Is Global Warming Good?
By John McCormick
WELL, PROBABLY NOT, BUT, BELIEVE it or not there is definitely a strong case to be made for the idea that global warming may not be all bad.
Briefly the problem is that we should now be entering the next ice age
The reason is based both in geological evidence and something called the Milankovitch Theory. The theory itself is simple to understand although a lot of preliminary information is necessary for it to make sense.
There is a major debate about global warming but it isn’t the one you hear about from politicians.
In fact, only the scientifically ignorant or those with agendas of their own (or those who are paid to dissimulate) actually deny that the Earth is getting warmer and nearly 97 percent of climate scientists also attribute this warming to human activity such as generation of greenhouse gases.
Not that the cause matters when discussing the consequences.
Scientifically at least, there is no real debate about the existence of global warming, but let’s take a quick look at the situation before going into the question of whether it is good or bad.
Global Climate Change, the Big Picture
Climate is a big picture kind of science. It definitely isn’t weather. A few decades of extreme cold someplace isn’t any proof that the Earth as a whole isn’t warming—in fact, it can be evidence of extreme weather due to climate change.
Also, direct measurements of temperatures are only useful based on how accurate and complete historical records are, but most of the planet has never been exposed to a thermometer and global warming is just that, global, so local measurements may be irrelevant.
Given that situation, we can still look at major climatic indicators and one of the biggest, most obvious, and also least open to debate is the amount of ice on the planet.
You used to be able to walk to the North Pole. Even in July. Now you need a boat. The Northwest Passage which tempted explorers for centuries now exists and will soon provide a reliable shortcut between Western Europe and the West coast of the U.S. as well as the Far East—over the poles. As the ice retreats even further, icebergs will be less of a threat.
Glaciers, which are nothing more or less than big piles of ice which had been growing at a steady pace for about 3,000 years, suddenly stopped growing and began to shrink about the beginning of the industrial/steam age. In fact, the shrinkage is accelerating and can be seen by anyone, even from one year to the next. Tens of thousands of acres which used to be covered by nice shiny snow and ice are now bare ground being heated by the Sun.
What’s the Question?
So, because this is a science column, if global warming isn’t up for debate among scientists, just what is the big debate?
Simply enough, the emerging debate is whether or not global warming is bad. A subset of that debate is, if it is actually good, has it gone too far? That probably sounds crazy. Actually it isn’t.
Given that the industrial revolution has caused the Earth to warm up, with all the potential consequences we hear about from Al Gore and others, most of which are almost certainly accurate, problems such as changes in rain patterns, droughts, rising ocean levels, and so forth, how can it be good?
Consider the following:
1. We are rapidly depleting the soil and water in places such as the midwest which will soon be completely unproductive as they already are in parts of California.
Might it be a good idea to force people to stop farming in those places and perhaps move to areas, such as in Canada or the northern U.S. previously too cold to farm? The USDA climate zones have already moved one or two zones north in the past 30 years, meaning you can grow things in the north that could previously only grow in the southern parts of the U.S.
Similar situations exist in other countries.
2. We have too many people on the planet. Not too many of any one kind, just plain too many for the limited resources of the planet to support long-term.
Given that, is decreasing land surface due to rising ocean levels going to encourage further reductions in birth rates, possibly even resulting in a slowly declining population?
3. Given that both of those ideas are highly debatable and lead to many unpleasant consequences both politically and from a simple humanitarian viewpoint, there is one additional argument which is a lot more convincing.
The next ice age is due to really get rolling sometime between today and 1,500 years from today.
The real question we face is, will it be easier to live with a three degree rise in temperature which will occur by about the same time we seriously deplete oil supplies in 2090, or so? Or, easier for the species to survive being buried under a sheet of ice 300 feet (91.44 meters) thick?
Ice Age? What Ice Age?
You probably never heard about or gave any thought to the coming ice age. Many scientists believe we know what causes ice ages and therefore can predict them.
Simply put, the planet will warm or cool based on two major factors.
First is the amount of greenhouse gases in the atmosphere—the cause of global warming. If there was less methane and carbon dioxide in the air, more heat would radiate back into space. The Second factor in determining the temperature of the planet is simply how much heat reaches the surface in the form of solar radiation.
The amount of heat reaching the surface depends on three things: one, how hot the Sun is; two, how close the Earth is to the Sun; and three, the precise orientation of the planet in its orbit.
Earth Science 101
We have seasons mostly because the Earth’s axis tilts. By definition, summer in a hemisphere occurs when the axis tilts toward the Sun, making one hemisphere more nearly perpendicular to the Sun’s rays, increasing the temperature, while the other is tilted away, reducing the amount of solar radiation landing on a given area.
