The mid-Holocene climatic transition in the Mediterranean: Causes and consequences

Abstract

In the Mediterranean there is often no clear time gap separating an early-Holocene period of nature-dominated environmental change from a human-dominated late-Holocene one. This mid-Holocene 'melange' has been the subject of debates that have often been polarised between support for climatic causation and those favouring anthropogenic explanations for changes in vegetation, river flooding, wildfire regimes, etc. One way to shed light on the causes of mid-Holocene landscape changes is to focus on natural archives, such as lake and cave isotopes, the records of which can be unambiguously attributed to climatic forcing. These primary climate proxies can then be compared and contrasted with secondary or response variables, such as pollen and microcharcoal data, which can be the product of either climate changes or human activity or both, ideally using a multiproxy approach. In addition, synthesised primary palaeoclimate data can be compared with regional-scale climate modelling simulations. Both model output and proxy data suggest an east-west division in Mediterranean climate history. They indicate that the eastern Mediterranean experienced an increase in winter-season precipitation during the early Holocene, followed by an oscillatory decline after similar to 6 ka BP. In western parts of the Mediterranean, early-Holocene changes in precipitation were smaller in magnitude and less coherent spatially, and maximum increases occurred during the mid Holocene, around 6-3 ka BP, before declining to present-day values. Coincident with and partly stimulated by these climatic changes, complex societies developed across the Mediterranean, particularly in eastern parts of the basin during the Bronze Age. In consequence, by the mid-first millennium BC, human-induced land cover conversion, a drier and more variable climate, and changed fire regimes combined to establish typical sclerophyllous vegetation and landscapes in the circum-Mediterranean region

Early and mid-holocene environmental conditions in the eastern Adriatic recorded in speleothems from Mala Špilja cave and Velika Špilja cave (Mljet island, Croatia)

“…As it is already shown by numerous researches (e.g. Bar-Matthews et al 1997Magny et al 2009;Bar-Matthews & Ayalon 2011;Brayshaw et al 2011;Giraudi et al 2011;Peyron et al 2011;Roberts et al 2011;Zanchetta et al 2011Zanchetta et al , 2014Zanchetta et al , 2016Rudzka et al 2012;Combourieu-Nebout et al 2013;Finné et al 2014) the Adriatic and Mediterranean basins are highly sensitive to climate changes and significant differences between the eastern and western basins are evident. Although stalagmites MSM-1 and VSM-1 have longer depositional period, the purpose of this paper is to give preliminary results for the Holocene environmental settings.…”

Climate and vegetation changes during the Lateglacial and early–middle Holocene at Lake Ledro (southern Alps, Italy)

“…These rapid climatic changes are recorded throughout the Mediterranean region, but their characteristic effects can vary spatially (e.g. Magny et al, 2003Magny et al, , 2011Fletcher et al, 2010;Roberts et al, 2011). In the context of low Holocene temperature variations in the Alps (±1 • C; Heiri et al, 2003), precipitation, reflected by lake-level changes (e.g.…”

Contrasting patterns of climatic changes during the Holocene across the Italian Peninsula reconstructed from pollen data

“…These data show a complex pattern of climatic change across the Mediterranean during the Holocene, with strong spatial and temporal variability (e.g. Tzedakis, 2007;Peyron et al, 2011;Roberts et al, 2011). Recent lake-level records from Italy suggest a northsouth partitioning of Holocene climate in the central Mediterranean at ∼ 40 • N (Magny et al, 2012b).…”