| 1. |
- Büntgen, Ulf, et al.
(författare)
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Global wood anatomical perspective on the onset of the Late Antique Little Ice Age (LALIA) in the mid-6th century CE
- 2022
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Ingår i: Science Bulletin. - : Elsevier BV. - 2095-9273. ; 67:22, s. 2336-2344
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Tidskriftsartikel (refereegranskat)abstract
- Linked to major volcanic eruptions around 536 and 540 CE, the onset of the Late Antique Little Ice Age has been described as the coldest period of the past two millennia. The exact timing and spatial extent of this exceptional cold phase are, however, still under debate because of the limited resolution and geographical distribution of the available proxy archives. Here, we use 106 wood anatomical thin sections from 23 forest sites and 20 tree species in both hemispheres to search for cell-level fingerprints of ephemeral summer cooling between 530 and 550 CE. After cross-dating and double-staining, we identified 89 Blue Rings (lack of cell wall lignification), nine Frost Rings (cell deformation and collapse), and 93 Light Rings (reduced cell wall thickening) in the Northern Hemisphere. Our network reveals evidence for the strongest temperature depression between mid-July and early-August 536 CE across North America and Eurasia, whereas more localised cold spells occurred in the summers of 532, 540–43, and 548 CE. The lack of anatomical signatures in the austral trees suggests limited incursion of stratospheric volcanic aerosol into the Southern Hemisphere extra-tropics, that any forcing was mitigated by atmosphere-ocean dynamical responses and/or concentrated outside the growing season, or a combination of factors. Our findings demonstrate the advantage of wood anatomical investigations over traditional dendrochronological measurements, provide a benchmark for Earth system models, support cross-disciplinary studies into the entanglements of climate and history, and question the relevance of global climate averages.
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| 2. |
- Buntgen, U., et al.
(författare)
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Recognising bias in Common Era temperature reconstructions
- 2022
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Ingår i: Dendrochronologia. - : Elsevier BV. - 1125-7865 .- 1612-0051. ; 74
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Tidskriftsartikel (refereegranskat)abstract
- A steep decline in the quality and quantity of available climate proxy records before medieval times challenges any comparison of reconstructed temperature and hydroclimate trends and extremes between the first and second half of the Common Era. Understanding of the physical causes, ecological responses and societal consequences of past climatic changes, however, demands highly-resolved, spatially-explicit, seasonally-defined and absolutely-dated archives over the entire period in question. Continuous efforts to improve existing proxy records and reconstruction methods and to develop new ones, as well as clear communication of all uncertainties (within and beyond academia) must be central tasks for the paleoclimate community.
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| 3. |
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| 4. |
- Charpentier Ljungqvist, Fredrik, et al.
(författare)
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Assessing non-linearity in European temperature-sensitive tree-ring data
- 2020
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Ingår i: Dendrochronologia. - : Elsevier BV. - 1125-7865 .- 1612-0051. ; 59
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Tidskriftsartikel (refereegranskat)abstract
- © 2019 The Authors We test the application of parametric, non-parametric, and semi-parametric calibration models for reconstructing summer (June–August) temperature from a set of tree-ring width and density data on the same dendro samples from 40 sites across Europe. By comparing the performance of the three calibration models on öpairs” of tree-ring width (TRW) and maximum density (MXD) or maximum blue intensity (MXBI), we test whether a non-linear temperature response is more prevalent in TRW or MXD (MXBI) data, and whether it is associated with the temperature sensitivity and/or autocorrelation structure of the dendro parameters. We note that MXD (MXBI) data have a significantly stronger temperature response than TRW data as well as a lower autocorrelation that is more similar to that of the instrumental temperature data, whereas TRW exhibits a öredder” variability continuum. This study shows that the use of non-parametric calibration models is more suitable for TRW data, while parametric calibration is sufficient for both MXD and MXBI data – that is, we show that TRW is by far the more non-linear proxy.
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| 5. |
- Charpentier Ljungqvist, Fredrik, et al.
