Mittelalterliche Warmperiode

In der neuen Arbeit von Wang et al., Climate changes inferred from integrated multi-site pollen data in northern Taiwan (Abstract), werden fossile Pollendaten von "10 lake sediments and 2 land cores" zusammengefasst, um "the alteration of forest covered areas in northern Taiwan with changes in humidity and temperature over the last 2000 years" zu verbinden. Zur MWP äußern sich die Forscher wie folgt: Our results suggested hat the climate in northern Taiwan was stably cool and dry during 2000-1000 cal. yr BP, but changed to wet and warm during 1000-500 cal. yr BP, which corresponded to the Medieval Warm Period (MWP). In addition, an increased density and dispersal of Tsuga pollen corresponding to 500-200 cal. yr BP was observed, which corresponded to the Little Ice Age (LIA).

Hong-Chun et al. legen in der April-Ausgabe des Journal of Asian Earth Sciences eine Arbeit, mit dem Titel The Delta13O and Delta13C records in an aragonite stalagmite from Furong Cave, Chongqing, China: A-2000-year record of monsoonal climate vor. Aus dem Abstract: A 7-cm long aragonite stalagmite, FR0510-1, from Furong Cave, Chongqing, was dated by 210Pb and 230Th methods, revealing a-2000-year record of climate history under the influence of the East Asian Monsoon. [...] During the past 2000 years, climate in Chongqing was realtively wet in the intervals of 50 BC-AD 250, AD 1150-1450 and AD 1600-1950, and relatively dry during the periods of AD 250-1150 and AD 1450-1600. Dry conditions were prevailing over the Medieval Warm Period, whereas wet climates were dominant during the most time of the Little Ice Age in Chongqing area.

Neulich stieß ich auf dem Blog skepticalscience auf einen schwachen Blogbeitrag, gestaltet von einem gewissen Daniel Bailey. Da sich in diesem Beitrag in meinen Augen in nicht intellektuell redlicher Weise mit der MWP beschäftigt wird, entschloß ich mich dazu, einige Kommentare abzugeben. Ein schwerer Fehler, wie sich im Nachhinein herausstellte - ad hominem Attacken, ehrrührige Beleidigungen. Aus diesem Grunde werde ich mir besagten Beitrag in diesem Post genauer ansehen. Bailey beginnt seinen Beitrag "Icing the Medieval Warm Period" mit einigen einleitenden Bemerkungen, die für uns nicht von Interesse sind. Er führt dann aus: One of the commonly raised objections from those who would have us debate even the existence of gravity is that " It was warmer in the Medieval Warm Period ." This is an innocent, but untrue, claim clearly unsupported by the available literature . Indeed, Martin-Chivelet et al reveals the 20th Century as the time with highest surface t...

Ran et al. veröffentlichen in der Märzausgabe von Palaeogeography, Palaeoclimatology, Palaeoecology eine interessante Studie mit dem Titel Diatom-based reconstruction of palaeoceanographic changes on the North Icelandic shelf during the last millennium . Aus dem Abstract: Warm and stable conditions with relatively strong influence of the Irminger current on the North Icelandic shelf are indicated during the interval AD 940-1300, corresponding in time to the Medieval Warm Period (MWP).

Seit kurzem ist auf sciencedirect ein eingereichtes und akzeptiertes Manuskript von Martin-Chivelet et al., unter dem Titel Land surface temperature changes in Northern Iberia since 4000 yr BP, based on Delta13 C of speleothems als "Article in press" abrufbar. Aus dem Abstract: Main climatic recognized periods are: [...] (5) 1350-750 yr BP warm period (Medieval Warm Period) punctuated by two cooler events at ~ 1250 and ~ 850 yr BP;

This epoch appears to show most of the same characteristics as the post-glacial epoch both in the Northern Hemisphere and in the Antarctic, only in less degree, perhaps because of its shorter duration. The Arctic pack ice had melted so far back that appearences of drift ice in waters near Iceland and Greenland south of 70° N. were rare in the 800s and 900s and apparently unknown between 1020 and 1200, when a rapid increase of frequency began. This evidence hardly supports Brooks' suggeston that the Arctic Ocean again became ice-free during this epoch, though "permanent" ice was probably limited to inner Arctic areas north of 80° N. and possibly not including the Canadian Archipelago (to judge from occasional exploits there by the Old Norse Greenland colonist).[1] From the evidence of early Norse burials and plant roots in ground now permanently frozen in southern Greenland, annual mean temperatures there must have been 2°-4°C. above present values. It seems probable that ...

In der neuen Studie Drought duration and frequency in the U.S. Corn Belt during the last millennium (AD 992-2004) (Pdf-Format, ca. 890 KB), stellen sich die Autoren der nicht ganz unwichtigen Aufgabe, (to) "characterize the historic occurrence, duration, and frequency of drought events" (Stambaugh et al., 155). Aus dem Abstract: We used a new long tree-ring chronology developed from the central U.S. to reconstruct annual drought and characterize past drought duration, frequency, and cycles in the U.S. Corn Belt region during the last millennium. This is the first paleoclimate reconstruction achieved with subfossil oak wood in the U.S. and increases the current dendroclimatic record in the central U.S. agricultural region by over 500 years. A tree ring-width drought response function was calibrated and verified against monthly instrumental Palmer Hydrologic Drought Index (PHDI) during the summer season (JJA). Für uns von Interesse, das Mittelalter. Wir finden dazu in der ...