While I can agree with the premise that perhaps regions of the planet were warmer then today during Medieval times, the idea that it is somehow relevant to current anthropogenic global warming is non sequitur, on top of the assumption that warmth in one region equates to warming globally.Influence of Dramatic Climate Shifts on European Civilizations: The Rise and Fall of the Vikings and the Little Ice Age
This one really had me scratching my head. It appears to be written by Scott Mandia, Professor of Physical Science, Suffolk County Community College. It was last updated in 2009 so it is a bit dated.
His Conclusions are just a page from the IPCC report. They appear to be just tacked on at the end. There is no continuity. They do not match his data and are unrelated to his topic which is the Influence of Dramatic Climate Shifts on European Culture. Subtitle is the Rise and Fall of the Vikings and the Little Ice Age. They appear to be hastily done as if to satisfy the demands of someone else. After reading some of his other writings it appears that his own overall view goes against some of the data in that specific paper.
In several places he has added notes to the general public , "My position on the current global warming is the same as the overwhelming majority of international climate scientists: the current rate of global warming is unprecedented and is being caused by humans. In no way can my summary of the research regarding the impact of regional climate change on the Viking civilization and Europe during the Little Ice Age be used to "prove" the current global warming is due to a natural cycle. Today's global climate is significantly warmer than that of the regional warmth of the Medieval Warm Period."
Did his research go against common climate beliefs? Maybe. It depends upon whether the Medieval Warm Period was regional or global. But... what did he say or show that was so horrible?
In his section "Determining the Climate Record" The Little Ice Age in Europe - Influence of Dramatic Climate Shifts on European Civilizations: The Rise and Fall of the Vikings and the Little Ice Age He posted several early charts by Mann (Everyone knows I'm skeptical of Mann's research and why.) Mann's regional charts start toward the end of the Medieval Warm Period (600-1150 AD). In general, Mann's charts show the Subtropic North Atlantic, Western Greenland, Fennoscandia, Eastern China, and the Tropical Andes (I assume they are looking at Columbia and Venezuela) as being as warm or warmer in the Medieval Warm Period than today. It shows Western North America and Central England (but it warmed up a little later) as being cooler. He also shows the Northern Hemisphere as being cooler as a whole.
Mandia then presents charts on proxy data (Oxygen Isotope Record, Tree Rings, and North Atlantic Ice) which clearly show that the Medieval Warm Period around the year 1150 was as warm or warmer than today. His discussion of Glaciers only covers the Little Ice Age and not the Medieval Warm Period. He then talks about other sources which I believe are also important to any discussion of historical times. Things like a book written in 1125 talking about swimming a Fiord which humans cannot do today and survive. He uses several of these references in his discussion of the Little Ice Age in Europe. The Little Ice Age in Europe - Influence of Dramatic Climate Shifts on European Civilizations: The Rise and Fall of the Vikings and the Little Ice Age One of which says:
He really shouldn’t have made references to today. That is probably why he changed his conclusion. I guess we'll never know what his original conclusions were.