(författare)
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Climate and society in European history
- 2021
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Ingår i: Wiley Interdisciplinary Reviews. - : Wiley. - 1757-7780 .- 1757-7799. ; 12:2
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Forskningsöversikt (refereegranskat)abstract
- This article evaluates 165 studies from various disciplines, published between 2000 and 2019, which in different ways link past climate variability and change to human history in medieval and early modern Europe (here, c. 700-1815 CE). Within this review, we focus on the identification and interpretation of causal links between changes in climate and in human societies. A revised climate-society impact order model of historical climate-society interactions is presented and applied to structure the findings of the past 20 years' scholarship. Despite considerable progress in research about past climate-society relations, partly expedited by new palaeoclimate data, we identify limitations to knowledge, including geographical biases, a disproportional attention to extremely cold periods, and a focus on crises. Furthermore, recent scholarship shows that the limitations with particular disciplinary approaches can be successfully overcome through interdisciplinary collaborations. We conclude the article by proposing recommendations for future directions of research in the climatic change-human history nexus.
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| 6. |
- Charpentier Ljungqvist, Fredrik, 1982-, et al.
(författare)
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Climatic signatures in early modern European grain harvest yields
- 2023
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Ingår i: Climate of the Past. - 1814-9324 .- 1814-9332. ; 19:12, s. 2463-2491
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Tidskriftsartikel (refereegranskat)abstract
- The association between climate variability and grain harvest yields has been an important component of food security and economy in European history. Yet, inter-regional comparisons of climate–yield relationships have been hampered by locally varying data types and the use of different statistical methods. Using a coherent statistical framework, considering the effects of diverse serial correlations on statistical significance, we assess the temperature and hydroclimate (precipitation and drought) signatures in grain harvest yields across varying environmental settings of early modern (ca. 1500–1800) Europe. An unprecedentedly large network of yield records from northern (Sweden), central (Switzerland), and southern (Spain) Europe are compared with a diverse set of seasonally and annually resolved palaeoclimate reconstructions. Considering the effects of different crop types and time series frequencies, we find within regions consistent climate–harvest yield associations characterized by a significant summer soil moisture signal in Sweden, winter temperature and precipitation signals in Switzerland, and spring and annual mean temperature signals in Spain. The regional-scale climate–harvest associations are weaker than the recently revealed climate signals in early modern grain prices but similar in strength to modern climate–harvest relationships at comparable spatial scales. This is a noteworthy finding considering the uncertainties inherent in both historical harvest and palaeoclimate data.
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| 7. |
- Charpentier Ljungqvist, Fredrik, 1982-
(författare)
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Corona : ett historiskt perspektiv på vår tids pandemi
- 2020
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Bok (populärvet., debatt m.m.)abstract
- Under historien har allvarliga epidemier och pandemier varit ett återkommande gissel för mänskligheten. Men när ett nytt coronavirus fick spridning i hela världen i början av 2020 hade det gått över femtio år sedan den senaste all-varliga pandemin, och reaktionen blev närmast panikartad. Katastrofscenarier baserade på fragmentariska data fick många att befara att tiotals miljoner människor skulle dö av viruset. Samhällen stängdes ned, undantagslagar som annars är reserverade för krig togs i bruk. Men viruset fortsatte att sprida sig som en löpeld.Snart blev det allt tydligare att covid-19 är en betydligt mindre dödlig sjukdom än vad många hade befarat, och att viruset redan var så spritt att det blivit omöjligt att stoppa. I oktober 2020 uppskattade Världshälsoorganisationen att 800 miljoner människor i världen blivit smittade, tjugo gånger fler än antalet bekräftade fall, samtidigt som bara två av tusen smittade verkar avlida i sjukdomen globalt. I ljuset av hur tidigare pandemier upphört kommer spridningen av coronaviruset att ebba ut först efter två till tre år, när runt en tredjedel av världens befolkning blivit smittad och immun.Historikern och klimatforskaren Fredrik Charpentier Ljungqvist sätter här in coronapandemin i ett historiskt perspektiv och jämför den med tidigare pandemier, från antiken till modern tid. En utförlig genomgång görs av pandemins förlopp, den vetenskapliga oenigheten om hur farligt viruset är, diskussionen om flockimmunitet och vaccin samt de olika åtgärderna för att hejda smittspridningen.
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| 8. |
- Charpentier Ljungqvist, Fredrik, 1982-
(författare)
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Digerdöden – inte så dödlig som det sägs
- 2022
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Ingår i: Svenska dagbladet. - 1101-2412. ; , s. 50-51
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Pesten påstås ofta ha tagit livet av halva Europas befolkning. Men ny forskning som har spårat förändringar i kulturlandskapet genom att studera borrkärnor med pollen från sjöar och våtmarker ger en helt annan bild.
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