Five Large 13th Century C.E. Volcanic Eruptions Recorded in Antarctica Ice Cores

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Review by Anders Svensson of the manuscript ‘Five large 13^th century CE volcanic eruptions recorded in Antarctic ice cores’ submitted to Atmosphere by Cole-Dai et al.

The authors are identifying five large volcanic eruptions in the 13th century that are recorded in four Antarctic ice cores as elevated levels of sulfuric acid. Four of the eruptions are also recorded in a Greenland ice core suggesting that those are major eruptions in a global context. The authors are arguing that this is an unusual high occurrence of large volcanic eruptions in the last two millennia suggesting that the climatic impact of the series of eruptions could be important.

Generally, the paper is well written, documented and with figures, tables and references. My only comment is concerning the quite limited use of and referencing to Greenland ice cores in the study. To convince us the identified eruption are indeed large on a global scale, it is important to document their presence in both Antarctica and Greenland.

I suggest the authors to include the Sigl et al. (2014) sulfate record from the NEEM S1 ice core in which at least three of the eruptions are easily identified and also listed in Table 1 of that paper.

I also encourage the authors to take a look at supplementary material of Sinnl et al. (2022), Table 3), where the same three eruptions are identified as tie points in six Greenland ice cores from different locations.

In my view, it is mostly three out of the five eruptions identified in Antarctica that are large enough to have a significant global climatic impact. But the impact of those eruptions may still be significant. Maybe the authors could estimate the accumulated effect of the 13^th century eruptions and compare to the accumulated effect of the 19^th century eruptions that are discussed in the manuscript? I am thinking of an approach similar to that taken in the work of Abbott et al. (2021), Table 1, or that of Lin et al. (2023), Figure 3, that is based on the work of Toohey and Sigl (2017), but including the new records presented in the manuscript.

References:

Abbott, P. M., Niemeier, U., Timmreck, C., Riede, F., McConnell, J. R., Severi, M., Fischer, H., Svensson, A., Toohey, M., Reinig, F., and Sigl, M.: Volcanic climate forcing preceding the inception of the Younger Dryas: Implications for tracing the Laacher See eruption, Quaternary Science Reviews, 274, 10.1016/j.quascirev.2021.107260, 2021.

Lin, J., Abbott, P. M., Sigl, M., Steffensen, J. P., Mulvaney, R., Severi, M., and Svensson, A.: Bipolar ice-core records constrain possible dates and global radiative forcing following the ∼74 ka Toba eruption, Quaternary Science Reviews, 312, 10.1016/j.quascirev.2023.108162, 2023.

Sigl, M., McConnell, J. R., Toohey, M., Curran, M., Das, S. B., Edwards, R., Isaksson, E., Kawamura, K., Kipfstuhl, S., Krüger, K., Layman, L., Maselli, O. J., Motizuki, Y., Motoyama, H., Pasteris, D. R., and Severi, M.: Insights from antarctica on volcanic forcing during the common era, Nature Climate Change, 4, 693-697, 10.1038/nclimate2293, 2014.

Sinnl, G., Winstrup, M., Erhardt, T., Cook, E., Jensen, C. M., Svensson, A., Vinther, B. M., Muscheler, R., and Rasmussen, S. O.: A multi-ice-core, annual-layer-counted Greenland ice-core chronology for the last 3800 years: GICC21, Clim. Past, 18, 1125-1150, 10.5194/cp-18-1125-2022, 2022.

Toohey, M., and Sigl, M.: Volcanic stratospheric sulfur injections and aerosol optical depth from 500ĝ€BCE to 1900ĝ€CE, Earth System Science Data, 9, 809-831, 10.5194/essd-9-809-2017, 2017.

Author Response

Response to Reviews for Five large 13th century CE volcanic eruptions recorded in Antarctic ice cores submitted to Atmosphere by Cole-Dai et al. submitted to Atmosphere

                We thank the reviewers for their positive comments and constructive criticism. Here we detail our response to all comments and questions. Reviewer comments and questions are in italics and responses are in boldface.

