Hydrology and Earth System Sciences Discussions, 2015
ABSTRACT This paper presents the occurrence, cause and frequency changes of floods, their develop... more ABSTRACT This paper presents the occurrence, cause and frequency changes of floods, their development and distribution along the southern part of the upper Rhine River and of 14 of its tributaries in France and Germany covering the period from 1480 BC. Special focus is given on the temporal and spatial variations and underlying meteorological causes which show a significant change over space and time. Examples are presented how long-term information can help to improve transnational risk and risk management analysis while connecting single historical and modern extreme events.
Mitteleuropa ist reich an schriftlichen Zeugnissen, welche für die letzten 500 Jahre in ausreiche... more Mitteleuropa ist reich an schriftlichen Zeugnissen, welche für die letzten 500 Jahre in ausreichender Dichte und Qualität vorliegen, um für nahezu jeden Monat ein differenziertes Bild der thermischen und hygrischen Bedingungen zeichnen zu können. Diese Differenzierung erlaubt die Zuordnung der Aussagen zu sieben Intensitätsklassen, welche für die thermischen Angaben von -3 für extrem kalt bis hin zu +3 für extrem heiß reicht. Für den Zeitraum von 1000-1500 ist eine jahreszeitliche Auflösung mit mindestens dreistufiger [-1 0 1] Bewertung möglich. Diese indexbasierten Bewertungen für die letzten 1000 Jahre wurden durch Glaser (2008) zu einer durchgängigen Reihe zusammengestellt und bilden eine Grundlage der hier vorgestellten methodischen Arbeiten. Die Untersuchungen beziehen sich v.a. auf Hinweise zur Temperatur, die methodischen Überlegungen können jedoch auch auf andere indexbasierte Witterungsangaben erweitert werden. Eine Ausgangsfrage dieser Arbeit war, ob diese Indizes mittel- ...
New evidence from documentary sources provides detailed climatic information to fill the Middle E... more New evidence from documentary sources provides detailed climatic information to fill the Middle East gap in Medieval Climate Anomaly reconstructions. The Middle East region harbors a wealth of documentary and natural archives that contain detailed information on climate conditions and events. To date, however, only a few proxy-based climate reconstruc-tions are available from the area for the assessment of thermal and hydroclimatic characteristics of the Medieval Climate Anomaly (MCA). Existing chronologies and reconstructions mostly provide infor-mation for specific seasons and hydrocli-matic parameters (commonly precipitation and droughts). The reconstructions are based on natural proxies such as tree rings (e.g., Touchan et al., 2007), pollen records (Kaniewski et al., 2010), speleothems (e.g., Bar Matthews et al., 1997; Frumkin et al., 1991; Fleitmann et al., 2004), lake sedimen-tary records (e....
For portable fuel cell systems a multitude of applications have been presented over the past few ... more For portable fuel cell systems a multitude of applications have been presented over the past few years. Most of these applications were developed for indoor use, and not optimised for outdoor conditions. The key problem concerning this case is the cold start ability of the ...
The start up behaviour of PEM fuel cells below 0 • C is one of the most challenging tasks to be s... more The start up behaviour of PEM fuel cells below 0 • C is one of the most challenging tasks to be solved before commercialisation. The automotive industry started to develop solutions to reduce the start up time of fuel cell systems in the middle of the nineties. The strategies varied from catalytic combustion of hydrogen on the electrode catalyst to fuel starvation or external stack heating via cooling loops to increase the stack temperature.
Büntgen et al. (2015; hereinafter B15) present the result of new research which question the resu... more Büntgen et al. (2015; hereinafter B15) present the result of new research which question the results of Wetter et al. 2014, ( hereinafter W14) and Wetter et al. (2013, hereinafter W13) regarding European climate in 1540. B15 conclude from tree-ring evidence that the results based on documentary data of W14 Bprobably overstated the intensity and duration of the 1540 Climatic Change
This chapter summarises the climatic and environmental information that can be inferred from prox... more This chapter summarises the climatic and environmental information that can be inferred from proxy archives of the Baltic Sea area during the past millennium (1000 years). The proxy archives mainly comprise tree-ring analyses together with historical documents on extreme weather events and weather-related disasters. In addition to the reconstructed climate, climatic conditions are simulated using a regional climate model covering the Baltic Sea area. The chapter focuses on three of the main climatic periods of the past millennium: the Medieval Warm Period (900-1350), the Transitional Period (1350-1550) and the Little Ice Age (1550-1850). During these main historical climatic periods, climatic conditions were not uniform. Shorter warm/cool and wet/dry fluctuations were observed depending on regional factors.
