One of the critical pieces of evidence that undermines the catastrophic global warming narrative is the existence of the Medieval Warming Period and the Little Ice Age. The catastrophists dismiss it as merely a local phenomenon in Europe, but modern temperature measurements suggest otherwise.
The Medieval Warm Period
Around a thousand years ago, medieval Europe went through an economic, demographic, and cultural boom, and it seems much of the reason was the unusually warm climate. Wine grapes were grown in Scotland, and the Vikings colonized Greenland and were able to farm the land in places that today have permafrost.
A few hundred years later, Europe experienced what’s called the Little Ice Age. The summers were chilly and wet, and the winters were harsh. In 1687, an Ottoman chronicler in Istanbul wrote that “this winter was severe to a degree that had not been seen in a very long time. For fifty days, the roads were closed, and people could not go outside. In cities and villages, the snow buried many houses.”
At the end of the 19th century, the Little Ice Age concluded, and the world recovered from the deep freeze. Today, the average temperature in Istanbul in January, usually the coldest month of the year, is 43°F. It snows in the winter, but nothing like during the Little Ice Age.
Until 1998, the scientific community assumed that the above climate history was a global phenomenon, which was highly inconvenient for those who wished to peddle catastrophism. As if on cue, Dr. Michael Mann produced the so-called hockey stick graph based on tree rings, and the Little Ice age was declared a regional cooling while the climate was stable globally. Although Mann’s work has since been debunked as substandard science, other scientists produced similar results from other climate proxies.
Correlation
Independent scientist Willis Eschenbach was not satisfied with this conclusion and wanted to test how well the climate of a small region correlated with global temperature. He quickly realized that the local variation is much larger on short time scales of days, months, and years. Therefore, he filtered away most of the short-term signal and only compared trends stretching decades and centuries. What he found shocked him.
Central England and the world were surprisingly highly correlated. The data showed that 67% of the global temperature in the last 170 years could be correctly predicted from this tiny patch of land. Repeating the calculation for the United States, which covers about 2% of the globe’s area, he found an even higher match of 76%.
Graphs courtesy Willis Eschenbach, Wattsupwiththat.com
Eschenbach realized that the public climate data allowed him to make a correlation map of the whole world. He compared global temperature with every one degree longitude by one degree latitude region of the entire planet. The result was, again, shocking and illuminating. The local climates of landmasses are highly correlated with global temperature.
In practice, one can accurately measure long-term global trends by gauging the temperature in a small region of the world. Consequently, the Medieval Warm Period and the Little Ice Age recorded in Europe were likely global phenomena.
Inconvenient Truth
This conclusion throws a giant wrench into the machinery of climate doom because it implies that there is nothing unusual about the warming of the 20th century. Although human carbon dioxide emissions have undoubtedly contributed, there is a fair chance that much of the observed warming is still just a natural rebound from the Little Ice Age.