In addition, in the summer, the daylight hours are considerably longer.
If Earth’s orbit were circular and if the Earth’s axis always pointed in the same direction, then climate would change less over very long periods of time.
But, as with many things, what we were taught in high school was a vast simplification of the actual situation.
Precession
Consider a toy gyroscope. Almost everyone has seen or played with one at some point. Because of its spinning mass, a gyroscope tends to stand up if placed one axis end down on a hard surface. But remember what happens next—the gyroscope doesn’t simply stand up straight, it begins to wobble with the top of the axle/axis moving in a circular pattern. That motion is called precession and it occurs in every gyroscope which exists in a gravitational field.
In the case of the Earth, this movement of the axis is known as precession of the equinox. The axis of the Earth moves along its circular path at the rate of about one degree every 70+ years. It completes one cycle in 70 × 360 or about 26,000 years.
That means the Earth gets the same amount of solar radiation on each specific region only once every 26,000 years. From that cause alone, it is constantly changing and thus the climate is constantly going to change.
If the Earth were a simple sphere like a tennis ball, that wouldn’t be true, but with different hemispheres having very different surfaces (water vs. land area in particular), it matters on Earth.
So, we have one major climate-affecting variable—precession.
Axial Tilt
Earth globes usually come with a built-in tilt of about 23 degrees.
Again, if everything were fixed the axial tilt would always be the same, but it turns out that, in addition to changing direction, the actual amount of tilt also changes in a highly predictable way.
While kids are taught that the Earth’s axis tilts 23.5 degrees, causing seasons, it is actually 23.44 degrees and, over a period of about 40,000 years, it varies between 22.1 and 24.5 degrees.
Doesn’t sound like much perhaps, but when it comes to a planetary climate which can profoundly alter the way life exists by changing just a single degree, changing the axial tilt by nearly 2.5 degrees is definitely significant.
(To be completely accurate, the tilt also has a slight random change or nutation which repeat in an average of about 18 years, but the effect is tiny.)
Now we have two ways the solar heating of the Earth changes on a highly predictable manner, precession and the change in axial tilt.
Orbital Eccentricity
I’m pretty eccentric, as are many writers. Scientists also seem eccentric to most people, so that makes me doubly eccentric. The Earth’s orbit is also eccentric.
You probably know the Earth is about 93,000,000 miles from the center of the Sun. That is on an average, in part because the Sun wobbles a bit due to forces from the planets. Just as the planets are held in orbit by the Sun, gravity is a two-way street, and the orbiting planets cause the Sun to orbit the actual center of the solar system.
You probably also know the orbit is not a true circle but an ellipse.
I am willing to bet that a lot of “Perihelion” readers could quote the most basic law of planetary orbits—“equal areas in equal times”—the second of Kepler’s three laws of planetary motion, which are still the basis of orbital calculations.
1. The orbit of every planet is an ellipse with the Sun at (actually just very close to) one of the two foci.
2. A line joining a planet and the Sun sweeps out equal areas during equal intervals of time.
3. The square of the orbital period of a planet is proportional to the cube of the semi-major axis of its orbit.
These have been known since the early part of the 17th century.
But I’m also willing to bet that most readers don’t know that the spatial orientation of the axis of the orbit (technically the semi-major axis—the line connecting the two foci of the ellipse) is not fixed. Say the long axis of the ellipse currently points toward one star. It didn’t used to point there and won’t in the future,
That is, the long axis of the orbit also moves.
The eccentricity of the orbit also changes from nearly a circle (eccentricity 0.0034) to more elliptical (eccentricity of 0.058) over a period of about 100,000 years. Today, Earth’s orbital eccentricity is about 0.0167 circular.
The major cause of this periodic change is the gravitational effect of the major gas giant planets Jupiter and Saturn.
Although most people accept that the Earth orbits the Sun (this can actually be treated as a matter of convenience because it’s much simpler mathematically), there are some Earth centric concepts still in scientific use. For example, the measure of distance, one astronomical unit (1 A.U.) is the distance from the Earth to the Sun. Another such measurement is the plane of orbits of the planets or inclination, which is based on Earth’s orbit being considered the plane of the solar system.
Perihelion
No, not this magazine, but Earth’s place in orbit. Perihelion means point of closest approach. In the case of Earth’s orbit, perihelion takes place in early January these days, but the fact that the orbital axis changes direction, this changes over time.
Obviously, we get more heat from the Sun when we are closest to Old Sol. Because the Earth tilts on its axis, and this tilt precesses, sometimes one hemisphere will be tilted away from the Sun (summer) while the other is tilted away (winter).