The heat waves of 2003 in Western Europe and 2010 in Russia, commonly labelled as rare climatic a... more 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 Climatic Change Climatic Change 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
We present a multi-archive, multi-proxy summer temperature reconstruction for the European Alps c... more We present a multi-archive, multi-proxy summer temperature reconstruction for the European Alps covering the period AD 1053e1996 using tree-ring and lake sediment data. The new reconstruction is based on nine different calibration approaches and errors were estimated conservatively. Summer temperatures of the last millennium are characterised by two warm (AD 1053e1171 and 1823e1996) and two cold phases (AD 1172e1379 and 1573e1822). Highest pre-industrial summer temperatures of the 12th century were 0.3 C warmer than the 20th century mean but 0.35 C colder than proxy derived temperatures at the end of the 20th century. The lowest temperatures at the end of the 16th century were w1 C lower than the 20th century mean.
A comparison of seasonally resolved temperature reconstructions from various regions in Europe sh... more A comparison of seasonally resolved temperature reconstructions from various regions in Europe shows a high coherence for medium term changes, despite the fact that these reconstructions are derived from different proxies, such as historical documentary data, tree ring parameters and speleotherms, each with different temporal and spatial resolution. Deviations from this coherence do not necessarily reflect errors but can be
This paper presents a temperature reconstruction of the past 1000 years for Central Europe, based... more This paper presents a temperature reconstruction of the past 1000 years for Central Europe, based on chronological records. The advantages and limitations of this hermeneutic, text-based approach are discussed and the statistic methodology is introduced. Historical documents represent direct observation of weather and atmospheric conditions with highest temporal resolution available and precise dating. A major advantage of these extensive data is that they allow the reconstruction of large numbers of variables such as winter temperature, precipitation, pressure patterns or climate extremes as well as floods or storms. Within this hermeneutic climatological research approach, even human impacts and social dimensions of climate development can be examined. In order to quantify the historical information, statistical methods are applied, based on an index approach.
Land-use/land-cover (LULC) change is an important climatic force, and is also affected by climate... more Land-use/land-cover (LULC) change is an important climatic force, and is also affected by climate change. In the present study, we aimed to assess the regional scale impact of LULC on climate change using Jiangxi Province, China, as a case study. To obtain reliable climate trends, we applied the standard normal homogeneity test (SNHT) to surface air temperature and precipitation data for the period 1951-1999. We also compared the temperature trends computed from Global Historical Climatology Network (GHCN) datasets and from our analysis. To examine the regional impacts of land surface types on surface air temperature and precipitation change integrating regional topography, we used the observation minus reanalysis (OMR) method. Precipitation series were found to be homogeneous. Comparison of GHCN and our analysis on adjusted temperatures indicated that the resulting climate trends varied slightly from dataset to dataset. OMR trends associated with surface vegetation types revealed a strong surface warming response to land barrenness and weak warming response to land greenness. A total of 81.1 % of the surface warming over vegetation index areas (0-0.2) was attributed to surface vegetation type change and regional topography. The contribution of surface vegetation type change decreases as land cover greenness increases. The OMR precipitation trend has a weak dependence on surface vegetation type change. We suggest that LULC integrating regional topography should be considered as a force in regional climate modeling.
