Fredrik Charpentier Ljungqvist

Fredrik Charpentier Ljungqvist


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Arbetar vid Historiska institutionen
Telefon 08-16 35 11
Besöksadress Universitetsvägen 10 D, plan 9
Rum D 860
Postadress Historia 106 91 Stockholm

Om mig

Fredrik Charpentier Ljungqvist är docent i både historia och i naturgeografi och knuten till Historiska institutionen och Bolincentret för klimatforskning, bägge vid Stockholms universitet, samt är Pro Futura Scientia Fellow vid Swedish Collegium for Advanced Study i Uppsala. Han forskar både inom historia och paleoklimatologi (klimathistoria) och har publicerat många vetenskapliga och populärvetenskapliga artiklar inom båda ämnena. Charpentier Ljungqvist är även författare till de populärvetenskapliga böckerna Klimatet och människan under 12 000 år (Dialogos 2017) och Den långa medeltiden (Dialogos 2015) och Global nedkylning (Norstedts 2009). Han är medlem av den europeiska arbetsgruppen i forskningsprogrammet Past Global Changes (PAGES) 2k, ledamot av den vetenskapliga styrgruppen för forskningsprogrammet Integrated History and Future of People on Earth (IHOPE), samt sitter i redaktionsrådet för Historisk tidskrift. I september 2016 vann han Cliopriset för att ”förmedla färska vetenskapliga insikter till en bred publik”. Han verkade som gästforskare vid Department of Geography vid University of Cambridge, Storbritannien, oktober 2017 till april 2018 samt oktober 2018 till april 2019 och var utsedd till gästprofessor i miljövetenskap vid Lanzhou University i Kina för perioden juli 2017 till juni 2019.


Bibliometriska data:
Senast uppdaterat den 13 februari 2021.

ISI Web of Knowledge [Google Scholar]

Antal indexerade publikationer: 68 [86]
Totalt antal citeringar: 2494 [3733]
Genomsnittligt antal citeringar per publikation: 37,22 [43.40]
H-index: 23 [26]

Högt citerade i fältet (ISI): 8


I urval från Stockholms universitets publikationsdatabas
  • 2020. Fredrik Charpentier Ljungqvist (et al.). Dendrochronologia 59

    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 pairs 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 redder 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.

  • 2019. Fredrik Charpentier Ljungqvist (et al.). Environmental Research Letters 14 (8)

    The long-term relationship between temperature and hydroclimate has remained uncertain due to the short length of instrumental measurements and inconsistent results from climate model simulations. This lack of understanding is particularly critical with regard to projected drought and flood risks. Here we assess warm-season co-variability patterns between temperature and hydroclimate over Europe back to 850 CE using instrumental measurements, tree-ring based reconstructions, and climate model simulations. We find that the temperature-hydroclimate relationship in both the instrumental and reconstructed data turns more positive at lower frequencies, but less so in model simulations, with a dipole emerging between positive (warm and wet) and negative (warm and dry) associations in northern and southern Europe, respectively. Compared to instrumental data, models reveal a more negative co-variability across all timescales, while reconstructions exhibit a more positive co-variability. Despite the observed differences in the temperature-hydroclimate co-variability patterns in instrumental, reconstructed and model simulated data, we find that all data types share relatively similar phase-relationships between temperature and hydroclimate, indicating the common influence of external forcing. The co-variability between temperature and soil moisture in the model simulations is overestimated, implying a possible overestimation of temperature-driven future drought risks.

  • 2019. Fredrik Charpentier Ljungqvist (et al.). Journal of Climate 32 (9), 2441-2482

    Systematic comparisons of proxy-based reconstructions and climate model simulations of past millennium temperature variability offer insights into climate sensitivity and feedback mechanisms, besides allowing model evaluation independently from the period covered by instrumental data. Such simulation-reconstruction comparisons can help to distinguish more skillful models from less skillful ones, which may subsequently help to develop more reliable future projections. This study evaluates the low-frequency simulation-reconstruction agreement within the past millennium through assessing the amplitude of temperature change between the Medieval Climate Anomaly (here, 950-1250 CE) and the Little Ice Age (here, 1450-1850 CE) in PMIP3 model simulations compared to proxy-based local and continental-scale reconstructions. The simulations consistently show a smaller temperature change than the reconstructions for most regions in the Northern Hemisphere, but not in the Southern Hemisphere, as well as a partly different spatial pattern. A cost function analysis assesses how well the various simulations agree with reconstructions. Disregarding spatial correlation, significant differences are seen in the agreement with the local temperature reconstructions between groups of models, but insignificant differences are noted when compared to continental-scale reconstructions. This result points toward a limited possibility to rank models by means of their low-frequency temperature variability alone. The systematically lower amplitude of simulated versus reconstructed temperature change indicates either too-small simulated internal variability or that the analyzed models lack some critical forcing or have missing or too-weak feedback mechanisms. We hypothesize that too-cold initial ocean conditions in the models-in combination with too-weak internal variability and slow feedbacks over longer time scales-could account for much of the simulation-reconstruction disagreement.

  • 2018. Fredrik Charpentier Ljungqvist (et al.). Journal of Archaeological Science 98, 81-92

    Variations in building activity reflect demographic, economic and social change during history. Tens of thousands of wooden constructions in Europe have been dendrochronologically dated in recent decades. We use the annually precise evidence from a unique dataset of 49 640 tree felling dates of historical constructions to reconstruct temporal changes in building activity between 1250 and 1699 CE across a large part of western and central Europe largely corresponding to the former Holy Roman Empire of the German Nation. Comparison with annual records of 9772 plague outbreaks shows that construction activity was significantly negatively correlated to the number of plague outbreaks, with the greatest decrease in construction following the larger outbreaks by three to four years after the start of the epidemics. Preceding the Black Death (1346-1353 CE) by five decades and the Great Famine (1315-1322 CE) by two decades, a significant decline in construction activity at c. 1300 CE is indicative of a societal crisis, associated with population stagnation or decline. Another dramatic decline in building activity coincides with the Thirty Years' War (1618-1648 CE) and confirms the devastating nature of this conflict. While construction activity was significantly lower during periods of high grain prices, no statistically robust relationship between the number of felling dates and past temperature or hydroclimate variations is found. This study demonstrates the value of dendrochronological felling dates as an indicator for times of crisis and prosperity during periods when documentary evidence is limited.

  • 2018. Fredrik Charpentier Ljungqvist, Andrea Seim. Journal of Archaeological Science 21, 849-861

    The Late Viking Age Swedish runestones are commonly acknowledged as early Christian monuments. Using geostatistical techniques and descriptive statistics, we systematically investigate the regional-to-local spatiotemporal patterns of 1302 ornamentally dated Swedish runestones regarding the timing and speed of the Christianisation process. After quantitative geostatistical analyses of the age distribution patterns of Swedish runestones, we evaluate whether the observed patterns correspond to the pace and pattern of Christianisation, as represented by the presence of mission bishoprics, early church sites, late pagan grave sites and royal estates. We identify seven distinct age groups of runestones and statistically significant regional-to-local spatiotemporal differences in the age and age spread of runestones. The oldest runestones, with the smallest age spread, are found in south-western medieval Sweden, and the youngest, as well as the largest age spread, in the north-east, respectively. We find that runestones are significantly older close to early ecclesiastical sites, regardless of the analytical level, and significantly younger near to late pagan graves. The results obtained are inconclusive as to whether runestones are older near royal estates. Our results support that the spatiotemporal patterns of runestone sites mirror the timing of the Christianisation process and that geostatistical approaches to larger archaeological or historical data sets can add new dimensions to the understanding of the spatial dimensions of past societal changes.

  • 2017. Fredrik Charpentier Ljungqvist. Issues and Concepts in Historical Ecology, 41-83
  • 2017. Fredrik Charpentier Ljungqvist.

    I boken presenteras för första gången på svenska resultaten från den senaste klimathistoriska forskningen för en bred publik. I en välblandad mix av historia och klimatvetenskap får läsaren följa med på en medryckande resa genom världshistorien då kraftiga och plötsliga klimatförändringar emellanåt dramatiskt förändrat livsvillkoren för miljoner människor.

    För 6 000 år sedan var till exempel Sahara en frodig savann i stället för världens största öken, samtidigt som klimatet var varmt nog i Sverige för sköldpaddor och vilda vindruvor.  Senare under historien har stora variationer i monsunregnen i Asien gett upphov till antingen välstånd eller hungersnöd för miljontals människor.

    För tusen år sedan kollapsade indianska civilisationer av torka, samtidigt som ett varmare klimat tillät nordbor att kolonisera södra Grönland. Den så kallade lilla istiden, som kulminerade på 1600-talet, orsakade försörjningskriser i Europa och Kina och på många andra håll i världen.

    Författaren ger oss åtskilliga spännande och lärorika exempel på hur klimatförändringar under historien påverkat utvecklingen i olika delar av världen och hur människor hanterat eller inte hanterat konsekvenserna av klimatförändringar. Det är insikter som är mycket relevanta i vår tid.

  • 2017. Bo Christiansen, Fredrik Charpentier Ljungqvist. Reviews of geophysics 55 (1), 40-96

    Knowledge of the temperature variability during the last one to two millennia is important for providing a perspective to present-day climate excursions, for assessing the sensitivity of the climate to different forcings, and for providing a test bed for climate models. Since systematic instrumental temperature records only extend back to the nineteenth century, such knowledge mainly relies on climate-sensitive proxy data. Here we critically assess some of the many challenges related to large-scale multiproxy temperature reconstructions. We begin with a review of available large-scale temperature reconstructions, focusing on the differences in low-frequency variability and the response to natural forcings such as major volcanic eruptions and changes in total solar irradiance. Then, we discuss different proxy selection strategies, review previously used reconstruction methods, and discuss their ability to reconstruct the amplitude of the low-frequency variability. To shed additional light on the challenges of large-scale reconstructions, we investigate the spatial and temporal correlation structures in the observed temperature field and discuss the implications of these correlation structures regarding the required number and positions of proxies. We demonstrate how the unavoidable uncertainty related to noisy proxies will show up as bias and variance in the reconstruction and that the partition between these forms of errors depends on the reconstruction method. Pseudo-proxy experiments are conducted to further discuss the influence of noise and the requirements regarding the geographical location and number of proxies necessary for reliably reconstructing the low-frequency variability. We conclude with recommendations for future large-scale temperature reconstructions.

  • 2016. Fredrik Charpentier Ljungqvist.

    Denna bok behandlar lagregleringen av den expanderande kungamakten i det högmedeltida Danmark, Norge och Sverige ur ett komparativt perspektiv. Utifrån bevarat lagmaterial undersöks utvecklingen av kungamaktens rättsliga och militära befogenheter och funktioner i relation till tingsmenigheternas och kyrkans förändrade maktställning. Dessa statsrättsliga frågeställningar, som ägnats förhållandevis lite intresse under senare år, blir belysta utifrån den numera omfattande internationella forskningen om den medeltida statsbildningsprocessen i Europa.

    Såväl danskt, norskt som svenskt lagmaterial ger uttryck för en påtaglig ökning av samhälleliga funktioner underställda en allt starkare kungamakt. Likväl framträder samtidigt betydande internordiska skillnader avseende såväl omfattningen av, som formerna för, den kungliga maktutövningen. Den lagreglerade kungamakten var, i de flesta avseenden, starkast och tidigast utvecklad i Norge och svagast och senast utvecklad i Sverige.

    Studien visar att den allt mer centraliserade och institutionaliserade kungliga maktutövningen, som präglades av en ökad ensamrätt till bruket av legitimt våld, kan betraktas som uttryck för en pågående statsbildningsprocess. Lagregleringen av rättslig makt framstår som avsevärt viktigare för denna utveckling än regleringen av militär eller fiskal makt. Ett annat viktigt resultat är att kunglig exekutiv makt först uppträdde efter etableringen av dömande, och i många avseenden även lagstiftande, kunglig makt.

  • 2016. Fredrik Charpentier Ljungqvist (et al.). Nature 532 (7597), 94-98

    Accurate modelling and prediction of the local to continental-scale hydroclimate response to global warming is essential given the strong impact of hydroclimate on ecosystem functioning, crop yields, water resources, and economic security. However, uncertainty in hydroclimate projections remains large, in part due to the short length of instrumental measurements available with which to assess climate models. Here we present a spatial reconstruction of hydroclimate variability over the past twelve centuries across the Northern Hemisphere derived from a network of 196 at least millennium-long proxy records. We use this reconstruction to place recent hydrological changes and future precipitation scenarios in a long-term context of spatially resolved and temporally persistent hydroclimate patterns. We find a larger percentage of land area with relatively wetter conditions in the ninth to eleventh and the twentieth centuries, whereas drier conditions are more widespread between the twelfth and nineteenth centuries. Our reconstruction reveals that prominent seesaw patterns of alternating moisture regimes observed in instrumental data across the Mediterranean, western USA, and China have operated consistently over the past twelve centuries. Using an updated compilation of 128 temperature proxy records, we assess the relationship between the reconstructed centennial-scale Northern Hemisphere hydroclimate and temperature variability. Even though dry and wet conditions occurred over extensive areas under both warm and cold climate regimes, a statistically significant co-variability of hydroclimate and temperature is evident for particular regions. We compare the reconstructed hydroclimate anomalies with coupled atmosphere-ocean general circulation model simulations and find reasonable agreement during pre-industrial times. However, the intensification of the twentieth-century-mean hydroclimate anomalies in the simulations, as compared to previous centuries, is not supported by our new multi-proxy reconstruction. This finding suggests that much work remains before we can model hydroclimate variability accurately, and highlights the importance of using palaeoclimate data to place recent and predicted hydroclimate changes in a millennium-long context.

  • 2015. Fredrik Charpentier Ljungqvist.

    Medeltidshistorikern Fredrik Charpentier Ljungqvist bjuder på en lättläst exposé över den politiska, ekonomiska, sociala och kulturella utvecklingen i Norden under tusen år med utgångspunkt i de senaste rönen från arkeologisk och historisk forskning. Den långa medeltiden är en introduktion till Nordens historia från folkvandringstiden på 500-talet fram till reformationen på 1500-talet. Till skillnad från tidigare översiktsverk behandlas här hela Norden, och inte bara ett enskilt nordiskt land, och den traditionella uppdelningen mellan medeltid och forntid överges.

    Ett av kapitlen skildrar den politiska utvecklingen, men i övrigt står de sociala förhållandena i centrum i denna översikt. Hur bodde man och vad åt man? Vilka möjligheter fanns det att resa och hur utvecklades skeppsbyggnadskonsten? När skedde klimatförändringar och hur påverkade de människor? Vilka redskap användes i jordbruket, för hantverk och för att bygga hus och skepp? I vilken grad levde människor av självförsörjning och hur utvecklad var handeln? Hur såg lag och rätt ut?

    I boken behandlas allt från framväxten av nordiska kungariken och städer till jordbrukets och konsthantverkets utveckling och människors hälsa under forna tider. Vi får bekanta oss med livet för såväl kungar som trälar och följa med genom sociala omvälvningar som kristnandet, digerdöden och ståndssamhällets framväxt. Geografiskt rör vi oss från den karga nordnorska kusten i norr till den bördiga danska myllan i söder, med avstickare till Island och Grönland och med vikingafärder i öster- och västerled.

Visa alla publikationer av Fredrik Charpentier Ljungqvist vid Stockholms universitet

Senast uppdaterad: 10 mars 2021

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