The sky is falling, the sky is falling!! Or so it would seem if you read the guest columns and the letters in the Daily Hampshire Gazette.
It’s all about how human activity is responsible for global warming (climate change if you prefer). These letters are full of angst over how we have (or may soon have) reached the “tipping point” whereby the climate will become so hot that it cannot be reversed and that civilization is at stake.
At the root of all this is the enemy – us – because we have caused this condition and must work feverishly to reduce carbon emissions. We are even arguing about whether or not Earth has become warmer in the last 10 years or if temperatures have remained steady.
I’d like to suggest that we take a much longer look at climate change. What has happened in the last 10 years or 100 years or 1,000 years is but an instant in time compared to our planetary history.
Our current warming trend began about 11,000 years ago as the glaciers began to melt; glaciers which, at that time, covered all of Canada and New England, as well as large parts of Europe and Russia. We ought to ask ourselves how is it that this warming trend began 10,000 years before man had any serious influence on the environment.
The answer is that this current warming period is only the latest in a series of about 15 of cooling (glacial) and warming (inter-glacial) events in the last 1.2 million years. So, if man hadn’t the ability to influence the climate back then, what caused us to go from really, really cold times to really, really hot times and then back again 15 times?
We need to look to geologic history to find answers. When I took geology 60 years ago, we were taught that there were four glacial-interglacial stages that were worked out by geologists studying glacial features such as moraines. Since then, geologists have studied rock strata from under the ocean and found a much more nuanced record of glaciation and warming.
So we know that there were many alternating periods of warming and cooling. So what caused them? We can take a look at any geology 101 textbook to find the answer. For example, we could examine “Historical Geology,” by Reed Wicander and James Monroe, currently used in colleges.
This textbook describes the history of the Pleistocene epoch in which we find a discussion of the Milankovitch theory, which asserts that there are three things that create the conditions for climate change. The first has to do with the wobble associated with Earth’s rotation which moves the North Pole nearer to the sun and farther away from the sun over time. The second has to do with the elliptical orbit of the Earth around the sun which places the Northern Hemisphere sometimes closer and sometimes farther away from the sun. The last has to do with precession of the equinoxes where currently the Earth is closest to the Sun in January. Each of these occurrences has their own cycle in time.
The important conclusion to carry away from this is that greenhouse gases are the result of global warming, not the cause of global warming. Global warming is caused by the changing positions of the Earth and the Sun. When the Earth warms up as a result of these physical changes in position, the oceans and the tundra get warmer and release greenhouse gases.
The history of these cyclic changes indicates the need to prepare for several more thousand years of warming with rising sea levels and all of the other changes associated with these events.
Although human activity may have contributed some minor amount of greenhouse gases, it is not the driver of climate change; the driver of climate change is the normal cycle of the Earth’s changing position with the sun.
Dennis Burke, of Belchertown, is retired from a career in information technology and logistics management. His avocation is geology, in which he majored at the University of Massachusetts Amherst.