 

Reviewer 1 (Review by Anders Svensson)

Generally, the paper is well written, documented and with figures, tables and references. My only comment is concerning the quite limited use of and referencing to Greenland ice cores in the study. To convince us the identified eruption are indeed large on a global scale, it is important to document their presence in both Antarctica and Greenland.

I suggest the authors to include the Sigl et al. (2014) sulfate record from the NEEM S1 ice core in which at least three of the eruptions are easily identified and also listed in Table 1 of that paper.

I also encourage the authors to take a look at supplementary material of Sinnl et al. (2022), Table 3), where the same three eruptions are identified as tie points in six Greenland ice cores from different locations.

Response: We thank Dr. Anders Svenssen for the encouraging comments. In our manuscript, we have used data from mostly our own ice cores or ice cores we analyzed and studied. For data relevant to this work of other ice cores, we have cited the sources/papers of those data, but chose not to use the data directly. Following the reviewer’s suggestions, we in the revised manuscript insert/include some NEEM S1 data in Tables 1 and 3 with proper citation.

In my view, it is mostly three out of the five eruptions identified in Antarctica that are large enough to have a significant global climatic impact. But the impact of those eruptions may still be significant. Maybe the authors could estimate the accumulated effect of the 13th century eruptions and compare to the accumulated effect of the 19th century eruptions that are discussed in the manuscript? I am thinking of an approach similar to that taken in the work of Abbott et al. (2021), Table 1, or that of Lin et al. (2023), Figure 3, that is based on the work of Toohey and Sigl (2017), but including the new records presented in the manuscript.

We appreciate these comments and references by Dr. Svenssen. We are not sure what the reviewer means by “accumulated effect”. Table 1 in Abbott et al. 2021 is a comparison of volcanic deposition in Greenland vs. in Antarctica and inter-hemispheric (asymmetry) ratio. Another reviewer also suggested that we use the difference between volcanic deposition in Antarctica and Greenland to estimate the latitudinal locations of some of the volcanoes of the 13th-century eruptions. Our response here is similar to the response to that suggestion: inter-hemispheric distribution of volcanic aerosols of tropical eruptions is a complex process affected by  factors such as the quasi-biennial oscillation (QBO). Further, Table 1 in Abbott et al. extrapolates atmospheric aerosol mass loading of volcanic eruptions from ice core data of volcanic deposition flux. We think that that effort belongs to another paper in the future. Similarly, Figure 3 in Lin et al. 2023 is about calculating aerosol optical depth and radiative forcing; such work may be undertaken for the 13^th century eruptions in the future.

Reviewer 2 Report

Comments and Suggestions for Authors

This paper points out that there are five major sulphate peaks in Antarctic ice cores during the 13th century; and that this number is larger than the average for the Holocene (ca. 1.5), and therefore this may provide evidence for an unusually strong climate forcing from large explosive eruptions in the 13th century. This seems like a reasonable interpretation, but it would be valuable for the authors to evaluate some of the uncertainties in their analysis: 

- can they be confident that these events were low latitude eruptions (and therefore larger than high latitude SH events?) 

- are there any sulphur isotope data for any of these peaks, that might offer additional constraints on whether the sulphur was processed in the stratosphere, or not? (e.g. papers by Andrea Burke and others?)

- what is the uncertainty in scaling from a local deposition flux to inferring the climate impact, given that different atmospheric chemistry and transport models struggle to replicate deposition fluxes? (e.g. L Marshall et al .. volcanic sulphate deposition after Tambora, Atmospheric Chemistry and Physics 18 (3), 2307-2328, 2018) 

Minor points 

Table 1 – can you give some location information for the cores? Lat / long? Very simple map?

Line 108 ‘remarkably’ might be a better alternative for ‘astonishingly’

 

Line 164 – worth noting in the text that this is a deposition flux? 

 

Author Response

Response to Reviews for Five large 13th century CE volcanic eruptions recorded in Antarctic ice cores submitted to Atmosphere by Cole-Dai et al. submitted to Atmosphere

                We thank the reviewers for their positive comments and constructive criticism. Here we detail our response to all comments and questions. Reviewer comments and questions are in italics and responses are in boldface.

