-day case with deforestation on both cropland and grazing land (DCGL), and 3) a case with deforestation exclusively on cropland, representing an extreme afforestation scenario with food production maintained (DCL). The study is well-designed, well-executed, and well-written in general. The methodology is solid with meticulous model setup and decision-making. The results exhibit a wealth of information, and the authors manage to present them clearly with in-depth and comprehensive discussions. The research question and findings are of novelty and great scientific implications. I recommend publication with only minor revisions needed.

Major Comments:

• The afforestation part (section 3.2) is surprisingly short compared to the deforestation part (section 3.1). I assume the intent is to avoid repetition since these two effects share great similarities though opposite in sign; however, I’d recommend either moving this DCL scenario entirely to supporting info, or the authors should elaborate more on how much of the deforestation impacts are “reversible” and what impacts are “irreversible”.
• There is an excess use of acronyms throughout the manuscript. I don’t think it is worth introducing acronyms if they are only used once or twice, such as DGVM (line 63), PPFD (line 144), TOA (line 311), etc. Scenario naming is also a bit opaque, as DCL and DCGL are visually similar and not intuitively distinguishable. Renaming may improve clarity.

Minor Comments:

Line 270: Previously you mentioned “changes in canopy densities changes dry deposition O3 fluxes”, but this O3 deposition flux decrease (1.5%) seems proportional to overall O3 decrease (1.6%)? Did you mean that spatial redistribution, rather than total flux, is the key point?

Figure 7: I’d recommend adding “VOC-sensitive”, “transitional”, and “NOx-sensitive” in panel (a) color bar, and adding “<-- more VOC-sensitive” and “more NOx-sensitive -->” in panel (b) color bar. It will help the audience to understand the figure even by it alone.

Line 290: Please justify the choice of 0.7 and 0.9 as thresholds for ozone regime classification. Are these based on prior literature or model-specific sensitivity tests?

Line 441: typo: “DCGl” to “DCGL”