Author
Andrea Seim
Other affiliations: University of Gothenburg, Swiss Federal Institute for Forest, Snow and Landscape Research, University of Innsbruck
Bio: Andrea Seim is an academic researcher from University of Freiburg. The author has contributed to research in topics: Climate change & Dendroclimatology. The author has an hindex of 17, co-authored 35 publications receiving 1022 citations. Previous affiliations of Andrea Seim include University of Gothenburg & Swiss Federal Institute for Forest, Snow and Landscape Research.
Topics: Climate change, Dendroclimatology, Geography, Juniper, Holocene
Papers
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Lamont–Doherty Earth Observatory1, University of East Anglia2, University of Freiburg3, Royal Netherlands Meteorological Institute4, Queen's University Belfast5, University of Padua6, University of Ljubljana7, University of Mainz8, Cornell University9, Stockholm University10, Dresden University of Technology11, University of Barcelona12, United States Department of State13, Deutsches Archäologisches Institut14, Czech University of Life Sciences Prague15, Istanbul University16, University of Gothenburg17, University of Oxford18, University of Pavia19, University of Forestry, Sofia20, Norwegian University of Science and Technology21, University of Arizona22, Nicolaus Copernicus University in Toruń23, University of St Andrews24, Technische Universität München25
TL;DR: Megadroughts reconstructed over north-central Europe in the 11th and mid-15th centuries reinforce other evidence from North America and Asia that droughts were more severe, extensive, and prolonged over Northern Hemisphere land areas before the 20th century, with an inadequate understanding of their causes.
Abstract: Climate model projections suggest widespread drying in the Mediterranean Basin and wetting in Fennoscandia in the coming decades largely as a consequence of greenhouse gas forcing of climate. To place these and other “Old World” climate projections into historical perspective based on more complete estimates of natural hydroclimatic variability, we have developed the “Old World Drought Atlas” (OWDA), a set of year-to-year maps of tree-ring reconstructed summer wetness and dryness over Europe and the Mediterranean Basin during the Common Era. The OWDA matches historical accounts of severe drought and wetness with a spatial completeness not previously available. In addition, megadroughts reconstructed over north-central Europe in the 11th and mid-15th centuries reinforce other evidence from North America and Asia that droughts were more severe, extensive, and prolonged over Northern Hemisphere land areas before the 20th century, with an inadequate understanding of their causes. The OWDA provides new data to determine the causes of Old World drought and wetness and attribute past climate variability to forced and/or internal variability.
429 citations
ETH Zurich1, Université du Québec2, Queen's University Belfast3, Swiss Federal Institute of Aquatic Science and Technology4, University of Auckland5, University of Erlangen-Nuremberg6, University of Padua7, Stockholm University8, University of Cambridge9, Austral University of Chile10, University of Vermont11, Lamont–Doherty Earth Observatory12, William Paterson University13, University of Mainz14, University of Guelph15, University of Lorraine16, University of Tennessee17, Swedish Polar Research Secretariat18, Russian Academy of Sciences19, West Virginia University20, Deutsches Archäologisches Institut21, University of Arizona22, Sukachev Institute of Forest23, Siberian Federal University24, Mendel University25, University of Gothenburg26, Swansea University27, University of Western Ontario28, Nagoya University29, University of Innsbruck30, University of New South Wales31, Harvard University32, University of Freiburg33, Paul Scherrer Institute34, University of Geneva35, Indiana State University36, National Scientific and Technical Research Council37, College of Wooster38, University of St Andrews39, Hampshire College40, Chinese Academy of Sciences41
TL;DR: The identification of distinct 14C excursions in 484 individual tree rings enable the authors to confirm the dating of 44 dendrochronologies from five continents, and suggest a global exposure to strong solar proton radiation.
Abstract: Though tree-ring chronologies are annually resolved, their dating has never been independently validated at the global scale Moreover, it is unknown if atmospheric radiocarbon enrichment events of
128 citations
TL;DR: In this article, the authors studied how twentieth century climate change affected the growth of European beech (Fagus sylvatica L.) nearby its south-eastern distribution limit in Albania and Macedonia on the Balkan Pen- insula.
Abstract: Future changes in tree growth, associated with a warmer and drier climate, are predicted for many species and locations across the European Mediterranean Basin. How- ever, quantification of the intensity and severity of related consequences for forest ecosystem functioning and produc- tivity remains challenging. Species-specific distribution limits that are particularly sensitive to small changes in the ambient climate may provide an ideal test bed to assess the nature of past growth trends and extremes and their respon- sible controls. Here, we seek to understand how twentieth century climate change affected the growth of European beech (Fagus sylvatica L.) nearby its south-eastern distri- bution limit in Albania and Macedonia on the Balkan Pen- insula. We sampled 93 living trees from undisturbed mixed forest stands at *1,450 m a.s.l. and 29 timbers from nearby historical buildings. Application of different tree-ring detrending techniques allowed robust composite chronolo- gies with varying degrees of high- to low-frequency vari- ability to be developed back to 1648 AD. Comparison with local meteorological station measurements and continental grid-box climate indices revealed spatiotemporal instability in growth-climate response patterns. Nevertheless, year-to- year and decadal-long fluctuations in radial beech growth were significantly (P \ 0.001) negatively correlated at - 0.61 with June-September temperature over the 1951-1995 period. This (inverse) relationship between increased beech growth and decreased summer temperature is somewhat indicative for the importance of plant-available soil mois- ture, which likely controls ring width formation near the species-specific south-eastern distribution limit. Significant positive correlations between beech growth and drought (scPDSI; r = 0.57) confirm metabolistic drought con- straints. However, an unexpected late twentieth century growth increase not only contradicts the previously observed growth dependency to summer soil moisture, but also denies any putative drought-induced forest ecosystem suppression in this part of the Mediterranean Basin.
122 citations
TL;DR: In this article, the authors focus on an extensive mortality event in Norway spruce (Picea abies (L.) H. Karst) and European beech (Fagus sylvatica) forests in Germany, following successive 2018 and 2019 hot droughts.
60 citations
University of Cambridge1, Stockholm University2, University of Freiburg3, Complutense University of Madrid4, Bjerknes Centre for Climate Research5, Lamont–Doherty Earth Observatory6, University of Giessen7, Université catholique de Louvain8, University of Gothenburg9, Chinese Academy of Sciences10, Swansea University11, University of Mainz12, Russian Academy of Sciences13, University of Basel14
TL;DR: The long-term relationship between temperature and hydroclimate has remained uncertain due to the short length of instrumental measurements and inconsistent results from climate model simulations as discussed by the authors. But the relationship between temperatures and hydrology has been shown to be relatively stable.
Abstract: The long-term relationship between temperature and hydroclimate has remained uncertain due to the short length of instrumental measurements and inconsistent results from climate model simulations. ...
55 citations
Cited by
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Queen's University Belfast1, University of St Andrews2, Aix-Marseille University3, Historic England4, University of Sheffield5, University of Oxford6, Alfred Wegener Institute for Polar and Marine Research7, Xi'an Jiaotong University8, University of Minnesota9, Nanjing Normal University10, University of Hohenheim11, University of Kiel12, Lawrence Livermore National Laboratory13, University of California, Santa Cruz14, ETH Zurich15, University of Waikato16, Woods Hole Oceanographic Institution17, Heidelberg University18, Cornell University19, Lund University20, University of New South Wales21, University of Arizona22, University of Groningen23, University of Bristol24, University of Glasgow25, University of California, Irvine26, University of Bern27, Aarhus University28, Nagoya University29, Swiss Federal Institute for Forest, Snow and Landscape Research30, National Museum of Japanese History31, University of Bologna32
TL;DR: In this article, the international 14C calibration curves for both the Northern and Southern Hemispheres, as well as for the ocean surface layer, have been updated to include a wealth of new data and extended to 55,000 cal BP.
Abstract: Radiocarbon (14C) ages cannot provide absolutely dated chronologies for archaeological or paleoenvironmental studies directly but must be converted to calendar age equivalents using a calibration curve compensating for fluctuations in atmospheric 14C concentration. Although calibration curves are constructed from independently dated archives, they invariably require revision as new data become available and our understanding of the Earth system improves. In this volume the international 14C calibration curves for both the Northern and Southern Hemispheres, as well as for the ocean surface layer, have been updated to include a wealth of new data and extended to 55,000 cal BP. Based on tree rings, IntCal20 now extends as a fully atmospheric record to ca. 13,900 cal BP. For the older part of the timescale, IntCal20 comprises statistically integrated evidence from floating tree-ring chronologies, lacustrine and marine sediments, speleothems, and corals. We utilized improved evaluation of the timescales and location variable 14C offsets from the atmosphere (reservoir age, dead carbon fraction) for each dataset. New statistical methods have refined the structure of the calibration curves while maintaining a robust treatment of uncertainties in the 14C ages, the calendar ages and other corrections. The inclusion of modeled marine reservoir ages derived from a three-dimensional ocean circulation model has allowed us to apply more appropriate reservoir corrections to the marine 14C data rather than the previous use of constant regional offsets from the atmosphere. Here we provide an overview of the new and revised datasets and the associated methods used for the construction of the IntCal20 curve and explore potential regional offsets for tree-ring data. We discuss the main differences with respect to the previous calibration curve, IntCal13, and some of the implications for archaeology and geosciences ranging from the recent past to the time of the extinction of the Neanderthals.
2,800 citations
University of Waikato1, University of New South Wales2, University of Sheffield3, Australian Nuclear Science and Technology Organisation4, University of California, Irvine5, Historic England6, University of Auckland7, University of Oxford8, University of Arizona9, James Cook University10, Queen's University Belfast11, ETH Zurich12
TL;DR: In this article, the Southern Hemisphere curve (SHCal20) is proposed to estimate the mean Southern Hemisphere offset to be 36 ± 27 14C yrs older than the Northern Hemisphere offset, based upon a comparison of Southern Hemisphere tree-ring data compared with contemporaneous Northern Hemisphere data.
Abstract: Early researchers of radiocarbon levels in Southern Hemisphere tree rings identified a variable North-South hemispheric offset, necessitating construction of a separate radiocarbon calibration curve for the South. We present here SHCal20, a revised calibration curve from 0–55,000 cal BP, based upon SHCal13 and fortified by the addition of 14 new tree-ring data sets in the 2140–0, 3520–3453, 3608–3590 and 13,140–11,375 cal BP time intervals. We detail the statistical approaches used for curve construction and present recommendations for the use of the Northern Hemisphere curve (IntCal20), the Southern Hemisphere curve (SHCal20) and suggest where application of an equal mixture of the curves might be more appropriate. Using our Bayesian spline with errors-in-variables methodology, and based upon a comparison of Southern Hemisphere tree-ring data compared with contemporaneous Northern Hemisphere data, we estimate the mean Southern Hemisphere offset to be 36 ± 27 14C yrs older.
535 citations
TL;DR: Lamb's latest book on the earth's changing climate is a carefully crafted work covering four areas: the physical basis of climate and climate change, the methods of climate reconstruction, the history of climate since the height of the last glaciation, and the impact of climate on human affairs as discussed by the authors.
Abstract: H. H. Lamb's latest book on the earth's changing climate is a carefully crafted work covering four areas: the physical basis of climate and climate change, the methods of climate reconstruction, the history of climate since the height of the last glaciation, and the impact of climate on human affairs. The book will be of particular interest to three groups. Atmospheric scientists interested in the long history of climate behavior (but perhaps overwhelmed by Lamb's all-encompassing work on the topic, Climate: Past, Present and Future, vol. II, Methuen, New York), will find Climate History and the Modern World to be a good titration of the fuller work. Scientists in other fields, including social scientists grappling with issues of climate-society interaction, will find the book a good entree into the field. Finally, Lamb himself suggests that the book will be useful to resource managers and other decision makers trying to avoid negative climate impacts. With this last audience in mind, no doubt, Lamb has chosen a style that eschews extensive footnoting and references (though sufficient citations are included to lead to further information). This works quite well and seems reasonable in view of his carefully documented previous writings.
464 citations
TL;DR: The megadrought-like trajectory of 2000–2018 soil moisture was driven by natural variability superimposed on drying due to anthropogenic warming, which pushed an otherwise moderate drought onto a trajectory comparable to the worst SWNA megadroughts since 800 CE.
Abstract: Severe and persistent 21st-century drought in southwestern North America (SWNA) motivates comparisons to medieval megadroughts and questions about the role of anthropogenic climate change. We use hydrological modeling and new 1200-year tree-ring reconstructions of summer soil moisture to demonstrate that the 2000-2018 SWNA drought was the second driest 19-year period since 800 CE, exceeded only by a late-1500s megadrought. The megadrought-like trajectory of 2000-2018 soil moisture was driven by natural variability superimposed on drying due to anthropogenic warming. Anthropogenic trends in temperature, relative humidity, and precipitation estimated from 31 climate models account for 47% (model interquartiles of 35 to 105%) of the 2000-2018 drought severity, pushing an otherwise moderate drought onto a trajectory comparable to the worst SWNA megadroughts since 800 CE.
427 citations