Change search
ReferencesLink to record
Permanent link

Direct link
Reconstruction of the Extratropical NH Mean Temperature over the Last Millennium with a Method that Preserves Low-Frequency Variability
Stockholm University, Faculty of Humanities, Department of History.
2011 (English)In: Journal of Climate, ISSN 0894-8755, E-ISSN 1520-0442, Vol. 24, no 23, 6013-6034 p.Article in journal (Refereed) Published
Abstract [en]

A new multiproxy reconstruction of the Northern Hemisphere extratropical mean temperature over the last millennium is presented. The reconstruction is performed with a novel method designed to avoid the underestimation of low-frequency variability that has been a general problem for regression-based reconstruction methods. The disadvantage of this method is an exaggerated high-frequency variability. The reconstruction is based on a set of 40 proxies of annual to decadal resolution that have been shown to relate to the local temperature. The new reconstruction shows a very cold Little Ice Age centered around the 17th century with a cold extremum (for 50-yr smoothing) of about 1.1 K below the temperature of the calibration period, AD 1880–1960. This cooling is about twice as large as corresponding numbers reported by most other reconstructions. In the beginning of the millennium the new reconstruction shows small anomalies in agreement with previous studies. However, the new temperature reconstruction decreases faster than previous reconstructions in the first 600 years of the millennium and has a stronger variability. The salient features of the new reconstruction are shown to be robust to changes in the calibration period, the source of the local temperatures, the spatial averaging procedure, and the screening process applied to the proxies. An ensemble pseudoproxy approach is applied to estimate the confidence intervals of the 50-yr smoothed reconstruction showing that the period AD 1500–1850 is significantly colder than the calibration period.

Place, publisher, year, edition, pages
Boston: American Meteorological Society , 2011. Vol. 24, no 23, 6013-6034 p.
Keyword [en]
Temperature reconstruction, proxy data, Medieval Warm Period, Little Ice Age, global warming, climate change, pseudoproxy, low-frequency climate variability
National Category
Climate Research
Research subject
Physical Geography; Meteorology
URN: urn:nbn:se:su:diva-64761DOI: 10.1175/2011JCLI4145.1ISI: 000298020500004OAI: diva2:458560
Available from: 2011-11-23 Created: 2011-11-23 Last updated: 2012-01-29Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

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

Search outside of DiVA

GoogleGoogle Scholar
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: 35 hits
ReferencesLink to record
Permanent link

Direct link