A seesaw in Mediterranean precipitation during the Roman Period linked to millennial-scale changes in the North Atlantic

Abstract

We present a reconstruction of the change in climatic humidity around the Mediterranean between 3000–1000 yr BP. Using a range of proxy archives and model simulations we demonstrate that climate during this period was typified by a millennial-scale seesaw in climatic humidity between Spain and Israel on one side and the Central Mediterranean and Turkey on the other, similar to precipitation anomalies associated with the East Atlantic/West Russia pattern in current climate. We find that changes in the position and intensity of the jet stream indicated by our analysis correlate with millennial changes in North Atlantic sea surface temperature. A model simulation indicates the proxies of climatic humidity used in our analysis were unlikely to be influenced by climatic aridification caused by deforestation during the Roman Period. That finding is supported by an analysis of the distribution of archaeological sites in the Eastern Mediterranean which exhibits no evidence that human habitation distribution changed since ancient times as a result of climatic aridification. Therefore we conclude that changes in climatic humidity over the Mediterranean during the Roman Period were primarily caused by a modification of the jet stream linked to sea surface temperature change in the North Atlantic. Based on our findings, we propose that ocean-atmosphere coupling may have contributed to regulating Atlantic Meridional Overturning Circulation intensity during the period of analysis

Paleohydrology reconstruction and Holocene climate variability in the South Adriatic Sea

“…2.6 and 1.6 ka (Dermody et al, 2012). These events, mainly related to the position and intensity of the jet streams, have been correlated to millennial changes in North Atlantic oscillation mode (Chen et al, 2011;Dermody et al, 2012). …”

Seasonality variations in the Central Mediterranean during climate change events in the Late Holocene

“…Relatively humid conditions during the reign of the Romans, the Roman Humid Period (RHP, 1950-2400cal. years BP, Grauel et al, 2013b, are generally associated with a more southern pathway of the westerlies, increasing winter precipitation in the region (Dermody et al, 2012). In general, observed millennial scale climate variability in the Northern Mediterranean during the Holocene has been explained by changes in extent of high northern latitude climate during winter (Rohling and Pälike, 2005;Peyron et al, 2011;Combourieu-Nebout et al, 2013).…”

The PMIP4 contribution to CMIP6 – Part 3: The last millennium, scientific objective, and experimental design for the PMIP4 <i>past1000</i> simulations

“…In parts of the world where ALCC led to quasi-permanent deforestation and where climate is tightly coupled to land surface conditions, we might expect regional climate to have been strongly influenced by biogeophysical feedbacks (e.g. Cook et al, 2012;Dermody et al, 2012;Pongratz et al, 2009;Strandberg et al, 2014). Additionally, permanent deforestation and loss of soil carbon as a result of cultivation (e.g.…”