A global compilation of diatom silica oxygen isotope records from lake sediment – trends, and implications for climate reconstruction
Abstract. Oxygen isotopes in biogenic silica (δ18OBSi) from lake sediments allow for quantitative reconstruction of past hydroclimate and proxy–model comparison in terrestrial environments. The signals of individual records have been attributed to different factors, such as air temperature (Tair), atmospheric circulation patterns, hydrological changes and lake evaporation. While every lake will have its own set of drivers of d18O, here we explore the extent to which regional or even global signals emerge from a series of palaeoenvironmental records. For this purpose, we have identified and compiled 71 down–core records published to date and complemented these datasets with additional lake basin parameters (e.g. lake water residence time and catchment size) to best characterize the signal properties. Records feature widely different temporal coverage and resolution ranging from decadal–scale records covering the last 150 years to records with multi–millennial scale resolution spanning glacial–interglacial cycles. Best coverage in number of records (N = 37) and datapoints (N = 2112) is available for northern hemispheric (NH) extra–tropic regions throughout the Holocene (corresponding to Marine Isotope Stage 1; MIS 1). To address the different variabilities and temporal offsets, records were brought to a common temporal resolution by binning and subsequently filtered for hydrologically open lakes with lake water residence times < 100 yrs. For mid– to high–latitude (> 45° N) lakes, we find common δ18OBSi patterns during both the Holocene and the Common Era and maxima and minima corresponding to known climate episodes such as the Holocene Thermal Maximum (HTM), Neoglacial Cooling, Medieval Climate Anomaly (MCA) and the Little Ice Age (LIA). These patterns are in line with long–term Tair changes supported by previously published climate reconstructions from other archives as well as Holocene summer insolation changes. In conclusion, oxygen isotope records from NH extratopic lake sediments feature a common climate signal at centennial (for CE) and millennial (for Holocene) time scales despite stemming from different lakes in different geographic locations and constitute a valuable proxy for past climate reconstructions.
Philip Meister et al.
Status: open (extended)
- RC1: 'Comment on cp-2022-96', Anonymous Referee #1, 12 Mar 2023 reply
- RC2: 'Comment on cp-2022-96', Witold Bagniewski, 23 May 2023 reply
Philip Meister et al.
Philip Meister et al.
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Review of manuscript submitted to Climate of the Past by Philip Meister and colleagues: A global compilation of diatom silica oxygen isotope records from lake sediment – trends, and implications for climate reconstruction
The temperature dependence of oxygen isotope fractionation makes them a widely applied (paleo)climatology tool. Oxygen isotope ratios (expressed as δ18O) in diatom biogenic silica represent a valuable archive, but their interpretation and model-archive comparison can be complicated, particularly in lakes. Here, Meister and colleagues compile published lake diatom δ18O records to address the extent to which a common signal can be observed. They find 54 lakes in total, from 71 publications, that have available data. Compiling, binning and filtering the data, they observe commonalities in lake diatom δ18O records over the common era and a consistent, decreasing trend over the Holocene, which is broadly consistent with existing palaeoclimate (particularly temperature) records and understanding of the δ18O proxy.
In general, this is a useful compilation that seems comprehensive and thorough and achieved in a sensible way, and is being made available via an appropriate repository (Pangaea.de). The introduction largely sets out the state-of-the-art (and Fig. 1 is particularly useful, I feel). The compilation and standardisation seems like a large effort the authors should be commended for. The topic of the manuscript falls within the scope of Climate of the Past, and the conclusions are largely supported by the data. The manuscript is generally well written (although with scope for tightening the language and a few typological/grammatical errors that could be caught with a through proofread) and the figures are clear. Overall, I think this is a manuscript and a data compilation that deserves to be published, and will hopefully stimulate more work in the field (especially given their Fig. A1B which shows declining production of lake diatom δ18O data).
