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An interlaboratory evaluation of a chemical profiling method for a nerve agent precursor was performed by eight chemical analytical laboratories with a wide global distribution. A set of chemical attribution signatures (i.e. impurities) present in methylphosphonic dichloride (DC) were analysed by gas chromatography-mass spectrometry (GC/MS). The GC/MS analyses were performed with the individual instrumentation and analytical methods used by the laboratories in proficiency tests organized by the Organisation for the Prohibition of Chemical Weapons (OPCW). Two batches of DC, produced by two different production routes, were dispatched together with one reference sample. By the use of a targeted MS-library, sixteen chemical attribution signatures were analysed in the DC samples. Retention indices, mass spectra and relative peak areas of the GC/MS data were evaluated. When the within batch-data of the eight laboratories were compared, similarity values of 0.720-0.995 were obtained. In addition, the two different batches had clearly unique chemical attribution profiles, as indicated by a large between batch-distance similarity values of 0.509-0.576. Retention indices showed less than +/- 14 retention index unit variation for the 16 chemical attribution signatures. This study showed the potential of getting consistent chemical profiling data over multiple laboratories by the use of retention indices for alignment of GC/MS-data. The results indicate that the GC/MS instrumentation and methods used at most OPCW designated laboratories are valid tools for the acquisition of chemical profiling data of importance for the attribution analysis to study suspected production or use of chemical warfare agents.

Although chemical warfare agents (CWAs) are prohibited under international law, there have been numerous crimes that violates the 1997 Chemical Weapons Convention (CWC) during the last decade, especially in the civil war in Syria where sarin, mustard gas and chlorine have all been used. CWAs have also been used in political assassinations and attempts thereof. In such situations, it is important to identify the deployed CWA and to find information on how it was produced, as this information is potentially of considerable value for any ensuing judicial process. The development and use of advanced analytical methods and multivariate data analysis methods are required to produce this kind of robust forensic evidence and intelligence. This thesis describes conducted research that aims at retrospectively tracing the synthesis methods applied in the production of CWAs. In three studies, methods for the determination of the employed synthetic route have been assessed. The relative distribution of the impurities gave a unique profile – in effect a “chemical fingerprint” - that was used for retrospective determination of the production method of a specific CWA. The study in paper I was done on the nerve agent Russian VX, S-[2-(diethylamino)ethyl] O-isobutyl metylphosphonothioate, while paper II and III focused on sulfur mustard, bis(2-chloroethyl)sulfide. This thesis discusses the study set up, the choice of analytical methods, methods for data processing and the manner in which classification methods have been employed. The studies shows that the classification models could clearly separate the six production routes used in paper I and the five routes used in paper II. In paper III, a novel non-targeted approach in combination with high-resolution mass spectrometry allowed detection of additional low-concentration compounds in the sulfur mustard samples. This method produced data with sufficient information for classifying samples according to the production method of th, 2022-11-02: ISBN (PDF) has been corrected in the E-version.Funding agencies: FOI

Although chemical warfare agents (CWAs) are prohibited under international law, there have been numerous crimes that violates the 1997 Chemical Weapons Convention (CWC) during the last decade, especially in the civil war in Syria where sarin, mustard gas and chlorine have all been used. CWAs have also been used in political assassinations and attempts thereof. In such situations, it is important to identify the deployed CWA and to find information on how it was produced, as this information is potentially of considerable value for any ensuing judicial process. The development and use of advanced analytical methods and multivariate data analysis methods are required to produce this kind of robust forensic evidence and intelligence. This thesis describes conducted research that aims at retrospectively tracing the synthesis methods applied in the production of CWAs. In three studies, methods for the determination of the employed synthetic route have been assessed. The relative distribution of the impurities gave a unique profile – in effect a “chemical fingerprint” - that was used for retrospective determination of the production method of a specific CWA. The study in paper I was done on the nerve agent Russian VX, S-[2-(diethylamino)ethyl] O-isobutyl metylphosphonothioate, while paper II and III focused on sulfur mustard, bis(2-chloroethyl)sulfide. This thesis discusses the study set up, the choice of analytical methods, methods for data processing and the manner in which classification methods have been employed. The studies shows that the classification models could clearly separate the six production routes used in paper I and the five routes used in paper II. In paper III, a novel non-targeted approach in combination with high-resolution mass spectrometry allowed detection of additional low-concentration compounds in the sulfur mustard samples. This method produced data with sufficient information for classifying samples according to the production method of th, 2022-11-02: ISBN (PDF) has been corrected in the E-version.Funding agencies: FOI

Although chemical warfare agents (CWAs) are prohibited under international law, there have been numerous crimes that violates the 1997 Chemical Weapons Convention (CWC) during the last decade, especially in the civil war in Syria where sarin, mustard gas and chlorine have all been used. CWAs have also been used in political assassinations and attempts thereof. In such situations, it is important to identify the deployed CWA and to find information on how it was produced, as this information is potentially of considerable value for any ensuing judicial process. The development and use of advanced analytical methods and multivariate data analysis methods are required to produce this kind of robust forensic evidence and intelligence. This thesis describes conducted research that aims at retrospectively tracing the synthesis methods applied in the production of CWAs. In three studies, methods for the determination of the employed synthetic route have been assessed. The relative distribution of the impurities gave a unique profile – in effect a “chemical fingerprint” - that was used for retrospective determination of the production method of a specific CWA. The study in paper I was done on the nerve agent Russian VX, S-[2-(diethylamino)ethyl] O-isobutyl metylphosphonothioate, while paper II and III focused on sulfur mustard, bis(2-chloroethyl)sulfide. This thesis discusses the study set up, the choice of analytical methods, methods for data processing and the manner in which classification methods have been employed. The studies shows that the classification models could clearly separate the six production routes used in paper I and the five routes used in paper II. In paper III, a novel non-targeted approach in combination with high-resolution mass spectrometry allowed detection of additional low-concentration compounds in the sulfur mustard samples. This method produced data with sufficient information for classifying samples according to the production method of th, 2022-11-02: ISBN (PDF) has been corrected in the E-version.Funding agencies: FOI

Although chemical warfare agents (CWAs) are prohibited under international law, there have been numerous crimes that violates the 1997 Chemical Weapons Convention (CWC) during the last decade, especially in the civil war in Syria where sarin, mustard gas and chlorine have all been used. CWAs have also been used in political assassinations and attempts thereof. In such situations, it is important to identify the deployed CWA and to find information on how it was produced, as this information is potentially of considerable value for any ensuing judicial process. The development and use of advanced analytical methods and multivariate data analysis methods are required to produce this kind of robust forensic evidence and intelligence. This thesis describes conducted research that aims at retrospectively tracing the synthesis methods applied in the production of CWAs. In three studies, methods for the determination of the employed synthetic route have been assessed. The relative distribution of the impurities gave a unique profile – in effect a “chemical fingerprint” - that was used for retrospective determination of the production method of a specific CWA. The study in paper I was done on the nerve agent Russian VX, S-[2-(diethylamino)ethyl] O-isobutyl metylphosphonothioate, while paper II and III focused on sulfur mustard, bis(2-chloroethyl)sulfide. This thesis discusses the study set up, the choice of analytical methods, methods for data processing and the manner in which classification methods have been employed. The studies shows that the classification models could clearly separate the six production routes used in paper I and the five routes used in paper II. In paper III, a novel non-targeted approach in combination with high-resolution mass spectrometry allowed detection of additional low-concentration compounds in the sulfur mustard samples. This method produced data with sufficient information for classifying samples according to the production method of th, 2022-11-02: ISBN (PDF) has been corrected in the E-version.Funding agencies: FOI

