Medieval warm Period

... 11. PE Damon and JL Jirikowic, Solar forcing of global climate change?. Radiocarbon After Four Decades An Interdisciplinary Perspective, Springer-Verlag, New York (1992) p. 117–127 . 12. PE Damon and JL Jirikowic, Solar forcing of global climate change. ...

The Outer Banks barrier islands of North Carolina, USA, contain a geologic record of inlet activity that extends from ca. 2200 cal yr BP to the present, and can be used as a proxy for storm activity. Optically stimulated luminescence (OSL) dating (26 samples) of inlet-fill and flood tide delta deposits, recognized in cores and geophysical data, provides the basis for understanding the chronology of storm impacts and comparison to other paleoclimate proxy data. OSL ages of historical inlet fill compare favorably to historical documentation of inlet activity, providing confidence in the technique. Comparison suggests that the Medieval Warm Period (MWP) and Little Ice Age (LIA) were both characterized by elevated storm conditions as indicated by much greater inlet activity relative to today. Given present understanding of atmospheric circulation patterns and sea-surface temperatures during the MWP and LIA, we suggest that increased inlet activity during the MWP responded to intensified hurricane impacts, while elevated inlet activity during the LIA was in response to increased nor'easter activity. A general decrease in storminess at mid-latitudes in the North Atlantic over the last 300 yr has allowed the system to evolve into a more continuous barrier with few inlets.

... The 1.0 and 0.8%o reduc-tion in summer and winter Ô180 values, respectively, between AD 975 and AD 1720 signals the climate change from the highs of Medieval warming (Medieval Warm Period or MWP) to the lows of Little Ice Age (LIA) cooling. ...

Le connessioni tra quadri ambientali e fenomeni economici hanno visto di recente un crescente interesse. In un campo connotato da un così forte carattere interdisciplinare sono varie le difficoltà che si incontrano, non solo nello scambio di conoscenze, ma anche nella stessa impostazione delle ricerche. Ambiente, clima, biologia, ecosistemi sono terreni di studio su cui convergono varie discipline, che richiedono un fondamentale chiarimento delle diverse prospettive di conoscenza e dei rispettivi presupposti, senza dei quali si rimane inevitabilmente immersi in una specie di “babele” di linguaggi in cui non sempre è facile districarsi. Il testo intende portare un contributo nell'ambito della storia ambientale e climatica del Medioevo; e costituisce una rielaborazione della relazione tenuta e discussa in occasione del Convegno internazionale del Centro Italiano di Studi di Storia e Arte di Pistoia (2015) sul tema "La crescita economica dell'Occidente medievale. Un tema storico non ancora esaurito".

 Abstract-This article discusses the history of traditional medicine in Central Asia. Central Asia is one of the centers of traditional medicine. Since ancient times, medicine has developed here. In the period of the Muslim Renaissance, medicine rose to its peak here. One well-known tabib was Abu Sakhl Masikhiy. He wrote a book on medicine "Kitob al-Mi'a." He was one of the mentors of Ibn Sina and encouraged to write a canon of medical science. The Canon of Medicine-is the great medical work of Avicenna. Their completed in 1025. Great Unani physicians of the East Al-Beruny and Abu Ali ibn Sina (Avicenna) wrote their enormous works in the Arabian language. Avicenna and his school played a big role in the development of medicine in the world. Above-mentioned proposals can be inferred: In Central Asia, Unani medicine developed for many centuries, this area was one of the hotbeds of this school and has a peculiar character.

The level of Cliff Lake, a small, subalpine, moraine-dammed lake in California’s south central Sierra Nevada, was approximately 5 m lower than present for 50 years or more approximately 600 years ago, this determined by radiocarbon dating of wood recovered from a submerged tree stump found in the lake. This finding corresponds to commensurate data from throughout much of western North America, suggesting the duration and magnitude of terminal medieval megadrought was similar throughout the region. Ultimately this datum helps give credence to the perspective that though late Holocene climate in California was indeed variable, the effects of terminal Medieval megadrought was similar across both time and broad geographic expanse.

Spring Cave is situated just below the Baboon Point escarpment in Elands Bay and is one of only a handful of central west coast sites with deposits dating to the Medieval Warm Anomaly (MWA, c. 1300-650 cal BP). This was a climatological period of global significance that brought hot and dry conditions to much of the South African west coast, an ecologically stressed period affecting people, animals and plants alike. Although Spring Cave also dates to before and after the MWA, a large amount of its deposits date to this period. Earlier research on the central west coast has shown that most MWA-dated sites are situated at high elevations and near the coast, and that such placement in the landscape allowed monitoring of the movement of game, predators, and groups of people with or without livestock. High mobility, seeking safety and shelter at higher elevations, and a close watch on the landscape were part of general adaptive strategies, but people at Spring Cave may have added repeated ritual slaughter of small carnivores to the range of coping mechanisms. Doing so, according to ethno-historical records among herding groups, would have brought good luck and well-being. When considering Spring Cave's entire sequence, broad late Holocene regional patterns are also confirmed: i) higher frequencies of exotic lithic raw materials before 3000 cal BP; and ii) greater emphasis on gathering limpets after 2000 BP, while mussels dominate assemblages before then. Moreover, metrical data on limpets, mussels and Cape rock lobster suggest that these species were not processed before their transport back to the cave, an observation at variance with barnacles and fish.

7～10世紀の暖候期（5～10月）における気候について、六国史と『日本紀略』を対象史料として検討した。長雨や干ばつを中心に集計した結果、干ばつは7世紀末～8世紀、長雨は9世紀の特に後半に多く記載されていた。理化学的な気温復元結果から、前者は温暖化の時代であり、7月における干ばつの増加と関連があるとみられる。後者のうち、879～887年は7月に長雨が多く、梅雨前線の北上が遅かったことが示唆される。これに加え、平安遷都という都城の立地条件の変化が史料編者の意識を変化させた可能性もある。また、理化学的 データではとらえきれないスケールの小さい変動も記載の変化に関わっていたと考えられる。

This paper discuss climate variations in summer half years (May to October) from the 7th to 10th century in the Kinki region of west central Japan based on historical documents. Most previous research used the compilations of meteorological references contained in various unspecified documents. That method of research may be effective when examining climate variations after the 17th century since numerous documents are available. However, before 10th century, few documents are available, and their different features are likely to lead to nonstandardized analysis. Many of the Japanese documentary sources that potentially could have been used to reconstruct the climate from the 7th to 10th century have been lost. This research therefore relied specifically on the Rikkokushi and Nihon-Kiryaku. The former, one of the oldest documents in Japan, was compiled before 887 and consists of six official books. The latter contains records from before 1036, was written in the late 11th century, and was based on the Rikkokushi and many other documents. The terms “a long rain” or “drought” are treated seriously in this analysis because of the large scale they represent. Their occurrence in every 10-day period was counted in this study to discuss changes in the summer climate, because there are numerous comments in ancient texts on the amount of rainfall during the Japanese rainy season and the various stages of production of the staple crop of rice. The results of analysis showed that drought was much more common from the late 7th to 8th century and that long rains were more common in the 9th century, especially from 850 to 887. Mentions of drought in July increased in the late 8th century, which suggests that the occurrence of a northerly polar front connected with warming may have corresponded with the “medieval warm period” defined by other scientific research. The increase in the mentions of long rains in July from 879 to 887 suggests the relation of a southerly polar front associated with cooling. On the other hand, the results could be related not only to polar fronts but also to other climatic and anthropological factors. For example, the increase in long rains in the early 9th century despite the absence of marked temperature changes between the late 8th to the early 9th century could indicate that moving the capital in 794 from Nara to the Kyoto basin with its many rivers shifted the focus of ancient writers to flooding or other phenomena resulting from heavy rainfall.

Values of δ13C are frequently reported with radiocarbon dates from organic materials. In C3 plants δ13C values have been linked to changes in water use efficiency as a response to arid conditions. By calculating 13C discrimination (Δ13C) from 13C isotopic composition (δ13C), archaeologists can gain potentially valuable inference into past climate conditions. Values of Δ13C reflect the process of discrimination against heavier 13C isotopes of carbon by comparing the δ13C of samples to that of the atmosphere, and can be calculated when records of atmospheric δ13CO2 are available. The present study examines a 1300 year history of radiocarbon-derived Δ13C from the Lower Alentejo of Portugal using charcoal recovered from excavations of a series of medieval habitation sites in the study area. To calculate Δ13C, the posterior means generated from Bayesian change-point analysis of δ13CO2 records were used. Archaeological data were then compared to contemporary ecological studies of Δ13C of the same taxa against instrumental records of climate. Values of Δ13C fell within mean ranges for the taxa through a period of population growth between the 7th and 10th centuries AD. During the height of the Medieval Warm Period in the 11th century AD Δ13C values frequently fell to low levels associated with arid conditions. At this time environmental degradation and erosion were documented. Values of Δ13C increased for a brief period in the early 12th century AD before the rural Lower Alentejo was largely abandoned for nearly two centuries. Another period of aridity occurred in the 16th and 17th centuries AD. Radiocarbon-derived Δ13C is a potentially useful paleoclimate proxy for archaeologists provided that results can be paired with observed Δ13C variation in studies that pair these data with instrumental climate records.

The hypoxic zone in the Baltic Sea has increased in area about four times since 1960 and widespread oxygen deficiency has severely reduced macro benthic communities below the halocline in the Baltic Proper and the Gulf of Finland, which in turn has affected food chain dynamics, fish habitats and fisheries in the entire Baltic Sea. The cause of increased hypoxia is believed to be enhanced eutrophication through increased anthropogenic input of nutrients, such as nitrogen and phosphorus. However, the spatial variability of hypoxia on long time-scales is poorly known: and so are the driving mechanisms. We review the occurrence of hypoxia in modern time (last c. 50 years), modern historical time (AD 1950–1800) and during the more distant past (the last c. 10 000 years) and explore the role of climate variability, environmental change and human impact. We present a compilation of proxy records of hypoxia (laminated sediments) based on long sediment cores from the Baltic Sea. The cumulated results show that the deeper depressions of the Baltic Sea have experienced intermittent hypoxia during most of the Holocene and that regular laminations started to form c. 8500–7800 cal. yr BP ago, in association with the formation of a permanent halocline at the transition between the Early Littorina Sea and the Littorina Sea s. str. Laminated sediments were deposited during three main periods (i.e. between c. 8000–4000, 2000–800 cal. yr BP and subsequent to AD 1800) which overlap the Holocene Thermal Maximum (c. 9000–5000 cal. yr BP), the Medieval Warm Period (c. AD 750–1200) and the modern historical period (AD 1800 to present) and coincide with intervals of high surface salinity (at least during the Littorina s. str.) and high total organic carbon content. This study implies that there may be a correlation between climate variability in the past and the state of the marine environment, where milder and dryer periods with less freshwater run-off correspond to increased salinities and higher accumulation of organic carbon resulting in amplified hypoxia and enlarged distribution of laminated sediments. We suggest that hydrology changes in the drainage area on long time-scales have, as well as the inflow of saltier North Sea waters, controlled the deep oxic conditions in the Baltic Sea and that such changes have followed the general Holocene climate development in Northwest Europe. Increased hypoxia during the Medieval Warm Period also correlates with large-scale changes in land use that occurred in much of the Baltic Sea watershed during the early-medieval expansion. We suggest that hypoxia during this period in the Baltic Sea was not only caused by climate, but increased human impact was most likely an additional trigger. Large areas of the Baltic Sea have experienced intermittent hypoxic from at least AD 1900 with laminated sediments present in the Gotland Basin in the Baltic Proper since then and up to present time. This period coincides with the industrial revolution in Northwestern Europe which started around AD 1850, when population grew, cutting of drainage ditches intensified, and agricultural and forest industry expanded extensively.

