The fly wants the credit.
Around twenty thousand years ago, sheets of ice thousands of feet thick lay over northern reaches of Europe and Asia, and over all of Canada and New England, spreading as far south as Ohio, the Dakotas, and Washington state. When this ice was at its greatest depth, perhaps a mile in thickness, the water in the oceans worldwide was about 300 feet lower than today.
This is commonly called the ice age, although geologists and climatologists tell us it was part of a much longer period they call a “glacial age”, and they point out that we are technically still in one that began about two and a half million years ago. Those who have watched the Ice Age movies, with their woolly mammoths, saber-toothed tigers, and primitive humans, are aware that we actually did have a recent icy period, when those creatures were indeed present, and probably the same people who have seen the movies might also assume that it ended when the ice receded from the United States about 13,000 years ago.
Anthropologists have deduced that about 16,000 years ago, when the sea had dropped between Russia and Alaska leaving a frozen “land bridge”, the first humans wandered from Asia into North America, because there was no Bering Strait to cross. It was colder than now, but there was only permafrost between the two continents, not open water.
Scientists generally accept the geological evidence that there have been at least five long glacial ages, each one lasting millions of years. In at least one such period, the glacial age centered around 850 million years ago, the oceans were practically empty and ice covered the earth from both poles almost to the equator. From a quarter million miles in space it looked like a snowball earth.
The current glacial age, the one we are still in, began about two and a half million years ago, at the beginning of the Pleistocene epoch. It is during the Pleistocene when modern mammals, especially the larger and smarter ones, began to take over the earth. But the Pleistocene is considered to have ended about 11,000 years ago, and we are now in the Holocene epoch, which is the period of mankind’s rapid development. The current glacial age, you see, has continued into a new epoch.
In a glacial age, such as the present one, the atmosphere worldwide cools by an average of as little as six degrees Celsius, or ten degrees Fahrenheit, and stays cooler, and the average temperature of the earth’s surface, that is, the ground temperature, drops too. Precipitation continues year after year, more and more as snow, but cannot melt, and so snow falls onto the previous year’s snow and thickens into ice sheets over parts of several continents. The polar ice spreads, and mountain glaciers grow longer and deeper.
During the warmest periods between one glacial age and the next, there is no lasting ice to speak of around the globe, even at the north and south poles. That is how it was just a few million years before the Pleistocene, for instance. Plants grew all over the continent of Antarctica and there was warm open water at the north pole. Since humans did not exist at this point — or if they did, were not organized into industrial nations — humans did not cause palm trees to grow at the south pole.
A little thing to keep in mind as you look at the earth, by the way: In the southern hemisphere, there is a great land mass at the south pole — the continent Antarctica — and virtually nothing but oceans around it for thousands of miles. In the northern hemisphere it’s just the opposite. There is a great expanse of water at the north pole — a sea — and virtually nothing but land around it for thousands of miles.
Even though the ice sheets have melted partway back so they now cover just the polar areas, we are still in the latest glacial age, because the Greenland and Antarctic ice sheets still exist and the sea at the north pole is still frozen over. By definition, when these ice sheets have melted, the current glacial age will have ended, and we will anticipate that a sixth great glacial age will begin some millions of years later — we’ll have to wait and see. This complete polar melting will happen, once again, whether mankind exists or not.
During a glacial age, though, there are pulses of intense glaciation, and periods of rapid warming which we call interglacials. It is just such a glaciation that brought us the most recent “ice age” that peaked 20,000 years ago, and for the entire time since then, that is for the past 20,000 years, we appear to be warming into an interglacial period which, if it isn’t the end of the glacial age, may last a few thousand more years. This current warming could last until the ice sheets are all melted, but if it doesn’t, and turns abruptly cold again, it could plunge us back into another few thousand years with ice sheets creeping over the continents — but that would still be part of an overall warming trend. Eventually, the glacial age will end and there will likely be no natural ice to be found anywhere on earth.