Although chemical warfare agents (CWAs) are prohibited under international law, there have been numerous crimes that violates the 1997 Chemical Weapons Convention (CWC) during the last decade, especially in the civil war in Syria where sarin, mustard gas and chlorine have all been used. CWAs have also been used in political assassinations and attempts thereof. In such situations, it is important to identify the deployed CWA and to find information on how it was produced, as this information is potentially of considerable value for any ensuing judicial process. The development and use of advanced analytical methods and multivariate data analysis methods are required to produce this kind of robust forensic evidence and intelligence. This thesis describes conducted research that aims at retrospectively tracing the synthesis methods applied in the production of CWAs. In three studies, methods for the determination of the employed synthetic route have been assessed. The relative distribution of the impurities gave a unique profile – in effect a “chemical fingerprint” - that was used for retrospective determination of the production method of a specific CWA. The study in paper I was done on the nerve agent Russian VX, S-[2-(diethylamino)ethyl] O-isobutyl metylphosphonothioate, while paper II and III focused on sulfur mustard, bis(2-chloroethyl)sulfide. This thesis discusses the study set up, the choice of analytical methods, methods for data processing and the manner in which classification methods have been employed. The studies shows that the classification models could clearly separate the six production routes used in paper I and the five routes used in paper II. In paper III, a novel non-targeted approach in combination with high-resolution mass spectrometry allowed detection of additional low-concentration compounds in the sulfur mustard samples. This method produced data with sufficient information for classifying samples according to the production method of th, 2022-11-02: ISBN (PDF) has been corrected in the E-version.Funding agencies: FOI

Bakgrund: Alla diabetiker erbjuds screening av ögonbottnen för diabetesretinopati så att den ska kunna upptäckas och behandlas i tid. Enligt Region Skånes riktlinje för screening av diabetesretinopati kan en traditionell funduskamera eller en wide field ka-mera som täcker 80 procent av näthinnan användas, något som hittills enbart Optos kan. Syftet med studien var att undersöka hälso- och sjukvårdspersonalens uppfattningar om Optos i samband med screening av diabetesretinopati. Metod: Femton ögonmottagningar visade sig använda Optos. Av dessa deltog tio i tvär-snittsenkätstudien. En webbenkät utformades bestående av öppna och multiple-choice frågor. Fritextsvaren analyserades med innehållsanalys som resulterade i ett antal kategorier och respektive svarsfrekvenser. Resultat: Optos uppfattades som en användar- och patientvänlig metod vilken kan öka tillgängligheten. Skärpan i Optomap uppfattades vara god, men något sämre än i fun-dusbilderna. Några uppfattade Optos som en bra metod för screening av diabetesretino-pati. Andra ansåg att användning av Optos skulle innebära en patientrisk. Då den sämre centrala skärpan skulle kunna leda till underdiagnosticering alternativt att Optomaps stora täckningsgrad skulle kunna vara anledning till en överdiagnosticering. Ett stort externt bortfall begränsar studieresultatets generaliserbarhet. Slutsats: Uppfattningar huruvida Optos anses vara lämpligt att användas i samband med screening av diabetesretinopati går isär och lämpliga användningsområden behöver definieras närmare., Background: Screening for retinopathy is offered to all diabetics to allow detection and treatment on time. According to a regional guideline for screening of diabetic retino-pathy traditional fundus camera may be used or a wide field camera picturing 80 % of the retina, something nowadays only Optos can do. Aim of this study was to investigate health personnel’s attitude towards Optos in the context of diabetic retinopathy screening. Methods: Fifteen eye clinics using Optos were identified and ten of those took part in this survey. Self-administered questionnaires with multiple-choice and open questions were used. Free text answers were analysed using context analysis with determination of frequencies for the evolving categories. Results: Optos was perceived as being user and patient friendly, as well as being able to increase accessibility. Optomap had good but digital fundus pictures better perceived acuity. According to some was Optos a good method for screening of diabetic retino-pathy and inappropriate according to others apprehending a patient risk. Expecting underdiagnosis due to less central acuity alternatively overdiagnosis due to Optomap covering 80 % of the retina. High drop-out rate eventuates limited validity. Conclusions: Diverging attitudes emerged whether Optos is suitable for screening of diabetic retinopathy. Its appropriate use needs to be defined in further detail.

Bakgrund: Alla diabetiker erbjuds screening av ögonbottnen för diabetesretinopati så att den ska kunna upptäckas och behandlas i tid. Enligt Region Skånes riktlinje för screening av diabetesretinopati kan en traditionell funduskamera eller en wide field ka-mera som täcker 80 procent av näthinnan användas, något som hittills enbart Optos kan. Syftet med studien var att undersöka hälso- och sjukvårdspersonalens uppfattningar om Optos i samband med screening av diabetesretinopati. Metod: Femton ögonmottagningar visade sig använda Optos. Av dessa deltog tio i tvär-snittsenkätstudien. En webbenkät utformades bestående av öppna och multiple-choice frågor. Fritextsvaren analyserades med innehållsanalys som resulterade i ett antal kategorier och respektive svarsfrekvenser. Resultat: Optos uppfattades som en användar- och patientvänlig metod vilken kan öka tillgängligheten. Skärpan i Optomap uppfattades vara god, men något sämre än i fun-dusbilderna. Några uppfattade Optos som en bra metod för screening av diabetesretino-pati. Andra ansåg att användning av Optos skulle innebära en patientrisk. Då den sämre centrala skärpan skulle kunna leda till underdiagnosticering alternativt att Optomaps stora täckningsgrad skulle kunna vara anledning till en överdiagnosticering. Ett stort externt bortfall begränsar studieresultatets generaliserbarhet. Slutsats: Uppfattningar huruvida Optos anses vara lämpligt att användas i samband med screening av diabetesretinopati går isär och lämpliga användningsområden behöver definieras närmare., Background: Screening for retinopathy is offered to all diabetics to allow detection and treatment on time. According to a regional guideline for screening of diabetic retino-pathy traditional fundus camera may be used or a wide field camera picturing 80 % of the retina, something nowadays only Optos can do. Aim of this study was to investigate health personnel’s attitude towards Optos in the context of diabetic retinopathy screening. Methods: Fifteen eye clinics using Optos were identified and ten of those took part in this survey. Self-administered questionnaires with multiple-choice and open questions were used. Free text answers were analysed using context analysis with determination of frequencies for the evolving categories. Results: Optos was perceived as being user and patient friendly, as well as being able to increase accessibility. Optomap had good but digital fundus pictures better perceived acuity. According to some was Optos a good method for screening of diabetic retino-pathy and inappropriate according to others apprehending a patient risk. Expecting underdiagnosis due to less central acuity alternatively overdiagnosis due to Optomap covering 80 % of the retina. High drop-out rate eventuates limited validity. Conclusions: Diverging attitudes emerged whether Optos is suitable for screening of diabetic retinopathy. Its appropriate use needs to be defined in further detail.

