| 1. |
- Esper, Jan, et al.
(författare)
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Environmental drivers of historical grain price variations in Europe
- 2017
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Ingår i: Climate Research (CR). - : Inter-Research Science Center. - 0936-577X .- 1616-1572. ; 72:1, s. 39-52
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Tidskriftsartikel (refereegranskat)abstract
- Grain price (GP) volatility has been a central constituent of European commerce, with fluctuations in barley, rye and wheat prices having been carefully documented over centuries. However, a thorough understanding of the climatic and environmental drivers of long-term GP variations is still lacking. Here, we present a network of historical GP records from 19 cities in central and southern Europe for the 14th to 18th centuries. Spatial variability at interannual to multidecadal scales within this network was compared with reconstructed warm-season temperatures and hydro climatic conditions. We show that European GPs are tightly coupled with historical famines and that food shortages coincide with regional summer drought anomalies. Direct correlations between historical GP and reconstructed drought indices are low, hardly exceeding r = -0.2. Yet if the analysis is focused on extreme events, the climatic controls on high-frequency price variations become obvious: GPs were exceptionally high during dry periods and exceptionally low during wet periods. In addition, we find that GP variations were affected by temperature fluctuations at multidecadal timescales. The influence of summer temperatures is particularly strong over the 1650-1750 period, subsequent to the Thirty Years' War, reaching r = -0.40 at the European scale. This observation is supported by the lack of correlation among regional GP clusters during the period of hostilities and increased inter-regional correlation thereafter. These results demonstrate that the exchange of goods and spatial coherence of GP data in Europe were controlled both by socio-political and environmental factors, with environmental factors being more influential during peacetime.
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| 2. |
- Esper, Jan, et al.
(författare)
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European summer temperature response to annually dated volcanic eruptions over the past nine centuries
- 2013
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Ingår i: Bulletin of Volcanology. - : Springer Science and Business Media LLC. - 0258-8900 .- 1432-0819. ; 75:7, s. 736-
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Tidskriftsartikel (refereegranskat)abstract
- The drop in temperature following large volcanic eruptions has been identified as an important component of natural climate variability. However, due to the limited number of large eruptions that occurred during the period of instrumental observations, the precise amplitude of post-volcanic cooling is not well constrained. Here we present new evidence on summer temperature cooling over Europe in years following volcanic eruptions. We compile and analyze an updated network of tree-ring maximum latewood density chronologies, spanning the past nine centuries, and compare cooling signatures in this network with exceptionally long instrumental station records and state-of-the-art general circulation models. Results indicate post-volcanic June-August cooling is strongest in Northern Europe 2 years after an eruption (-0.52 +/- 0.05 degrees C), whereas in Central Europe the temperature response is smaller and occurs 1 year after an eruption (-0.18 +/- 0.07 degrees C). We validate these estimates by comparison with the shorter instrumental network and evaluate the statistical significance of post-volcanic summer temperature cooling in the context of natural climate variability over the past nine centuries. Finding no significant post-volcanic temperature cooling lasting longer than 2 years, our results question the ability of large eruptions to initiate long-term temperature changes through feedback mechanisms in the climate system. We discuss the implications of these findings with respect to the response seen in general circulation models and emphasize the importance of considering well-documented, annually dated eruptions when assessing the significance of volcanic forcing on continental-scale temperature variations.
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| 3. |
- Esper, Jan, et al.
