Our primary energy source is the Sun. Earth’s temperature is controlled by three things:
1. How hot the Sun’s surface is,
2. The Earth to Sun Geometry,
3. The Earth’s atmosphere and its surface which act as a filter and as a reflector trapping some radiation and sending some back into space.
Some of the arguing about Global Warming has to do with whether it is real. Some of the arguing has to do with the why. For example, man made or not man made. I will show you that it is bad. It is bad if man made. It is bad if not man made. It is bad because ice all over the earth is melting. It is real for the same reason. It is hard to get a global temperature because it differs from point-to-point, it differs by time of year, it differs by time of day, with the weather, etc. So we let the ice do it for us. The ice pack size depends on the average temperature of the Earth over a period of years. The pack size is determined by the temperature over N years, 365 x 24 x 7.
I hear you asking, “So what is wrong with a little ice melting??” Well besides the polar bears dying off, that ice melting will raise water levels all over earth (there is a lot of ice—mucho, mucho ice.) We have built lots of big cities right next to water, like Manhattan, San Francisco, Los Angeles, Chicago, Tokyo, Detroit, Cleveland, New Orleans, Sidney, London, and hundreds of others. This seemed good, providing easy access to water for shipping and sewage disposal and, if fresh water, also for drinking and irrigation. It will not seem so good when the ice melts, the water rises, and these cities drown. Ask New Orleans. Other problems include failed agriculture, new pests, and new diseases. One of the problems is that the ice helps regulate Earth’s temperature by reflecting sunlight back out into space. As the ice goes, there will be a greater jump in temperature. Engineers call this “positive feedback”. Systems with positive feedback can be hard to regulate and can “run away”.
Temperature and radiation calculations must be done in the absolute, or Kelvin temperature scale. The only difference between this and the centigrade scale, now called the Celsius scale is the location of zero. In Celsius, zero is the freezing point of water. In Kelvin zero is the temperature of outer space, the temperature where all available energy is gone. The difference is 273.15 degrees. So in the Kelvin scale, zero is outer space, and all available energy is gone and 273.15 is the freezing point of water. One hundred higher, 373.15 is the boiling point of water. (In contrast, in Celsius, outer space is -273.15 and water freezes at zero and boils at 100.) Finally degrees have become kelvins. On the bright side, my keyboard has no degree symbol, and if I have to type out “degree”, well, in honor of Lord Kelvin who wrote the paper on the need for an absolute scale, I can type “kelvin”.
Some of the things published on global warming delve into the far past to look for explanations. These scientists are trying to find past times when earth got hotter and carbon dioxide rose. They suggest this rise in Earth temperature was due to an Earth warmed by increased solar output, or changed Earth-Sun geometry. This temperature rise squoze (past tense of squeeze) carbon dioxide out of the oceans causing the atmospheric carbon dioxide level to rise. This explains a rising atmospheric carbon dioxide as due to a hotter Sun or a changed earth-sun geometry warming-up earth, initiating a carbon dioxide rise from gas leaving the waters of Earth. This may well have happened several times in the far past. There are two problems here. First, there were no instruments in the far past and no written records (we are before the invention of writing here). So we are stuck with reading cores of ice and mantle. There is much interpretation involved, however, I do think the evidence shows exactly that has happened in the past. The second problem is, that is NOT what is happening NOW. Here is the NOW story in brief:
1. We burned one trillion barrels of oil, about twice that of coal, a bunch of natural gas (basically methane), and a few forests in about 50-100 years,
2. The products of that burning are mainly water and carbon dioxide,
3. The water does not create a problem, but the carbon dioxide is stable and relatively heavy. Some of it gets used by plant life, some of it goes into solution in water, but an extra 100 ppmv has hung around in our atmosphere, and this is increasing by 2 ppmv/year, [ppmv = parts per million by volume],
4. This extra carbon dioxide along with extra methane (from more animals, more people, more sewage, and more trash) has trapped extra radiation on Earth, causing the temperature to rise.
The above NOW scenario happens mostly from 1950 to today. It is based on modern measurements recorded when they were taken. I entered the University of Chicago in 1950 and the instruments of that time were quite good. The numbers I have used come from sources on the web. Mostly, they are available from multiple sources. You can just google them up. None of them have been “cherry picked” to prove a point.
