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Originally posted by Faiol
study a little about al gore and you will have to assume that global warming is a hoax, otherwise, there is something very wrong with that guy
Results of ice-core drilling as well as sea ice monitoring show that there is no extensive melting of the ice in most of the Antarctic. Experts are, however, concerned about ice melting on the western coast of the continent. Read more: www.digitaljournal.com...
Originally posted by Maslo
False.
Medieval Warm period was local and average GLOBAL temperatures were COOLER than today.
The ‘Mediaeval Warm Period’ drought recorded in Lake Huguangyan, tropical South China
Abstract: The geochemistry of dated sediment cores from Lake Huguangya n (21º9¢N, 110º17¢E), tropical South
China, reveals distinct stratigraphical patterns in total organic and inorganic carbon (TOC, TIC), biogenic silica
(BS) and total nitrogen (TN) over the past 1400 years. In this hydrologically closed lake, TIC variations may
re ect changes in the precipitation/evaporation ratio, which controls the evaporative enrichment of carbonate.
TOC, BS and TN in the sediment are proxy indicators of lake productivity and nutrient input, which we believe
are linked to local precipitation. High TIC content correlates with low concentrations of TOC, BS and TN,
and indicates two drought episodes dated to ad 670–760 and ad 880–1260 in the sediments of Lake Huguangyan.
Local historical chronicles support these data, suggesting that the climate of tropical South China was
dry during the Mediaeval Warm Period (MWP) and wet during the Little Ice Age (LIA). The detected
MWP drought is temporally correlated with evidence for lower precipitation on the Guliya (China) and
Quelccaya (Peru) ice caps, and with increased salinity in Moon Lake (US Great Plains).
...
Putting the rise of the Inca Empire within
a climatic and land management context
The rapid expansion of the Inca from the Cuzco area of highland Peru produced the largest empire in the New World between ca. AD 1400–1532. Although this meteoric rise may in part be due to the adoption of innovative societal strategies, supported by a large labour force and standing army, we argue that this would not have been possible without increased crop productivity, which was linked to more favourable climatic conditions. A multi-proxy, high-resolution 1200-year lake sediment record was analysed at Marcacocha, 12 km north of Ollantaytambo, in the heartland of the Inca Empire. This record reveals a period of sustained aridity that began from AD 880, followed by increased warming from AD 1100 that lasted beyond the arrival of the Spanish in AD 1532. These increasingly warmer conditions allowed the Inca and their predecessors the opportunity to exploit higher altitudes from AD 1150, by constructing agricultural terraces that employed glacial-fed irrigation, in combination with deliberate agroforestry techniques. There may be some important lessons to be learnt today from these strategies for sustainable rural development in the Andes in the light of future climate uncertainty.
The Case for a Global Medieval Warm Period Grows Ever Stronger
Reference
Hong, B., Liu, C.-Q., Lin, Q.-H., Yasuyuki, S., Leng, X.-T., Wang, Y., Zhu, Y.-X. and Hong, Y.-T. 2009. Temperature evolution from the δ18O record of Hani peat, Northeast China, in the last 14000 years. Science in China Series D: Earth Sciences 52: 952-964. Of the Medieval Warm Period (MWP), Hong et al. (2009) write that "because it is a distinct warm period nearest to the modern warming period and happened before the Industrial Revolution, it naturally becomes a [source of] comparison with modern warming." And in this regard, they add that "a universal concern in academic circles is [1] whether it also existed outside the European region and [2] whether it is a common phenomenon."
In a study designed to broach both questions, the authors extracted cores of peat from a location close to Hani Village, Liuhe County, Jilin Province, China (42°13'N, 126°31'E); and they used them to develop, as they describe it, "a peat cellulose δ18O temperature proxy record proximately existing for 14,000 years."
Their efforts revealed, first of all, that the MWP had indeed held sway on the Chinese mainland over the period AD 700-1400, peaking at about AD 900. And the eight researchers report that phenological data from east China (Ge et al., 2006) and tree-ring records from west China (Yang et al., 2000) also indicate that "the temperature on the Chinese mainland was distinctly warmer during the MWP." In fact, they say MWP temperatures were as much as "0.9-1.0°C higher than modern temperatures (Zhang, 1994)."