(författare)
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Testing the hypothesis of post-volcanic missing rings in temperature sensitive dendrochronological data
- 2013
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Ingår i: Dendrochronologia. - : Elsevier BV. - 1125-7865 .- 1612-0051. ; 31:3, s. 216-222
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Tidskriftsartikel (refereegranskat)abstract
- The precise, annual dating control, inherent to dendrochronology, has recently been questioned through a combined analysis of tree-growth and coupled climate models (Mann et al. (2012; hereafter MAN12)) suggesting single tree-rings in temperature limited environments are missing following large volcanic events. We test this hypothesis of missing, post-volcanic rings by using a compilation of maximum late-wood density (MXD) records that are typically used for reconstructing temperature and the detection of volcanic events, together with a unique set of long instrumental station data from Europe reaching back into the early 18th century. We investigate the temporal coherence between tree-ring MXD and observed summer temperatures before and after the most significant, precisely dated, volcanic event of the past 1000 years, the 1815 Tambora eruption widely known as the cause for the 1816 year without a summer. Comparison of existing and newly developed MXD chronologies from cold environments in Northern Scandinavia ((r) over bar North = 0.70, N=3) and the European Alps, including the Pyrenees, ((r) over bar central = 0.46, N=4) reveals significant interseries correlations over the 1722-1976 common period, suggesting coherence among these independently developed timeseries. Comparisons of these data with observed JJA temperatures - from 1722 to 1976, a 94-year pre-Tambora (1722-1815), and a 94-year post-Tambora (1817-1910) period - reveals significant and temporally stable correlations ranging from 0.32 to 0.68. However, if we assume the 1816 ring is missing in the MXD chronologies (i.e., shift the pre-Tambora data by one year), all proxy/instrumental correlations fall apart approaching zero. Results from an additional experiment, where the long instrumental record is replaced by an annually resolved, 500-year, summer temperature reconstruction derived from documentary evidence, corroborates the findings from the first experiment: significant positive correlations with the unmolested chronologies and zero correlation with the perturbed chronologies back to 1500 AD. These elementary analyses indicate that either the tree-ring chronologies are correctly dated, i.e., no is ring missing in the year without a summer, or that both the long instrumental and documentary records contain dating uncertainties. As the latter is unlikely, we conclude the MAN12 hypothesis on post-volcanic missing rings can be rejected based on simple comparisons of tree-ring, instrumental and documentary data over the past 300-500 years from Central and Northern Europe.
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| 4. |
- Holmgren, Karin, 1959-, et al.
(författare)
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Mediterranean Holocene climate and human societies
- 2014
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Ingår i: Past Global Changes Magazine. - : Past Global Changes (PAGES). - 1811-1602 .- 1811-1610 .- 2411-605X .- 2411-9180. ; 22:2, s. 110-110
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 5. |
- Holmgren, Karin, et al.
(författare)
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Mediterranean Holocene climate, environment and human societies
- 2016
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Ingår i: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791 .- 1873-457X. ; 136, s. 1-4
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Tidskriftsartikel (refereegranskat)abstract
- This paper introduces the reader to a special issue of articles that explores links and processes behind societal change, climate change and environmental change in a Holocene perspective in the Mediterranean region. All papers are, by purpose, co-authored by scientists representing different disciplines. The cross-cutting theme has been to reach beyond simple explanations of potential climate-society relationships and advance our understanding on how to improve research methods and theories in the field. The thirteen papers in this issue address these questions in three different ways, by i) conceptual/methodological approaches; ii) review papers; and iii) case studies.
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| 6. |
- Wang, Jianglin, et al.
