Temperaturvariationen und Jahrringe | Temperature variation and tree rings

The paper reviews some of the current objectives, concepts and results of dendroclimatic research focusing on long-term temperature trends and large-scale, tree-ring based temperature reconstructions. We discuss the significance of single treering parameters, their qualities and limitations, and address the issue of emphasizing climatic signals in long series of tree-ring records. We conclude with a discussion of current challenges faced by dendroclimatological research.

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Sampling density and date influence spatial representation of tree ring reconstructions

10.5194/cp-2020-31 ◽

2020 ◽

Author(s):

Justin T. Maxwell ◽

Grant L. Harley ◽

Trevis J. Matheus ◽

Brandon M. Strange ◽

Kayla Van Aken ◽

...

Keyword(s):

Soil Moisture ◽

Spatial Variability ◽

Tree Ring ◽

Tree Rings ◽

Large Scale ◽

The United States ◽

Severe Drought ◽

Ring Network ◽

Tree Ring Data ◽

The Us

Abstract. Our understanding of the natural variability of hydroclimate before the instrumental period (ca. 1900 in the United States; US) is largely dependent on tree-ring-based reconstructions. Large-scale soil moisture reconstructions from a network of tree-ring chronologies have greatly improved our understanding of the spatial and temporal variability in hydroclimate conditions, particularly extremes of both drought and pluvial (wet) events. However, certain regions within these large-scale reconstructions in the US have a sparse network of tree-ring chronologies. Further, several chronologies were collected in the 1980s and 1990s, thus our understanding of the sensitivity of radial growth to soil moisture in the US is based on a period that experienced multiple extremely severe droughts and neglects the impacts of recent, rapid global change. In this study, we expanded the tree-ring network of the Ohio River Valley in the US, a region with sparse coverage. We used a total of 72 chronologies across 15 species to examine how increasing the density of the tree-ring network influences the representation of reconstructing the Palmer Meteorological Drought Index (PMDI). Further, we tested how the sampling date influenced the reconstruction models by creating reconstructions that ended in the year 1980 and compared them to reconstructions ending in 2010 from the same chronologies. We found that increasing the density of the tree-ring network resulted in reconstructed values that better matched the spatial variability of instrumentally recorded droughts and to a lesser extent, pluvials. By sampling tree in 2010 compared to 1980, the sensitivity of tree rings to PMDI decreased in the southern portion of our region where severe drought conditions have been absent over recent decades. We emphasize the need of building a high-density tree-ring network to better represent the spatial variability of past droughts and pluvials. Further, chronologies on the International Tree-Ring Data Bank need updating regularly to better understand how the sensitivity of tree rings to climate may vary through time.

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The significance of climate and solar variability on historical European grain prices

10.5194/egusphere-egu2020-11257 ◽

2020 ◽

Author(s):

Fredrik Charpentier Ljungqvist ◽

Peter Thejll ◽

Bo Christiansen ◽

Andrea Seim ◽

Claudia Hartl ◽

...

Keyword(s):

Early Modern ◽

Tree Ring ◽

Early Modern Europe ◽

Solar Forcing ◽

Time And Space ◽

Climate Signal ◽

Temperature Reconstructions ◽

Modern Europe ◽

Grain Prices

Grain was the most important food source for a majority of the population in early modern Europe (c. 1500&#8211;1800). The price level and volatility had huge societal effects: high prices tended to increase mortality, decrease fertility as well as affect overall consumption patterns. To what extent climate variability influenced the long-term grain price evolution in early modern Europe has for a long time been a matter of debate. Recent advances in high-resolution palaeoclimatology and historical climatology have made it possible to reassess the grain price&#8211;climate relationship in time and space with unprecedented detail (Esper et al. 2017). We analyse the climate signal in 56 multi-centennial long series of annual prices of barley, oat, rye, and wheat across Europe. The grain price&#8211;climate relationship in regional clusters of grain price data is analysed using both tree-ring based temperature reconstructions, documentary-based temperature reconstructions, tree-ring based drought reconstructions, and early temperature and precipitation instrumental data, considering possible different climate responses in each grain type and different seasonal targets. In addition, we systematically investigate whether, and to what extent, the imprints of variations in solar forcing, including possible lag effects, can be detected in the grain prices.We find a highly significant and persistent negative temperature&#8211;price relationship (i.e., cold = high prices and vice versa) across all of Europe and for all four grain types using both temperature reconstructions and instrumental temperature data. Excluding the Thirty Years&#8217; War (1618&#8211;1648) and the period following the French Revolution (1789), this relationship is as strong as r = &#8211;0.41 between the annual average of all the 56 included European grain price series and the reconstructed June&#8211;August temperature for the previous year. The correlations to drought and precipitation are, on the other hand, mainly insignificant and inconsistent in time and space. The evidence for the existence of the effect of solar forcing variations on early modern European grain prices is not strong, although we can detect statistically significant grain price&#8211;solar forcing relationships for certain regions. In conclusion, we find much stronger evidence than hitherto reported for long-term temperature imprints on historical grain prices in Europe, implying that temperature variability and change have been a more important factor in European economic history, even in southern Europe, than commonly acknowledged.&#160;Reference:Esper J., et al., 2017. Environmental drivers of historical grain price variations in Europe. Clim. Res. 72: 39&#8211;52.