...
doi:10.1016/j.quaint.2007.06.001
Copyright © 2007 Elsevier Ltd and INQUA All rights reserved.
Extreme Nile floods and famines in Medieval Egypt (AD 930–1500) and their climatic implications
References and further reading may be available for this article. To view references and further reading you must purchase this article.
Fekri A. Hassana,
aInstitute of Archaeology, University College London, 31-34 Gordon Square, WC1H 0PY, London, UK
Available online 7 June 2007.
Abstract
Nile gauge records of variations in Nile floods from the 9th century to the 15th century AD reveal pronounced episodes of low Nile and high Nile flood discharge. Historical data reveal that this period was also characterized by the worst known famines on record. Exploratory comparisons of variations in Nile flood discharge with high-resolution data on sea surface temperature of the North Atlantic climate from three case studies suggest that rainfall at the source of the Nile was influenced by the North Atlantic Oscillation. However, there are apparently flip-flop reversals from periods when variations in Nile flood discharge are positively related to North Atlantic warming to periods where the opposite takes place. The key transitions occur atAD 900, 1010, 1070, 1180, 1350 and 1400. The putative flip-flop junctures, which require further confirmation, appear to be quite rapid and some seem to have had dramatic effects on Nile flood discharge, especially if they recurred at short intervals, characteristic of the period from the 9th to the 14th century, coincident with the so-called Medieval Warm Period. The transition from one state to the other was characterized by incidents of low, high or a succession of both low and high extreme floods. The cluster of extreme floods was detrimental causing famines and economic disasters that are unmatched over the last 2000 years.
P. D. Tyson, W. Karlén, K. Holmgren and G. A. Heiss (in press)
The Little Ice Age and Medieval Warming in South Africa. South African Journal of Science.
--------------------------------------------------------------------------------
The Little Ice Age and Medieval Warming in South Africa
P. D. Tyson1, W. Karlén2, K. Holmgren2 and G. A. Heiss3.
1Climatology Research Group, University of the Witwatersrand
2Department of Physical Geography, Stockholm University
3Geomar, Wischhofstr. 1-3, 24148 Kiel, Germany; present address: German Advisory Council on Global Change (WBGU), P.O. Box 120161, 27515 Bremerhaven, Germany, E-mail: [email protected]
Abstract
The Little Ice Age, from around 1300 to 1800, and medieval warming, from before 1000 to around 1300 in South Africa, are shown to be distinctive features of the regional climate of the last millennium. The proxy climate record has been constituted from oxygen and carbon isotope and colour density data obtained from a well-dated stalagmite derived from Cold Air Cave in the Makapansgat Valley.
The climate of the interior of South Africa was around 1oC cooler in the Little Ice Age and may have been over 3°C higher than at present during the extremes of the medieval warm period. It was variable throughout the millennium, but considerably more so during the warming of the eleventh to thirteenth centuries. Extreme events in the record show distinct teleconnections with similar events in other parts of the world, in both the northern and southern hemispheres. The lowest temperature events recorded during the Little Ice Age in South Africa are shown to be coeval with the Maunder and Sporer Minima in solar irradiance. The medieval warming is shown to have been coincided with the cosmogenic 10Be and 14C isotopic maxima recorded in tree rings elsewhere in the world during the Medieval Maximum in solar radiation.