Route determination of sulfur mustard was accomplished through comprehensive nontargeted screening of chemical attribution signatures. Sulfur mustard samples prepared via 11 different synthetic routes were analyzed using gas chromatography/high-resolution mass spectrometry. A large number of compounds were detected, and multivariate data analysis of the mass spectrometric results enabled the discovery of route-specific signature profiles. The performance of two supervised machine learning algorithms for retrospective synthetic route attribution, orthogonal partial least squares discriminant analysis (OPLS-DA) and random forest (RF), were compared using external test sets. Complete classification accuracy was achieved for test set samples (2/2 and 9/9) by using classification models to resolve the one-step routes starting from ethylene and the thiodiglycol chlorination methods used in the two-step routes. Retrospective determination of initial thiodiglycol synthesis methods in sulfur mustard samples, following chlorination, was more difficult. Nevertheless, the large number of markers detected using the nontargeted methodology enabled correct assignment of 5/9 test set samples using OPLS-DA and 8/9 using RF. RF was also used to construct an 11-class model with a total classification accuracy of 10/11. The developed methods were further evaluated by classifying sulfur mustard spiked into soil and textile matrix samples. Due to matrix effects and the low spiking level (0.05% w/w), route determination was more challenging in these cases. Nevertheless, acceptable classification performance was achieved during external test set validation: chlorination methods were correctly classified for 12/18 and 11/15 in spiked soil and textile samples, respectively., Funding agencies: This work was funded by the Swedish Ministry of Defence and the Swedish Civil Contingencies Agency

Route determination of sulfur mustard was accomplished through comprehensive nontargeted screening of chemical attribution signatures. Sulfur mustard samples prepared via 11 different synthetic routes were analyzed using gas chromatography/high-resolution mass spectrometry. A large number of compounds were detected, and multivariate data analysis of the mass spectrometric results enabled the discovery of route-specific signature profiles. The performance of two supervised machine learning algorithms for retrospective synthetic route attribution, orthogonal partial least squares discriminant analysis (OPLS-DA) and random forest (RF), were compared using external test sets. Complete classification accuracy was achieved for test set samples (2/2 and 9/9) by using classification models to resolve the one-step routes starting from ethylene and the thiodiglycol chlorination methods used in the two-step routes. Retrospective determination of initial thiodiglycol synthesis methods in sulfur mustard samples, following chlorination, was more difficult. Nevertheless, the large number of markers detected using the nontargeted methodology enabled correct assignment of 5/9 test set samples using OPLS-DA and 8/9 using RF. RF was also used to construct an 11-class model with a total classification accuracy of 10/11. The developed methods were further evaluated by classifying sulfur mustard spiked into soil and textile matrix samples. Due to matrix effects and the low spiking level (0.05% w/w), route determination was more challenging in these cases. Nevertheless, acceptable classification performance was achieved during external test set validation: chlorination methods were correctly classified for 12/18 and 11/15 in spiked soil and textile samples, respectively., Funding agencies: This work was funded by the Swedish Ministry of Defence and the Swedish Civil Contingencies Agency

Route determination of sulfur mustard was accomplished through comprehensive nontargeted screening of chemical attribution signatures. Sulfur mustard samples prepared via 11 different synthetic routes were analyzed using gas chromatography/high-resolution mass spectrometry. A large number of compounds were detected, and multivariate data analysis of the mass spectrometric results enabled the discovery of route-specific signature profiles. The performance of two supervised machine learning algorithms for retrospective synthetic route attribution, orthogonal partial least squares discriminant analysis (OPLS-DA) and random forest (RF), were compared using external test sets. Complete classification accuracy was achieved for test set samples (2/2 and 9/9) by using classification models to resolve the one-step routes starting from ethylene and the thiodiglycol chlorination methods used in the two-step routes. Retrospective determination of initial thiodiglycol synthesis methods in sulfur mustard samples, following chlorination, was more difficult. Nevertheless, the large number of markers detected using the nontargeted methodology enabled correct assignment of 5/9 test set samples using OPLS-DA and 8/9 using RF. RF was also used to construct an 11-class model with a total classification accuracy of 10/11. The developed methods were further evaluated by classifying sulfur mustard spiked into soil and textile matrix samples. Due to matrix effects and the low spiking level (0.05% w/w), route determination was more challenging in these cases. Nevertheless, acceptable classification performance was achieved during external test set validation: chlorination methods were correctly classified for 12/18 and 11/15 in spiked soil and textile samples, respectively., Funding agencies: This work was funded by the Swedish Ministry of Defence and the Swedish Civil Contingencies Agency

Route determination of sulfur mustard was accomplished through comprehensive nontargeted screening of chemical attribution signatures. Sulfur mustard samples prepared via 11 different synthetic routes were analyzed using gas chromatography/high-resolution mass spectrometry. A large number of compounds were detected, and multivariate data analysis of the mass spectrometric results enabled the discovery of route-specific signature profiles. The performance of two supervised machine learning algorithms for retrospective synthetic route attribution, orthogonal partial least squares discriminant analysis (OPLS-DA) and random forest (RF), were compared using external test sets. Complete classification accuracy was achieved for test set samples (2/2 and 9/9) by using classification models to resolve the one-step routes starting from ethylene and the thiodiglycol chlorination methods used in the two-step routes. Retrospective determination of initial thiodiglycol synthesis methods in sulfur mustard samples, following chlorination, was more difficult. Nevertheless, the large number of markers detected using the nontargeted methodology enabled correct assignment of 5/9 test set samples using OPLS-DA and 8/9 using RF. RF was also used to construct an 11-class model with a total classification accuracy of 10/11. The developed methods were further evaluated by classifying sulfur mustard spiked into soil and textile matrix samples. Due to matrix effects and the low spiking level (0.05% w/w), route determination was more challenging in these cases. Nevertheless, acceptable classification performance was achieved during external test set validation: chlorination methods were correctly classified for 12/18 and 11/15 in spiked soil and textile samples, respectively., Funding agencies: This work was funded by the Swedish Ministry of Defence and the Swedish Civil Contingencies Agency

Route determination of sulfur mustard was accomplished through comprehensive nontargeted screening of chemical attribution signatures. Sulfur mustard samples prepared via 11 different synthetic routes were analyzed using gas chromatography/high-resolution mass spectrometry. A large number of compounds were detected, and multivariate data analysis of the mass spectrometric results enabled the discovery of route-specific signature profiles. The performance of two supervised machine learning algorithms for retrospective synthetic route attribution, orthogonal partial least squares discriminant analysis (OPLS-DA) and random forest (RF), were compared using external test sets. Complete classification accuracy was achieved for test set samples (2/2 and 9/9) by using classification models to resolve the one-step routes starting from ethylene and the thiodiglycol chlorination methods used in the two-step routes. Retrospective determination of initial thiodiglycol synthesis methods in sulfur mustard samples, following chlorination, was more difficult. Nevertheless, the large number of markers detected using the nontargeted methodology enabled correct assignment of 5/9 test set samples using OPLS-DA and 8/9 using RF. RF was also used to construct an 11-class model with a total classification accuracy of 10/11. The developed methods were further evaluated by classifying sulfur mustard spiked into soil and textile matrix samples. Due to matrix effects and the low spiking level (0.05% w/w), route determination was more challenging in these cases. Nevertheless, acceptable classification performance was achieved during external test set validation: chlorination methods were correctly classified for 12/18 and 11/15 in spiked soil and textile samples, respectively., Funding agencies: This work was funded by the Swedish Ministry of Defence and the Swedish Civil Contingencies Agency

Collecting data under field conditions for forensic investigations of chemical warfare agents calls for the use of portable instruments. In this study, a set of aged, crude preparations of sulfur mustard were characterized spectroscopically without any sample preparation using handheld Raman and portable IR instruments. The spectral data was used to construct Random Forest multivariate models for the attribution of test set samples to the synthetic method used for their production. Colored and fluorescent samples were included in the study, which made Raman spectroscopy challenging although fluorescence was diminished by using an excitation wavelength of 1064 nm. The predictive power of models constructed with IR or Raman data alone, as well as with combined data was investigated. Both techniques gave useful data for attribution. Model performance was enhanced when Raman and IR spectra were combined, allowing correct classification of 19/23 (83%) of test set spectra. The results demonstrate that data obtained with spectroscopy instruments amenable for field deployment can be useful in forensic studies of chemical warfare agents.

Chemical attribution signatures (CAS) associated with different synthetic routes used for the production of Russian VX (VR) were identified. The goal of the study was to retrospectively determine the production method employed for an unknown VR sample. Six different production methods were evaluated, carefully chosen to include established synthetic routes used in the past for large scale production of the agent, routes involving general phosphorus-sulfur chemistry pathways leading to the agent, and routes whose main characteristic is their innate simplicity in execution. Two laboratories worked in parallel and synthesized a total of 37 batches of VR via the six synthetic routes following predefined synthesis protocols. The chemical composition of impurities and byproducts in each route was analyzed by GC/MS-EI and 49 potential CAS were recognized as important markers in distinguishing these routes using Principal Component Analysis (PCA). The 49 potential CAS included expected species based on knowledge of reaction conditions and pathways but also several novel compounds that were fully identified and characterized by a combined analysis that included MS-CI, MS-EI and HR-MS. The CAS profiles of the calibration set were then analyzed using partial least squares discriminant analysis (PLS-DA) and a cross validated model was constructed. The model allowed the correct classification of an external test set without any misclassifications, demonstrating the utility of this methodology for attributing VR samples to a particular production method. This work is part one of a three-part series in this Forensic VSI issue of a Sweden-United States collaborative effort towards the understanding of the CAS of VR in diverse batches and matrices. This part focuses on the CAS in synthesized batches of crude VR and in the following two parts of the series the influence of food matrices on the CAS profiles are investigated., Funding agencies: the Swedish Civil Contingencies Agency (under Contract 2014–5170) and the Department of Homeland Security, Science and Technology Directorate, Chemical Forensic Program (under Contract # HSHQPM-10-X-00014 and HSHQPM-11-X-00247), United States

A multivariate model was developed to attribute samples to a synthetic method used in the production of sulfur mustard (HD). Eleven synthetic methods were used to produce 66 samples for model construction. Three chemists working in both participating laboratories took part in the production, with the aim to introduce variability while reducing the influence of laboratory or chemist specific impurities in multivariate analysis. A gas chromatographic/mass spectrometric data set of peak areas for 103 compounds was subjected to orthogonal partial least squares - discriminant analysis to extract chemical attribution signature profiles and to construct multivariate models for classification of samples. For one- and two-step routes, model quality allowed the classification of an external test set (16/16 samples) according to synthesis conditions in the reaction yielding sulfur mustard. Classification of samples according to first-step methodology was considerably more difficult, given the high purity and uniform quality of the intermediate thiodiglycol produced in the study. Model performance in classification of aged samples was also investigated., Funding agencies: the Swedish Civil Contingencies Agency [grant number 2014–5170], Sweden, and the Department of Homeland Security, Science and Technology Directorate, Chemical Biological Division [grant number HSHQPM-16-X-00102], United States.

This paper offers new high-resolution oxygen and carbon isotope data from Stalagmite S1 from Mavri Trypa Cave, SW Peloponnese. Our data provide the climate background to the destruction of the nearby Mycenaean Palace of Nestor at Pylos at the transition from Late Helladic (LH) IIIB to LH IIIC, similar to 3150-3130 years before present (before AD 1950, hereafter yrs BP) and the subsequent period. S1 is dated by 24 U-Th dates with an averaged precision of +/- 26 yrs (2s), providing one of the most robust paleoclimate records from the eastern Mediterranean for the end of the Late Bronze Age (LBA). The delta O-18 record shows generally wetter conditions at the time when the Palace of Nestor at Pylos was destroyed, but a brief period of drier conditions around 3200 yrs BP may have disrupted the Mycenaean agricultural system that at the time was likely operating close to its limit. Gradually developing aridity after 3150 yrs BP, i.e. subsequent to the destruction, probably reduced crop yields and helped to erode the basis for the reinstitution of a central authority and the Palace itself.

This paper offers new high-resolution oxygen and carbon isotope data from Stalagmite S1 from Mavri Trypa Cave, SW Peloponnese. Our data provide the climate background to the destruction of the nearby Mycenaean Palace of Nestor at Pylos at the transition from Late Helladic (LH) IIIB to LH IIIC, similar to 3150-3130 years before present (before AD 1950, hereafter yrs BP) and the subsequent period. S1 is dated by 24 U-Th dates with an averaged precision of +/- 26 yrs (2s), providing one of the most robust paleoclimate records from the eastern Mediterranean for the end of the Late Bronze Age (LBA). The delta O-18 record shows generally wetter conditions at the time when the Palace of Nestor at Pylos was destroyed, but a brief period of drier conditions around 3200 yrs BP may have disrupted the Mycenaean agricultural system that at the time was likely operating close to its limit. Gradually developing aridity after 3150 yrs BP, i.e. subsequent to the destruction, probably reduced crop yields and helped to erode the basis for the reinstitution of a central authority and the Palace itself.

This paper offers new high-resolution oxygen and carbon isotope data from Stalagmite S1 from Mavri Trypa Cave, SW Peloponnese. Our data provide the climate background to the destruction of the nearby Mycenaean Palace of Nestor at Pylos at the transition from Late Helladic (LH) IIIB to LH IIIC, similar to 3150-3130 years before present (before AD 1950, hereafter yrs BP) and the subsequent period. S1 is dated by 24 U-Th dates with an averaged precision of +/- 26 yrs (2s), providing one of the most robust paleoclimate records from the eastern Mediterranean for the end of the Late Bronze Age (LBA). The delta O-18 record shows generally wetter conditions at the time when the Palace of Nestor at Pylos was destroyed, but a brief period of drier conditions around 3200 yrs BP may have disrupted the Mycenaean agricultural system that at the time was likely operating close to its limit. Gradually developing aridity after 3150 yrs BP, i.e. subsequent to the destruction, probably reduced crop yields and helped to erode the basis for the reinstitution of a central authority and the Palace itself.