Monthly temperature series for Central Europe back to AD 1500 are developed from documentary inde... more Monthly temperature series for Central Europe back to AD 1500 are developed from documentary index series from Germany, Switzerland and the Czech Republic (1500-1854) and 11 instrumental temperature records . Documentary evidence from the Low Countries, the Carpathian Basin and Poland are used for cross-checking for earlier centuries. The instrumental station records are corrected for inhomogeneities, including insufficient radiation protection of early thermometers and the urban heat island effect. For overlapping period (1760-1854), the documentary data series correlate with instrumental temperatures, most strongly in winter (86% explained variance in January) and least in autumn (56% in September). For annual average temperatures, 81% of the variance is explained. Verification statistics indicate high reconstruction skill for most months and seasons. The last 20 years (since 1988) stand out as very likely the warmest 20-year period, accounting for the calibration uncertainty and decreases in proxy data quality before the calibration period. The new reconstruction displays a previously unobserved P. Dobrovolný (B) · R. Brázdil · M. Halíčková · J. Macková Climatic Change long-term decrease in DJF, MAM and JJA temperature variability over last five centuries. Compiled monthly, seasonal and annual series can be used to improve the robustness of gridded large-scale European temperature reconstructions and possible impact studies. Further improvement of the reconstruction would be achieved if documentary data from other European countries are further developed.
We use long instrumental temperature series together with available field reconstructions of sea-... more We use long instrumental temperature series together with available field reconstructions of sea-level pressure (SLP) and three-dimensional climate model simulations to analyze relations between temperature anomalies and atmospheric circulation patterns over much of Europe and the Mediterranean for the late winter/early spring (January-April, JFMA) season. A Canonical Correlation Analysis (CCA) investigates interannual to interdecadal covariability between a new gridded SLP field reconstruction and seven long instrumental temperature series covering the past 250 years. We then present and discuss prominent atmospheric circulation patterns related to anomalous warm and cold JFMA conditions within different European areas spanning the period 1760-2007. Next, using a data assimilation technique, we link gridded SLP data with a climate model (EC-Bilt-Clio) for a better dynamical understanding of the relationship between large scale circulation and European climate. We thus present an alternative approach to reconstruct Climatic Change (2010) 101:201-234 203 aspect in the rapidly developing field of 'historical climatology ' (e.g. Brázdil et al. 2005;. Recently, a rare opportunity for a large group of historical climatologists to engage in a collective undertaking that links with other climate research areas (e.g. dendroclimatology and other natural proxy sources) and climate modeling, has been offered in context of the EU 6th Framework Program project MILLENNIUM ; http://ralph.swan.ac.uk/millennium/).
... Rüdiger Glaser·Dirk Riemann·Johannes Schönbein·Mariano Barriendos· Rudolf Brázdil·Chiara Bert... more ... Rüdiger Glaser·Dirk Riemann·Johannes Schönbein·Mariano Barriendos· Rudolf Brázdil·Chiara Bertolin·Dario Camuffo·Mathias Deutsch· Petr Dobrovolný·Aryan van ... triggered by an advection of warm air masses causing rain and (partly) the melting of the snow cover within the ...
Two European temperature reconstructions for the past half-millennium, January-to-April air tempe... more Two European temperature reconstructions for the past half-millennium, January-to-April air temperature for Stockholm (Sweden) and seasonal temperature for a Central European region, both derived from the analysis of documentary sources and long instrumental records, are compared with the output of climate Climatic Change simulations with the model ECHO-G. The analysis is complemented by comparisons with the long (early)-instrumental record of Central England Temperature (CET). Both approaches to study past climates (simulations and reconstructions) are burdened with uncertainties. The main objective of this comparative analysis is to identify robust features and weaknesses in each method which may help to improve models and reconstruction methods. The results indicate a general agreement between simulations obtained with temporally changing external forcings and the reconstructed Stockholm and CET records for the multi-centennial temperature trend over the recent centuries, which is not reproduced in a control simulation. This trend is likely due to the long-term change in external forcing. Additionally, the Stockholm reconstruction and the CET record also show a clear multi-decadal warm episode peaking around AD 1730, which is absent in the simulations. Neither the reconstruction uncertainties nor the model internal climate variability can easily explain this difference. Regarding the interannual variability, the Stockholm series displays, in some periods, higher amplitudes than the simulations but these differences are within the statistical uncertainty and further decrease if output from a regional model driven by the global model is used. The long-term trend of the Central European temperature series agrees less well with the simulations. The reconstructed temperature displays, for all seasons, a smaller difference between the present climate and past centuries than is seen in the simulations. Possible reasons for these differences may be related to a limitation of the traditional 'indexing' technique for converting documentary evidence to temperature values to capture long-term climate changes, because the documents often reflect temperatures relative to the contemporary authors' own perception of what constituted 'normal' conditions. By contrast, the amplitude of the simulated and reconstructed inter-annual variability agrees rather well.
