Dear Authors

Thank you for the reply to the review comments.

I am happy to invite you to submit a suitably revised manuscript. Please take all comments by the reviewers carefully into account during the revision process and please aim to remove potential sources of misunderstanding or confusion when revising the text.

Specifically, I would like to highlight the following issues:

1) When revising your manuscript, please give appropriate attention to the issue of aggregated versus spatially-explicit estimates as raised by reviewer 1 in his first “technical remarks on p.2 line 52” and as reiterated further in the comment on Figure 2b (“Figure 2b depicts the uncertainties in AFOLU emissions and (coincidence or not) the regions with the highest emissions have also the highest uncertainty. What does this mean for the overall conclusion and robustness about the authors claim that this spatial explicit approach is better than the country level estimates from FAOSTAT en EDGAR, since the uncertainties are so high?”).

2) Reviewer 2 raises issues regarding gross versus net fluxes, emissions and the like. As diverse communities are likely to use your data it is important to avoid any misunderstanding. What may be obvious for the authors may not be obvious for others.

The terms “net” and “gross” should be carefully explained in the revised manuscript; you provide some indication on how this could be achieved in your reply to comment 6.
Please provide in the revised manuscript a definition of how you use the terms “net” and “gross”.

Please also clarify your statement around line 100 here or in the method section in the revised MS. The text in the submitted version reads: “Net land use emissions balance the emissions by the sources with the absorptions by the sinks and offer emission data that are closer to what the atmosphere receives from human activities.”

-To which temporal and spatial scales do your definitions of net (and gross) apply?
-Are legacy fluxes (such as regrowth of previously cleared forests or burned areas) included in your definitions or not?
-Are “net land use emissions” equal to (i) net anthropogenic land use emissions of carbon or GHG from the land to the atmosphere evaluated as difference in the sum of source and sink fluxes relative to a natural reference state or equal to (ii) the sum of fluxes of carbon (or GHGs) to (from) the atmosphere from (to) an area under anthropogenic use or (iii) something else?
-Is “the absorption by the sinks” natural or anthropogenically-induced?
-Is abandoned land included in your assessment?

While I appreciate that this information is largely provided in the manuscript, I recommend to give a clear and explicit explanation of your definitions of net and gross early on in the manuscript. It might also be good to refer to alternative definitions of land use emissions as for example applied by the modelling community to provide additional context for the general reader.

3) A brief discussion on the interpretation of the fire fluxes from woodlands, forests, and peatlands is required in the main text to avoid confusion. Specifically, you may explain why tropical fire emissions from GFED are taken here as anthropogenic and move the information of the first sentence on top of page 5 in the SOM to the main text.

4) I recommend to add a brief discussion on potential double counting (reviewer 2: comments 10-12) in the revised manuscript.

5) I recommend to add a statement in the conclusion section that gross emissions as determined in this study are not to be confused with the overall net land-to-atmosphere flux due to human land use. This difference arises as important components of the overall terrestrial and atmospheric carbon balance such as legacy effects and changes in litter and soil organic matter are not included in this work.

I would appreciate to receive also a manuscript version where your changes are indicated/highlighted by using track change or similar tools. This would ease the further assessment of your work.

Thank you for submitting your work to Biogeosciences. I am looking forward to read your revised manuscript.

Your sincerely,

Fortunat Joos

Dear Authors

Thank you very much for responding to the comments by the reviewers and the editor and for revising your manuscript.

Your revised manuscript has been sent again to review and I have meanwhile received two reviews for your revised manuscript. Referee 2 reviewed already the originally submitted version, while referee 3 has been newly nominated. Both reviewers suggest to accept your manuscript for publication after minor revisions. Please see also the pdf file uploaded by reviewer 2. Based on my own reading, I offer a few additional comments below.

May I ask you to provide a response to the remaining comments and to submit a suitably revised version of your manuscript.

Thank you very much for submitting your work to Biogeosciences. I am looking forward to receive your reply and your revised manuscript.

Yours sincerely,

Fortunat Joos

Comments on the revised manuscript:

1) There are still issues regarding gross versus net. In your reply you emphasize that your approach considers gross emissions and you do not want to provide a definition for net emissions: “Since we do not work with net emissions, we prefer to concentrate on defining gross emissions, and skipping other definitions to avoid confusions.” However, in SI section 2 you write about “our net AFOLU balance”. E.g on p. 27 “Our net AFOLU balance included sequestration processes from soils under crops, and from paddy rice, both through organic matter fixation (dSOC)”. This may give the impression that all GHG sources and sinks with respect to the atmosphere are included in your assessement of a “net AFOLU balance”. This is apparently not the case, e.g. neglect of regrowth after fire, of the delay of carbon emissions from product pool or neglect of forest sinks and neglect of area with forest gain in the Harris et al data. Thus, the term “net” appears potentially misleading and should be omitted.

2) On a similar note, the caption and headings in table 8 refers simply to “emissions”. It is important that you clarify that these are “gross emissions” in the table and headings.

3) Referee 2 asked in his first review for “Also a direct comparison of the CO2 component with the GCP would enhance the credibility of this study.” Such a comparison with GCP and also with results from the Biogeosciences Special Issue: REgional Carbon Cycle Assessment and Processes (RECCAP) is still missing.

4) It is necessary that your findings are described in an overall context in the conclusion section (see my previous comment #5). The manuscript and the supplementary information deal with many different fluxes and complex issues. Thus, it is important for this type of work to put your findings into an overall perspective for the general reader. Arguably, the influence on AFOLU on the atmospheric carbon balance appears very relevant. It is thus important to point out that gross emissions as determined in this study are not to be confused with the overall net land-to-atmosphere flux due to human land use. This difference arises as important components of the overall terrestrial and atmospheric carbon balance such as legacy effects and changes in litter and soil organic matter are not included in this work. IPCC AR5 WGI Table 6.3 indicates net emissions to the atmosphere from land use change for Central and South America, Africa and Tropical Asia of about 2.5 PgCO2/yr (0.69 PgC/yr ) for the 2000s and (and global net emissions of 1.1 PgC/yr in table 6.1 of WGI AR5). Your table 2 indicates gross emissions of CO2 of 11 PgCO2/yr for a similar period (2000 to 2005). Such differences are relevant and should be spelled out clearly and in a quantitative way in your conclusion section.

5) The term “gross” should be included in the title.

6) SI: section 3, p33 typo: “Table 6 isplays“

7) SI p33 : “Table 8 shows a brief overview of the included variables” Please check table number (I think it should be table 7)

Dear authors

Thank you for your detailed reply and the revised manuscript. I am happy to accept your manuscript for publication (publish subject to technical correction).

I find the proposed title somewhat awkward as not the assessment is “gross” but the emissions. It is also quite long. Please consult with a native English speaker. Here a first suggestion: “Hotspots of tropical land use: patterns and uncertainties in gross emissions for the period 2000-2005”. You use the term “gross assessment” in the main text and you may wish to change this as well.

Thank you for sending your work to Biogeosciences.

With best regards, Fortunat Joos