Those who read cores to tell of things long past do some amazing things. Some scientists see this global crisis as a “look what we can do” opportunity. Others are fearful of change and are cherry picking to avoid a simple modern truth. There are a number of responses to challenge.
One is: “Shoot the messenger”. This has been thoroughly used, by emperors, kings, dictators, generals, admirals, and scoundrels. It uniformly fails and causes great suffering. It should be rejected.
Second is the “Ostrich response”. Head in the sand and denial, denial, denial. This has not worked any better. It should be rejected.
The winner in door three is Meet It and Defeat It. In the depth of the Great Depression, an American President said: “Fear is the only thing we have to fear.” [Franklin D. Roosevelt, and he got it right.]
NOW GLOBAL WARMING EXAMINED
There are three things which determine the temperature of the Earth:
The first is the radiation output of the Sun.
The second is the relationship of Earth to Sun, both orbit and orientation (which way Earth’s rotation axis is pointing and where it is in its orbit).
The third is Earth’s atmosphere which controls where the Sun’s radiant output goes and how much heat the Earth gives back to Space, (which except for the Sun can be considered to be at absolute zero temperature) and how much gets trapped, and the Earth’s surface where snow and ice reflect energy back out.
All of these things can change. The vacuum of Space has no effect on the photons which carry energy from Sun to Earth and from Earth to Space.
The output of the Sun can increase or decrease.
The Earth’s orbit is very stable and constant based on the laws of physics, but its orientation is not. The Earth is spinning in the Sun’s gravitational field, and like any spinning top, it can change orientation. For all you techies, reference here is to precession, nutation, and orbit rotation, but astrological, supported at center of mass, not a tip supported top. Also, ice can build on one side or another of our spinning planet—Earth and cause a shift of axis. Records in ice and mantel cores suggest that this has happened a number of times. Also, changes in magnetization of earthly material suggests pole changes (axis changes) in the past. Milutin Milankovitch, a Serbian mathematician, developed a theory of Earth’s gyrations. Google Milankovitch – Wikipedia. The Milankovitch cycle is a few times 10,000 years, so is not a cause of current changes. Changes due to ice buildup are very slow. We are looking for fast changes, of the order of 10-to-50 years.
The Earth’s atmosphere controls what happens to radiation passing through it. This effects both radiation from Sun to Earth and radiation from Earth to Space. The atmosphere treats radiation from Sun to Earth differently from radiation from Earth to Space. There are two reasons for this. First, Sun to Earth radiation starts at the top of the atmosphere and travels down. Earth to Space starts at the bottom and travels up. The top of the atmosphere is different from the bottom. For one thing, the top is thinner (lower pressure; less gas molecules per cubic foot). A gas like carbon dioxide, which is heavier than oxygen or nitrogen (the two main components of the atmosphere) will be richer at the bottom than the top, just based on its weight. The second reason for the difference is that the radiation is very different. The Sun is very hot. Its surface temperature (black-body equivalent) is about 5800 kelvin, absolute scale, or about 5500 degrees Celsius. Water boils at 100 degrees Celsius. (Celsius is the modern name for centigrade.) This causes radiation of short wavelength—lots of visible and ultraviolet. (The interior of the Sun is very much hotter, but radiation is determined by the surface temperature.) The Earth’s surface temperature is much lower. Earth is (very approximately) about 270 kelvin absolute scale, which is (very approximately) about zero Celsius. Its radiation is in the infrared area. Click for Encyclopedia of Earth, Electromagnetic Radiation This is an excellent article on radiation from Earth and from Sun. The next two graphs are from that site.
Solar and Earth radiation. The difference in peak wavelength is twenty-to-one. The difference in intensity is 3.4 million-to-one. Of course, the Sun only occupies 4.8 millionths of Earth’s total sky, whereas all the rest is Space at 0 kelvin. This is a good thing, else we would boil or roast.