 

Reviewer 2

This paper points out that there are five major sulphate peaks in Antarctic ice cores during the 13th century; and that this number is larger than the average for the Holocene (ca. 1.5), and therefore this may provide evidence for an unusually strong climate forcing from large explosive eruptions in the 13th century. This seems like a reasonable interpretation, but it would be valuable for the authors to evaluate some of the uncertainties in their analysis:

- can they be confident that these events were low latitude eruptions (and therefore larger than high latitude SH events?)

Response: As we discuss in the manuscript, four of the five volcanic event signals in Antarctica ice cores have matching signals in Greenland ice cores. These so-called bipolar events are likely very large eruptions by volcanoes located in the low latitudes and this type of eruptions tend to exert significant climate forcing due to the large amount of volcanic aerosols and the global distribution of the aerosols. Their climate impact is stronger than eruptions in the high southern latitudes.

- are there any sulphur isotope data for any of these peaks, that might offer additional constraints on whether the sulphur was processed in the stratosphere, or not? (e.g. papers by Andrea Burke and others?)

Response: We do not have sulfur isotope data for these volcanic events in our Antarctica and Greenland ice cores.

- what is the uncertainty in scaling from a local deposition flux to inferring the climate impact, given that different atmospheric chemistry and transport models struggle to replicate deposition fluxes? (e.g. L Marshall et al .. volcanic sulphate deposition after Tambora, Atmospheric Chemistry and Physics 18 (3), 2307-2328, 2018)

Response: Using ice core volcanic deposition flux to infer atmospheric aerosol mass loading (the so-called transfer function) and subsequently quantitative impact on climate is a very important but different area of research on volcanic impact on climate. In addition to the paper mentioned by the reviewer, numerous papers deal with this topic. The papers paint a general picture of very large uncertainties when ice core data are used to estimate aerosol mass loading (and vice versa) by modeling. We do not have the expertise or sufficient data to estimate the uncertainty of the radiative forcing by these 13^th century volcanic eruptions.

Minor points

Table 1 – can you give some location information for the cores? Lat / long? Very simple map?

We now include location information for all the ice cores in Table 1.

Line 108 ‘remarkably’ might be a better alternative for ‘astonishingly’

We feel that the exact match between the date (1259) in the Crete core, which was determined with very limited data and overall ice core dating capabilities some 40 years ago and the date in WDC, which was obtained with the state-of-the-art methods and data, is beyond simply remarkable. We think “astonishingly” conveys the sense of this amazing match better than “remarkably”.

Line 164 – worth noting in the text that this is a deposition flux?

We insert the word “deposition” in the sentence.

Reviewer 3 Report

Comments and Suggestions for Authors

I have provided in-text comments to the attached PDF.

I think the paper could use a little bit of editing (some spelling mistakes) and clarification of some details. I think the results and discussion could use a little re-organization, and the conclusion could use some "pizazz." This paper applies new calculations to pre-existing data sets, and because of that, it feels thin on data. This is okay, but I think it needs to be more clearly stated somewhere that this is more like a reanalysis of data and not using newly collected data. Many of the methods used in this paper have been done elsewhere and on other cores which also makes the methods section feel thin. This paper looks at the 13th century when there were more large volcanic eruptions in a short period than in any other century in the past 2000 years. It would be nice to see some more discussion about how this data could help narrow the search for potential source volcanoes. Maybe something more about the differences in volcanic flux in each core/polar region. I feel like I need just a little bit more.

Comments for author File: Comments.pdf

Author Response

Response to Reviews for Five large 13th century CE volcanic eruptions recorded in Antarctic ice cores submitted to Atmosphere by Cole-Dai et al. submitted to Atmosphere

                We thank the reviewers for their positive comments and constructive criticism. Here we detail our response to all comments and questions. Reviewer comments and questions are in italics and responses are in boldface.

 

Reviewer 3

I have provided in-text comments to the attached PDF.

