In the first century AD, an ancient Roman named Columella wrote an agricultural treatise called, “De re rustica.” In it, he discussed global warming that had turned areas once too cold for agriculture into thriving farm communities. Columella cites an authority named Saserna who recorded many such cases. According to Saserna, “regions which formerly, because of the unremitting severity of winter, could not safeguard any shoot of the vine or the olive planted in them, now that the earlier coldness has abated and weather is becoming more clement, produce olive harvests and the vintages of Bacchus [wine] in greatest abundance.”
In the Middle Ages, people began recording the temperature and climate-related phenomena, such as the dates when plants began to blossom annually. They were aware of a warming trend that began around 900 and a cooling trend that began around 1300. We know that during the warm period, the Vikings established settlements in Greenland where perpetual ice had previously covered the land. Ancient Norse records tell us that these settlements were abandoned after 1250 when falling temperatures made farming less viable and spreading ice in the sea made transportation more difficult.
The cooling trend led to heavy rains in 14th century Europe that were too much for the crops, leading to reduced agricultural output and numerous famines. In the 15th century, a warming trend returned, which lasted until the middle of the 16th century when temperatures again started to fall.
By the 17th century, it was clearly apparent that a cooling trend was altering sea routes, changing the kinds of crops farmers could grow, fishing patterns and so on. Glaciers began to advance rapidly in many places and rivers that had long been ice-free year round started to freeze in the winter. This “little ice age” continued well into the 19th century. Since then, we have been in a warming cycle that appears to have accelerated around 1950.
The point of this review is that we know a great deal about climate changes from the historical record and need not rely solely on scientific studies of core samples, tree rings and so on. These changes occurred long before industrialization and could not possibly have been man-made in any way whatsoever. They don’t prove that man is not now affecting the climate through carbon dioxide emissions, but they do tell us that temporary warming trends are common in human history. It may only be a matter of time before another cooling trend comes along.
Bruce Bartlett is a former senior fellow with the National Center for Policy Analysis of Dallas, Texas. Bartlett is a prolific author, having published over 900 articles in national publications, and prominent magazines and published four books, including Reaganomics: Supply-Side Economics in Action.
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