What is known and what is proven are two different things. Remember. Mann's hockey stick, with his methodology, is recreated with random data as well.
Accident or design?
It's also recreated with both contemporary (Jones et al 1998, Crowley and Lowery 2000) and more recent reconstructions. Coincidink? Conspiracy? Or could it be that hemispheric and global temperatures have actually followed that general pattern? :shock:
Fifteen millenium-plus wide scale paleoclimate studies since 2000, excluding low-resolution reconstructions (such as Marcott et al 2013).
[Edit: From an old post, so at least one link, the second, is no longer active.]
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Crowley and Lowery 2000, How Warm Was the Medieval Warm Period?; AMBIO: A Journal of the Human Environment 29(1):51-54. 2000
(behind a paywall; reconstruction reproduced in Crowley 2000)
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Esper et al 2002, Low-Frequency Signals in Long Tree-Ring Chronologies for Reconstructing Past Temperature Variability; VOL 295 SCIENCE
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Moberg et al 2005, Highly variable Northern Hemisphere temperatures reconstructed from low- and high-resolution proxy data; NATURE |VOL 433
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D'Arrigo et al 2006, On the long-term context for late twentieth century warming; JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 111
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Juckes et al 2007, Millennial temperature reconstruction intercomparison and evaluation; Clim. Past, 3, 591–609
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Frank et al 2007, Adjustment for proxy number and coherence in a large-scale temperature reconstruction; GEOPHYSICAL RESEARCH LETTERS, VOL. 34
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Hegerl and co 2007, Detection of Human Influence on a New, Validated 1500-Year Temperature Reconstruction; JOURNAL OF CLIMATE VOLUME 20
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Mann et al 2008, Proxy-based reconstructions of hemispheric and global surface temperature variations over the past two millennia; PNAS vol. 105 no. 36
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Loehle and McCulloch 2008, Correction to: A 2000-Year Global Temperature Reconstruction Based on Non-tree Ring Proxies; Energy & Environment· Vol. 19, No. 1
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Ljungqvist, F. C. 2010, A new reconstruction of temperature variability in the extratropical northern hemisphere during the last two millennia; Geografiska Annaler: Series A (Swedish Society for Anthropology and Geography)
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McShane and Wyner 2011, A Statistical Analysis of Multiple Temperature Proxies: Are Reconstructions of Surface Temperatures Over the Last 1000 Years Reliable?; The Annals of Applied Statistics, Vol. 5, No. 1, 5–44
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Christiansen and Ljungqvist 2011, Reconstruction of the Extratropical NH Mean Temperature over the Last Millennium with a Method that Preserves Low-Frequency Variability; JOURNAL OF CLIMATE VOLUME 24
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Christiansen and Ljungqvist 2012, The extra-tropical Northern Hemisphere temperature in the last two millennia: reconstructions of low-frequency variability; Clim. Past, 8, 765–786
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PAGES 2k Consortium 2013, Continental-scale temperature variability during the past two millennia; NATURE GEOSCIENCE | VOL 6
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Shi et al 2013, Northern Hemisphere temperature reconstruction during the last millennium using multiple annual proxies; Clim. Res., 56, 231–244