I think the paper could use a little bit of editing (some spelling mistakes) and clarification of some details. I think the results and discussion could use a little re-organization, and the conclusion could use some "pizazz." This paper applies new calculations to pre-existing data sets, and because of that, it feels thin on data. This is okay, but I think it needs to be more clearly stated somewhere that this is more like a reanalysis of data and not using newly collected data. Many of the methods used in this paper have been done elsewhere and on other cores which also makes the methods section feel thin. This paper looks at the 13th century when there were more large volcanic eruptions in a short period than in any other century in the past 2000 years. It would be nice to see some more discussion about how this data could help narrow the search for potential source volcanoes. Maybe something more about the differences in volcanic flux in each core/polar region. I feel like I need just a little bit more.

Response: The reviewer pointed out the spelling of the word “volcanos”. We now use “volcanoes” throughout the manuscript.

Received? This word is a little off

We replaced the word “receipt” with “reception”.

I would add something to the text about the data that is being analyzed in this paper was originally analyzed by Winski, etc and we are using the publicly available data from Arctic Data Center (https://arcticdata.io/) and U.S. Antarctic Program Data Center 257 (https://www.usap-dc.org/). Some of the paper feels thin on methods and new data because the authors are using existing data in a new way.

Response: The original data of ion concentrations in the SPC14 ice core were described (analytical methodology, temporal resolution, dating, etc.) by Winski and others. However, Winski et al. (2019 and 2021) did not analyze the sulfate data to construct records of volcanic eruptions. All the SPC14 volcanic-specific data (deposition fluxes) are new (previously un-published). In our original manuscript, we cite those papers for the original ion concentration data. We feel this is sufficient with respect to the source of the concentration data.

With respect to methods, all aspects of the methodology used in this work have been well described in the literature. We provide numerous citations where details of the methodology can be found. We would be glad to provide any method information which the reviewer could specify that is important to presenting this work.

I would add year or C.E. to the dates.

We use C.E. for the 13^th century (and other) dates at the beginning of the manuscript. Since all dates in this work are for C.E., we feel it is not necessary to add C.E. to every date after the initial mentioning of C.E. dates.

I would add that the reason this was correlated is because there was also Bi-polar tephra found with the deposit. Which has only happened once. JM Palais, MS Germani, GA Zielinski, Interhemispheric transport of volcanic ash from a 1259 A.D. volcanic eruption to the Greenland and Antarctic ice sheets. Geophys Res Lett 19, 801–804 (1992).

The initial correlation between the volcanic signal in Greenland and in Antarctica cores was made by Langway, Clausen and Hammer (1988), as stated in our manuscript. Further evidence that the same volcanic eruption was responsible for the bipolar sulfate signals came from study of the tephra particles in the ice layers of the sulfate signals. We include the information suggested by the reviewer in our revised manuscript: “The “1259 Eruption” in ice cores was studied extensively to determine the volcano responsible for this prominent ice core signal. Tephra (fine volcanic ash) associated with the sulfate signal was found in South Pole [19] and Summit, Greenland [20] ice cores and the chemical composition of the tephra suggested the El Chichón volcano in Mexico to be the source of the volcanic fallout.

Any comment about A13-5? It is the only event not discussed.

We have added the following regarding A13-5: “The average volcanic sulfate flux (19.2 kg km⁻²) of A13-5 (Eruption Year 1286) in Antarctica cores is comparable to that of A13-3. However, a volcanic sulfate signal appeared at the same time in Greenland ice cores (Table 3). This indicates that A13-5 is from a large eruption by a volcano in the low latitudes with significantly climate impact (see discussion in section 3.3).”

I think the location of the volcanoes (which are unknown except in the case of 1259) is one of the most important considerations that needs further discussion. 1259 is in both Hemispheres- easy. A13-3 is only found in the south and is likely a high impact eruptions but with only regional regional consequences. The other 3 should be targets for further consideration of climate impacts. Make some sort of statement saying how important these eruptions could be, and finding their location is important to better understand the impacts of bi-polar sulfate depositions.

Response: Sections 3.3 and 3.4 in this manuscript are devoted to this discussion. We have added this statement in the revised manuscript in Conclusions: “Of these four climatically important 13^th century volcanic eruptions, only A13-2 has been positively attributed to the responsible volcano (Samalas, [22]). The others remain “unknown” with respect to source volcanoes. It would be valuable to identify the source volcanoes in future research, as the climatic impact of a large eruption is also influenced by the exact location and the eruption characteristics.”

Is there any room to say A13-5 and A13-1 might be northern hemisphere tropics and A13-4 is southern hemisphere tropics? This being based on the relative abundance of the volcanic flux at each location.

This is a good question. In theory, one could use the difference (asymmetry ratio) between the volcanic deposition flux in Antarctica and that in Greenland to estimate the probable latitudinal location of the volcano. However, the hemispheric distribution of volcanic aerosols of a low latitude eruption is influenced by many eruption and atmospheric variables including the time or season of the eruption, the altitude of volcanic plumes, and the phases of the quasi-biennial oscillation (QBO). We feel that it is beyond the scope of this work to explore such a topic. Readers and reviewers are referred to Sigl et al., 2023 for a somewhat in-depth consideration of this topic.

I get what the author is saying but it is very clunky and could be simplified. The sentences that starts on line 191 seems out of place. I would combine the two paragraphs into one.

Volcanoes found at high latitudes are going to deposit aerosols in only one polar region. Whereas, large mid-latitude (tropical) eruptions have a will have a better chance of depositing in both polar regions.

We have followed the reviewer’s advice and combined the two paragraphs. Now it reads: “Large eruptions by volcanoes in the Southern Hemisphere and in the low latitudes (the tropics) of both hemispheres (between 20°N and 20°S) are likely to leave sulfate/sulfur/sulfuric acid deposit in Antarctic snow and may be detected in Antarctica ice cores [3]. Volcanic signals in Greenland cores are most likely from volcanoes in the Northern Hemisphere and the tropics. Therefore, when signals of an eruption are found in both Antarctica and Greenland ice cores, the so-called bipolar signals, the volcano responsible for the signals is likely located in the tropics [16]. The only exception is global distribution of volcanic aerosols of extraordinarily explosive eruptions by volcanoes in the high or mid-latitudes of Northern Hemisphere [16]. Based on this criterion, all five 13th century eruptions (A13-1 to A13-5) were most likely by volcanoes in Southern Hemisphere and/or the tropics.”

I find it odd that the introduction of the Greenland Core is here in volcano locations. I think this should be moved up and maybe under it's own subheading on Greenland Ice cores.

In the revised manuscript, we now include the NEEM core (NEEM S1) for data and for comparison with Antarctica cores. Both the Summit core (SM07 C4) and NEEM S1 are now first mentioned in Materials and Methods.

Reviewer 4 Report

Comments and Suggestions for Authors

Cole-Dai et al. investigate six sulfate records from ice cores in Antarctica and Greenland, finding that the frequency of major volcanic eruptions was highest in the 13th century, over the last two millennia. Four out of five of these eruptions likely originated from volcanoes within the low latitudes (between 20°N and 20°S). I believe this paper is well-suited for publication in the journal Atmosphere, although I have several comments that need to be addressed before it can be accepted

 

General Comments:

·       The manuscript includes only one record from Greenland ice cores. Given that line 215-216 hints at the existence of additional Greenland records, could these be included?

·       The impact of the high frequency of major volcanic eruptions on climate needs more detailed discussion (section 3.4). Currently, this section is poorly discussed.

·       The authors should clearly outline the contribution of this manuscript in both the introduction and the conclusion. As it stands, the significance and contribution of this study is not readily apparent. Are there any prior studies that focus on the number and magnitudes of these major volcanic eruptions over the last two millennia? What new insights does this study offer?

·       Please include a map displaying the locations of the ice cores.

·       I have noted a few minor comments in the attached PDF file.

Comments for author File: Comments.pdf

Author Response

Response to Reviews for Five large 13th century CE volcanic eruptions recorded in Antarctic ice cores submitted to Atmosphere by Cole-Dai et al. submitted to Atmosphere

                We thank the reviewers for their positive comments and constructive criticism. Here we detail our response to all comments and questions. Reviewer comments and questions are in italics and responses are in boldface.