This paper offers new high-resolution oxygen and carbon isotope data from Stalagmite S1 from Mavri Trypa Cave, SW Peloponnese. Our data provide the climate background to the destruction of the nearby Mycenaean Palace of Nestor at Pylos at the transition from Late Helladic (LH) IIIB to LH IIIC, similar to 3150-3130 years before present (before AD 1950, hereafter yrs BP) and the subsequent period. S1 is dated by 24 U-Th dates with an averaged precision of +/- 26 yrs (2s), providing one of the most robust paleoclimate records from the eastern Mediterranean for the end of the Late Bronze Age (LBA). The delta O-18 record shows generally wetter conditions at the time when the Palace of Nestor at Pylos was destroyed, but a brief period of drier conditions around 3200 yrs BP may have disrupted the Mycenaean agricultural system that at the time was likely operating close to its limit. Gradually developing aridity after 3150 yrs BP, i.e. subsequent to the destruction, probably reduced crop yields and helped to erode the basis for the reinstitution of a central authority and the Palace itself.

This paper offers new high-resolution oxygen and carbon isotope data from Stalagmite S1 from Mavri Trypa Cave, SW Peloponnese. Our data provide the climate background to the destruction of the nearby Mycenaean Palace of Nestor at Pylos at the transition from Late Helladic (LH) IIIB to LH IIIC, similar to 3150-3130 years before present (before AD 1950, hereafter yrs BP) and the subsequent period. S1 is dated by 24 U-Th dates with an averaged precision of +/- 26 yrs (2s), providing one of the most robust paleoclimate records from the eastern Mediterranean for the end of the Late Bronze Age (LBA). The delta O-18 record shows generally wetter conditions at the time when the Palace of Nestor at Pylos was destroyed, but a brief period of drier conditions around 3200 yrs BP may have disrupted the Mycenaean agricultural system that at the time was likely operating close to its limit. Gradually developing aridity after 3150 yrs BP, i.e. subsequent to the destruction, probably reduced crop yields and helped to erode the basis for the reinstitution of a central authority and the Palace itself.

This paper offers new high-resolution oxygen and carbon isotope data from Stalagmite S1 from Mavri Trypa Cave, SW Peloponnese. Our data provide the climate background to the destruction of the nearby Mycenaean Palace of Nestor at Pylos at the transition from Late Helladic (LH) IIIB to LH IIIC, similar to 3150-3130 years before present (before AD 1950, hereafter yrs BP) and the subsequent period. S1 is dated by 24 U-Th dates with an averaged precision of +/- 26 yrs (2s), providing one of the most robust paleoclimate records from the eastern Mediterranean for the end of the Late Bronze Age (LBA). The delta O-18 record shows generally wetter conditions at the time when the Palace of Nestor at Pylos was destroyed, but a brief period of drier conditions around 3200 yrs BP may have disrupted the Mycenaean agricultural system that at the time was likely operating close to its limit. Gradually developing aridity after 3150 yrs BP, i.e. subsequent to the destruction, probably reduced crop yields and helped to erode the basis for the reinstitution of a central authority and the Palace itself.

We develop and present a novel integrated water balance model that accounts for lake watergroundwater interactions, and apply it to the semi-closed freshwater Lake Babati system, Northern Tanzania, East Africa. The model was calibrated and used to evaluate the lake level sensitivity to changes in key hydro-climatic variables such as temperature, precipitation, humidity and cloudiness. The lake response to the Coupled Model Intercomparison Project, Phase 5 (CMIP5) output on possible future climate outcomes was evaluated, an essential basis in understanding future water security and flooding risk in the region. Results show high lake level sensitivity to cloudiness. Increased focus on cloud fraction measurement and interpretation could likely improve projections of lake levels and surface water availability. Modelled divergent results on the future (21st century) development of Lake Babati can be explained by the precipitation output variability of CMIP5 models being comparable to the precipitation change needed to drive the water balance model from lake dry-out to overflow; this condition is likely shared with many other East African lake systems. The developed methodology could be useful in investigations on change-driving processes in complex climatedrainage basinlake systems, which are needed to support sustainable water resource planning in data scarce tropical Africa.

We develop and present a novel integrated water balance model that accounts for lake watergroundwater interactions, and apply it to the semi-closed freshwater Lake Babati system, Northern Tanzania, East Africa. The model was calibrated and used to evaluate the lake level sensitivity to changes in key hydro-climatic variables such as temperature, precipitation, humidity and cloudiness. The lake response to the Coupled Model Intercomparison Project, Phase 5 (CMIP5) output on possible future climate outcomes was evaluated, an essential basis in understanding future water security and flooding risk in the region. Results show high lake level sensitivity to cloudiness. Increased focus on cloud fraction measurement and interpretation could likely improve projections of lake levels and surface water availability. Modelled divergent results on the future (21st century) development of Lake Babati can be explained by the precipitation output variability of CMIP5 models being comparable to the precipitation change needed to drive the water balance model from lake dry-out to overflow; this condition is likely shared with many other East African lake systems. The developed methodology could be useful in investigations on change-driving processes in complex climatedrainage basinlake systems, which are needed to support sustainable water resource planning in data scarce tropical Africa.

We develop and present a novel integrated water balance model that accounts for lake watergroundwater interactions, and apply it to the semi-closed freshwater Lake Babati system, Northern Tanzania, East Africa. The model was calibrated and used to evaluate the lake level sensitivity to changes in key hydro-climatic variables such as temperature, precipitation, humidity and cloudiness. The lake response to the Coupled Model Intercomparison Project, Phase 5 (CMIP5) output on possible future climate outcomes was evaluated, an essential basis in understanding future water security and flooding risk in the region. Results show high lake level sensitivity to cloudiness. Increased focus on cloud fraction measurement and interpretation could likely improve projections of lake levels and surface water availability. Modelled divergent results on the future (21st century) development of Lake Babati can be explained by the precipitation output variability of CMIP5 models being comparable to the precipitation change needed to drive the water balance model from lake dry-out to overflow; this condition is likely shared with many other East African lake systems. The developed methodology could be useful in investigations on change-driving processes in complex climatedrainage basinlake systems, which are needed to support sustainable water resource planning in data scarce tropical Africa.

This paper reviews the methodological and practical issues relevant to the ways in which natural scientists, historians and archaeologists may collaborate in the study of past climatic changes in the Mediterranean basin. We begin by discussing the methodologies of these three disciplines in the context of the consilience debate, that is, attempts to unify different research methodologies that address similar problems. We demonstrate that there are a number of similarities in the fundamental methodology between history, archaeology, and the natural sciences that deal with the past (“palaeoenvironmental sciences”), due to their common interest in studying societal and environmental phenomena that no longer exist. The three research traditions, for instance, employ specific narrative structures as a means of communicating research results. We thus present and compare the narratives characteristic of each discipline; in order to engage in fruitful interdisciplinary exchange, we must first understand how each deals with the societal impacts of climatic change. In the second part of the paper, we focus our discussion on the four major practical issues that hinder communication between the three disciplines. These include terminological misunderstandings, problems relevant to project design, divergences in publication cultures, and differing views on the impact of research. Among other recommendations, we suggest that scholars from the three disciplines should aim to create a joint publication culture, which should also appeal to a wider public, both inside and outside of academia., Special Issue: Mediterranean Holocene Climate, Environment and Human Societies

