Northern Hemisphere Extratropical 2000-Year and 500-Year Temperature Reconstructions

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Creator/Principal investigator(s):

Bo Christiansen - Danish Meteorological Institute

Fredrik Charpentier Ljungquist - Stockholm University

Description:

We present two new multi-proxy reconstructions of the extra-tropical Northern Hemisphere (30-90°N) mean temperature: a two-millennia long reconstruction reaching back to 1 AD and a 500-yr long reconstruction reaching back to 1500 AD. The reconstructions are based on compilations of 32 and 91 proxies, respectively, of which only little more than half pass a screening procedure and are included in the actual reconstructions. The proxies are of different types and of different resolutions (annual, annual-to-decadal, and decadal) but all have previously been shown to relate to local or regional temperature. We use a reconstruction method, LOCal (LOC), that recently has been shown to confidently reproduce low-frequency variability. Confidence intervals are obtained by an ensemble pseudo-proxy method that both estimates the variance and the bias of the reconstructions. The two-millennia long reconstruction shows a well defined Medieval Warm Period, with a peak warming ca. 950-1050AD reaching 0.6°C relative to the reference period 1880-1960 AD. The 500-yr long reconstruction confirms previous results

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Responsible department/unit:

Danish Meteorological Institute

Creator/Principal investigator(s):

Bo Christiansen - Danish Meteorological Institute

Fredrik Charpentier Ljungquist - Stockholm University

Identifiers:

SND-ID: ECDS 0083

Description:

We present two new multi-proxy reconstructions of the extra-tropical Northern Hemisphere (30-90°N) mean temperature: a two-millennia long reconstruction reaching back to 1 AD and a 500-yr long reconstruction reaching back to 1500 AD. The reconstructions are based on compilations of 32 and 91 proxies, respectively, of which only little more than half pass a screening procedure and are included in the actual reconstructions. The proxies are of different types and of different resolutions (annual, annual-to-decadal, and decadal) but all have previously been shown to relate to local or regional temperature. We use a reconstruction method, LOCal (LOC), that recently has been shown to confidently reproduce low-frequency variability. Confidence intervals are obtained by an ensemble pseudo-proxy method that both estimates the variance and the bias of the reconstructions. The two-millennia long reconstruction shows a well defined Medieval Warm Period, with a peak warming ca. 950-1050AD reaching 0.6°C relative to the reference period 1880-1960 AD. The 500-yr long reconstruction confirms previous results

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Time period(s) investigated:

1 — 2000

Contact persons for questions about the data:

Bo Christiansen

Fredrik Charpentier Ljungquist

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Publications

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Christiansen, B., and Ljungqvist, F.C. 2012: The extra-tropical Northern Hemisphere temperature in the last two millennia: reconstructions of low-frequency variability. Climate of the Past, 8: 765-786, www.clim-past.net/8/765/2012/, doi:10.5194/cp-8-765-2012.

If you have published anything based on these data, please notify us with a reference to your publication(s).

Published: 2019-10-08