Read here. Another major study affirms that pre-modern temperatures were unprecedented in terms of warming. The widely discredited Mann hockey-stick study, which even the IPCC 2007 report abandoned, has another stake driven through it as more complete research is being accomplished and published.
Scientist Fredrik Ljungqvist analyzed 60 different proxy reconstructions of annual mean temperatures. The reconstructions were from both the Northern and Southern hemispheres, and they represented both marine and terrestrial reconstructions. This is the broadest and largest study of its kind.
Ljungqvist determined that the vast number of reconstructions showed unprecedented warming from the the start of the Mid-Holocene Thermal Maximum period (approximately 8,000 years prior) to the onset of the Little Ice Age. Most of the reconstructions do not have current, modern warming coming close to rivaling the excessive 2°C warming that occurred for thousands of years. His study strongly indicates that this warming took place globally, with the high northern (polar) latitudes experiencing the greatest warming.
"A paper recently published in the journal Geographie examines 60 temperature proxies from around the globe and finds that the vast majority show the Earth was at least 1-2 C hotter than the pre-industrial period during the Holocene Climate Optimum from approximately 9000 to 5000 years ago. The warming of both the Holocene Climate Optimum and the Medieval Warming Period (~1000 years ago) are robust findings from the large number of proxies studied and refutes claims of the IPCC and Mann et al that the Medieval Warming Period was limited to Europe, finding that both were present in the Northern and Southern Hemispheres and were relatively synchronous." [Fredrik C. Ljungqvist 2011: Geograﬁe]