Climate Change 101
Jump back 18,000 years. The world was much different. The Great Lakes, the English Channel, and the Baltic Sea didn’t exist. North America, Europe, and Siberia were covered by giant ice sheets that averaged more than a mile in depth. The enormous weight of these glaciers pressed the land down. Sea level was 120 meters (393 feet) below present, so that much additional land was exposed. The level was down because so much water was tied up in the huge, thick glaciers.
NOAA’s Paleoclimatology website lays out the entire story in nearly understandable language. The link above takes you to Figure 2, which shows a point of view above the North Pole, 18,000 years ago, and if you study it carefully you’ll see that the ice came halfway down into the United States, and covered much of Europe as well. By this date the glaciers had probably begun to recede, but slowly. The illustration compares the ice cap 18,000 years BP (before present) with that of today, and you may observe how tiny the modern one appears.
Glacial periods on the Earth are cyclic. For the past 2.5 million years at least, glaciers have repeatedly formed, then melted. The last glacial period lasted from about 115 ka to 12 ka, where “ka” stands for “thousands of years ago”. We are currently in a warm interglacial period that began about 14,500 years ago, (the number can vary) according to scientists. As the ice melted, sea level rose. Depressions filled with water from the melt, which is how the Great Lakes came into being. The English Channel, the North Sea, and the Baltic took on their modern configuration.
As the glaciers retreated and the climate moderated, forests moved into the freshly uncovered land, and animal life did so as well. Humans occupied the new territory. In North America, we can find a few sites of the Clovis culture prior to 12,800 BP, at which point the climate became colder again for about 1300 years, in a spell known as the Younger Dryas. No Clovis artifacts have been found younger than that cycle, which ended about 11,500 BP.
The climate continued to moderate, but unevenly. Weather is always changing without the assistance of mankind. Cliff Harris at Harris-Mann Climatology explains what has happened in the past 4,500 years in a short video. Note that the Earth has been recovering from the “Little Ice Age” since about 1850. Note also that in the past there have been warmer periods than the current one, and all of this occurred before mankind began burning fossil fuels at a great rate, sometime in the late 1800’s.
The climate will always change, because there are natural processes that vary the heat received from the sun. Short term effects are caused by volcanic eruptions, which throw vast amounts of dust into the air; the dust spreads and reduces the amount of the sun’s heat that reaches the ground. Sunspot cycles cause cooling; when there are few to no spots, the Earth receives less sunlight.
The Earth’s orbit and inclination to the sun changes over long periods, and this is thought to be the cause of glacial ages. This topic is well-covered in the NOAA site.
If you are interested, you might check Dr. Roy Spencer’s blog. It is sometimes very technical, but has a great deal of information about climate and the effort to understand it.
Politicians, especially those on the left, have adopted anthropogenic (man-made) Climate Change as a cause to be pushed at all costs. In their view, the warming is caused by man and will create dire effects a few years from now. There are climate scientists, (or those who claim to be,) who support this idea, and some of them have falsified data to justify their warnings. To the contrary, it seems that Earth’s climate hasn’t warned in the past 16 years. There are many climate scientists who dispute the idea of approaching catastrophe, such as Cliff Harris and Roy Spencer, and I choose to believe them.
As the Starks say in Game of Thrones, “Winter is coming.”