My major criticism is that the discussion of the compilation is rather descriptive and qualitative. There is very little in the way of statistical analysis, which might be useful in parts of the discussion related to the magnitude of δ18O trends, regional differences in the timing of minima/maxima, and the presence or not of periods of stasis. To what extent can they be demonstrated to reflect ‘real’ underlying phenomena, vs. just being an artefact of low and noisy data availability? The comparison of the new NH compiled record to existing proxy data and insolation curves is also rather qualitative. Beyond this, the discussion focuses almost entirely on sites from >45 deg N, which is motivated only on L249 (unless I miss it elsewhere). Given the general paucity of data, it seems a shame not to exploit the compilation as much as possible. While other regions might be too data scarce to do the binning/filtering steps in e.g. Figs 5 and 6, do they contain useful information on the spatial pattens which could complement the discussion in e.g. section 4.2 and Fig. 7? Fig 5G and 6G each contain only two sites that meet the quality control criteria – is it really the case that there are not even two sites from e.g. South America or tropical Africa sites that are useful?
Fig 1/main text L105: Could diagenesis also be included in this figure? And/or more detail given in the main text? Presumably older samples are more susceptible to diagenetic overprinting? How can we be sure this is not a major driver of the observations?
L210: I would suggest a brief summary of the hydroLakes database is warranted, since L219 refers to a ‘geostatistical approach’, implying that values are not specific to a given lake, and many readers (including myself) would not be familiar with it. Would it not make sense to preferentially use the parameters as given in the original publications, supplementing them with hydroLakes only when necessary?
Fig 4: excludes 33 (of the 49 extant) lakes because the HydroLakes dataset doesn’t include their catchment area. I would suggest this is something that is relatively easy to define in a consistent way given a digital elevation model, with readily available topographic analysis tools, e.g. the ‘TopoToolbox’ for Matlab, or similar capabilities within ArcGIS or qGIS.
L233 “presumably” instead of “supposedly”?
L261: Does this approach of subtracting the mean of a record only work when every record covers the full timespan under consideration? Otherwise a record that covers only e.g. the mid to late Holocene would bias that period (because the mean subtracted from that record would be smaller than a record with an identical gradient/trend but longer coverage).
L270: It’s a bit unclear how many sites/records are actually used. L271 states 64 sites; L283 is states both 54 and 56 (i.e. 7 + 49); Table A1 has 53 lakes. Can this be clarified?
L275: Table A2 is mentioned before Table A1. Is A2 complete? There doesn’t seem to be enough lakes here to match the numbers given in the main text. Also, it might be helpful to include the number #X in both tables A1 and A2 somehow to allow cross referencing.
L285: “extant”? (rather than ‘still existing’)
L310: A reference to Downing and Duarte (2009) (their Fig 5) or similar might be useful here.
L351: ‘may correspond to more than one record’
L379: There can be some buffering even when t_res is less than sampling frequency, meaning the "full" amplitude is not necessarily displayed See e.g. Richter and Turekian (1993).
Fig 5: Presumably the axis labels shouldn’t read ‘kyr’ but ‘yr’?
L435: it seems like more could be done here with the records from other regions of the world.
L465: This seems like repetition/overlap with paragraphs starting L486 below. Is a ref here to fig 7 appropriate?
L473-5: An example of where more statistical rigor might help: how robust is this particular interpretations relative to a simpler view of consistently decreasing δ18O? (a straight line could be drawn through the ±1sd shading).
L489: ‘show a tendency’ (also L503)
Fig 7: Even if not discussed (see above) could the minima/maxima of records outside the northern hemisphere high latitudes be displayed here?
L505: Again, without more statistical rigor, from e.g. Fig. 6E/G I would be cautious about over interpreting these differences.
L520: presumably also because most biogenic production is in summer (particularly relevant for short residence time systems).
Fig 8 caption: subscripts and superscripts not displayed correctly.
L558: Fig. 8D is labelled June, here it says July.
L564: How far behind?
Section 4.4: given some of the discussion previously I would have expected some stronger/more explicit recommendations in this section, for how diatom δ18O can become a more useful proxy (beyond the rather generic ‘further research is needed…’).
L595: ‘would be consistent with’ or similar?
Downing, J.A., Duarte, C.M., 2009. Abundance and size distribution of lakes, ponds and impoundments, in: Likens, G.E. (Ed.), Encyclopedia of Inland Waters. Elsevier, Oxford, UK, pp. 469-478.
Richter, F.M., Turekian, K.K., 1993. Simple models for the geochemical response of the ocean to climatic and tectonic forcing. Earth and Planetary Science Letters 119, 121-131, doi: