Please accompany Greta Thunberg to San Giovanni di Terranova, Canada, and explain that when the Vikings of Erik the Red arrived in that region, almost a thousand years ago, they called it "Vinland", meaning "Land of Wine", because they saw the vines that grew there spontaneously. Then, add that today with an average annual night temperature of just one degree and with an average of minus ten throughout the long Canadian winter, the vines see them there only in photography. And to think that the Scandinavian explorer came from what then as now was the "Green Land", that is Greenland, where the "men of the north" had managed to grow wheat, a few thousand kilometers from what is now the northern limit of wheat cultivation.
Let us stop here and widen our horizons a little. We do not intend to enter into controversy with either Greta and her media follow-up or with the supporters of theories (mind you: theories) on the global warming as an anthropic product. We only want to start from the Canadian grapes and from the polar spikes taken as two symptoms of a different climatic situation from the current one and without a shadow of a doubt characterized by a northward movement (much to the north ...) of both the temperate and the mild climate. probably also of the sub-tropical one.
We are talking about symptoms, like pathologies, not temperatures, because today we are able to make a diagnosis of a patient who lived (and died) some centuries ago, both in the presence of the remains of the body and in front of only a well clinical picture described at the time of the disease, but not to indicate what body temperature he had during his illness.
In summary, we can say that Maria Tudor (in the portrait) had the swellings of the glands and abdomen typical of a fourth-stage uterine tumor at the time of death, not what temperature her organism had. Thus, we know for sure that in the so-called medieval hot period, between the tenth and mid-fourteenth century, most of the Alpine passes were free of snow and the glaciers melted in the summer period and that the winter season was limited to a few months. 'year. Not surprisingly, in the late Middle Ages, as many readers know as fans of military history, many important battles were fought also in the months of February, March and November, periods characterized by a mild climate that allowed the mobilization of peasant armies soldiers.
Thus, in the 1071 French and Flemish could fight the first battle of Cassel on February 22 and Emperor Henry IV the battle of Flarchheim even the 27 January 1080. In both cases, the weather and climate conditions had no consequences for operations.
In contrast, the British victory at the battle of Azincourt, fought on October 25 1415 was largely determined by the incessant thunderstorms and muddy fields that prevented the French from taking any advantage from the massive use of heavy cavalry. The pikes and archers of Britain did the rest ...
Thus, Greenland, Iceland and much of northern Europe became net importers of cereals produced in more temperate climates throughout the "small ice age", which lasted between the first half of the fourteenth and mid-nineteenth centuries. In this period the alpine glaciers reached the maximum extension of the last three millennia making the movement of the traditional Germanic traveling merchants towards southern Europe possible only in the short summer period.
Many symptoms make it possible to diagnose "medieval heat" and "small ice age" but nothing tells us of the actual temperature, despite attempts to determine it. In short, if the Seine and the Thames froze almost every year, we can deduce that, in the absence of testimonies of hot summers, the average annual temperature was probably less than now, given that this phenomenon has not even occurred since 1814.
We also know that during the nineteenth century the climate changed all the same: in the 1780 the waters of the port of New York froze for the last time in living memory, while between the 1896 and the 1911 (photo) three massive waves of heat in the summer period killed thousands of people in the Big Apple region. And that the climate has changed further is evidenced by the fact that during these waves the peaks of daytime temperatures fluctuated between the 30 and the 34 degrees, while today they are not rare points of 38 degrees in Manhattan. And yet, although the region is on average warmer, the northern limit of vine cultivation is still far from San Giovanni di Terranova. Likewise, on this side of the ocean there is no lack of attempts to reintroduce the vine in the British Isles, after almost seven centuries of absence. But they are sporadic and far from the results of the lower Middle Ages, when England became one of the world's leading wine producers.
Meanwhile, the young Greta, who will certainly not set foot in that of Terranova during her stay in North America, is probably going to receive the Nobel Peace Prize at the end of the year. Nobel Prize is not denied to anyone, even António Egas Moniz had it for the invention of the lobotomy: that thing we must not let ourselves be practiced, when they try to sell us a series of sometimes honest theories, some fanciful - but politically correct - for a certain datum commonly accepted by the international scientific community.
Photo: European Parliament / web