Patterns in data of extreme droughts/floods and harvest grades derived from historical documents in eastern China during 801–1910

Hao, Zhixin; Wu, Maowei; Zheng, Jingyun; Chen, Jiewei; Zhang, Xuezhen; Luo, Shiwei

doi:https://doi.org/10.5194/cp-16-101-2020

Articles | Volume 16, issue 1

https://doi.org/10.5194/cp-16-101-2020

© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Special issue:

Droughts over centuries: what can documentary evidence tell...

https://doi.org/10.5194/cp-16-101-2020

© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 16, issue 1

Research article

|

13 Jan 2020

Research article |

| 13 Jan 2020

Patterns in data of extreme droughts/floods and harvest grades derived from historical documents in eastern China during 801–1910

Zhixin Hao, Maowei Wu, Jingyun Zheng, Jiewei Chen, Xuezhen Zhang, and Shiwei Luo

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Final revised paper (published on 13 Jan 2020)
Supplement to the final revised paper
Preprint (discussion started on 11 Feb 2019)

Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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RC1: 'Referee Comment: Extreme droughts/floods and their impacts on harvest', Anonymous Referee #1, 20 Feb 2019
- AC1: 'Reply to all comments', Jingyun Zheng, 07 Jun 2019
RC2: 'review report', Anonymous Referee #2, 07 May 2019
- AC1: 'Reply to all comments', Jingyun Zheng, 07 Jun 2019
- AC2: 'Correction to AC1', Jingyun Zheng, 14 Jun 2019

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

ED: Reconsider after major revisions (20 Jun 2019) by Andrea Kiss

AR by Jingyun Zheng on behalf of the Authors (25 Jun 2019) Author's response Manuscript

ED: Referee Nomination & Report Request started (07 Jul 2019) by Andrea Kiss

RR by Anonymous Referee #1 (02 Aug 2019)

RR by Anonymous Referee #2 (10 Aug 2019)

Suggestions for revision or reasons for rejection

The author has made an effort to insert a paragraph describing data characteristics and basic statistics. This definitely helps to increase data transparency procedure. However their explanations about the nature of the written records, interpretation of the records, and the data statistics are not rigorous and likely to incur more problems at the epistemological level. In fact, from my perspective, the authors do not really face the real challenges that the reviewers proposed to them and just to repeat the problems in the paper or to ignore. Below are just some of the examples.

On page 3 line 23-29, the authors strictly assert that drought records in the historical documents can be regarded as meteorological drought rather than hydrological or agricultural drought, and same declaration also appears for flood records that reflect more rain rather than river or lake overflowing etc. The declarations are hard to be accepted or digested literally because it is obvious that both drought and flood phenomena and the intensity can be largely influenced by the population size, biological and geographical conditions even today. Thus, when authors purely declare so without providing further justifications, this can lead to a non-negligible mistrust and suspicion from the readers to question the reliability of the record data and the analysis. Also it is not clear for me on page 4 line13-16, how the number of 70% of ….can be derived. It is like the authors’ assertion without much logical reasonability to follow. The added content for validating the grade method on page 4 line 5-10 is somehow not surprising since in this case only stations with extreme grade and disaster were kept (omit grade 3, 40% of data) for comparing with precipitation data (of what years?) that seem to show good match between two sets of data. Yet, in the first referee report, a clear jump of bumper harvest records (Figure 4) was notified that corresponds to the coldest interval of LIA and many famine records exist in other documents. All those are against the authors’ findings in the study. But the authors only respond to this comment by repeating this ‘jump point’ in the paper(p13 in revision), without more in-depth reflections or discussions. Actually, from my viewpoint, the number of good harvest can simply be exaggerated by the dramatically increased number of official documents and local chronicle staring Qing dynasty (1644 CE), and the kind of the very basic record/data issues has not been seriously taken by the authors resulting in severe degradation of the research quality of the paper.

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ED: Reconsider after major revisions (03 Sep 2019) by Andrea Kiss

AR by Jingyun Zheng on behalf of the Authors (15 Oct 2019) Author's response Manuscript

ED: Referee Nomination & Report Request started (27 Oct 2019) by Andrea Kiss

RR by Anonymous Referee #1 (01 Nov 2019)

Suggestions for revision or reasons for rejection

The authors have accepted the key changes requested in the previous reviews. However, they have not been entirely consistent in applying those changes. It is important that throughout the text the authors carefully distinguish (1) the analysis of data in these databases of historical weather and harvests from (2) their interpretation of the underlying climatic and human history. Therefore, I would request the following minor revisions:

The abstract has added terms such as “reported” but needs to rework the language more carefully to reflect the new approach of the article. The following changes would be appropriate in order to make the meaning more precise and avoid inaccurate claims:
- “reported extreme droughts [floods] occurred” should be: “extreme droughts [floods] were reported” (or a similar phrase). The key distinction here is a report of a drought [flood] is not the same as the historical occurrence of drought [flood].
- “reconstructed grain harvest was poor [medium, high] in” should be: “the grain harvest was reconstructed as poor [medium, high] for” (or a similar phrase).
- “occurrence of reported extreme drought in any sub-region of eastern China was significantly associated with reduced harvests in the long-term average” should be: “frequency of reporting of extreme droughts was significantly associated over the long term with lower reconstructed harvests” (or a similar phrase).
- “association between harvest and extreme floods” should be: “associated between the reported frequency of extreme floods and reconstructed low harvests” (or a similar phrase).
- “other social factors” should be “other historical factors” to include other historical environmental changes, both natural and anthropogenic

On page 2, lines 20-34 have not been reworked to reflect the new approach of the article -- that is, to first discuss patterns in the data derived from the historical documents, and only then to discuss the interpretations of those patterns as historical climate impacts. This paragraph makes the unwarranted assumption that the reported frequencies of events in the historical documents represent real frequencies and that associations between the frequencies of reported disasters and extremes and variations in reconstructed grain harvests represent causation (i.e., climate impacts). The studies cited by Su et al. and Yin et al. present the same problems of historical method and epistemology as did the previous draft of this manuscript, as discussed in my previous review. Therefore, their results need to be qualified in the same manner. The authors may refer the reader to the discussion section for their causal interpretation.

In the sentence at the bottom of page 4 and top of page 5, it is important that the authors clarify that their method is based on an assumption that the probabilities for omitting drought and flood events in reporting and transmission of historical records were random and unbiased, for the reasons they have stated. They haven’t actually proven that omissions were random and unbiased. They have merely made a reasonable argument that it would be appropriate to proceed on this assumption.

Now that the authors have worked to distinguish their results (that is, the patterns and associations in their data) from their discussion (that is, the climate and historical interpretation of those associations), their use of a combined “Results and Discussion” section has become more confusing. For the sake of clarity, I would encourage the authors to rename section 3 as simply “Results” and turn subsection 3.4 into a new section, “Discussion.” Their discussion of results in the bottom of page 9 to the top of page 10 as well as their discussion of results at the top of page 12 might then be moved into the new “Discussion” section, as part of the authors’ climatic and historical interpretation of the patterns in the data. The fact that these pattern makes sense from a meteorological perspective supports the case that droughts had a significant historical impact on grain harvests. The authors may wish to state this point clearly in their discussion.

The revised sections, while mostly clear, should receive further review for correct English grammar and word use before publication.

Referee Report: PDF

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ED: Publish subject to minor revisions (review by editor) (16 Nov 2019) by Andrea Kiss

Dear Authors,

the manuscript did improve in all major points previously addressed by the reviewers. Still there some smaller points that should be solved: please, follow the advices of Reviewer 1. Additionally, I have two further comments that, I think, needs further consideration:
1) While drought is often a large-scale phenomenon, the impacts of floods are mostly restricted to the areas directly affected by floods. As the authors only discuss floods seemingly as a counterpoint of droughts (and it is not exactly that), in the latter case, the authors could as well mention that much precipitation / wet periods (with or without extraordinary floods) could as well be responsible for (larger-scale) bad harvest and harvest failures.
2) There is a clear and well-visible improvement in the 2.1 Data subchapter with examples from original source references and also with listing major advantages of the compiled dataset and indices they apply. However, the authors could also address any weaknesses of their databases, as their data are mainly available in compilations, and usually compilations are based on all kinds of contemporary and non-contemporary data mixed, with the (sometimes high) probability of misdating, doubling (tripling) events etc. Consequently, majority of the Chinese database, the paper is based on, is only available in a form that retracing the sources and the reconstruction steps ate not possible. Naturally, the authors cannot solve this problem all within this article; nevertheless, in one sentence (e.g. on page 4, btw. lines 20-25, after listing all advantages of the dataset) they should refer to this general problem or weakness.

After these smaller modifications, the paper will be ready for publication.
Thank you for your work.

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AR by Jingyun Zheng on behalf of the Authors (19 Nov 2019) Author's response Manuscript

ED: Publish as is (26 Nov 2019) by Andrea Kiss

Short summary

Using reconstructed extreme drought/flood chronologies and grain harvest series derived from historical documents, it is found that the frequency of reporting of extreme droughts in any subregion of eastern China was significantly associated with lower reconstructed harvests during 801–1910. The association was weak during the warm epoch of 920–1300 but strong during the cold epoch of 1310–1880, which indicates that a warm climate might weaken the impact of extreme drought on poor harvests.