In other words, it’s kind of like the tides at the seashore. If we compare the incoming tide to the cooling of the earth, and the outgoing tide to the warming of the earth, then we are currently near the end of an outgoing tide. You can stand on the beach, and the water surges over your feet (temporary cooling), then flows back out (temporary warming), then back over your feet again, and so on. But eventually it no longer reaches your feet, and you are left standing on wet sand. That is sort of where we are now with the current long glacial age. The most recent ice age that peaked 20,000 years ago was like one of the last surges that covers your feet on the beach. Now we’re waiting to see whether the wet sand dries out completely. Another surge or more may rush all the way up and touch your toes again — another mini-ice age. And then the waves will be gone and there will be a long wait on hot dry sand until the cooling begins once more, like the tide returning to the beach after a few hours.
Science has not yet come up with a good explanation of the forces of the universe that set this cycle in motion. There are theories and they all involve some very powerful forces, though. And they are comparable with, and probably tied to, other strong forces: the throbbing of pulsars, the bursts of gas emissions from the sun, the elasticity of orbits, and the waves of interstellar energy rays that wash over like unseen spirits.
Onto this cosmic time scale have arrived modern humans. Over the past hundred years or so, since Albert Einstein shook the earth with his strange theories, we have discovered all this stuff about the glacial ages. We have put a halt to the forest fires that used to burn for years over vast areas of the continents. Thus we may have stalled some of the natural warming. We have begun burning the “fossil fuel” left from decayed and buried forests instead, so maybe it’s a break-even.
Our population is so great, or more significantly, so small, that all the humans on earth, about seven billion people, could just about cover the island of Puerto Rico with 14 square feet per person – about the proximity that people enjoy on a dance floor, or on a crowded sidewalk, or when it’s crowded at the Springfield Fair. If all the people on earth were standing around like a crowd waiting for a speech from a political candidate, they could do it on Puerto Rico, and the rest of the earth would be devoid of humans. That’s how much space we actually take up on the earth.
There are those within this jostling crowd who believe that our human activity of the past hundred years, and especially of the past 20 years, has substantially affected the ebb and flow of the current glacial age — what is called the earth’s albedo. They want us to believe that the earth is warming because of our reckless activity, especially the burning of fossil fuel, and if we stop burning stuff and stop raising animals that expel methane, we will halt global warming.
Well, global warming is the nature of the cycle and the cycle of nature. Global warming is absolutely real and would forge ahead even if humans had not invented so much as a campfire. There is evidence that humans have contributed gases to help block the sunlight hitting the earth, and there is even debate whether that contributes to cooling or warming of the atmosphere, but there is no scientific evidence that human activity is affecting the outcome of the current glacial age. There is a difference between our suspicion that we are doing it and scientific evidence that we are doing it. That difference is profound. I am a scientist, so I will refrain from flattering myself with cosmic powers until I see the evidence.
I don’t make fun of people who reduce, re-use, and recycle. I am strongly involved in conservation on all levels. Waste and excess are deplorable for so many reasons that I don’t need political persuasion to avoid it and to practice good stewardship of the earth.
Science is the process of discovering facts and assembling them into coherent explanations of the world. Science is also dispassionate. If an explanation does not stand up to proof, it is discarded. If a theory has not been tested, it is not offered as proof. But a few loud scientists who favor a certain political position have been offering theories of human influence as proof of human influence. Having looked at the theories that explain the surges in global warming and cooling, I think humans are falsely blaming themselves if they believe that they have already made any impact on the forces of the universe. Humans who think we can reverse those cosmic forces deserve even more to be disregarded. They may call themselves scientists, but they are spreading superstition.
Such human folly — a sort of incredible arrogance, really — is as if a few of the sand crabs on the beach have suddenly decided that the crabs are collectively responsible for the disappearance of the water and the drying of the sand between tides, and so they force all the crabs to stay buried and completely still, on the premise that their sacrifice will make the water return.
Regarding those who believe humans have caused the earth to warm by roughly one degree in the last hundred years, Aesop may have said it best, 2,600 years ago: The fly sat on the axel-tree of the chariot wheel and said: What a dust I do raise!