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Differing pre-industrial cooling trends between tree rings and lower-resolution temperature proxies

Climate of the Past ◽

10.5194/cp-16-729-2020 ◽

2020 ◽

Vol 16 (2) ◽

pp. 729-742 ◽

Cited By ~ 1

Author(s):

Lara Klippel ◽

Scott St. George ◽

Ulf Büntgen ◽

Paul J. Krusic ◽

Jan Esper

Keyword(s):

Tree Ring ◽

Tree Rings ◽

Ice Core ◽

Temperature Sensitive ◽

Global Trends ◽

Temperature Changes ◽

Long Term Trends ◽

Sediment Data ◽

Common Era

Abstract. The new PAGES2k global compilation of temperature-sensitive proxies offers an unprecedented opportunity to study regional to global trends associated with orbitally driven changes in solar irradiance over the past 2 millennia. Here, we analyze pre-industrial long-term trends from 1 to 1800 CE across the PAGES2k dataset and find that, in contrast to the gradual cooling apparent in ice core, marine, and lake sediment data, tree rings do not exhibit the same decline. To understand why tree-ring proxies lack any evidence of a significant pre-industrial cooling, we divide those data by location (high Northern Hemisphere latitudes vs. midlatitudes), seasonal response (annual vs. summer), detrending method, and temperature sensitivity (high vs. low). We conclude that the ability of tree-ring proxies to detect pre-industrial, millennial-long cooling is not affected by latitude, seasonal sensitivity, or detrending method. Caution is advised when using multi-proxy approaches to reconstruct long-term temperature changes over the entire Common Era.

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A multi-century spring precipitation history for northern Iran derived from tree-ring δ18O

10.5194/egusphere-egu21-15355 ◽

2021 ◽

Author(s):

Zeynab Foroozan ◽

Jussi Grießinger ◽

Kambiz Pourtahmasi ◽

Achim Bräuning

Keyword(s):

Tree Ring ◽

Large Scale ◽

Regional Climate ◽

Spring Precipitation ◽

Northern Iran ◽

The Past ◽

Precipitation Record ◽

Hydroclimatic Variability ◽

Semi Arid

Knowledge about the long-term hydroclimatic variability is essential to analyze the historic course and recent impact of climate change, especially in semi-arid and arid regions of the world. In this study, we present the first tree-ring &#948;18O chronology for the semi-arid parts of northern Iran based on juniper trees. We were able to reconstruct past hydroclimatic variability for the past 500 years. The highly significant correlation between tree-ring &#948;18O and spring precipitation indicates the primary influence of spring moisture availability on &#948;18O variations. The thereof derived precipitation reconstruction reveals short and long-term variability of precipitation intensity, duration, and frequency of dry/wet events. During the past 500 years, the driest period occurred in the 16th century, whereas the 18th century was comparably wet. A gradual decline in the reconstructed spring precipitation is evident since the beginning of the 19th century, culminating in the continuing drought of the 20th century. An analysis of dry/wet years indicated that over the last three centuries, the occurrence of years with a relatively dry spring is increasing. In contrast, more humid spring conditions are decreasing. However, the overall frequency of the occurrence of extreme events increased over the past five centuries. In addition, past hydrological disasters recorded in Persian history were well represented in our reconstruction. Correlations between our reconstructed precipitation record and large-scale circulation systems revealed no significant influence of large-scale climatic drivers on spring precipitation variations in north Iran, which therefore seem to be mostly controlled by a regional climate forcing.

