European Tree Rings and Climate in the 16th Century

We present a selective review of tree-ring variability and inferred climate changes in Europe during the 16th century. The dendroclimatological evidence is assessed within the context of the last 500 years and some interpretational problems are discussed. The tree-ring evidence is compared with various non-dendroclimatic evidence. The body of evidence shows that a large region of mid and northern Europe experienced a sharp cooling at around 1570/80 that, at least in the north, marked a shift towards a prolonged period of cool conditions. This region had its southern boundary in the Alps and there is little evidence for a major cooling in southern Europe.     

The Little Ice Age history of the Glacier des Bossons (Mont Blanc massif, France): a new high-resolution glacier length curve based on historical documents

Historical and proxy records document that there is a substantial asynchronous development in temperature, precipitation and glacier variations between European regions during the last few centuries. The causes of these temporal anomalies are yet poorly understood. Hence, highly resolved glacier reconstructions based on historical evidence can give valuable insights into past climate, but they exist only for few glaciers worldwide. Here, we present a new reconstruction of length changes for the Glacier des Bossons (Mont Blanc massif, France), based on unevaluated historical material. More than 250 pictorial documents (drawings, paintings, prints, photographs, maps) as well as written accounts have been critically analysed, leading to a revised picture of the glacier’s history, especially from the mid-eighteenth century up to the 1860s. Very important are the drawings by Jean-Antoine Linck, Samuel Birmann and Eugène Viollet-le Duc, which depict meticulously the glacier’s extent during the vast advance and subsequent retreat during the nineteenth century. The new glacier reconstruction extends back to AD 1580 and proves maxima of the Glacier des Bossons around 1610/1643, 1685, 1712, 1777, 1818, 1854, 1892, 1921, 1941, and 1983. The Little Ice Age maximum extent was reached in 1818. Until the present, the glacier has lost about 1.5 km in length, and it is now shorter than at any time during the reconstruction period. The Glacier des Bossons reacts faster than the nearby Mer de Glace (glacier reconstruction back to AD 1570 available). The Mont Blanc area is, together with the valley of Grindelwald in the Swiss Alps (two historical glacier reconstructions available back to AD 1535, and 1590, respectively), among the two regions that are probably best-documented in the world regarding historical glacier data.     

The Initiation of the "Little Ice Age" in Regions Round the North Atlantic

The "Little Ice Age" was the most recent period during which glaciers extended globally, their fronts oscillating about advanced positions. It is frequently taken as having started in the sixteenth or seventeenth century and ending somewhere between 1850 and 1890, but Porter (1981) pointed out that the "Little Ice Age" may 'have begun at least three centuries earlier in the North Atlantic region than is generally inferred'. The glacial fluctuations of the last millennium have been traced in the greatest detail in the Swiss Alps, where the "Little Ice Age" is now seen as starting with advances in the thirteenth century, and reaching an initial culmination in the fourteenth century. In the discussion here, evidence from Canada, Greenland, Iceland, Spitsbergen and Scandinavia is compared with that from Switzerland. Such comparisons have been facilitated by improved methods of calibrating radiocarbon dates to calendar dates and by increasing availability of evidence revealed during the current retreat phase. It is concluded that the "Little Ice Age" was initiated before the early fourteenth century in regions surrounding the North Atlantic.     

Paleoclimatic inferences from glacial fluctuations on Svalbard during the last 20 000 years

The climate history of western Spitsbergen, Svalbard is deduced from variations of glaciers during the last 20 000 years. A major depression of the regional equilibrium line altitude (ELA) occurred during the Late Weichselian glacial maximum (18000–13000y ago) when low summer temperatures may have caused year-round snow accumulation on the ground. This rapid expansion of the glaciers also indicates nearby moisture sources, suggesting partly open conditions in the Norwegian Sea during the summers. A rapid glacial retreat around 13 000–12 500 y BP was caused by a sudden warming. During the Younger Dryas the ELA along the extreme western coast of Spitsbergen was not significantly lower than at present. In contrast to Fennoscandia, the British Isles and the Alps, there is no evidence for readvance of local glaciers during Younger Dryas on western Spitsbergen. This difference is attributed to a much dryer climate on Spitsbergen and probably only slight changes in sea surface temperatures. In addition, summer melting in this high arctic area is more sensitive to orbitally increased insolation. Around 10 000 y BP another rapid warming occurred and during early and mid Holocene the summer temperatures were significantly higher than at present. A temperature decline during the late Holocene caused regrowth of the glaciers which reached their maximum Holocene position during the last century.Contribution to Clima Locarno — Past and Present Climate Dynamics; Conference September 1990, Swiss Academy of Sciences — National Climate Program     

Evidence of climate change within the Adamello Glacier of Italy

We analyze a daily series of rainfall, snowfall, air temperature, and snow water equivalent at fixed dates from 40 high-altitude stations on the Adamello Glacier area (Italian Alps), for the period 1965–2007. Purposes of the study are (1) to investigate significant variation in time, (2) to evaluate effect of temperature changes on cryospheric water cycle, and (3) to evaluate underlying climate patterns and the most significant variables for climate change studies. We detect the presence of a trend using linear regression, moving window average and Mann Kendall test. Linear dependence of water related variables on temperatures is assessed. We find substantially unchanged atmospheric water input along with increasing temperature and rainfall, decreasing snowfall and snow water equivalent at thaw, and shortening of snow cover extent and duration. We carry out a principal components analysis which highlights patterns of precipitation distribution resulting from local temperature and external forcing. A set of the most representative variables for climate and glacier studies is then assessed. A comparison with three nearby Southern Alpine glacierized areas in Italy and Switzerland shows substantial agreement. In spite of the relative shortness of the series, the results here are of interest and can be used as a benchmark for climate change impact assessment for the Adamello Glacier area and southern Alps.     

天山乌鲁木齐河源１号冰川消融对气候变化的响应

目前气候变暖导致的冰川退缩,引起了全世界的广泛关注。 以新疆天山乌鲁木齐河源1号冰川为例,根据1958年以来的观测资料,研究了冰川消融对气候变化的响应。结果表明,近50 a来冰川在表面粒雪特征、成冰带、冰川温度、面积、厚度及末端位置等方面发生了显著变化,而这些变化均与气温的升高有着密切的联系;20世纪80年代以来的快速升温,使冰川的退缩出现了加速趋势,冰川融水径流量也呈加速增大趋势。     

The historical temperature series of Bologna (Italy): 1716–1774

The Bologna meteorological record is one of the oldest and most complete among the series already collected for Europe. Data from the regions south of the Alps being extremely sparse, this station is of great importance for all climatic reconstructions dating as far back as the beginning of the 18th century. The focus here is on the temperature series, because it presents some a priori problems with respect to the series analysis itself. These problems relate to the homogeneity of the temperature record, which is affected by the use of different thermometers within the record, the statistical reconstruction of the thermometric scales, and the drift in calibration of one of these instruments. After correcting for these heterogeneities, the temperature series indicate a thermal behaviour in agreement with other historical European sources. The Bologna series is characterised by a warm period during the first decades of the 18th century, with large decreases in temperature in 1740 and 1742, and a positive trend from 1742 to the end of the record. The behaviour of the Bologna temperature series is in good agreement with the series for Central England, De Bilt (Netherlands) and Padua (Italy).     

Long-term summer temperature variations in the Pyrenees

Two hundred and sixty one newly measured tree-ring width and density series from living and dry-dead conifers from two timberline sites in the Spanish Pyrenees were compiled. Application of the regional curve standardization method for tree-ring detrending allowed the preservation of inter-annual to multi-centennial scale variability. The new density record correlates at 0.53 (0.68 in the higher frequency domain) with May–September maximum temperatures over the 1944–2005 period. Reconstructed warmth in the fourteenth to fifteenth and twentieth century is separated by a prolonged cooling from ∼1450 to 1850. Six of the ten warmest decades fall into the twentieth century, whereas the remaining four are reconstructed for the 1360–1440 interval. Comparison with novel density-based summer temperature reconstructions from the Swiss Alps and northern Sweden indicates decadal to longer-term similarity between the Pyrenees and Alps, but disagreement with northern Sweden. Spatial field correlations with instrumental data support the regional differentiation of the proxy records. While twentieth century warmth is evident in the Alps and Pyrenees, recent temperatures in Scandinavia are relatively cold in comparison to earlier warmth centered around medieval times, ∼1450, and the late eighteenth century. While coldest summers in the Alps and Pyrenees were in-phase with the Maunder and Dalton solar minima, lowest temperatures in Scandinavia occurred later at the onset of the twentieth century. However, fairly cold summers at the end of the fifteenth century, between ∼1600–1700, and ∼1820 were synchronized over Europe, and larger areas of the Northern Hemisphere.     

Can Lichenometry be Used to Date the "Little Ice Age" Glacial Maximum in Iceland?

In Iceland, there are numerous examples of glacier advances dated to the latter half of the last century. However, in marked contrast to the Alps and northern Europe, the record of historical-age moraines before ca. 1850 is rather sparse. This paper examines to what extent this pattern reflects the actual history of glacier fluctuations, and to what extent it could be a function of preservation and dating of the geomorphological record. Measurements of Rhizocarpon geographicum sp. lichen thalli on ice-marginal moraines and sandur form the basis for the late "Little Ice Age" glacial chronology in south Iceland. Recent studies have converged on the view of a maximum glacier extent in the late nineteenth century, and not during earlier and possibly colder parts of the "Little Ice Age". Here, results of independent dating of moraine ridges and a jökulhlaup deposit demonstrate that conventional lichenometric techniques tend to cluster dates of these landforms to the 1860s-1880s, underestimating tephrochronological dates on the same landforms by >100 yr in some cases. A mid-eighteenth century glacial maximum may be better represented in the landform record than hitherto thought, with implications for reconstruction of North Atlantic circulation patterns.     

The Influence of Climatic Change on Price Fluctuations in Germany During the 16th Century Price Revolution

In our paper we analyze the influence of climatic changes on annual price fluctuations (harvest year) of agricultural products in Germany during the 16th century price revolution. The price series under analysis are from Nuremberg, Cologne, Augsburg, and Munich. The prices are compared with quarterly climatic indices for Germany, which cover the observation period 1500-1599. The main finding is that the length of the vegetation period is an important factor in determining grain price fluctuations. During the climatic deterioration in the 16th century, there is some evidence that the impact of climate (and therefore of supply fluctuations) on grain price fluctuations increases.     

Climatic fluctuations in Bohemia from the 16th century until the present

Summary This is paper appraises the possibilities of using written sources of weather information and indirect indicators of the climate of Bohemia. The data are related mainly to the socalled Bohemian vine and hop growing region (the lower reaches of the Ohe River). On the basis of these data climatic fluctuations from the 16th century up to the present are described. Characteristics of climatic types are presented: the continental type (1501–1560, 1681–1750), the oceanic type (1561–1630), and the ambiguous type (1631–1680). On the basis of instrumental observations of the station Prague Klementinum it is possible to describe fluctuations of air temperature since 1771 and fluctuations of precipitation since 1804. These series are the basis material for the analysis of the cyclicity of climatic fluctuations and for the study of possible causes of this cyclicity. The obtained information of the climate of Bohemia since the 16th century for forecasting the climate fluctuations by means of the so-called diagnostic methods, which are based on the method of analogies.With 7 Figures     

Evaluation of a Reconstruction of Winter and Summer Temperatures in the Low Countries, AD 764–1998

A new reconstruction of winter and summer temperatures in the Low Countries(the present-day Netherlands and Belgian Flanders), based upon documentary evidence from AD 764 to 1705 and extended by observationsto 1998, is compared with relevant paleo series from the European network. The Low Countries Temperature (LCT) reconstruction is well supported by existing evidence in both seasons from about 1300 onwards,on timescales ranging from annual to centennial.The spectral analysis confirms that the dominant oscillations in the LCT have counterparts in the independent data and that most of theperiodicities characteristic for the instrumental segment of the LCT are preserved in the reconstruction. Throughout thisperiod of reliable reconstruction there was no detectable inhomogeneity of the variances in either seasons.Prior to about 1300, there are few sources that can be used to evaluate LCT. It was possible to add some support for the LCT on decadal andcentennial timescales for the 12th and 13th centuries. However, there is no independent data for the first three centuriesof the reconstruction.The LCT series exhibits significant season-dependent variability on bidecadal and centennial timescales. The seasonality is particularly remarkable in the 10th and 15th centuries which were – on average – warm in the summer and cold in the winter.The 20th century was by far (three standard errors) the warmest century of the last millenniumin terms of winter temperatures, while the 13th century was warmest in terms of summer temperatures (by the narrow margin of one standard error).In both seasons, the coldest centennial period was centered around 1600. The present results place the reconstructed LCT series withinthe existing paleoclimatic network, and provide an insight into temperature variability in the Low Countries through the centuries.     

Climatic changes in Europe and the near east in the second millenium BC

The old pollen-analysis based picture of the climatic epoch Sub-Boreal in Europe, 3000 or 2500 to 800 BC, which embraces the second millenium, is in need of a thorough revision in light of the relatively recent researches in the Alps. The researches of concern are glacial-variation studies, mainly of the 1970s, and tree-ring density analyses of the subalpine zone of the late 1970s, reported in 1982.The results indicate that, after a warm and dry epoch ending about 1800 or 1700, a cold period set in in the Alps, lasting to about 1470 BC. (All dates below are BC unless otherwise stated; datings determined by radiocarbon analyses are subject to a maximum possible error of + or – 100 yrs.) This cold phase was followed by an approximately 70 yrs long warm phase. But the most pronounced change occurred about 1400, when rather abruptly a second cold phase was ushered in, continuing until about 1230. This second cold phase is often referred to under the name Löbben Phase, which is considered to have been the coldest and longest-sustained cold period of the past 8000 yrs, colder than the recent Little Ice Age of the CE (= Christian Era). Its temperature level is estimated (by G. Patzelt) to have been 0.7 to 1 °C colder than the present level in the Alps. The rise of level of the Swiss lakes, including Lake Constance testify that the Löbben Phase was associated with an enhanced rainfall.In the 13th and the beginning of the 12th centuries major and violent migrations took place from central Europe, including Hungary, and the southeast of the continent toward the south and the southeast, including the Near East as far as the Nile Delta. In order to elucidate if the cold-wet phases of the Alps were cold-wet in central Europe, we have carried out air temperature correlations between an Alpine station Säntis (2500 m MSL) and Budapest, for 1921–70. The correlation coefficient is 0.70 for the annual temperatures and 0.82 for July–September of the same years. Since glaciers grow in cold-wet summers, the high correlation for the summer months means that central Europe must have been cold in most of the cold summers of the Alps. But, cold, and especially cold-wet summers are detrimental to agriculture. Presumably, partial or total crop failures must have been relatively frequent in central Europe forcing the people to take to migration. Archeological evidence from Hungary indicates that there were hardly any settlements left, compared with the previous centuries.Finally, we quote evidence to show that some of the groups of the Sea Peoples, who tried to invade the Nile Delta about 1190, were of European origin. They abandoned their homeland, presumably because of a turn of the climate to cooler and wetter conditions. It is noted that our interpretation of the causes of migrations of the 13th century and beginning of the 12th, is different from that put forward by Weiss (1982).This paper formed the substance of an invited opening address to theInternational Workshop on Regional Implications of Future Climatic Change, held at the Weizmann Institute of Science, Rehovot, Israel, 28 April–2 May 1991.Visiting with the Department of Meteorology, University of Copenhagen, Copenhagen, Denmark, since 1986.     

