NOAA: Paleoclimatology Global Warming – The Data. 2006-11-10. „idea of a global or hemispheric „Medieval Warm Period” that was warmer than today however, has turned out to be incorrect”, „records that do exist show is that there was no multi-century periods when global or hemispheric temperatures were the same or warmer than in the 20th century”. (ang.).
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‘Apocalypse my arse’. spiked-online.com, 9 marca 2007. [dostęp 2010-01-28]. (ang.).
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Bradley, R.S. et al, „Climate Change in Medieval Times”, Science, 302 (2003): 404-405, „Large-scale reconstructions of mean annual or summer temperatures for the Northern Hemisphere show a decline in temperatures from 1000 A.D. to the late 19th century, followed by an abrupt rise in temperature (6). Such analyses, when scaled to the same base of reference, show that temperatures from 1000 to 1200 A.D. (or 1100 to 1200 A.D.) were almost the same (or 0.03 °C cooler) as from 1901 to 1970 A.D.
