What goes up must come down. This is a phrase we seem to understand as kids by simply throwing a ball in the air, but scientifically, we associate this phrase with the Laws of Motion and Gravitation discovered some 300 years ago by Sir Isaac Newton. However, this simple phrase does not just apply to moving objects influenced by gravity.
We also know that weather temperature goes up and then comes down. This is our sun at work. Scientists who study our planet’s climate over much longer periods have discovered that the average global temperature can change by as much as 15 degrees centigrade over a period of about 25,000 years. Relative to the age of the Earth, 4.5 billion (4,500,000,000) years, this is a brief period of time.
After starting from a very cold temperature and going up to a peak, the Earth’s average temperature then comes down again over a period of about 75,000 years. The data scientists have accumulated over decades indicate a repetitive pattern of going up and coming down over the last four 100,000-year periods. These natural cycles are what we associate with ice ages.
We learn from this data that it’s harder to keep the Earth warm than it is for it to get cold and stay cold. The reason for this remarkable change in average global temperature has to do with things that are beyond our control. These temperature swings involve changes in the shape of the Earth’s orbit around the sun due to the effects of gravitational forces pulling on the Earth from planets in our solar system. They also involve changes in the tilt of the Earth’s axis and the direction it points caused by the sun’s gravity, which creates a slight wobble in the Earth’s spinning motion.
There are many other things that affect the details of this dramatic temperature decline from its peak to its low, such as changes in the sun’s output, volcanic activity, shifts in the continents, changes in glacial ice distributions, and so on. This is a complicated process but there is little we can do about it. This is nature’s course that repeats itself and its effects are rather large.
During this process, the peak average global temperature can reach as high as 5 degrees centigrade above normal and 10 degrees centigrade below normal. No one would want to experience such a low average global temperature, but its occurrence is inevitable.
The last ice age ended about 14,000 years ago, so based upon existing scientific data, we may have about another 10,000 years or so of relatively warm climate to reach a peak and then head down over a period of about 75,000 years. The Earth will get very cold, ice will accumulate, and life will be less plentiful. If you are worried about your current heating bill, during this cold period, it will get much worse. Energy will be in great demand and real estate around the equator will be prime. Some plants and forests will die off and, along with them, the animals that depend upon them. There will be mass migrations to warmer parts of the Earth.
So, the Earth’s global average temperature will go up, but then it must come down. That’s the way it will be.