Published archaeological, palaeoenvironmental, and palaeoclimatic data from the Peloponnese in Greece are compiled, discussed and evaluated in order to analyse the interactions between humans and the environment over the last 9000 years. Our study indicates that the number of human settlements found scattered over the peninsula have quadrupled from the prehistoric to historical periods and that this evolution occurred over periods of climate change and seismo–tectonic activity. We show that societal development occurs both during periods of harsh as well as favourable climatic conditions. At some times, some settlements develop while others decline. Well-known climate events such as the 4.2 ka and 3.2 ka events are recognizable in some of the palaeoclimatic records and a regional decline in the number and sizes of settlements occurs roughly at the same time, but their precise chronological fit with the archaeological record remains uncertain. Local socio-political processes were probably always the key drivers behind the diverse strategies that human societies took in times of changing climate. The study thus reveals considerable chronological parallels between societal development and palaeoenvironmental records, but also demonstrates the ambiguities in these correspondences and, in doing so, highlights some of the challenges that will face future interdisciplinary projects. We suggest that there can be no general association made between societal expansion phases and periods of advantageous climate. We also propose that the relevance of climatic and environmental regionality, as well as any potential impacts of seismo-tectonics on societal development, need to be part of the interpretative frameworks., Special Issue: Mediterranean Holocene Climate, Environment and Human Societies

We develop and present a novel integrated water balance model that accounts for lake watergroundwater interactions, and apply it to the semi-closed freshwater Lake Babati system, Northern Tanzania, East Africa. The model was calibrated and used to evaluate the lake level sensitivity to changes in key hydro-climatic variables such as temperature, precipitation, humidity and cloudiness. The lake response to the Coupled Model Intercomparison Project, Phase 5 (CMIP5) output on possible future climate outcomes was evaluated, an essential basis in understanding future water security and flooding risk in the region. Results show high lake level sensitivity to cloudiness. Increased focus on cloud fraction measurement and interpretation could likely improve projections of lake levels and surface water availability. Modelled divergent results on the future (21st century) development of Lake Babati can be explained by the precipitation output variability of CMIP5 models being comparable to the precipitation change needed to drive the water balance model from lake dry-out to overflow; this condition is likely shared with many other East African lake systems. The developed methodology could be useful in investigations on change-driving processes in complex climatedrainage basinlake systems, which are needed to support sustainable water resource planning in data scarce tropical Africa.

Published archaeological, palaeoenvironmental, and palaeoclimatic data from the Peloponnese in Greece are compiled, discussed and evaluated in order to analyse the interactions between humans and the environment over the last 9000 years. Our study indicates that the number of human settlements found scattered over the peninsula have quadrupled from the prehistoric to historical periods and that this evolution occurred over periods of climate change and seismo-tectonic activity. We show that societal development occurs both during periods of harsh as well as favourable climatic conditions. At some times, some settlements develop while others decline. Well-known climate events such as the 4.2 ka and 3.2 ka events are recognizable in some of the palaeoclimatic records and a regional decline in the number and sizes of settlements occurs roughly at the same time, but their precise chronological fit with the archaeological record remains uncertain. Local socio-political processes were probably always the key drivers behind the diverse strategies that human societies took in times of changing climate. The study thus reveals considerable chronological parallels between societal development and palaeoenvironmental records, but also demonstrates the ambiguities in these correspondences and, in doing so, highlights some of the challenges that will face future interdisciplinary projects. We suggest that there can be no general association made between societal expansion phases and periods of advantageous climate. We also propose that the relevance of climatic and environmental regionality, as well as any potential impacts of seismo-tectonics on societal development, need to be part of the interpretative frameworks.

In a previous palaeoenvironmental study based on a high-resolution diatom record from a core sampled at the Agios Floros fen, SW Peloponnese, Greece, Cyclotella distinguenda was reported as exhibiting two morphs with distinct central area and stria arrangement, as well as a specific distribution throughout the sequence. In the present paper, we examine this morphological variability through detailed observations using light and scanning electron microscope combined with a simple statistical approach. Our new data suggest that the two morphs present substantial and constant differences in the structure and size of their central areas, the structure and number of their striae, the arrangement of their marginal fultoportulae/density of costae between fultoportulae, the shape of their rimoportulae and their alveolar chambers. On the basis of these morphological and stratigraphic variations one morph is described as a new species, Cyclotella paradistinguenda sp. nov., while the other is assigned to C. distinguenda and is also consistent with the original description of this taxon. The two species share well-defined central areas without fultoportulae, almost equal length striae and one rimoportula situated on a costa within the ring of marginal fultoportulae. Cyclotella paradistinguenda sp. nov. can be distinguished by a combination of the following characteristics: (1) large central area (1/3 of valve diameter), smooth or decorated with puncta and depressions, flat or concentrically undulated, (2) distinct, narrow striae (12-15/10 mu m) consisting of one or two short rows of areolae of the same size expanding into three rows at the mantle, (3) marginal fultoportulae on each first to third costae (4) poorly developed alveolar chambers and rimoportula. Based on the stratigraphic distribution and the associated flora in the Agios Floros sequence, it can be inferred that C. paradistinguenda sp. nov. is tolerant of shallower water conditions with lower nutrient availability

A paleolimnological record from the central Messenian plain (southwestern Peloponnese, southern Greece) indicates rapid changes in the water level and chemistry of a transient lake on the flanks of the Taygetos Mountains during the last c. 6000years. The analyses are based on diatoms as well as carbon and nitrogen isotopes from bulk sediments in a 7.5-m-long sediment core retrieved from the drained fen of Agios Floros, at the northern banks of the ancient River Pamisos. The sequence consists of fen peat in the uppermost section underlain by lacustrine sediments, which are punctuated by two layers of clay with diatomaceous silt bands. High accumulation rate is recorded in the oldest part of the section (up to 23mm/yr), particularly during two decadal-long periods centered at c. 5700 and c. 5300 cal. BP. The diatom record reveals pronounced peaks in the planktonic taxon Cyclotella distinguenda, which correspond to the laminated sequences, reflecting the rapid development of a deep lake with an open water environment during these two time periods. Another two events with intermediate water levels are inferred at c. 5200 and c. 4600 cal. BP. These short-lived phases were probably, to a large extent, caused by local tectonic processes and the consequent hydrological anomalies of the nearby karst springs, although abrupt climatic changes with enhanced precipitation might have also played a role. At c. 4500 cal. BP, our data suggest the development of terrestrial conditions in this area, which can be attributed to the decreasing activity/dry up of springs, probably associated with more arid climate. After c. 2500 cal. BP, the diatom record infers a return to wetter conditions, probably as a response to more humid climate with marked seasonality and human activities, developing the present-day environment with cultivated and seasonally semi-flooded fields.