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Setting the tree-ring record straight

10.5194/egusphere-egu2020-19795 ◽

2020 ◽

Author(s):

Josef Ludescher ◽

Armin Bunde ◽

Ulf Büntgen ◽

Hans Joachim Schellnhuber

Keyword(s):

Tree Ring ◽

Temperature Reconstruction ◽

Climate Impacts ◽

Model Data ◽

Mathematical Transformation ◽

Harvest Dates ◽

Temperature Reconstructions ◽

Historical Temperature ◽

Historical Model

Tree-ring chronologies are the main source for annually resolved and absolutely dated temperature reconstructions of the last millennia and thus for studying the intriguing problem of climate impacts. Here we focus on central Europe and compare the tree-ring based temperature reconstruction with reconstructions from harvest dates, long meteorological measurements, and historical model data. We find that all data are long term persistent, but in the tree-ring based reconstruction the strength of the persistence quantified by the Hurst exponent is remarkably larger (h = 1.02) than in the other data (h = 0.52 &#8722; 0.69), indicating an unrealistic exaggeration of the historical temperature variations. We show how to correct the tree-ring based reconstruction by a mathematical transformation that adjusts the persistence and leads to reduced amplitudes of the warm and cold periods. The new transformed record agrees well with both the observational data and the harvest dates-based reconstructions and allows more realistic studies of climate impacts. It confirms that the present warming is unprecedented.

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Large scale climate signals of a European oxygen isotope network from tree-rings – predominantly caused by ENSO teleconnections?

10.5194/cp-2020-39 ◽

2020 ◽

Cited By ~ 1

Author(s):

Daniel F. Balting ◽

Monica Ionita ◽

Martin Wegmann ◽

Gerhard Helle ◽

Gerhard H. Schleser ◽

...

Keyword(s):

Atmospheric Circulation ◽

Tree Ring ◽

Tree Rings ◽

Large Scale ◽

Southern Oscillation ◽

Circulation Pattern ◽

Isotopic Signature ◽

Atmospheric Circulation Patterns ◽

Climate Signals ◽

Instrumental Records

Abstract. We investigate the annual variability of δ18O tree ring records from sites distributed all over Europe covering the last 400 years. An Empirical Orthogonal Function (EOF) analysis reveals two distinct modes of variability on the basis of the existing δ18O tree ring records. The first mode of δ18O variability is associated with anomaly patterns of the El Niño-Southern Oscillation (ENSO) and reflects a multi-seasonal climatic signal. The ENSO signal is visible for the last 130 years, but is found weak during the period 1600 to 1850 suggesting that the relationship between ENSO and the European climate may not stable over time. The second mode of δ18O variability, which captures an out-of-phase variability between northwestern and southeastern European δ18O tree ring records, is related to a regional summer atmospheric circulation pattern revealing a pronounced centre over the North Sea. Locally, the δ18O anomalies associated with this mode show the same (opposite) sign with temperature (precipitation). We infer that the investigation of large-scale atmospheric circulation patterns and related teleconnections far beyond instrumental records can be done with oxygen isotopic signature derived from tree rings. However, the European δ18Ocel tree network needs to be consolidated and updated, as well as additional research on the stationarity of reconstructed climate signals and the stationarity of teleconnections is advisable.

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Sampling density and date along with species selection influence spatial representation of tree-ring reconstructions

Climate of the Past ◽

10.5194/cp-16-1901-2020 ◽

2020 ◽

Vol 16 (5) ◽

pp. 1901-1916

Author(s):

Justin T. Maxwell ◽

Grant L. Harley ◽

Trevis J. Matheus ◽

Brandon M. Strange ◽

Kayla Van Aken ◽

...

Keyword(s):

