Our own planetary history demonstrates this principle with extreme clarity. Not so long ago, in the nineteen-sixties and seventies, scientists were actually predicting a new ice age in the not-too-distant future. Their observations drew much from the past, since the northern hemisphere was once covered by glaciers that reached as far south as the central regions of today’s America.
Furthermore, recent history reinforced their cooling hypothesis. Climatologists refer to a "Little Ice Age," which was observed in Europe between the 13th and mid-19th centuries. As late as 1816, the famous "year without a summer," witnessed freezing temperatures and frozen crops in Europe, Newfoundland and Canada. Midsummer ice on rivers and lakes, with accompanying blizzards, were recorded as far south as Pennsylvania.
It is hardly a surprise that the common factor in this climatic aberration seems to have been the Sun. It is well known that this period was marked by the virtual absence of turbulent solar storms. At times, sunspots were simply absent. Most of the time, they appeared with extreme rarity. Sunspots, by the way, are among the most well documented events in the history of astronomical observation. Literally centuries of observations are available.
Well known to astronomers is the so-called "Maunder Minimum." It marks the period from 1645 to 1715, when solar observers counted few, if any sunspots. In the year 1670, not a single one was seen. The three decades at the heart of this historical epoch produced only about 50 sunspots, as opposed to the normal 40 to 50 thousand for a similar period!
This situation, lasting about five centuries, brought the northern hemisphere much cooler temperatures than normal, in exact synchronization with diminished solar activity. More sunspots brought more heat, and vice versa. Certainly, human endeavors were in no way connected with the changes, since they happened long before the Industrial Revolution.
Interestingly, the years just prior to the Little Ice Age are referred to as "The Medieval Warm Period." During this period, explorers from Iceland were led westward from Iceland across the northern Atlantic by the famed explorer Erik the Red, whose forbearers had originally come from Norway. Around A.D. 982, they came to a lush new territory, so rich and green that they immediately colonized it. Because its southern regions were covered with lush vegetation, they promptly named it Greenland. Crops and vines flourished. Trade routes were established. Even an archdiocese from the Norwegian church was established there!
Needless to say, Greenland isn’t green anymore. After about four and a half centuries, rapid cooling quickly covered Greenland with ice. The Norwegians retreated back to their homeland. The fifteenth century brought Greenland a "Little Ice Age." From that day to this, the territory is still encrusted with ice that continues to accumulate, sometimes hundreds of feet deep, where crops used to grow and villages thrived.