On-line Publication Documentation System for Stockholm University
Full DescriptionUpdate record
Publication type: Article in journal (Reviewed scientific)
Author: Grudd, H (Department of Physical Geography and Quaternary Geology)
Title: Torneträsk tree-ring width and density ad 500–2004: a test of climatic sensitivity and a new 1500-year reconstruction of north Fennoscandian summers
In: Climate Dynamics
Publisher: Springer, Berlin / Heidelberg
Volume: 31
Pages: 843-857
Year: 2008
Available: 2009-01-30
ISSN: 1432-0894
Department: Department of Physical Geography and Quaternary Geology
Language: English [en]
Subject: Physical geography, Climatology
Abstract: This paper presents updated tree-ring width (TRW) and maximum density (MXD) from Torneträsk in northern Sweden, now covering the period ad 500–2004. By including data from relatively young trees for the most recent period, a previously noted decline in recent MXD is eliminated. Non-climatological growth trends in the data are removed using Regional Curve Standardization (RCS), thus producing TRW and MXD chronologies with preserved low-frequency variability. The chronologies are calibrated using local and regional instrumental climate records. A bootstrapped response function analysis using regional climate data shows that tree growth is forced by April–August temperatures and that the regression weights for MXD are much stronger than for TRW. The robustness of the reconstruction equation is verified by independent temperature data and shows that 63–64% of the instrumental inter-annual variation is captured by the tree-ring data. This is a significant improvement compared to previously published reconstructions based on tree-ring data from Torneträsk. A divergence phenomenon around ad 1800, expressed as an increase in TRW that is not paralleled by temperature and MXD, is most likely an effect of major changes in the density of the pine population at this northern tree-line site. The bias introduced by this TRW phenomenon is assessed by producing a summer temperature reconstruction based on MXD exclusively. The new data show generally higher temperature estimates than previous reconstructions based on Torneträsk tree-ring data. The late-twentieth century, however, is not exceptionally warm in the new record: On decadal-to-centennial timescales, periods around ad 750, 1000, 1400, and 1750 were equally warm, or warmer. The 200-year long warm period centered on ad 1000 was significantly warmer than the late-twentieth century (p < 0.05) and is supported by other local and regional paleoclimate data. The new tree-ring evidence from Torneträsk suggests that this “Medieval Warm Period” in northern Fennoscandia was much warmer than previously recognized.
Medieval Warm Period thesis contradicts the unprecedented warming
However, one must mention that, already the first half of the statement, that about the unprecedented warming, elicits significant question marks in many climate scientists and even at many historians. Wasn’t there something like the medieval warm period? And in the opinion of many scientists, wasn’t it warmer during this period than today?
The idea of a medieval warm period was formulated for the first time in 1965 by the English climatologist Hubert H. Lamb [1]. Lamb, who founded the UK Climate Research Unit (CRU) in 1971, saw the peak of the warming period from 1000 to 1300, i.e. in the High Middle Ages. He estimated that temperatures then were 1-2 ° C above the normal period of 1931-1960. In the high North, it was even up to 4 degrees warmer. The regular voyages of the Vikings between Iceland and Greenland were rarely hindered by ice, and many burial places of the Vikings in Greenland still lie in the permafrost.
Glaciers were smaller than today
Also the global retreat of glaciers that occurred in the period between about 900 to 1300 [2] speaks for the existence of the Medieval Warm Period. An interesting detail is that many glaciers pulling back since 1850 reveal plant remnants from the Middle Ages, which is a clear proof that the extent of the glaciers at that time was lower than today [3].
...
The Medieval Warm Period (MWP) or Medieval Climate Optimum was a time of warm climate in the North Atlantic region, that may also have been related to other climate events around the world during that time, including in China,[1] New Zealand,[2] and other countries[3][4][5][6][7][8][9] lasting from about AD 950–1250.[10] It was followed by a cooler period in the North Atlantic termed the Little Ice Age. Some refer to the event as the Medieval Climatic Anomaly as this term emphasizes that effects other than temperature were important.[11][12]
Despite substantial uncertainties, especially for the period prior to 1600 when data are scarce, the warmest period prior to the 20th century very likely occurred between 950 and 1100, but temperatures were probably between 0.1°C and 0.2°C below the 1961 to 1990 mean and significantly below the level shown by instrumental data after 1980. The heterogeneous nature of climate during the ‘Medieval Warm Period’ is illustrated by the wide spread of values exhibited by the individual records.[13]
Originally posted by Agent_USA_Supporter
Sorry to buff your claims of a the Medieval Warming Period which i find it laughably but dont or did you noticed that during the the Medieval ages there were wars? oh and how do expect those knights and pawns in there armors had water during there combat?
edit on 2-11-2010 by Agent_USA_Supporter because: (no reason given)