Dendrochronological data from alluvial forests had long been regarded as unsuitable for climatolo... more Dendrochronological data from alluvial forests had long been regarded as unsuitable for climatologically reconstructions because of the doctrine that dendrochronological data shows the best climate signal if obtained near to climatologically boundaries. Enhanced preparation techniques in combination with high resolution optical scanning allow for precise wood-anatomical analyses, which offer new insight from dendrochronologies hitherto regarded as not to be ideal. This abstract presents a new approach of interpreting climate data derived from dendrochronological proxies from alluvial forests and presents the potential of a time series covering the past 10k years with seasonal resolution for the climate signal, as well as information about flood events within the floodplains. The region of the Main valley in south western Germany offers a large number of written climate proxies, which had been researched and catalogued by the work of Glaser (2008). The available information extends b...
Hydrology and Earth System Sciences Discussions, 2015
ABSTRACT This paper presents the occurrence, cause and frequency changes of floods, their develop... more ABSTRACT This paper presents the occurrence, cause and frequency changes of floods, their development and distribution along the southern part of the upper Rhine River and of 14 of its tributaries in France and Germany covering the period from 1480 BC. Special focus is given on the temporal and spatial variations and underlying meteorological causes which show a significant change over space and time. Examples are presented how long-term information can help to improve transnational risk and risk management analysis while connecting single historical and modern extreme events.
Mitteleuropa ist reich an schriftlichen Zeugnissen, welche für die letzten 500 Jahre in ausreiche... more Mitteleuropa ist reich an schriftlichen Zeugnissen, welche für die letzten 500 Jahre in ausreichender Dichte und Qualität vorliegen, um für nahezu jeden Monat ein differenziertes Bild der thermischen und hygrischen Bedingungen zeichnen zu können. Diese Differenzierung erlaubt die Zuordnung der Aussagen zu sieben Intensitätsklassen, welche für die thermischen Angaben von -3 für extrem kalt bis hin zu +3 für extrem heiß reicht. Für den Zeitraum von 1000-1500 ist eine jahreszeitliche Auflösung mit mindestens dreistufiger [-1 0 1] Bewertung möglich. Diese indexbasierten Bewertungen für die letzten 1000 Jahre wurden durch Glaser (2008) zu einer durchgängigen Reihe zusammengestellt und bilden eine Grundlage der hier vorgestellten methodischen Arbeiten. Die Untersuchungen beziehen sich v.a. auf Hinweise zur Temperatur, die methodischen Überlegungen können jedoch auch auf andere indexbasierte Witterungsangaben erweitert werden. Eine Ausgangsfrage dieser Arbeit war, ob diese Indizes mittel- ...
New evidence from documentary sources provides detailed climatic information to fill the Middle E... more New evidence from documentary sources provides detailed climatic information to fill the Middle East gap in Medieval Climate Anomaly reconstructions. The Middle East region harbors a wealth of documentary and natural archives that contain detailed information on climate conditions and events. To date, however, only a few proxy-based climate reconstruc-tions are available from the area for the assessment of thermal and hydroclimatic characteristics of the Medieval Climate Anomaly (MCA). Existing chronologies and reconstructions mostly provide infor-mation for specific seasons and hydrocli-matic parameters (commonly precipitation and droughts). The reconstructions are based on natural proxies such as tree rings (e.g., Touchan et al., 2007), pollen records (Kaniewski et al., 2010), speleothems (e.g., Bar Matthews et al., 1997; Frumkin et al., 1991; Fleitmann et al., 2004), lake sedimen-tary records (e....
