Tuesday, August 20, 2013

New paper finds another 2 non-hockey-sticks in Italy

A new paper published in Climate of the Past reconstructs annual temperatures from pollen in Sicily, Italy over the past 6,700 years and finds another 2 non-hockey-sticks with temperatures warmer than modern temperatures multiple times in the past, including during the Roman and Minoan Warming Periods. 
Two different pollen temperature proxies shown by red and yellow lines. Vertical axis is years before the present.
Clim. Past, 9, 1969-1984, 2013

L. Sadori1, E. Ortu2, O. Peyron2,3, G. Zanchetta4, B. Vannière2, M. Desmet5, and M. Magny2
1Dipartimento di Biologia Ambientale, Università di Roma "La Sapienza", Piazzale Aldo Moro 5, 00185 Roma, Italy
2CNRS, UMR6249, Laboratoire Chrono-Environnement, 16 route de Gray, 25030 Besançon cedex, France
3CBAE, UMR5059, CNRS, Université Montpellier 2, Montpellier, France
4Dipartimento di Scienze della Terra, Università di Pisa, Via S. Maria 53, 56126 Pisa, Italy
5EA 6293 GéHCO, Université de Tours, 37000 Tours, France

Abstract. The aim of this study is to investigate climate changes and human activities under the lens of palynology. Based on a new high-resolution pollen sequence (PG2) from Lago di Pergusa (667 m a.s.l., central Sicily, Italy) covering the last 6700 yr, we propose a reconstruction of climate and landscape changes over the recent past in central Sicily. Compared to former studies from Lago di Pergusa (Sadori and Narcisi, 2001), this work provides a reconstruction of the evolution of vegetation and climate over the last millennia in central Sicily, indeed completing previous results with new pollen data, which is particularly detailed on the last 3000 yr.

Joint actions of increasing dryness, climate oscillations, and human impact shaped the landscape of this privileged site. Lago di Pergusa, besides being the main inland lake of Sicily, is very sensitive to climate change and its territory was inhabited and exploited continuously since the Palaeolithic. The lake sediments turned out to be a good observatory for natural phenomena that occurred in the last thousands of years.

Results of the pollen-based study are integrated with changes in magnetic susceptibility and a tephra layer characterization. The tephra layer was shown to be related to the Sicanians' event, radiocarbon dated at 3055 ± 75 yr BP (Sadori and Narcisi, 2001).

We performed palaeoclimate reconstructions by MAT (Modern Analogues Technique) and WAPLS (Weighted Average Partial Least Square). Palaeoclimate reconstructions based on the core show important climate fluctuations throughout the Holocene. Climate reconstruction points out four phases of cooling and enhanced wetness in the last three millennia (2600–2000, 1650–1100, 850–550, 400–200 cal BP, corresponding to the periods between 650–50 BC, and 300–850, 1100–1400, 1550–1750 AD, respectively). This appears to be the evidence of local responses to global climate oscillations during the recent past.

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