Soil Moisture ◽

Spatial Variability ◽

Tree Ring ◽

Tree Rings ◽

Large Scale ◽

The United States ◽

Species Selection ◽

Ring Network ◽

Calibration Period ◽

The Us

Abstract. Our understanding of the natural variability of hydroclimate before the instrumental period (ca. 1900 CE in the United States) is largely dependent on tree-ring-based reconstructions. Large-scale soil moisture reconstructions from a network of tree-ring chronologies have greatly improved our understanding of the spatial and temporal variability in hydroclimate conditions, particularly extremes of both drought and pluvial (wet) events. However, certain regions within these large-scale network reconstructions in the US are modeled by few tree-ring chronologies. Further, many of the chronologies currently publicly available on the International Tree-Ring Data Bank (ITRDB) were collected in the 1980s and 1990s, and thus our understanding of the sensitivity of radial growth to soil moisture in the US is based on a period that experienced multiple extremely severe droughts and neglects the impacts of recent, rapid global change. In this study, we expanded the tree-ring network of the Ohio River valley in the US, a region with sparse coverage. We used a total of 72 chronologies across 15 species to examine how increasing the density of the tree-ring network influences the representation of reconstructing the Palmer Meteorological Drought Index (PMDI). Further, we tested how the sampling date and therefore the calibration period influenced the reconstruction models by creating reconstructions that ended in the year 1980 and compared them to reconstructions ending in 2010 from the same chronologies. We found that increasing the density of the tree-ring network resulted in reconstructed values that better matched the spatial variability of instrumentally recorded droughts and, to a lesser extent, pluvials. By extending the calibration period to 2010 compared to 1980, the sensitivity of tree rings to PMDI decreased in the southern portion of our region where severe drought conditions have been absent over recent decades. We emphasize the need of building a high-density tree-ring network to better represent the spatial variability of past droughts and pluvials. Further, chronologies on the ITRDB need updating regularly to better understand how the sensitivity of tree rings to climate may vary through time.

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How does varying water supply affect oxygen isotope variations in needles and tree rings of Scots pine?

Tree Physiology ◽

10.1093/treephys/tpaa082 ◽

2020 ◽

Vol 40 (10) ◽

pp. 1366-1380

Author(s):

Galina Timofeeva ◽

Kerstin Treydte ◽

Harald Bugmann ◽

Yann Salmon ◽

Andreas Rigling ◽

...

Keyword(s):

Water Supply ◽

Tree Ring ◽

Scots Pine ◽

Tree Rings ◽

Water Movement ◽

Rooting Depth ◽

Long Term Effects ◽

Mature Trees ◽

Alpine Valley

Abstract In many regions, drought is suspected to be a cause of Scots pine decline and mortality, but the underlying physiological mechanisms remain unclear. Because of their relationship to ecohydrological processes, δ18O values in tree rings are potentially useful for deciphering long-term physiological responses and tree adaptation to increasing drought. We therefore analyzed both needle- and stem-level isotope fractionations in mature trees exposed to varying water supply. In a first experiment, we investigated seasonal δ18O variations in soil and needle water of Scots pine in a dry inner Alpine valley in Switzerland, comparing drought-stressed trees with trees that were irrigated for more than 10 years. In a second experiment, we analyzed twentieth-century δ18O variations in tree rings of the same forest, including a group of trees that had recently died. We observed less 18O enrichment in needle water of drought-stressed compared with irrigated trees. We applied different isotope fractionation models to explain these results, including the Péclet and the two-pool correction, which considers the ratio of unenriched xylem water in the needles to total needle water. Based on anatomical measurements, we found this ratio to be unchanged in drought-stressed needles, although they were shorter. The observed lower 18O enrichment in needles of stressed trees was therefore likely caused by increased effective path length for water movement within the leaf lamina. In the tree-ring study, we observed lower δ18O values in tree rings of dead trees compared with survivors during several decades prior to their death. These lower values in declining trees are consistent with the lower needle water 18O enrichment observed for drought-stressed compared with irrigated trees, suggesting that this needle-level signal is reflected in the tree rings, although changes in rooting depth could also play a role. Our study demonstrates that long-term effects of drought are reflected in the tree-ring δ18O values, which helps to provide a better understanding of past tree physiological changes of Scots pine.

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Temperature and Precipitation in Mongolla Based on Dendroclimatic Investigations

IAWA Journal ◽

10.1163/22941932-90000696 ◽

1999 ◽

Vol 20 (3) ◽

pp. 339-354 ◽

Cited By ~ 18

Author(s):

Gordon Jacoby ◽

Rosanne D' Arrigo ◽

Neil Pederson ◽

Brendan Buckley ◽

Chultamiin Dugarjav ◽

...

Keyword(s):

Tree Ring ◽

Large Scale ◽

The Arctic ◽

Proxy Record ◽

Future Studies ◽

Temperature And Precipitation ◽

Important Addition ◽

Precipitation Variation ◽

Reconstructed Precipitation

Recent tree-ring studies in Mongolia provide evidence of unusual warming that is in agreement with large-scale reconstructed and recorded temperatures for the Northem Hemisphere and the Arctic. The Mongolian proxy record for temperature extends back over 450 years and is an important addition to the global tree-ring database. Precipitation reconstructions based on tree rings reflect recent increases but show that the increases are within the long-term range of variations. There is evidence for quasi-solar periodicity in long-term reconstructed precipitation variation, also shown by previous studies. Mongolia has excellent sampling resources for future studies.

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