The spatial context is criticalwhen assessing present-day climate anomalies, attributing them to potential forcings and making statements regarding their frequency and severity in a long-term perspective. Recent international initiatives have expanded the number of high-quality proxy-records and developed new statistical reconstruction methods. These advances allow more rigorous regional past temperature reconstructions and, in turn, the possibility of evaluating climate models on policy-relevant, spatiotemporal scales. Here we provide a new proxy-based, annually-resolved, spatial reconstruction of the European summer (June-August) temperature fields back to 755 CE based on Bayesian hierarchical modelling (BHM), together with estimates of the European mean temperature variation since 138 BCE based on BHM and composite-plus-scaling (CPS). Our reconstructions compare well with independent instrumental and proxy-based temperature estimates, but suggest a larger amplitude in summer temperature variability than previously reported. Both CPS and BHM reconstructions indicate that the mean 20th century European summer temperature was not significantly different from some earlier centuries, including the 1st, 2nd, 8th and 10th centuries CE. The 1st century (in BHM also the 10th century) may even have been slightly warmer than the 20th century, but the difference is not statistically significant. Comparing each 50 yr period with the 1951-2000 period reveals a similar pattern. Recent summers, however, have been unusually warm in the context of the last two millennia and there are no 30 yr periods in either reconstruction that exceed the mean average European summer temperature of the last 3 decades (1986-2015 CE). A comparison with an ensemble of climate model simulations suggests that the reconstructed European summer temperature variability over the period 850-2000 CE reflects changes in both internal variability and external forcing on multi-decadal time-scales. For pan-Eur

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.

This paper reviews the methodological and practical issues relevant to the ways in which natural scientists, historians and archaeologists may collaborate in the study of past climatic changes in the Mediterranean basin. We begin by discussing the methodologies of these three disciplines in the context of the consilience debate, that is, attempts to unify different research methodologies that address similar problems. We demonstrate that there are a number of similarities in the fundamental methodology between history, archaeology, and the natural sciences that deal with the past (palaeoenvironmental sciences), due to their common interest in studying societal and environmental phenomena that no longer exist. The three research traditions, for instance, employ specific narrative structures as a means of communicating research results. We thus present and compare the narratives characteristic of each discipline; in order to engage in fruitful interdisciplinary exchange, we must first understand how each deals with the societal impacts of climatic change. In the second part of the paper, we focus our discussion on the four major practical issues that hinder communication between the three disciplines. These include terminological misunderstandings, problems relevant to project design, divergences in publication cultures, and differing views on the impact of research. Among other recommendations, we suggest that scholars from the three disciplines should aim to create a joint publication culture, which should also appeal to a wider public, both inside and outside of academia.

We develop and present a novel integrated water balance model that accounts for lake watergroundwater interactions, and apply it to the semi-closed freshwater Lake Babati system, Northern Tanzania, East Africa. The model was calibrated and used to evaluate the lake level sensitivity to changes in key hydro-climatic variables such as temperature, precipitation, humidity and cloudiness. The lake response to the Coupled Model Intercomparison Project, Phase 5 (CMIP5) output on possible future climate outcomes was evaluated, an essential basis in understanding future water security and flooding risk in the region. Results show high lake level sensitivity to cloudiness. Increased focus on cloud fraction measurement and interpretation could likely improve projections of lake levels and surface water availability. Modelled divergent results on the future (21st century) development of Lake Babati can be explained by the precipitation output variability of CMIP5 models being comparable to the precipitation change needed to drive the water balance model from lake dry-out to overflow; this condition is likely shared with many other East African lake systems. The developed methodology could be useful in investigations on change-driving processes in complex climatedrainage basinlake systems, which are needed to support sustainable water resource planning in data scarce tropical Africa.

We develop and present a novel integrated water balance model that accounts for lake watergroundwater interactions, and apply it to the semi-closed freshwater Lake Babati system, Northern Tanzania, East Africa. The model was calibrated and used to evaluate the lake level sensitivity to changes in key hydro-climatic variables such as temperature, precipitation, humidity and cloudiness. The lake response to the Coupled Model Intercomparison Project, Phase 5 (CMIP5) output on possible future climate outcomes was evaluated, an essential basis in understanding future water security and flooding risk in the region. Results show high lake level sensitivity to cloudiness. Increased focus on cloud fraction measurement and interpretation could likely improve projections of lake levels and surface water availability. Modelled divergent results on the future (21st century) development of Lake Babati can be explained by the precipitation output variability of CMIP5 models being comparable to the precipitation change needed to drive the water balance model from lake dry-out to overflow; this condition is likely shared with many other East African lake systems. The developed methodology could be useful in investigations on change-driving processes in complex climatedrainage basinlake systems, which are needed to support sustainable water resource planning in data scarce tropical Africa.

Multi-proxy analysis was performed on a radiocarbon-dated core, collected from a relic oxbow lake in theLimpopo River-plain, Mozambique, with the aim to reconstruct paleo-environment and past flooding of thelower river system over the past c. 800 years. An additional objective was to evaluate and investigate the potentialuse of different proxies as recorders of paleo-flooding events and paleo-environmental variability within thefloodplain. The proxies applied in this study were: mineral magnetic properties, grain-size distribution, organiccarbon content and diatom microfossil assemblages.We found that sediment grain-size and mineral magneticproperties of the minerogenic fraction were the most sensitive proxies in terms of detecting signals from highintensityriver-discharge events. In the 800 year long sequence, variations in sand content, magnetic susceptibilityand saturation isothermal remnant magnetization suggest at least four major flooding events at the siteduring the reconstructed period; in the mid-1200, late-1300, mid-1500 AD and during the last century. Thediatom proxy reflects the development of the site from an open oxbow lake to a mainly terrestrial area. Thediatom assemblage indicates that open lake conditions prevailed at the site between c. AD 1200–1400, withperiodic inundation by marine water, most likely due to late Holocene sea-level changes. From c. AD 1400 andonwards, diatoms were rarely deposited at the site, which indicates drier conditions. This was a result of soilformation and gradual in-filling of the lake, a processwhich possiblywas accentuated by a regionally dry climatesituation. Our study shows that oxbow lakes and the proxies used here have great potential for reconstructingflooding events, a knowledge that is crucial for potential prediction and mitigation of flooding events inMozambique in the future. Although chronological uncertainties limit comparisons to other paleoenvironmentalrecords, it seems that the flooding events recorded

A rainfall dipole mode characterized by negative correlation between subtropical southern Africa and equatorial eastern Africa is identified in instrumental observation data in the recent 100 years. The dipole mode shows a pronounced oscillation signal at a time scale of about 18 years. This study investigates the underlying dynamical mechanisms responsible for this dipole pattern. It is found that the southern African rainfall dipole index is highly correlated to the land-sea contrast along the east coast of Africa. When the land-sea thermal contrast strengthens, the easterly flow toward the continent becomes stronger. The stronger easterly flow, via its response to east coast topography and surface heating, leads to a low pressure circulation anomaly over land south of the maximum easterly flow anomalies and thus causes more rainfall in the south. On a decadal time scale, an ENSO-like SST pattern acts to modulate this land-sea contrast and the consequent rainfall dipole. During a wet in the south and dry in the north dipole, there are warm SSTs over the central Indian Ocean and cold SSTs over the western Indian Ocean. The cold SSTs over the western Indian Ocean further enhance the land-sea contrast during austral summer. Moreover, these cold western Indian Ocean SSTs also play an important role in regulating land temperature, thereby suppressing clouds and warming the land via increased shortwave radiation over the less-cloudy land. This cloud-SST coupling acts to further strengthen the land-sea contrast.

Multi-proxy analysis was performed on a radiocarbon-dated core, collected from a relic oxbow lake in the Limpopo River-plain, Mozambique, with the aim to reconstruct paleo-environment and past flooding of the lower river system over the past c. 800 years. An additional objective was to evaluate and investigate the potential use of different proxies as recorders of paleo-flooding events and paleo-environmental variability within the floodplain. The proxies applied in this study were: mineral magnetic properties, grain-size distribution, organic carbon content and diatom microfossil assemblages. We found that sediment grain-size and mineral magnetic properties of the minerogenic fraction were the most sensitive proxies in terms of detecting signals from high-intensity river-discharge events. In the 800 year long sequence, variations in sand content, magnetic susceptibility and saturation isothermal remnant magnetization suggest at least four major flooding events at the site during the reconstructed period; in the mid-1200, late-1300, mid-1500 AD and during the last century. The diatom proxy reflects the development of the site from an open oxbow lake to a mainly terrestrial area. The diatom assemblage indicates that open lake conditions prevailed at the site between c. AD 1200-1400, with periodic inundation by marine water, most likely due to late Holocene sea-level changes. From c. AD 1400 and onwards, diatoms were rarely deposited at the site, which indicates drier conditions. This was a result of soil formation and gradual in-filling of the lake, a process which possibly was accentuated by a regionally dry climate situation. Our study shows that oxbow lakes and the proxies used here have great potential for reconstructing flooding events, a knowledge that is crucial for potential prediction and mitigation of flooding events in Mozambique in the future. Although chronological uncertainties limit comparisons to other paleo-environmental records, it seems that the fl

The present day distribution of Miombo savanna-woodland in Mozambique has been attributed to an expansion due to the clearing of original coastal forests through agriculture and use of fire. Here, we test this hypothesis using palaeoecological data from Lake Nhauhache, situated in the Vilankulo region. Our analysis shows that Brachystegia, one of the main constituents of the Miombo, has varied over time, and its variability seems to be driven by hydrological changes related to climatic variability rather than by land-use changes. The analyses show that Brachystegia was most common during ad 200-700 when a marshy forest/shrub community was dominant. After ad 700, this community changes to a dominance of Syzygium and Fagara linked to gradually rising water levels. Brachystegia remains in low abundance and fluctuating over time. From ad 1000, a general decline in trees/shrubs in favour of grasses concurs with an increase in grass pollen (possibly cereal) and charcoal, most probably as a result of farming activities. The decline in tree taxa was probably exacerbated by periodic droughts after c. ad 1200 as indicated by the diatom assemblage. In the period ad 1700 to late 1800, arboreal pollen is well represented, and this is concurrent with the diatom record suggesting high lake levels.

Past climates provide a test of models' ability to predict climate change. We present a comprehensive evaluation of state-of-the-art models against Last Glacial Maximum and mid-Holocene climates, using reconstructions of land and ocean climates and simulations from the Palaeoclimate Modelling and Coupled Modelling Intercomparison Projects. Newer models do not perform better than earlier versions despite higher resolution and complexity. Differences in climate sensitivity only weakly account for differences in model performance. In the glacial, models consistently underestimate land cooling (especially in winter) and overestimate ocean surface cooling (especially in the tropics). In the mid-Holocene, models generally underestimate the precipitation increase in the northern monsoon regions, and overestimate summer warming in central Eurasia. Models generally capture large-scale gradients of climate change but have more limited ability to reproduce spatial patterns. Despite these common biases, some models perform better than others., AuthorCount:9

The present day distribution of Miombo savanna-woodland in Mozambique has been attributed to an expansion due to the clearing of original coastal forests through agriculture and use of fire. Here, we test this hypothesis using palaeoecological data from Lake Nhauhache, situated in the Vilankulo region. Our analysis shows that Brachystegia, one of the main constituents of the Miombo, has varied over time, and its variability seems to be driven by hydrological changes related to climatic variability rather than by land-use changes. The analyses show that Brachystegia was most common during ad 200-700 when a marshy forest/shrub community was dominant. After ad 700, this community changes to a dominance of Syzygium and Fagara linked to gradually rising water levels. Brachystegia remains in low abundance and fluctuating over time. From ad 1000, a general decline in trees/shrubs in favour of grasses concurs with an increase in grass pollen (possibly cereal) and charcoal, most probably as a result of farming activities. The decline in tree taxa was probably exacerbated by periodic droughts after c. ad 1200 as indicated by the diatom assemblage. In the period ad 1700 to late 1800, arboreal pollen is well represented, and this is concurrent with the diatom record suggesting high lake levels., AuthorCount:3

We present stable isotope data (delta O-18, delta C-13) from a detrital rich stalagmite from Kapsia Cave, the Peloponnese, Greece. The cave is rich in archeological remains and there are reasons to believe that flooding of the cave has directly affected humans using the cave. Using a combination of U-Th and C-14 dating to constrain a site-specific correction factor for (Th-232/U-238) detrital molar ratio, a linear age model was constructed. The age model shows that the stalagmite grew during the period from ca. 950 BC to ca. AD 830. The stable oxygen record from Kapsia indicates cyclical changes of close to 500 yr in precipitation amount, with rapid shifts towards wetter conditions followed by slowly developing aridity. Superimposed on this signal, wetter conditions are inferred around 850, 700, 500 and 400-100 BC, and around AD 160-300 and AD 770; and driest conditions are inferred to have occurred around 450 BC, AD 100-150 and AD 650. Detrital horizons in the stalagmite indicate that three major floods took place in the cave at 500 BC, 70 BC and AD 450. The stable carbon isotope record reflects changes in biological activity being a result of both climate and human activities. (c) 2014 University of Washington., AuthorCount:6

A 350-year-long, well-dated delta O-18 stalagmite record from the summer rainfall region in South Africa is positively correlated with regional air surface temperatures at interannual time scales. The coldest period documented in this record occurred between 1690 and 1740, slightly lagging the Maunder Minimum (1645-1710). A temperature reconstruction, based on the correlation between regional surface temperatures and the stalagmite delta O-18 variations, indicates that parts of this period could have been as much as 1.4 degrees C colder than today. Significant cycles of 22, 11 and 4.8 years demonstrate that the solar magnetic and the El Nino-Southern Oscillation cycle could be important drivers of multidecadal to interannual climate variability in this region. The observation that the most important driver of stalagmite delta O-18 on interannual time scales from this subtropical region is regional surface temperature cautions against deterministic interpretations of delta O-18 variations in low-latitude stalagmites as mainly driven by the amount of precipitation., AuthorCount:7

Fossil pollen and diatoms have been analyzed in a sediment sequence from a topographically closed crater lake in northern Tanzania (Lake Duluti), with the aim to reconstruct past changes in lake level and vegetation dynamics. The results provide a new paleoenvironmental record from equatorial Africa covering the period c. AD 1000 to AD 1800. Overall, the pollen and diatom records generate comparable stories of dry and wet periods. Dry conditions are inferred at c. AD 1040-1470, c. AD 1510-1640 and C. AD 1650-1670 with the lowest lake levels at c. AD 1260-1290 and AD 1600-1640. Wetter conditions occurred c. AD 1640-1650 and c. AD 1670-1790. The chronology is based on combined analyses of Pb-210 activity and AMS C-14 on bulk sediment, and a Bayesian model was applied to establish the age-depth relationship. The hydroclimatic record from Lake Duluti shows good correlation with several East African lakes in a centennial time perspective, although comparison of high frequency variability in the region is hampered by dating uncertainties., AuthorCount:9