The atmosphere can direct Sun to Earth radiation back out to Space by reflecting or scattering it. It also absorbs some of this radiation, sending some back to Space. This can get magnified by particles in the atmosphere. We know of two ways this can happen. It can happen by a collision between a meteorite and earth. There was such a collision about 65 million years ago, at the Cretaceous-Tertiary (K-T) boundary. It placed a thin layer of Iridium over the entire planet, and it wiped out the dinosaurs and many other species. It can also happen by volcanic explosion such as that of Krakatoa in 1883 which destroyed most of the island and dropped Earth’s temperature by several degrees for several years. But these are extreme happenings. We have nothing like this in our last 100 years.
As the Sun warms the Earth, Earth’s temperature rises until the energy going from Earth to Space is the same as the energy going from Sun to Earth. The system is in stable balance at that point. Earth’s temperature will change until that balance is reached.
STABILITY: Occurs when Earth’s temperature is such that Radiation-In = Radiation-Out.
Some of the data in this article is from the NASA SUN FACT SHEET. Click here to go to it.
Some data in this article was taken from the NASA EARTH FACT SHEET. Click here to go to it.
The solid angle occupied by the Sun from Earth was taken from Click here for Solid Angle per Wikipedia.The text is: Sun and Moon
The Sun and Moon are both seen from Earth at an apparent diameter of about 0.5°, thus they each cover a solid angle of about 0.20 deg2 or square degrees, thus they each cover a fractional area of approximately 0.00048% of the total celestial sphere which is about 6 × 10−5 steradian.
The fractional area of 4.8 millionths is used here is calculations. (Multiply the Sun’s radiant energy by 0.0000048.) The extra two zeros are because we have changed per cent into per unit.)
Radiant energy output and temperature of the radiating body are linked by: E = T (in kelvins) raised to the 4th power, times the Steffan-Boltsmann constant, represented in the equation by the Greek letter sigma. T raised to the 4th power is T times T times T times T, so energy goes up really fast with temperature. In the case of Sun-to-Earth, this is then multiplied by the fraction of the sky occupied by the Sun. In the case of Earth-to-Space, the multiplier is one. For incoming radiation, we must subtract the amount reflected or scattered back out into Space. In the case of Earth-to-Space, we must subtract the amount of outgoing radiation absorbed by molecules in the atmosphere and converted to heat.
If we ignore the reflection back into Space, and the absorption and conversion to heat, we have a simple balance wherein the Earth will heat up [T(Earth)] until it radiates as much power as it is receiving from the Sun which is at surface temperature [T(Sun)]. An analogy to this is a wash basin with water entering from a faucet (Incoming radiation) and leaving through a drain (Outgoing radiation). The water in the bowl rises, increasing the outflow until Inflow and Outflow match. For Sun and Earth, we have 5778 kelvin exp(4), [temperature from the NASA Sun Fact Sheet], times 0.0000048, size of Sun in the sky, equals T(Earth)exp(4). Remember, we are ignoring reflection and absorption. The constant is on both sides of the equation and cancels out. The result is an Earth temperature of 270.5 kelvin, or -2.7 degrees Celsius. This is a good ballpark number. The Earth surface has enormous amounts of water and of ice, so it must be somewhere in the neighborhood of 0 degree Celsius. Now, if we make Earth 1 kelvin hotter, the Sun must get 21 kelvin hotter. (Run the math!!) Have all the scientists on Earth missed a 21 kelvin solar surface increase?? Have all the scientists on Earth missed the spectral shift that goes with a 21 kelvin increase?? I doubt it!!
We are pretty good here in 2010 at measuring temperature. We are superb at spectral. The chance of all the scientists on earth missing the spectral shift that goes with a 21 kelvin Sun warmup is between slim and none, and slim just ran out the door. Also, we not only observe the Sun from Earth, but also from Space.
Okay, but what about the Earth changing orbit or orientation. Galileo first observed the moons of Jupiter with a homemade telescope on January 7 of 1610. It was a small scope which rested on a table and was aimed with thumb and fingers. Modern professional telescopes are very large, are housed in concrete domes which rest on solid concrete foundations and are aimed by motors and computers. The astronomer supplies the computer with coordinates. The earth’s orbital motion and axis drift are programmed into the computer. If the earth departs from its expected path even slightly, telescopes all over the earth will be pointed the wrong way. The shout will be heard from pole-to-pole.
We are left with the atmosphere. We have not had any large meteorite strikes or large volcano explosions recently. This leaves the atmosphere’s infrared transparency. Gas molecules tumble, rotate, gyrate, and vibrate. They do this at infrared frequencies. So molecules like methane and carbon dioxide absorb infrared. Here we have a match with our warming problem. Methane is up because there are more of us and we are raising more animals. People and animals, cows in particular, generate methane. Carbon dioxide is up because in 50 to 100 years we have burned one-trillion barrels of oil, an even greater amount of coal, a bunch of natural gas, and a few forests here and there. This has raised atmospheric carbon dioxide from 300 ppmv (300 parts per million by volume) to 400 ppmv. It is further increasing at 2 ppmv per year. Where is the surprise in this?? What part of high school physics and chemistry is confusing our befuddled ones?? There are NO 200, 500, 1000, 10 thousand, or 100 thousand year old measurements involved here. No reading of ice or mantle cores. No reading of tree rings. No Milankovitch orbital calculations. No deep solar science. All the significant data involved here comes during my lifetime and was done with reasonable “modern” professional instruments. It is all available on the web and from multiple sources.
This link to the Hydrogen Now Journal will take you through the carbon dioxide calculation. The result is that we have burned enough fossil fuel to account for the rise in atmospheric carbon dioxide.
So why should we care if the earth warms a few degrees?? Less winter clothes maybe?? There are a lot of answers to this, and some of them are complex, but I will cover some of the major ones. It is easy to brush this off with impertinent remarks, about polar bears, and about people obsessing about the weather. We, homo sapiens (us so- called humans) inherited this planet and all of its species. I believe we have a custodial obligation. That said, some species are continually lost, and I would not rebuild our civilization just to save the polar bears. But, all over planet earth, major cities are built right up against the water. Water serves to drink, to irrigate our crop, dispose of our sewage, and to transport our goods. Building your city right by the water seemed like a good idea. If we let the ice caps melt, hundreds of cities will be inundated by rising water. Do those persons with flip polar bear remarks have some flip drowned city remarks?? See how well they go over in New Orleans!!
We almost manage to get most of earth’s human population fed, but even a small change in average temperature can effect both crops and pests. Crop growth may suffer. New pests may flourish. These things can be fixed, but not in a few years. In say 100 to 200 years, we can develop new plant strains and find new pest controls. In 10 to 30 years, we may not succeed. Changes in temperature distribution can cause changes in human disease and disease vectors. How prepared is the USA to deal with Malaria?? Ebola fever?? Finally, we live on a spinning top. The earth spins in the Sun’s gravitational field. Melt enough ice and we could get an axis shift. I don’t know if we could survive that.
Finally, I would like to say a word about the stupidity of shooting the messenger. Kings, Emperors, Dictators, Generals, and Admirals have all made the mistake of dealing with news they perceived as bad by shooting the messenger. History has demonstrated again and again that this does not work. Shooting the messenger does not solve the problem. The kingdom, army, navy, whatever is short one messenger. The leader suffers. His people suffer. Let us be done with this stupidity.
Al Gore, who put this problem into the form of both a book and a visual show that was good enough to win an Oscar and to mobilize action on a major scale named it “An Inconvenient Truth”. The truth part holds up. It may not be so inconvenient. At present rate of consumption and the self-published reserve figures of oil producing countries, which if anything may be inflated, we have only 37 years of oil remaining. Improved methods of oil recovery and new finds may extend this, but those are countered by growth in demand from China, India, and elsewhere. A supply of 37 years is a pretty good guess. Improvements in efficiency extend this and give us more time to find an oil alternate, which we must do because all gone is all gone. Efficiency is its own reward. You don’t have to pay for oil you don’t have to buy. A focus on an oil replacement now instead of say 20-30 years from now gives us many more options. There are a bunch of middle east countries which have been living off the oil of the land, and it will be a pleasure watching them learn to do an honest day’s work.
The dangers are flooding, starvation, and disease. The cause is excessive methane and excessive carbon dioxide in our atmosphere. The cure is to reduce these excess gases through efficiency, and to shift from oil, natural gas, and coal, to solar, wind, water, earth, and nuclear.