New paper shows Earth was significantly hotter during past several thousand years

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.

Number of temperature proxies hotter than pre-industrial values shown above the horizontal zero line for the a) Northern hemisphere and b) Southern hemisphere. The x axis shows the number of years before the present. Note the Earth has only warmed 0.65 C since the pre-industrial period (in recovery from the Little Ice Age shown ~500 years ago).