The loss of the Norse Western Settlement in Greenland around the mid-fourteenth century has long been taken as a prime example of the impact of changing climate on human populations. This study employs an interdisciplinary approach combining historical documents, detailed archaeological investigations, and a high-resolution proxy climate record from the Greenland Ice Sheet Project 2 (GISP2) to investigate possible causes

The development during the nineteenth and twentieth centuries of the sciences of meteorology and climatology and their subdisciplines has made possible an ever-increasing understanding of the climate of the past. In particular, the refinement of palaeoclimatic proxy data has meant that the climate of the past thousand years has begun to be extensively studied. In the context of this research, it has often been suggested that a warm epoch occurred in much of northern Europe, the north Atlantic, and other parts of the world, from around the ninth through the fourteenth centuries, and that this was followed by a decline in temperatures culminating in a "Little Ice Age" from about 1550 to 1850 (see e.g. Lamb, 1965, 1977; Flohn, 1978). The appelations "Medieval Warm Period" and "Little Ice Age" have entered the literature and are frequently used without clear definition. More recently, however, these terms have come under closer scrutiny (see, e.g. Ogilvie, 1991, 1992; Bradley and Jones, 1992; Mikami, 1992; Briffa and Jones, 1993; Bradley and Jones, 1993; Hughes and Diaz, 1994; Jones et al., 1998; Mann et al., 1999; Crowley and Lowery, 2000). As research continues into climatic fluctuations over the last 1000 to 2000 years, a pattern is emerging which suggests a far more complex picture than early research into the history of climate suggested. In this paper, the origins of the term "Little Ice Age" are considered. Because of the emphasis on the North Atlantic in this volume, the prime focus is on research that has been undertaken in this region, with a perspective on the historiography of historical climatology in Iceland as well as on the twentieth-century climate of Iceland. The phrase "Little Ice Age" has become part of the scientific and popular thinking on the climate of the past thousand years. However, as knowledge of the climate of the Holocene continues to grow, the term now seems to cloud rather than clarify thinking on the climate of the past thousand years. It is hoped that the discussion here will encourage future researchers to focus their thinking on exactly and precisely what is meant when the term "Little Ice Age" is used.

The lake level history, here based on the relative abundance of Ca (gypsum), is used for tracing past hydrological conditions in Central Asia. Lake level was close to a minimum before approximately a.d. 300, at about a.d. 600, a.d. 1220, a.d. 1400 and since 1960s it is lowering again. Lake water level was lowest during the fourteenth or early fifteenth centuries as indicated by a coeval settlement, which today is still under water near the well-dated mausoleum of Kerderi. Pollen data from riparian vegetation indicate generally wet conditions between a.d. 400 and a.d. 900, intermitted by short intervals with drier conditions (AD 550–600; a.d. 650–700) and riverbanks were again dry from a.d. 900–1150, a.d. 1450–1550, and from a.d. 1970 onward moisture decreased steadily. Irrigation activities were at a maximum between 300 b.c. and a.d. 300 (Classical Antiquity) and between a.d. 800 and a.d. 1300 (Medieval Age) and after a.d. 1960.

The surface temperature changes for the last 4000 years in northern inland Iberia (an area particularly sensitive to climate change) are determined by a high resolution study of carbon stable isotope records of stalagmites from three caves (Kaite, Cueva del Cobre, and Cueva Mayor) separated several tens of kilometers away in N Spain. Despite the local conditions of each cave, the isotopic series show a good overall coherence, and resulted to be strongly sensitive to surface temperature changes. The record reflects alternating warmer and colder intervals, always within a temperature range of 1.6 °C. The timing and duration of the intervals were provided by 43 230Th- 234U (ICP-MS) ages. Main climatic recognized periods are: (1) 3950-3000 yr BP: warm period punctuated by cool events around ~ 3950, 3550 and 3250 yr BP; (2) 2850-2500 yr BP cold interval (Iron Age Cold Period); (3) 2500-1650 yr BP moderate warm period (Roman Warm Period), with maximum temperatures between 2150 and 1750 yr BP; (4) 1650-1350 yr BP cold interval (Dark Ages Cold Period), with a thermal minimum at ~ 1500 yr BP; (5) 1350-750 yr BP warm period (Medieval Warm Period) punctuated by two cooler events at ~ 1250 and ~ 850 yr BP; (6) 750-100 yr BP cold period (Little Ice Age) with extremes occurring at 600-500 yr BP, 350-300 yr BP, and 150-100 yr BP; and (7) the last 150 years, characterized by rapid but no linear warming (Modern Warming). Remarkably, the presented records allow direct comparison of recent warming with former warm intervals such as the Roman or the Medieval periods. That comparison reveals the 20th century as the time with highest surface temperatures of the last 4000 years for the studied area. Spectral analysis of the time series shows consistent climatic cycles of ~ 400, ~ 900 and ~ 1300 yr, comparable with those recognized in the North Atlantic marine record, the Greenland ice cores, and other terrestrial records for the middle-late Holocene, suggesting common climate forcing mechanisms related to changes in solar irradiance and North Atlantic circulation patterns.

Establishing natural climate variability becomes particularly important in large urban areas in anticipation of droughts. We present a well-dated bi-decadal record of vegetation, climate, land use, and fire frequency from a tidal marsh in the Hudson River Estuary. The classic Medieval Warm Period is evident through striking increases in charcoal and Pinus dominance from ∼800–1300 A.D., paralleling paleorecords southward along the Atlantic seaboard. Higher inputs of inorganic sediment during this interval suggest increased watershed erosion during drought conditions. The presence of the Little Ice Age ensues with increases in Picea and Tsuga, coupled with increasing organic percentages due to cooler, moister conditions. European impact is manifested by a decline in arboreal pollen due to land clearance, increased weedy plant cover (i.e., Ambrosia, Plantago, and Rumex), and an increase in inorganic particles to the watershed.

The genesis and development of the submerged notch occurring along the Northern Adriatic limestone coasts, surveyed at depth ranging between −0.35 and −2.8m and amplitude consistent with the local tide is discussed using new and published data on its elevation and data on limestone lowering rates, collected using a micro-erosion meter and a traversing micro-erosion meter. Coastal limestone lowering rates

New optically stimulated and radiocarbon ages for alluvial fan and lake deposits in the Mojave Desert are presented, which greatly improves the temporal resolution of surface processes. The new Mojave Desert climate-landscape record is particularly detailed for the late Holocene. Evidence from ephemeral lake deposits and landforms indicates times of sustained stream flow during a wet interval of the latter part of the Medieval Warm Period at ca. AD 1290 and during the Little Ice Age at ca. AD 1650. The former lakes postdate megadroughts of the Medieval Warm Period, whereas the latter match the Maunder Minimum of the Little Ice Age. Periods of alluvial fan aggradation across the Mojave Desert are 14–9 cal ka and 6–3 cal ka. This timing largely correlates to times of increased sea-surface temperatures in the Gulf of California and enhanced warm-season monsoons. This correlation suggests that sustained alluvial fan aggradation may be driven by intense summer-season storms. These data s...

A ca. 1400-yr record from a raised bog in Isla Grande, Tierra del Fuego, Argentina, registers climate fluctuations, including a Medieval Warm Period, although evidence for the 'Little Ice Age'is less clear. Changes in temperature and/or precipitation were inferred from plant macrofossils, pollen, fungal spores, testate amebae, and peat humification. The chronology was established using a 14C wiggle-matching technique that provides improved age control for at least part of the record compared to other sites. These new data are presented and ...

考古遺跡で検出された洪水痕跡について、気象災害データとしての有用性と問題点を探る目的で、古気候データとの整合性を検証した。研究では現代の気象観測データも古気候データに援用した。洪水痕跡の形成と古気候データはあまり一致しない。その背景として，河川の自己調節や人間活動などが考えられる。今後、この研究で用いられたデータや方法論に課題がないかを再評価していく必要がある。

In this paper, I discussed relationship between past climate data and archaeological flood evidences. Additionally, I tensed modern instrumental meteorological record to supplement historical data. In conclusion, it was found out that past climate change and archaeological data were not inconsistent with each other, and that another factor, such as a change in the course of a river, were more important.