Are current temperatures hotter than ever?
Not so far
Was there a Medieval Warm Period somewhere in the world in addition to the area surrounding the North Atlantic Ocean, where its occurrence is uncontested? This question is of utmost importance to the ongoing global warming debate, for if the Medieval Warm Period is found to have been a global climatic phenomenon, and if the locations where it occurred were as warm in medieval times as they are currently, there is no need to consider the temperature increase of the past century as anything other than the natural progression of the persistent millennial-scale oscillation of climate that regularly brings the earth several-hundred-year periods of modestly higher and lower temperatures that are totally independent of variations in atmospheric CO2 concentration.
via CO2 Science.
The CO2 Science web site thus introduces a literature review of temperature studies around 950–1400, known traditionally as the Medieval Warm Period.
The review concludes that the findings of the 24 studies examined suggest “there is nothing that is unusual, unnatural or unprecedented about the current level of Earth’s warmth, which further suggests that the historical increase in the atmosphere’s CO2 concentration may not have had anything to do with concomitant 20th-century global warming.”
The Center for the Study of Carbon Dioxide and Global Change was founded by Dr Craig D. Idso (the present chairman), Dr Sherwood B. Idso is its President and Dr Keith E. Idso its Vice President. Craig and Keith are brothers, Sherwood is their father; each is a respected scientist with an impressive publication record.
h/t WUWT, who includes this handy comparison: