Change search
ReferencesLink to record
Permanent link

Direct link
The extra-tropical Northern Hemisphere temperature in the last two millennia: reconstructions of low-frequency variability
Danish Meteorological Institute.
Stockholm University, Faculty of Humanities, Department of History.
2012 (English)In: Climate of the Past, ISSN 1814-9324, Vol. 8, no 2, 765-786 p.Article in journal (Refereed) Published
Abstract [en]

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. 950–1050 AD reaching 0.6 °C relative to the reference period 1880–1960 AD. The 500-yr long reconstruction confirms previous results obtained with the LOC method applied to a smaller proxy compilation; in particular it shows the Little Ice Age cumulating in 1580–1720 AD with a temperature minimum of −1.0 °C below the reference period.  The reconstructed local temperatures, the magnitude of which are subject to wide confidence intervals, show a rather geographically homogeneous Little Ice Age, while more geographical inhomogeneities are found for the Medieval Warm Period. Reconstructions based on different subsets of proxies show only small differences, suggesting that LOC reconstructs 50-yr smoothed extra-tropical NH mean temperatures well and that low-frequency noise in the proxies is a relatively small problem.

Place, publisher, year, edition, pages
2012. Vol. 8, no 2, 765-786 p.
Keyword [sv]
Temperature reconstruction, Medieval Warm Period, Little Ice Age, global warming, climate change
National Category
Climate Research
Research subject
Physical Geography; Meteorology; History
URN: urn:nbn:se:su:diva-75416DOI: 10.5194/cp-8-765-2012ISI: 000304059700026OAI: diva2:516463
Available from: 2012-09-12 Created: 2012-04-18 Last updated: 2012-09-12Bibliographically approved

Open Access in DiVA

Christiansen and Ljungqvist 2012(3405 kB)1437 downloads
File information
File name FULLTEXT01.pdfFile size 3405 kBChecksum SHA-512
Type fulltextMimetype application/pdf

Other links

Publisher's full text

Search in DiVA

By author/editor
Charpentier Ljungqvist, Fredrik
By organisation
Department of History
In the same journal
Climate of the Past
Climate Research

Search outside of DiVA

GoogleGoogle Scholar
Total: 1437 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 463 hits
ReferencesLink to record
Permanent link

Direct link