(författare)
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Causes of East Asian Temperature Multidecadal Variability Since 850 CE
- 2018
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Ingår i: Geophysical Research Letters. - 0094-8276 .- 1944-8007. ; 45:24, s. 13485-13494
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Tidskriftsartikel (refereegranskat)abstract
- The drivers of multidecadal- to centennial-scale variability in East Asian temperature, apparent in temperature reconstructions, are poorly understood. Here we apply a multivariate regression analysis to distinguish the influences of large-scale modes of internal variability (Atlantic Multidecadal Oscillation and Pacific Multidecadal Oscillation) and external natural (orbital, solar, and volcanic) and anthropogenic (greenhouse gas concentrations, aerosols, and land use changes) forcings on East Asian warm-season temperature over the period 850-1999 CE (Common Era). We find that similar to 80% of the temperature change on time scales longer than 30 years can be explained including all drivers over the full-length period. The Pacific Multidecadal Oscillation was the most important driver of multidecadal temperature variability during the Medieval Climate Anomaly (here 950-1250), while solar contribution was important during the Little Ice Age (here 1350-1850). Since 1850, two thirds of temperature change can be explained with anthropogenic forcing, whereas one third was related mainly to the Atlantic Multidecadal Oscillation and volcanic forcing. Plain Language Summary The Atlantic Multidecadal Oscillation (AMO) and Pacific Multidecadal Oscillation (PMO) are suggested to be key components of internal temperature variability globally and in the Northern Hemisphere. However, the contribution of the AMO and PMO to temperature at regional/continental scales in preindustrial times is still unclear. Here we use a multivariate regression analysis to distinguish the AMO and PMO contributions to the East Asian temperature multidecadal (> 30 years) changes from the influence of external (orbital solar, volcanic, and anthropogenic) forcings. We find that the contribution of the AMO and PMO is of similar magnitude as solar and volcanic forcing during the period 850-1999 CE (Common Era). We apply the same approach to three subperiods and find that the PMO, solar forcing, and anthropogenic forcing contributed most during the periods 950-1250, 1350-1850, and 1850-1999, respectively.
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| 7. |
- Wang, Jianglin, et al.
(författare)
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Internal and external forcing of multidecadal Atlantic climate variability over the past 1,200 years
- 2017
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Ingår i: Nature Geoscience. - 1752-0894 .- 1752-0908. ; 10:7, s. 512-517
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Tidskriftsartikel (refereegranskat)abstract
- The North Atlantic experiences climate variability on multidecadal scales, which is sometimes referred to as Atlantic multidecadal variability. However, the relative contributions of external forcing such as changes in solar irradiance or volcanic activity and internal dynamics to these variations are unclear. Here we provide evidence for persistent summer Atlantic multidecadal variability from AD 800 to 2010 using a network of annually resolved terrestrial proxy records from the circum-North Atlantic region. We find that large volcanic eruptions and solar irradiance minima induce cool phases of Atlantic multidecadal variability and collectively explain about 30% of the variance in the reconstruction on timescales greater than 30 years. We are then able to isolate the internally generated component of Atlantic multidecadal variability, which we define as the Atlantic multidecadal oscillation. We find that the Atlantic multidecadal oscillation is the largest contributor to Atlantic multidecadal variability over the past 1,200 years. We also identify coherence between the Atlantic multidecadal oscillation and Northern Hemisphere temperature variations, leading us to conclude that the apparent link between Atlantic multidecadal variability and regional to hemispheric climate does not arise solely from a common response to external drivers, and may instead reflect dynamic processes.
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| 8. |
- Wetter, Oliver, et al.
(författare)
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The year-long unprecedented European heat and drought of 1540-a worst case
- 2014
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Ingår i: Climatic Change. - : Springer Science and Business Media LLC. - 0165-0009 .- 1573-1480. ; 125:3-4, s. 349-363
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Tidskriftsartikel (refereegranskat)abstract
- The heat waves of 2003 in Western Europe and 2010 in Russia, commonly labelled as rare climatic anomalies outside of previous experience, are often taken as harbingers of more frequent extremes in the global warming-influenced future. However, a recent reconstruction of spring-summer temperatures for WE resulted in the likelihood of significantly higher temperatures in 1540. In order to check the plausibility of this result we investigated the severity of the 1540 drought by putting forward the argument of the known soil desiccation-temperature feedback. Based on more than 300 first-hand documentary weather report sources originating from an area of 2 to 3 million km(2), we show that Europe was affected by an unprecedented 11-month-long Megadrought. The estimated number of precipitation days and precipitation amount for Central and Western Europe in 1540 is significantly lower than the 100-year minima of the instrumental measurement period for spring, summer and autumn. This result is supported by independent documentary evidence about extremely low river flows and Europe-wide wild-, forest- and settlement fires. We found that an event of this severity cannot be simulated by state-of-the-art climate models.
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