Many events have helped shape human evolution but among two of the most significant are TWO Ice Ages (glaciations). Together these two glaciation events are known as the “Wurm Glaciation Period.” Generally, this period is dated between 115 kya to about 11.7 kya. This period had warming periods amid the cold and ice and the average annual temperature in the Alpine regions was below -3 celsius (26 degrees Fahrenheit).
The Wurm Glaciation was mainly in the Alps or Europe but there were corresponding glaciations globally at the same time. In North and Central Europe we have the Weichselian Glaciation. In North America we had the Wisconsin Glaciation.
The primary contributor to the first glaciation during the Wurm Period is the eruption of Mt Toba in Sumatra, Indonesia. That was a huge volcano that erupted 73 kya and blasted 2800 km (671 cubic miles) of material into the planet’s atmosphere. The ash cloud spread across the northern hemisphere dumping volcanic ash as it moved. In India, for example, ash from Mt Toba was an astounding 18 feet deep! Ice core samples show us that global temps dropped about 61 degrees in Greenland over a period of 6 years. Essentially, this volcanic eruption resulted in what is called a “Volcanic Winter.” It dimmed the solar radiation coming from the Sun and that resulted in vegetation dying off. This, in turn, resulted in a mass extinction event as herbivores began to die of starvation. Of course it affected the rest of the food chain as well as food became scarce for carnivores and ancient humans. Africa was in the midst of a drought at this time and the eruption seems not to have done much there but one thing we do know is that it altered the genomes in surviving populations at the time.
Because the ash cloud lowered the amount of solar radiation (sunlight) getting to Earth, temperatures dropped with some dropping lower in some places than in others. Temps fell and it began to snow. Eventually the snow from the previous snow began not to melt so new snow was piled atop the old and, thus, glaciers were formed. These glaciers wiped out most of the evidence of humans at this time. Sea levels fell as the planet’s water became locked up in ice creating more shorelines and land bridges between continents of the time and former islands. Ancient humans living in the north began to migrate southward and this caused problems (conflict) for the ancient people who were already living in those southern regions. As this first glaciation period ended sea levels rose again and once again they covered any evidence of ancient man having been in some ancient places and shores.
The second glaciation period was between 30 kya and lasted until about 12 kya. It was more severe than the first but it had LESS effect on humans because by this time they had culturally evolved by having learned to build better shelters and make and wear clothing. Thus, humans during this time were better able to cope with the cold. Sea levels fell once again and this time by about 427 feet lower than they are today! This gave Eurasia land access to North America, Japan, Australia, Africa, et al. The English Channel became dry and one could walk from France to England and even onward to Ireland. This is the youngest and last glaciation on our planet and any history prior to the end of this ice age is known as “prehistory” while anything after is referred to as “history.” Thus, all recorded human history has taken place in the 12,000 years since the end of the last glaciation!
Both of these ice ages severely reduced Eurasian populations and, of course, as temps rose and the interglacial began those population sized began to increase once again. It was also about 12 kya that agriculture began and humans transitioned from hunter-gatherers to farmers. This aided population growth as well.
When we consider these events we can clearly see that CLIMATE is a significant selector. In fact, CLIMATE IS THE STRONGEST SELECTOR! A “selector” is anything that increases or decreases the reproductive success of a population. So, climate is important and when climate changes in catastrophic ways, catastrophic changes begin to happen!
Our planet has endured many cataclysms in the past. In some of these cataclysms some remnant of humans has survived but most have not! In some places these past cataclysms caused the extinction of humans! This is a scenario that has been repeated again and again over the eons of time and it will happen again. We who are alive today live in a FALSE sense of safety! We think that since today is the same as yesterday surely tomorrow will be the same. But one never knows what tomorrow may bring! NOTHING guarantees that tomorrow will be the same as today!! Should some catastrophe like the Toba eruption happen today it would have major effects on modern human civilization. Crops would fail and animals would begin to die and, thus, humans would begin to die of starvation, disease, and a host of other causes. Our infrastructures would fail and if you’re depending on that electric heater to keep you warm you’d better reconsider as there will be no electricity! Climate change is REAL! It is happening NOW! The way I see it we are entering into a new glaciation period not a warming period. I might be wrong or I might be right but whatever it is, heat or cold, humans and civilization are guaranteed to suffer!
Anything we can do to lessen that suffering MUST be done NOW. We can debate until hell freezes over and it does us NO GOOD WHATSOEVER! Our debate will not keep us from dying of the cold or heat!! Every nation, every people, every family needs to prepare for whatever is coming. Such preparation will help us survive. Lack of such preparation is only guaranteed to kill us!
Nature is most often harsh. She is often cruel and indifferent. She works by her own time clock NOT man’s! We’ve had plenty of warning that our global climate is changing and what we’ve mostly spent our time doing is debating and arguing. What we SHOULD have been doing is preparing!! NOW is the time for ACTION! The time for debate and arguing is OVER!!