Biodiversity in the high ranges of the Alps: Ethnobotanical and climate change perspectives

Alpine plants, those predominantly occurring above a treeline, contribute significantly to biodiversity in mountain systems. Thus, one might expect a considerable part of the Alpine flora to be ethnobotanically relevant as has been documented for the Eastern Himalaya. As climate change, especially global warming, may lead to the extinction of Alpine plants, at least locally, loss of alpine species might be important to local people who rely on traditional medicine. How this holds for the Alps will be discussed in this contribution.The Alps are different from the Himalayas in that land use has changed dramatically during the past century. Rural life and culture has changed and much land has been abandoned or is under modern land use systems (industrial farming, tourism, urbanisation). Though much traditional knowledge has disappeared, traditional medicinal practices are still popular as supplemental to modern medicine. In a representative region in the Central Alps, traditional healers use 268 plants species of which 158 can be considered native to that area. Of the 25 predominantly Alpine species three are restricted to the highest Alps where warming might lead to their extinction. In the Alps some ornamental plants are of particular interest from an ethnobotanical point of view. People are apparently much more interested in what happens to Edelweiss (Leontopodium alpinum) than to medicinal plants. Other famous ornamentals (Leontopodium, Rhododendron, Gentiana, Anemone species) do not grow at critical high elevations, but could disappear locally from mountains which are too low in elevation.     

The ‘Little Ice Age’ glacial expansion in western Scandinavia: summer temperature or winter precipitation?

Reconstructing the temporal and spatial climate development on a seasonal basis during the last few centuries, including the ‘Little Ice Age’, may help us better understand modern-day interplay between natural and anthropogenic climate variability. The conventional view of the climate development during the last millennium has been that it followed a sequence of a Medieval Warm Period, a cool ‘Little Ice Age’ and a warming during the later part of the 19th century and in particular during the late 20th/early 21st centuries. However, recent research has challenged this rather simple sequence of climate development. Up to the present, it has been considered most likely that the ‘Little Ice Age’ glacial expansion in western Scandinavia was due to lower summer temperatures. Data presented here, however, indicate that the main cause of the early 18th century glacial advance in western Scandinavia was mild and humid winters associated with increased precipitation and high snowfall on the glaciers.     

The Health of Glaciers: Recent Changes in Glacier Regime

Glacier wastage has been pervasive during the last century; small glaciers and those in marginal environments are disappearing, large mid-latitude glaciers are shrinking slightly, and arctic glaciers are warming. Net mass balances during the last 40 years are predominately negative and both winter and summer balances (accumulation and ablation) and mass turnover are increasing, especially after 1988. Two principal components of winter balance time-series explain about 50% of the variability in the data. Glacier winter balances in north and central Europe correlate with the Arctic Oscillation, and glaciers in western North America correlate with the Southern Oscillation and Northern Hemisphere air temperature. The degree of synchronization for distant glaciers relates to changes in time of atmospheric circulation patterns as well as differing dynamic responses.     

Documentary evidence of climate variability during cold seasons in Lesotho, southern Africa, 1833–1900

This study presents the first 19th century cold season climate chronology for the Kingdom of Lesotho in southern Africa. The chronology is constructed using a variety of documentary sources including letters, diaries, reports, monographs and newspaper articles obtained from southern African and British archives. Information relating to cold season weather phenomena during the austral autumn, winter and early spring months were recorded verbatim. Each of the cold seasons from 1833 to 1900 was then classified as “very severe”, “severe” or “normal/mild”, with a confidence rating ranging from low (1) to high (3) awarded against each annual classification. The accuracy of the document-derived chronology was verified against temperature data for Maseru for the period 1893–1900. Excellent correspondence of the document-derived chronology with the Maseru instrumental data and also with other global proxy temperature records for the 19th century is achieved. The results indicate 12 (18% of the total) very severe, 16 (23%) severe and 40 (59%) normal/mild cold seasons between 1833 and 1900. The overall trend is for more severe and snow-rich cold seasons during the early part of the study period (1833–1854) compared with the latter half of the 19th century (with the exception of the 1880s). A reduction in the duration of the frost season by over 20 days during the 19th century is also tentatively identified. Several severe to very severe cold seasons in Lesotho follow after major tropical and SH volcanic eruptions; such years are usually characterized by early frosts, and frequent and heavy snowfalls. The blocking of solar radiation and the enhanced northward displacement of polar fronts that are directly or indirectly associated with volcanic events, may account for many of the most severe Lesotho winters during the 19th century.     

Violins and climate

Summary This paper explores the possibility of using ring-width measurements derived from string instruments as a potential source of palaeoclimate information. From a data-base of 1800 measured series, we have identified two sub-sets that compare well with living high elevation spruce (Picea abies (L.) Karst) chronologies from the Bavarian Forest and Austrian Alps. The problems of using historical tree-ring data for dendroclimatic purposes are addressed and by combining the living and historic ring-width data from these two regions, a preliminary proxy of past June/July mean temperatures is developed. This proxy summer temperature record shows striking similarities with a tree-ring based temperature reconstruction for the Central Eastern Alps, the CLIMHIST June/July temperature record from Switzerland and glacial records from the Austrian Alps. This explorative study demonstrates that ring-width series from string instruments may allow the identification of generalised source regions of wood used for instrument making and, most importantly, provide a new unique source for palaeoclimate information at a variety of both temporal and spatial scales for high elevations in central Europe.     

Changes in Vascular Plant Biodiversity in the Netherlands in the 20th Century Explained by their Climatic and other Environmental Characteristics

In the Netherlands nation-wide databases are available with about 10 million records of occurrences of vascular plant species in the 20th century on a scale of approximately 1 km². These data were analysed with a view to identifying relationships between changes in botanical biodiversity and climatic and other environmental factors. Prior to analysis the data were corrected for several major forms of survey bias. The records were broken down into three periods: 1902–1949, 1975–1984 and 1985–1999. Using multiple regression analysis, differences between successive periods were related to plant functional characteristics as explanatory variables. Between the periods 1902–1949 and 1975–1984 there were small but significant increases in the presence of both thermophilic (‘warm’) and psychrophilic (‘cold’) species. However, in the final decades of the 20th century there was a marked increase in thermophilic species only, coinciding with the marked increase in ambient temperature observed during this period, evidence at least of a rapid response of Dutch flora to climate change. Urbanisation was also examined as an alternative explanation for the increase in thermophilic plant species and was found to explain only 50% of the increased presence of such species in the final decades of the 20th century. Besides temperature-related effects, the most important change during the 20th century was a strong decline in oligotrophic and a marked increase in eutrophic plant species.     

Climatic conditions in the Alps in the years about the year of Hannibal's crossing (218 BC)

Hannibal and his force (troops, pack animals and elephants) crossed the Alps from France to Italy in the autumn of 218 BC. An examination of treering density and glacier data for the Alps indicates that the year of crossing fell into a period when temperature conditions were much the same and, perhaps, slightly milder than those of the current century since about 1920 - a perid of almost worldwide warming. Absolutely dated tree-ring data for southern Central Europe corroborate that the growing periods of 218 BC and neighboring years were mild.As to the autumn month when the crossing was accomplished, temperature conditions favor the month of September. In the area of the passes, one of which was selected by Hannibal for the traversal at the approximate altitudes of 2000–2500 m MSL, the temperatures are, in the mean below freezing from about mid-October. The ancient historians (Polybius, Livy and others) do not mention frosbite casualties. Below-freezing temperatures would have seriously affected troops coming from North Africa and southern Spain. Presumably, temperatures were above freezing during the ascent phase and the rest of two days on the pass.By the 3rd century BC the Alpine glaciers were in a backward position compared with their position in 900-350 BC. This fact and the mildness of the climate, inferred from tree-ring analyses, suggest that ice conditions were not severe in the Alps in 218 BC.The author has been visiting with the Department of Meteorology, University of Copenhagen, since 1986.