The Medieval Climate Anomaly in the Mediterranean Region

Abstract

The Medieval Climate Anomaly (MCA) is a preindustrial phase of pronounced natural climate variability with a core period from 1000 to 1200 CE. The paper presents a synthesis that integrates palaeotemperature records from the Greater Mediterranean Region encompassing the past 1,500 years based on multiproxy data from 79 published land and marine sites. MCA warming dominated the Western Mediterranean (Iberia, NW Africa) as well as the northern land areas of the Central and Eastern Mediterranean region. MCA cooling prevailed in the Canary Current Upwelling System, southern Levant, and some sea areas of the Central and Eastern Mediterranean. Previous palaeoreconstructions suggest persistent positive Atlantic Multidecadal Oscillation (AMO+) and North Atlantic Oscillation (NAO+) conditions during the MCA, while the Little Ice Age was dominated by an AMO− and NAO− regime. During the past 150 years, AMO+ conditions are typically associated with warming episodes in the Mediterranean area. A similar relationship appears to have also been established during the MCA as the majority of all Mediterranean land sites experienced warm climate conditions. In contrast, the NAO typically leads to a characteristic west‐east temperature dipole pattern in the basin, as documented for the last decades. During NAO+ conditions the Western Mediterranean is generally warm (and dry), while large parts of the Central and Eastern Mediterranean are cold. Similar trends seem to have been developed during the MCA when the NAO+ regime led to consistent warming in the Western Mediterranean, while a significant number of sites with MCA cooling existed in the Central and Eastern Mediterranean.

Palynological evidence from a sub-alpine marsh of enhanced Little Ice Age snowpack in the Marrakech High Atlas, North Africa

“…The findings encourage further consideration of the Little Ice Age concept in the High Atlas setting. Overall, the prevailing paradigm in Morocco and the Western Mediterranean more widely is of a dry MCA and a wet Little Ice Age (Moreno et al 2012;Fletcher and Zielhofer 2013;Lüning et al 2017Lüning et al , 2019. This paradigm is supported by many Moroccan records, notably speleothems, lake-levels and tree-rings in the Middle Atlas (Esper et al 2007;Détriché et al 2009;Wassenburg et al 2013), and is broadly consistent with long term changes observed at Oukaïmeden.…”

Conflicts and the spread of plagues in pre-industrial Europe

“…It has been shown that warmer and wetter conditions favored the flea burden and host abundance (black rats or great gerbil) in the case of bubonic plague (Stenseth et al, 2006). While regional conditions may have promoted the second plague outbreak in Central Asia (Stenseth et al, 2006), the "pre" Little Ice Age (AD 1300-1550) was a wetter and cooler period in both Europe and Eurasia (Jones et al, 2001(Jones et al, , 2006Griggs et al, 2007;Kaniewski et al, 2011;Xoplaki et al, 2018;Lüning et al, 2019). Because rat/gerbil and flea blooms are favored by climate conditions not recorded from Eurasia to Europe (Lionello, 2012;Kushnir and Stein, 2019), and as rats were scarce in northern Europe during the plague outbreaks (Davis, 1986), the epidemics may have mostly spread via humanto-human transmission.…”

Neoglaciation in the Spanish Pyrenees: a multiproxy challenge

“…This, in turn, is the only direct information on glacial melting during the MCA in the Pyrenees, confirming the negative effect of the medieval warming for the survival of glaciers, even at high elevations. Morellón et al (2011) reported low lake levels and saline conditions in the Estanya Lake, Pre-Pyrenees, during medieval times, particularly between 1150 and 1300 CE, most likely due to the persistence of positive Atlantic Multidecadal Oscillation and North Atlantic Oscillation (Moreno et al 2012;Luning et al 2019).…”

“…For most areas in the world, particularly in the northern hemisphere, this process of cooling culminated during the Little Ice Age (LIA), whose generally accepted time span is between 1300 and 1850 AD (e.g., Holzhauser et al 2005;Joerin et al 2006;Wanner et al 2008Wanner et al , 2011Geirsdóttir et al 2009;Ivy-Ochs et al 2009;Nesje et al 2009;Le Roy et al 2015;Solomina et al 2016a;. Nevertheless, from the beginning of the Neoglacial until the onset of the LIA, the climate underwent other fluctuations, including the cooling of the Bronze Age, the warm Roman Period, the cold Dark Ages during the early Middle Ages (e.g., Holzhauser et al 2005;Wanner et al 2008Wanner et al , 2011Ivy-Ochs et al 2009), and the Medieval Climate Anomaly (MCA), characterized by sustained and relatively intense warming (Moreno et al 2012;Luning et al 2019). In a more detailed approach, even the LIA cannot be considered as a homogeneous, constantly cold period, since cold waves alternated with droughts and hot waves , thus confirming that the Holocene has been subjected to continuous climate variability.…”