New study: It was warmer during Roman and Medieval times

Four scientists - Jan Esper, Johannes Gutenberg University, Ulf Büntgen, the Swiss Federal Research Institute WSL, Mauri Timonen, Finnish Forest Research Institute and David C. Frank, Oeschger Centre for Climate Change Research, University of Bern - have studied northern Scandinavian summer temperatures of the past two millennia. Their new study, which has been published in Global  and Planetary Change 88-89 has produced some rather interesting results: 

Background

In introducing the report of their most recent study, the authors write that millennial-length temperature reconstructions have become "an important source of information to benchmark climate models, detect and attribute the role of natural and anthropogenic forcing agents, and quantify the feedback strength of the global carbon cycle." And, therefore, the four researchers have dedicated themselves and their talents to developing the most reliable long-term regional temperature reconstructions possible, focusing their attention most recently on parts of northern Sweden and Finland

What was learned
Most importantly from our point of view, the four researchers say that the new temperature history "provides evidence for substantial warmth during Roman and Medieval times, larger in extent and longer in duration than 20th century warmth."

What it means
As ever more data-inclusive and carefully-analyzed studies of palaeotemperature proxies are conducted, it is becoming ever more evident that there has not been anything unusual, unnatural or unprecedented about either the rate of warming or the level of warmth achieved during the 20th century, which further suggests that there is no real-world empirical evidence for any CO2-induced global or regional warming. It has all been natural.

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