Warm Mediterranean mid-Holocene summers inferred from fossil midge assemblages

Samartin, Stéphanie; Heiri, Oliver; Joos, Fortunat; Renssen, Hans; Franke, Jörg; Brönnimann, Stefan; Tinner, Willy (2017). Warm Mediterranean mid-Holocene summers inferred from fossil midge assemblages. Nature geoscience, 10(3), pp. 207-212. Nature Publishing Group 10.1038/ngeo2891

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Understanding past climate trends is key for reliable projections of global warming and associated risks and hazards. Uncomfortably large discrepancies between vegetation-based summer temperature reconstructions (mainly based on pollen) and climate model results have been reported for the current interglacial, the Holocene. For the Mediterranean region these reconstructions indicate cooler-than-present mid-Holocene summers, in contrast with expectations based on climate models and long-term changes in summer insolation. We present new quantitative and replicated Holocene summer temperature reconstructions based on fossil chironomid midges from the northern central Mediterranean region. The Holocene thermal maximum is reconstructed 9,000–5,000 years ago and estimated to have been 1–2 °C warmer in mean July temperature than the recent pre-industrial period, consistent with glacier and marine records, and with transient climate model runs. This combined evidence implies that widely used pollen-based summer temperature reconstructions in the Mediterranean area are significantly biased by precipitation or other forcings such as early land use. Our interpretation can resolve the previous discrepancy between climate models and quantitative palaeotemperature records for millennial-scale Holocene summer temperature trends in the Mediterranean region. It also suggests that pollen-based evidence for cool mid-Holocene summers in other semi-arid to arid regions of the Northern Hemisphere may have to be reconsidered, with potential implications for global-scale reconstructions.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Institute of Geography > Physical Geography > Unit Climatology
10 Strategic Research Centers > Oeschger Centre for Climate Change Research (OCCR)
08 Faculty of Science > Institute of Geography
08 Faculty of Science > Institute of Geography > Physical Geography
08 Faculty of Science > Department of Biology > Institute of Plant Sciences (IPS) > Palaeoecology
08 Faculty of Science > Physics Institute
08 Faculty of Science > Department of Biology > Institute of Plant Sciences (IPS)

UniBE Contributor:

Samartin, Stéphanie; Heiri, Oliver; Joos, Fortunat; Franke, Jörg; Brönnimann, Stefan and Tinner, Willy

Subjects:

500 Science > 580 Plants (Botany)
900 History > 910 Geography & travel
500 Science > 530 Physics

ISSN:

1752-0894

Publisher:

Nature Publishing Group

Language:

English

Submitter:

Peter Alfred von Ballmoos-Haas

Date Deposited:

02 Mar 2017 16:20

Last Modified:

22 May 2017 14:41

Publisher DOI:

10.1038/ngeo2891

BORIS DOI:

10.7892/boris.95559

URI:

https://boris.unibe.ch/id/eprint/95559

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