At perihelion, summer will be warmer and winter in the other hemisphere will be warmer than average. At two points of the orbit the axis will point in a neutral direction. At aphelion, the furthest distance in the orbit, we get cooler summers and cooler winters.
Currently the southern hemisphere (mostly water) is exposed to the most Sun at perihelion. In the same way, it is getting less than average direct sunlight in southern winter. This means both summer and winter are a bit more extreme just now. The difference may seem small, but is nearly seven percent.
(By the way, if you want to discuss global warming with someone who thinks or insists that we aren’t causing the global warming, just call it anthropogenic greenhouse emissions. The chances are that if they don’t believe in global warming they won’t understand the word and won’t want to expose the fact that they don’t.)
Milankovitch Cycles
Now we have enough background to finally get to the real topic of this article, the coming ice age and something called Milankovitch cycles.
Ice ages are thought to be caused by reduced warmth. Not really much of a theoretical stretch.
Because Earth’s orbit affects how much solar energy (heat) we get on the entire planet, the various cycles described above will affect the Earth’s temperature and thus could cause the periodic ice ages at their minimums and recovery to warmer periods when solar radiation changes.
During his time as a POW in WWI, Serbian mathematician and astronomer Milutin Milankovitch undertook a project where he charted the three major variable orbital characteristics: eccentricity, precession, and axial tilt (obliquity).
It seemed clear that with three major cycles directly related to the amount of solar energy reaching the Earth, if these were to combine at times to produce an energy input low, that would cause significant global cooling, perhaps a drastic cooling because increasing snow cover reflects more heat, causing more snow cover, etc.
The math is complex, but Milankovitch’s work led him to suggest that the data all showed the major ice ages coincided with the compound solar heating lows he found to be predicted by the interaction of these three major orbital cycles.
He wasn’t the first to propose this theory, but by the time his work was published it was backed up by enough geological evidence about previous ice ages to indicate that the Milankovitch Theory appears to be correct. Subsequent evidence has only strengthened the theory.
Now for the bad news. The math shows we should be entering a severe cooling period, consistent with the onset of an ice age.
Solar Activity
Less predictable (because we have recently jumped out of the predicted sunspot cycles) is the amount of solar activity, storms on the surface of the Sun, and, hence, the total amount of heat the Sun gives off.
This is not some esoteric measurement. It is easy for anyone interested to see for themselves. I personally had set up a solar observatory expecting a major sunspot cycle to be occurring by now. I sold off that equipment because the Sun is extremely quiet, making it uninteresting to amateur astronomers.
As “Perihelion” Contributing Editor Eric M. Jones has written here in the past, sunspots are at a low point at precisely when they were expected to be nearing a peak.
So far scientists simply have no explanation for this, so there is no way to predict whether this 100-year lull in solar activity is going to continue or quickly come to an end. The only prediction was that it shouldn’t be happening at all.
Because the surface of the Sun is hotter when there are lots of sunspots, the amount of solar radiation is nearing a low point with the quiet Sun. This, for better or worse, suggests that we should definitely be well into the beginning of a mini ice age.
Is the fact that we are instead experiencing global warming since about 1800 due to the greenhouse effect? Is it just a coincidence that the Steam Age also began then? Remember, Milankovitch cycles say it should be getting colder.
If we are in a period of man-made global warming should we be grateful, or otherwise? Can you say unintended consequences? Which brings us back to the earlier question, would it be easier to survive a major ice age, or mild global warming? Will global warming be counteracted by the combination of Milankovitch cycles and solar minimum?
The Double Whammy
If the global warming vs. ice age argument is correct, it is simply a brief respite for humanity.
Why? Simply enough, ice ages last not centuries but tens of millennia and even the most optimistic projections for peak oil and peak natural gas production suggest that in another 50 to 100 years at most we will begin to see a reduction in greenhouse gases simply because there will be few hydrocarbon fuels available to burn.
That, of course means that global warming will cease to be a factor, the planet will get cooler, and we won’t have fuel to keep warm.
Nuclear or thermonuclear power could easily provide heat energy, but not any greenhouse gases, so they would only have a temporary ameliorating effect on life styles and conditions.
Solar and wind energy will obviously be useless. Snow, ice build up, and low solar energy will reduce the efficiency of solar energy production. Windmills are unlikely to operate well in sub-zero temperatures.
Can things get a bit more complicated?
If nothing else, these questions should provide some fodder for more science fiction stories about global warming. 
Further Reading
Earth Fact Sheet.
More Solar System Facts.
Nature News Blog.
John McCormick is a trained physicist, science/technology journalist, and widely-published author with more than 17,000 bylines to his credit. He is a member of The National Press Club and the AAAS. His full bibliography can be accessed online.
