Dear authors of the manuscript “The climate in Poland (Central Europe) in the first half of the last millennium, revisited”, This study significantly furthers our understanding of climate variability in Poland during the first half of the last millennium. The new documentary records and the three tree-ring chronologies are noteworthy contributions to the paleoclimate research community. Archiving these records in a public database would substantially enhance the impact of this manuscript. However, the manuscript lacks a clear scientific question and a discussion of the related climate mechanisms. Here are my revised comments:

Main Comments:

1. The manuscript could be improved by introducing a clear scientific question or objective that it seeks to answer. It would also benefit from a detailed discussion on climate mechanisms related to the extreme events and warm periods.
2. Please clarify how your current reconstructions differ from and contribute uniquely to the existing body of work. While reconstructions are valuable, it is essential to interpret and provide insights from these reconstructions, such as information about extreme events, rather than merely listing them.
3. A detailed comparison, highlighting the similarities and differences between the tree-ring records and documentary records, could reinforce the benefits of using multiple proxies.

Specific Comments:

1. Lines 18-19: Clearly define the motivation and scientific question of your study.
2. Line 19: Consider incorporating all available quantitative climate reconstructions into your study, such as the gridded reconstructions (Neukom et al., 2019) and the reanalysis reconstruction (Tardif et al., 2019).
3. Line 50: The claim "Only a few papers also deal with a pre-1500 period" seems unsupported. Perhaps you could mention that there are significantly fewer studies dealing with the pre-1500 period compared to the post-1500 period.
4. Line 96: Please translate the information in Table S3 into English to facilitate the review process.
5. Line 183: Could you explain the reason for separating the sections before and after 1360 CE?
6. Lines 209-210: If this sentence does not contribute significant information, consider removing it.
7. Lines 257-259: Please clarify the logic in this sentence.
8. Lines 275-283: Please explain why tree-ring records respond to winter temperature in Poland, given that most tree-ring chronologies mainly respond to growing-season temperature, which directly impacts photosynthesis and the formation of growth rings (Fritts, 1976).
9. Lines 279-281: Please clarify what you mean by "the record today." Is it the instrumental record?
10. Lines 301-302: Consider including the instrumental temperature variability from 1951-2000 in Figure 10 A, B, C for a clearer comparison.
11. Lines 359-362: Comparing tree-ring chronologies directly could provide more insightful results.
12. Lines 391-392: Please explain why the reconstruction matches the simulation.
13. Lines 438-439: This information does not seem to fit in the results section. Consider moving it to a more appropriate section.
14. Lines 440-430: There appears to be a logical inconsistency in this section. The relationship between seasonal temperatures does not seem to justify a replacement.
15. Lines 462-463: This does not seem to be a conclusion.
16. The correlation coefficients in Table 1 for the tree-ring reconstructions are rather small, indicating that the explained variance in two out of three chronologies is less than 25%.

I hope these suggestions help enhance the clarity and impact of your manuscript.

References

Fritts, H., 1976. Tree rings and climate. The Blackburn Press, New Jersey.

Neukom, R., Steiger, N., Gómez-Navarro, J.J., Wang, J., Werner, J.P., 2019. No evidence for globally coherent warm and cold periods over the preindustrial Common Era. Nature 571, 550-554.

Tardif, R., Hakim, G.J., Perkins, W.A., Horlick, K.A., Erb, M.P., Emile-Geay, J., Anderson, D.M., Steig, E.J., Noone, D., 2019. Last millennium reanalysis with an expanded proxy database and seasonal proxy modeling. Clim. Past 15, 1251–1273.

Review of manuscript "The climate in Poland (Central Europe) in the first half of the last millennium, revisited".

This manuscript investigates climate variability in Poland over the first half of the last millennium, especially over the 15th century. The authors combine previously published climate reconstructions with novel time series from dendrochronological and documentary material. I am especially impressed with the extensive and detailed work on gathering all the documentary evidence (Tables S2 and S3).

As I do not have expertise in dendrosciences, I will focus mostly on the documentary evidence and the reconstruction created from these data. After taking into consideration the few suggestions pointed out below, I think this manuscript is well suited to EGUsphere.

Major

My major concern is related to the temperature reconstruction based on documentary evidence (lines 112–116 and 235–249, Fig 4.). The authors state that the reconstruction method is "described in a paper by Przybylak et al. (2005) and is therefore omitted here". However, I would strongly suggest including a brief description on the method, as well as adding some critical reflections on the potential biases of historical data. There are few reasons for this: 

1) As the documentary evidence presented by Przybylak et al. (2005) covered years 1501–1840, the transformation from the -3,...+3 index values into °C (Przybylak et al. 2005, Tables II and III) was done with a reference period when the documentary and meteorological data overlapped. This is not the case in the current study, as (as far as I understood) reference period 1951–2000 is used for the 1361–1500 reconstruction. Thus, is the method still applicable if the documentary and meteorological series do not overlap?

2) The approach described by Przybylak et al. (2005) is based on the assumption that "there were no significant changes in mean temperatures […] from the 16th to the 19th centuries" and thus "it can be assumed that any changes in temperature variance that occurred were insignificant" (Przybylak et al. 2005, 778). However, can we similarly assume that there were no changes in the mean and/or variance between the periods 1361–1500 and 1951–2000?

3) The reconstruction (Fig. 5) indicates that 15th century winters were systemically colder and summers warmer than during the later half of the 20th century, which provides further evidence on the transformation to a more continental climate during this period (lines 326–329). However, I was wondering whether the source material might contribute to the higher occurrence of colder/hotter anomalies as well? It is well established that historical weather descriptions contains bias in the focus of the observer and they emphasise extreme events (see, e.g., Brázdil et al. 2010, "European climate of the past 500 years" Climatic Change 101). The number of available weather descriptions (Fig. 2) and the frequency of extreme events (Table 2) show a similar temporal pattern. Thus, to what degree the increased number of mentioned cold/hot seasons can be explained by increasing source availability, especially because we know that historical records rarely record "average" weather?  

4) And last, related to the point above, it would be good to add a table of criteria (i.e. list of typical descriptions/events in the documentary sources) for the -3,…,+3 classification for both seasons. This would be informative for readers who are not familiar with what is considered as "typical" or "extreme" weather over the study area. Moreover, clearly defined classification criteria would help to assess the high frequency of the late 15th century extreme events as well (Table 2).

Moderate/minor

Please, provide further information on the meteorological data used, as the referred publication (Kożuchowski and Żmudzka, 2003) is not publicly available. Based on Fig 1, the meteorological data is coming from two stations, from Torun and Kraków?

Pay attention to terminology "current", "contemporary", and "present" (for example, lines 27, 239, 248, and 324). In many cases more accurate expression would be "latter half of the 20th century" or similar.

The manuscript includes quite a lot of additional material from previous publications (e.g., Fig. 10 and the section Summary and discussion. Also the abstract starts by mentioning these materials). Consider introducing these data, for example, in a supplementary table.

Technical

Line 22: Correct "date" as "data"

Lines 66 and 67: Bold font for the titles.

Table 1: Verification statistics are missing for Lesser Poland Scots pine and Silver fir.

Line 149: What are the "extreme thermal conditions" that the moon rings indicate? Extremely cold winters? Please clarify for non-specialist.

Lines 204 and 206. Winters 1280, 1306, and 1225. For example, in the case of winter 1280, does this mean the winter 1279/80 or 1280/81?

Line 255 and after. What the identified moon rings indicate? Colder winters?