For portable fuel cell systems a multitude of applications have been presented over the past few ... more For portable fuel cell systems a multitude of applications have been presented over the past few years. Most of these applications were developed for indoor use, and not optimised for outdoor conditions. The key problem concerning this case is the cold start ability of the ...
The start up behaviour of PEM fuel cells below 0 • C is one of the most challenging tasks to be s... more The start up behaviour of PEM fuel cells below 0 • C is one of the most challenging tasks to be solved before commercialisation. The automotive industry started to develop solutions to reduce the start up time of fuel cell systems in the middle of the nineties. The strategies varied from catalytic combustion of hydrogen on the electrode catalyst to fuel starvation or external stack heating via cooling loops to increase the stack temperature.
Büntgen et al. (2015; hereinafter B15) present the result of new research which question the resu... more Büntgen et al. (2015; hereinafter B15) present the result of new research which question the results of Wetter et al. 2014, ( hereinafter W14) and Wetter et al. (2013, hereinafter W13) regarding European climate in 1540. B15 conclude from tree-ring evidence that the results based on documentary data of W14 Bprobably overstated the intensity and duration of the 1540 Climatic Change
This chapter summarises the climatic and environmental information that can be inferred from prox... more This chapter summarises the climatic and environmental information that can be inferred from proxy archives of the Baltic Sea area during the past millennium (1000 years). The proxy archives mainly comprise tree-ring analyses together with historical documents on extreme weather events and weather-related disasters. In addition to the reconstructed climate, climatic conditions are simulated using a regional climate model covering the Baltic Sea area. The chapter focuses on three of the main climatic periods of the past millennium: the Medieval Warm Period (900-1350), the Transitional Period (1350-1550) and the Little Ice Age (1550-1850). During these main historical climatic periods, climatic conditions were not uniform. Shorter warm/cool and wet/dry fluctuations were observed depending on regional factors.
The heat waves of 2003 in Western Europe and 2010 in Russia, commonly labelled as rare climatic a... more 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 Climatic Change Climatic Change 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
We present a multi-archive, multi-proxy summer temperature reconstruction for the European Alps c... more We present a multi-archive, multi-proxy summer temperature reconstruction for the European Alps covering the period AD 1053e1996 using tree-ring and lake sediment data. The new reconstruction is based on nine different calibration approaches and errors were estimated conservatively. Summer temperatures of the last millennium are characterised by two warm (AD 1053e1171 and 1823e1996) and two cold phases (AD 1172e1379 and 1573e1822). Highest pre-industrial summer temperatures of the 12th century were 0.3 C warmer than the 20th century mean but 0.35 C colder than proxy derived temperatures at the end of the 20th century. The lowest temperatures at the end of the 16th century were w1 C lower than the 20th century mean.
A comparison of seasonally resolved temperature reconstructions from various regions in Europe sh... more A comparison of seasonally resolved temperature reconstructions from various regions in Europe shows a high coherence for medium term changes, despite the fact that these reconstructions are derived from different proxies, such as historical documentary data, tree ring parameters and speleotherms, each with different temporal and spatial resolution. Deviations from this coherence do not necessarily reflect errors but can be
This paper presents a temperature reconstruction of the past 1000 years for Central Europe, based... more This paper presents a temperature reconstruction of the past 1000 years for Central Europe, based on chronological records. The advantages and limitations of this hermeneutic, text-based approach are discussed and the statistic methodology is introduced. Historical documents represent direct observation of weather and atmospheric conditions with highest temporal resolution available and precise dating. A major advantage of these extensive data is that they allow the reconstruction of large numbers of variables such as winter temperature, precipitation, pressure patterns or climate extremes as well as floods or storms. Within this hermeneutic climatological research approach, even human impacts and social dimensions of climate development can be examined. In order to quantify the historical information, statistical methods are applied, based on an index approach.
