Now that the coronavirus has been dealt with, we need to deal with other world crises, chief among them climate change. That’s the advice we are hearing. Having made an effort to educate myself on the subject, I thought it time to weigh in and challenge the prevailing sky-is-falling mentality swirling around the issue. No, I don’t deny the existence of anthropogenic warming caused by rising levels of atmospheric CO2; rather, I challenge the notion that warming is a new thing and a bad thing in itself, a thing that needs to be immediately curtailed in order to save the planet!
The point of departure for my intellectual inquiry was the fact that long before humankind was able to produce anthropogenic CO2 in sufficient quantity to affect the climate, there had been extreme fluctuations in climate, alternating between ice ages and warming periods. What had been responsible for those fluctuations? Could knowledge of their causes inform the current debate on climate change? My query led me to the work of Milutin Milanković (1879–1958), a Serbian polymath whose investigation into celestial mechanics went a long way in explaining those fluctuations.
The basis for understanding Milanković cycles, as they have come to be known, is what every schoolchild learns in science class: The earth revolves on its axis in an orbit around the sun, and the earth’s axis is slightly tilted, which causes the seasons. Summer occurs when the axis is tilted toward the sun, and winter occurs when the axis is tilted away from the sun. But Milanković’s calculations demonstrated variability in this axial tilt, the positions going from least tilted to most tilted and back again to least tilted in cycles that run about 41,000 years. All else being equal, the more pronounced the tilt, the longer and hotter the summer days and the shorter and colder the winter days.
Long before humankind was able to produce anthropogenic CO2 in sufficient quantity to affect the climate, there were extreme fluctuations in climate.
In addition to working out the math behind this dipping back and forth of the axis, Milanković also worked out the math behind a wobbly motion of the axis called axial precession, also known as the precession of the equinoxes. This is frequently compared to the wobbling of a spinning top, often misleadingly illustrated by a top whose point stays spinning in one spot while the body of the top sways out and around in a circle, kind of like the way a person trying to stand at attention with his feet together sways around in a strong wind.
But that’s not completely right. Here’s an accurate description involving an imaginary top. Hold a pencil vertically, point down, gripping it in the middle between your thumb and index finger. Tip it slightly from the vertical and lower the point down to the surface of a writing pad. The pencil is the axis of an imaginary spherical top, the sharpened end the tip on which the top spins, the eraser end the spindle that is twirled to get the top spinning. With your other hand, pinch the pencil near the point and move the point around so as to literally draw a circle on the writing pad. As the circle takes shape on paper, the eraser end of the pencil will also be tracing out a little circle in the air. These circles mark the path of axial precession. The earth’s axis takes almost 26,000 years to make full circles like this. The implication here is that summer and winter won’t always occur at the same opposite sides of the earth’s orbit; as the axis precesses, the opposite positions of the earth’s tilt toward or away from the sun will gradually slide around the earth’s orbital path.
The third and final of Milanković’s cycles involves orbital eccentricity. The orbit of the earth around the sun isn’t perfectly round; it is elliptical. So the earth’s distance from the sun varies. The point at which the earth is closest to the sun is called the perihelion, and the point at which the earth is the farthest from the sun is called the aphelion. And of course, all else being equal, the earth will be warmer when it is closer to the sun and cooler what it is farther away. Because of the axial precession described in the preceding paragraph, every possible axial tilt configuration — minimal, maximal, toward the sun, away from the sun, and everything in between — will eventually get its turn to fall on the perihelion and on the aphelion.
Climate alarmists give the impression that if CO2 levels could just somehow be rolled back to preindustrial levels, it would usher in a never-ending reign of climate that is just right.
Now here’s where I’m going with all this: when the celestial clockwork lines up just right, the northern hemisphere begins experiencing cooler summers, during which not as much of the snowfall from the previous winters melts away. The accumulating snow begins to form ice sheets, and eventually we have an ice age underway. Sea levels dramatically drop as more water ends up in the ice sheets. The ice sheets spread out and cover the sites of present-day New York, Boston, Chicago, Seattle, London, and Berlin. Nearly all of Canada and the Scandinavian countries are covered by ice. When the clockwork reverses itself and the ice begins to melt, large lakes form, dammed up by immense ice plugs that eventually give way, causing horrendous floods, multiple cubic kilometers of water per hour gushing out of these uncorked reservoirs. Sea levels dramatically rise as the melting ice sheets retreat. These extreme fluctuations in climate are the result of celestial mechanics beyond our control, and there’s not a damned thing we can do about them.
Or is there?
Dr. Dan Britt, Pegasus Professor of Astronomy and Planetary Sciences at the Department of Physics, University of Central Florida, makes a cogent case in his YouTube video “Orbits and Ice Ages” that increasing levels of atmospheric CO2 not only warm the planet but also help spread the warmth more evenly around the planet. The effect of this more evenly spread warmth is that it prevents ice ages from getting underway; although the Milanković cycles still crank along, things just can’t get quite cold enough to produce the advancing ice sheets that are the defining feature of an ice age. So anthropogenic warming can keep ice ages at bay, which is a good thing. Britt also points out that atmospheric CO2 levels in the distant past have been magnitudes of order greater than the levels of today.
According to this theory, here’s what happened that drastically lowered atmospheric CO2 levels and made the planet vulnerable to its ongoing string of ice ages: the subcontinent of India used to be a large island riding on its own tectonic plate. This tectonic plate slammed into southern Asia, pushing up the Tibetan plateau and the Himalayan mountains. Chemical processes associated with the natural weathering of such a huge mass of upthrust rock leached atmospheric CO2 out of the air until it was just a fraction of what it had been.
What about the time when the Laurentide ice sheet that covered much of North America to a depth of more than two miles melted?
Anyone truly concerned about the long-term stewardship of the planet ought to recognize the importance of being rid of extreme climate fluctuations that involve recurring ice ages. Yes, higher atmospheric CO2 levels might mean a permanently warmer planet with higher sea levels, but these changes wouldn’t occur overnight; the time frame would allow people to see the handwriting on the wall well in advance and plan accordingly. The gradual depletion of fossil fuel deposits would mark the end of anthropogenic warming caused by those sources and create market forces making alternative sources of energy necessarily more attractive options. And it’s not as if there would have to be a totally unmitigated rise in CO2 levels; credible low-tech technology such as the planting of sufficient acreages of trees would absorb large amounts of the CO2 helping to regulate its levels.
The disservice being done by climate alarmists lies in the fact that they give the impression that if CO2 levels could just somehow be rolled back to preindustrial levels, it would usher in a never-ending reign of climate that is just right. But that’s not the case; what about those Milanković cycles, Greta? At this writing, alarmists are fretting over the effect of the melting of the Greenland ice sheet on ocean currents. Well, what about the time when the Laurentide ice sheet that covered much of North America to a depth of more than two miles melted? That happened at the end of the last Ice Age. I’ll bet that really played hell with those ocean currents. And if CO2 levels could somehow be restored to preindustrial levels, it would mean that we’d have to deal with another Laurentide ice sheet again, somewhere down the line.
Climate alarmists love to imagine the effects of rising sea levels on New York City, posting photoshopped images of skyscrapers poking out of the water (do a Google image search for “New York underwater”). For something truly, apocalyptically terrifying, though, imagine New York City under an ice sheet a thousand feet thick.