 

Reviewer 4

General Comments:

• The manuscript includes only one record from Greenland ice cores. Given that line 215-216 hints at the existence of additional Greenland records, could these be included?

Response: In our original manuscript, we only used data from ice cores we worked on directly, with only one Greenland core (SM07C4). Wherever results from other Greenland cores were mentioned, we provided specific literature references.

Another reviewer suggested that we include comparable data from another Greenland core (NEEM S1) used by Sigl et al. (2013). We have followed this suggestion and now include NEEM data in Tables 1 and 3.

• The impact of the high frequency of major volcanic eruptions on climate needs more detailed discussion (section 3.4). Currently, this section is poorly discussed.

The topic of volcanic impact on climate is an important one and has been the subject of extensive research. We feel that that topic is not a focus of this work; rather, the focus here is on finding the evidence of those 13^th century eruptions. So, the discussion on this topic is limited. If the reviewer could suggest specific issues discuss regarding the climate impact, we would be glad to try.

• The authors should clearly outline the contribution of this manuscript in both the introduction and the conclusion. As it stands, the significance and contribution of this study is not readily apparent. Are there any prior studies that focus on the number and magnitudes of these major volcanic eruptions over the last two millennia? What new insights does this study offer?

In our original manuscript, we cite papers (Cole-Dai et al., 2000; 2021; Delmas et al., 1992; Ferris et al., 2011; Langway et al., 1995; Sigl et al., 2013; 2014; 2022; etc.) that have addressed this topic – number and magnitude of major volcanic eruptions from ice core records and potential climate impact.

We state in the original manuscript that “Despite their highly visible appearance in many bipolar ice core volcanic records, the signals of these 13th century eruptions have not been systematically examined.” This work offers a systematic examination of the 13^th century eruptions in the context of number and magnitude of eruptions in ice core records and their potential climate impact.

Our main conclusions were stated in Abstract (“Multiple Antarctica ice core records of past volcanic eruptions reveal that the number (5) of major eruptions (volcanic sulfate deposition flux greater than 10 kg km−2) is the highest in the 13th century in the last two millennia. Signals of four of the five eruptions are dated to the second half of the century, indicating consecutive major eruptions capable of causing sustained climate impact via known feedback processes.”), and in Conclusions (“Signals of five major (Large and Very Large) volcanic eruptions during the 13th century C.E. were detected and quantified in several well-dated Antarctica ice cores including a recent (2014) South Pole core. Four of the five eruptions occurred in the second half of the 13th century. Such centennial frequency of major climate-impacting eruptions is un-matched in the last two millennia and suggests strongest climate impact by explosive volcanism in that period.”).

• Please include a map displaying the locations of the ice cores.

Another reviewer suggested to indicate the locations of the ice cores in Antarctica and Greenland. In the revised manuscript, we now include the longitudes and latitudes of all ice cores used in this work.

• I have noted a few minor comments in the attached PDF file.

the readers may not know what is the major volcanic eruptions as you explain it later. please explain it already in the introduction.

Response: We think the meaning of “major” in major volcanic eruptions becomes clear as we present data on the magnitude of the ice core volcanic signals and how that is related to the magnitude of eruption aerosol mass. We do not feel it necessary to define “major” in Introduction.

(Table 1) please also put the latitude and longitude here for the locations of ice cores;. please also put the references for the published records and highlight the new record (it is more clear for readers)

We now include the longitudes and latitudes of all ice cores used in this work in Table 1.

References are provided in the text, when the results of previously published study on some of the cores are discussed (text related to Table 3). We do not think it necessary to provide the references in Table 1.

(Figure 1) should also put the time-scale for in the figure for better visualization

Figure 1 covers the 13^th century (~100 years). This is a relatively short time span (and depth interval) for ice cores. In such a short interval, time progresses almost linearly with depth. We do not think it is important to add a time axis to the graphs. Also, the five dated volcanic signals help to indicate time progression.

(1259) but in table2, it shows 1258?

The date here has been changed to 1258 to be consistent with Table 2.

We note that the signal of a large eruption usually spans a period of several years (Table 2). Use of a single year for the eruption signal could cause confusion, as the year may be the time the signal starts or the time of maximum deposition rate (concentration or flux). To compound the potential confusion, sometimes the date may refer to the year of eruption, which usually precedes the signal years by one or two years.

how do you calculate the duration?

The procedure to determine the duration of a volcanic signal in ice core has been described previously (e.g., Cole-Dai et al., 2000). Basically, the duration is the depth interval (converted to time using a timescale) in which volcanic sulfur/sulfate/sulfuric acid fallout is present or detected in measurement.

I am not quite understand here. why the low snow accumulation could lead to the longer duration time. also, it would be necessary to put accumulation information in Table1 for readers to better follow the explanation.

The explanation is provided in the text (“the longer durations were understood to result from post-deposition redistribution of volcanic deposit in a location (on East Antarctica Plateau) of extremely low snow accumulation rates”). The original description of the explanation is in the cited paper (Coe-Dai et al., 2000). Basically, fresh snow on the ground is blown around by wind while on the snow surface. The resuspended snow containing volcanic fallout will redeposit with fresher snow. This spread the volcanic signal from the original layers to adjacent layers leading to long deposition durations. This phenomenon (snow redistribution) is particularly significant in locations that receive very little snow year-round.

(Table 3) please also put the standard deviation for the averaged values of Antarctica records.

We now include standard deviations in Table 3 for volcanic flux in Antarctica cores.

in table 3, A13-2 refers to 1258, please be consistent.

As we explained earlier, the date such as this may refer to different times. In this sentence, the date (1257) is the year of the eruption, not the year when the eruption signal appears in ice cores. So, it is different, but not inconsistent, as they refer to different dates.

I think this part could be shorten. just say that the signal found in bipolar ice cores suggests the volcanic eruption is most likely located in the tropics. if the signal is only found in ice cores at one pole, it suggests that the volcanic eruption most likely happens at the mid or high latitudes at its hemisphere.

Another reviewer also pointed out a problem with these two paragraphs. We have revised them and they now reads: “Large eruptions by volcanoes in the Southern Hemisphere and in the low latitudes (the tropics) of both hemispheres (between 20°N and 20°S) are likely to leave sulfate/sulfur/sulfuric acid deposit in Antarctic snow and may be detected in Antarctica ice cores [3]. Volcanic signals in Greenland cores are most likely from volcanoes in the Northern Hemisphere and the tropics. Therefore, when signals of an eruption are found in both Antarctica and Greenland ice cores, so-called bipolar signals, the volcano responsible for the signals is likely located in the tropics [16]. The only exception is global distribution of volcanic aerosols of extraordinarily explosive eruptions by volcanoes in the high or mid-latitudes of Northern Hemisphere [16]. Based on this criterion, all five 13th century eruptions (A13-1 to A13-5) were most likely by volcanoes in Southern Hemisphere and/or the tropics.”

then why here only show one Greenland record, if there are other records available

We now use data from two Greenland cores, SM07 C4 and NEEM S1, per suggestion by another reviewer. There are a couple of reasons why we do not use more available data of Greenland ice cores (there are also data from additional Antarctica ice cores published by other researchers). One is that we try to use the data we have obtained from our own ice cores and measurements. In the case of Antarctica, we had a sufficiently large number of cores. Another is that, for Greenland, some of the data are inconsistent among cores (for example, G13-4 appears in SM07 C4, but not in NEEM S1, Table 3).

(Potential climate impact) I think this part needs more discussion

Here is our response to a previous comment by this reviewer: “The topic of volcanic impact on climate is an important one and has been the subject of intensive research. We feel that that topic is not a focus of this work; rather, the focus here is on finding the evidence of those 13^th century eruptions. So, the discussion on this topic is limited. If the reviewer could suggest specific issues to discuss regarding the climate impact, we would be glad to try.”