Land-use/land-cover (LULC) change is an important climatic force, and is also affected by climate... more Land-use/land-cover (LULC) change is an important climatic force, and is also affected by climate change. In the present study, we aimed to assess the regional scale impact of LULC on climate change using Jiangxi Province, China, as a case study. To obtain reliable climate trends, we applied the standard normal homogeneity test (SNHT) to surface air temperature and precipitation data for the period 1951-1999. We also compared the temperature trends computed from Global Historical Climatology Network (GHCN) datasets and from our analysis. To examine the regional impacts of land surface types on surface air temperature and precipitation change integrating regional topography, we used the observation minus reanalysis (OMR) method. Precipitation series were found to be homogeneous. Comparison of GHCN and our analysis on adjusted temperatures indicated that the resulting climate trends varied slightly from dataset to dataset. OMR trends associated with surface vegetation types revealed a strong surface warming response to land barrenness and weak warming response to land greenness. A total of 81.1 % of the surface warming over vegetation index areas (0-0.2) was attributed to surface vegetation type change and regional topography. The contribution of surface vegetation type change decreases as land cover greenness increases. The OMR precipitation trend has a weak dependence on surface vegetation type change. We suggest that LULC integrating regional topography should be considered as a force in regional climate modeling.
Monthly temperature series for Central Europe back to AD 1500 are developed from documentary inde... more Monthly temperature series for Central Europe back to AD 1500 are developed from documentary index series from Germany, Switzerland and the Czech Republic (1500-1854) and 11 instrumental temperature records . Documentary evidence from the Low Countries, the Carpathian Basin and Poland are used for cross-checking for earlier centuries. The instrumental station records are corrected for inhomogeneities, including insufficient radiation protection of early thermometers and the urban heat island effect. For overlapping period (1760-1854), the documentary data series correlate with instrumental temperatures, most strongly in winter (86% explained variance in January) and least in autumn (56% in September). For annual average temperatures, 81% of the variance is explained. Verification statistics indicate high reconstruction skill for most months and seasons. The last 20 years (since 1988) stand out as very likely the warmest 20-year period, accounting for the calibration uncertainty and decreases in proxy data quality before the calibration period. The new reconstruction displays a previously unobserved P. Dobrovolný (B) · R. Brázdil · M. Halíčková · J. Macková Climatic Change long-term decrease in DJF, MAM and JJA temperature variability over last five centuries. Compiled monthly, seasonal and annual series can be used to improve the robustness of gridded large-scale European temperature reconstructions and possible impact studies. Further improvement of the reconstruction would be achieved if documentary data from other European countries are further developed.
We use long instrumental temperature series together with available field reconstructions of sea-... more We use long instrumental temperature series together with available field reconstructions of sea-level pressure (SLP) and three-dimensional climate model simulations to analyze relations between temperature anomalies and atmospheric circulation patterns over much of Europe and the Mediterranean for the late winter/early spring (January-April, JFMA) season. A Canonical Correlation Analysis (CCA) investigates interannual to interdecadal covariability between a new gridded SLP field reconstruction and seven long instrumental temperature series covering the past 250 years. We then present and discuss prominent atmospheric circulation patterns related to anomalous warm and cold JFMA conditions within different European areas spanning the period 1760-2007. Next, using a data assimilation technique, we link gridded SLP data with a climate model (EC-Bilt-Clio) for a better dynamical understanding of the relationship between large scale circulation and European climate. We thus present an alternative approach to reconstruct Climatic Change (2010) 101:201-234 203 aspect in the rapidly developing field of 'historical climatology ' (e.g. Brázdil et al. 2005;. Recently, a rare opportunity for a large group of historical climatologists to engage in a collective undertaking that links with other climate research areas (e.g. dendroclimatology and other natural proxy sources) and climate modeling, has been offered in context of the EU 6th Framework Program project MILLENNIUM ; http://ralph.swan.ac.uk/millennium/).
... Rüdiger Glaser·Dirk Riemann·Johannes Schönbein·Mariano Barriendos· Rudolf Brázdil·Chiara Bert... more ... Rüdiger Glaser·Dirk Riemann·Johannes Schönbein·Mariano Barriendos· Rudolf Brázdil·Chiara Bertolin·Dario Camuffo·Mathias Deutsch· Petr Dobrovolný·Aryan van ... triggered by an advection of warm air masses causing rain and (partly) the melting of the snow cover within the ...
Two European temperature reconstructions for the past half-millennium, January-to-April air tempe... more Two European temperature reconstructions for the past half-millennium, January-to-April air temperature for Stockholm (Sweden) and seasonal temperature for a Central European region, both derived from the analysis of documentary sources and long instrumental records, are compared with the output of climate Climatic Change simulations with the model ECHO-G. The analysis is complemented by comparisons with the long (early)-instrumental record of Central England Temperature (CET). Both approaches to study past climates (simulations and reconstructions) are burdened with uncertainties. The main objective of this comparative analysis is to identify robust features and weaknesses in each method which may help to improve models and reconstruction methods. The results indicate a general agreement between simulations obtained with temporally changing external forcings and the reconstructed Stockholm and CET records for the multi-centennial temperature trend over the recent centuries, which is not reproduced in a control simulation. This trend is likely due to the long-term change in external forcing. Additionally, the Stockholm reconstruction and the CET record also show a clear multi-decadal warm episode peaking around AD 1730, which is absent in the simulations. Neither the reconstruction uncertainties nor the model internal climate variability can easily explain this difference. Regarding the interannual variability, the Stockholm series displays, in some periods, higher amplitudes than the simulations but these differences are within the statistical uncertainty and further decrease if output from a regional model driven by the global model is used. The long-term trend of the Central European temperature series agrees less well with the simulations. The reconstructed temperature displays, for all seasons, a smaller difference between the present climate and past centuries than is seen in the simulations. Possible reasons for these differences may be related to a limitation of the traditional 'indexing' technique for converting documentary evidence to temperature values to capture long-term climate changes, because the documents often reflect temperatures relative to the contemporary authors' own perception of what constituted 'normal' conditions. By contrast, the amplitude of the simulated and reconstructed inter-annual variability agrees rather well.
Dendrochronological data from alluvial forests had long been regarded as unsuitable for climatolo... more Dendrochronological data from alluvial forests had long been regarded as unsuitable for climatologically reconstructions because of the doctrine that dendrochronological data shows the best climate signal if obtained near to climatologically boundaries. Enhanced preparation techniques in combination with high resolution optical scanning allow for precise wood-anatomical analyses, which offer new insight from dendrochronologies hitherto regarded as not to be ideal. This abstract presents a new approach of interpreting climate data derived from dendrochronological proxies from alluvial forests and presents the potential of a time series covering the past 10k years with seasonal resolution for the climate signal, as well as information about flood events within the floodplains. The region of the Main valley in south western Germany offers a large number of written climate proxies, which had been researched and catalogued by the work of Glaser (2008). The available information extends b...
The Climate of the Mediterranean region: From the Past to the Future, 2012
The integration of climate information from instrumental data and documentary and natural archive... more The integration of climate information from instrumental data and documentary and natural archives; evidence of past human activity derived from historical, paleoecological, and archaeological records; and new climate modeling techniques promises major breakthroughs for our understanding of climate sensitivity, ecological processes, environmental response, and human impact. In this chapter, we review the availability and potential of instrumental data, less well-known written records, and terrestrial and marine natural proxy archives for climate in the Mediterranean region over the last 2000 years. We highlight the need to integrate these different proxy archives and the importance for multiproxy studies of disentangling complex relationships among climate, sea-level changes, fire, vegetation, and forests, as well as land use and other human impacts. Focusing on dating uncertainties, we address seasonality effects and other uncertainties in the different proxy records. We describe known and anticipated challenges posed by integrating multiple diverse proxies in high-resolution climate-variation reconstructions, including proxy limitations to robust reconstruction of the natural range of climate variability and problems specific to temporal scales from interannual to multicentennial. Finally, we highlight the potential of paleo models to contribute to climate reconstructions in the Mediterranean, by narrowing the range of climate-sensitivity estimates and by assimilating multiple proxies.
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Papers by Dirk Riemann