Global Warming

Global Warming

Introduction

We are hearing a lot in the popular press these days about global warming. Last month Holly asked me about it, and I realized that there are some conflicting ideas within our family, not on global warming itself, but on what my opinion of it is. Then the next week Joyce was at dinner with friends where John Doolittle, a congressman from California who lives in our ward, let it be known that he believed global warming to be a left-wing plot and that there was no science behind it. I am sitting in an airport now after chancing onto Rush Limbaugh in my rental car and listening to him expound on why it was a left-wing religion and utter nonsense.

This essay is not meant to be a scientific treatise on global warming. I am not going to scientific (or popular) literature for my ideas and claims. It is more along the lines of what I have learned and what I believe. These ideas may not all be correct, and if anyone has any evidence to the contrary I will listen to it.

What is global warming?

What is a greenhouse?

Down the hill from our house in Logan and across from Aggie Station there were several long buildings made of panes of glass – greenhouses. John Bugbee (appropriately named) was a biologist who grew exotic varieties of wheat in those greenhouses in an attempt to develop a strain of wheat that grew big ears but small stems for a source of food in space. The plants would have frozen in the Cache Valley winter, but instead of insulation he surrounded his plants with panes of glass.

Glass is an interesting substance. It is actually a super-cooled liquid and not a solid. Like the chip in your computer and like the material in fiber optics cables, it is made of sand (silicone). In this liquid state it is transparent to “visible” light.

Let me step backward and say something about light. What we call “light” is electromagnetic radiation with wavelengths between about 0.4 and 0.9 micrometers (1 micrometer or μm is equal to 1/1000000, or 10^-6, meters). Electromagnetic waves can, of course, have all possible wavelengths. The shortest wavelength waves are called “gamma rays.” Getting progressively longer, waves are called “x-rays,” then “ultraviolet rays,” and then “visible light.” Waves longer than visible are called, in order of wavelength, “infrared waves,” “terahertz waves,” “radio waves,” “extremely low frequency waves,” and so on. The names are different, and we experience them differently, but they are all basically the same thing. They are small electric and magnetic fields that vibrate back and forth at right angles to each other and move through space at the speed of light.

We sometimes call infrared waves “radiant heat.” This is because the waves are at the right frequency to move the atoms and molecules around in our skin. When molecules move faster it feels to us like it is getting warmer. In fact, temperature can be thought of as a measure of the speed of the random motions of the atoms or molecules in a material.

I need to explain one other concept. Physicists call it “black-body radiation.” It is simply that everything is warm. As I said, temperature is a measure of the motion of the particles that make up a material. Unless the material is at absolute zero, all of the molecules that make up the material are in motion. Because they are in motion, they radiate electromagnetic energy, much the same as the antenna on your cell phone radiates its signal. The hotter they are, the faster they vibrate, and the higher the frequency (shorter the wavelength) of the radiation. At room temperature this radiation is in the infrared. If the material gets hot (think about a filament in a light bulb or an element on an electric stove top) the radiation moves to the visible wavelengths. Because of its temperature, the sun radiates mostly at visible wavelengths.

Now back to glass and greenhouses: Glass is transparent to visible light, but opaque to infrared. Light from the sun passes through the glass almost unimpeded. When it strikes a molecule, either at a surface or in the air, the molecule absorbs the light and gets warm. It re-radiates its own black-body radiation, but since it is much cooler than the sun it radiates in the infrared. But the infrared light can’t go back through the glass, and is trapped in the greenhouse. Since more energy is coming in than can go out, the building heats up.

What is a greenhouse gas?

Our atmosphere acts like the glass panes on a greenhouse. If it weren’t so, all of the sun’s radiation would escape back into space and the Earth would be frozen. Like glass, our atmosphere is transparent at visible wavelengths and not as transparent in the infrared. Sunlight heats the ground and the air, but the infrared radiation from the warm Earth does not all escape back into space. Evidence of this is how clouds will keep the temperature warm at night, while if it is clear it gets cold.

The air we breathe is made up of a complex mixture of atoms, molecules, aerosols, and dust. Most (about four fifths) is nitrogen molecules (N₂). Most of the rest is made up of oxygen molecules (O₂). Each molecule in the air is “tuned” to certain frequencies. That is, because of the strength of the bonds between the atoms and between protons and electrons, they can only vibrate at certain frequencies. Like a guitar string, if you pluck it you only get one note. If you tighten the string and pluck it, you get a higher note. Because of this tuning, molecules can absorb light at certain wavelengths and not at others.

Because of strength or “tightness” of their molecular bonds, some molecules are better at absorbing infrared waves than others. The more of these molecules that there are in the air, the more opaque the air is to infrared radiation. Gases like nitrogen and oxygen are weak absorbers of infrared waves. The so-called greenhouse gases absorb infrared more efficiently and prevent its escape into space. Among the best absorbers of infrared in our air are water vapor, carbon dioxide, methane, ozone, aerosols, and dust.

What are natural sources (and sinks) of greenhouse gases?

All of the above greenhouse gases occur naturally in our atmosphere. There is a natural cycle that governs each gas and determines how much there is in the air. Water vapor is a good example. We all learned about the water cycle in school, how it evaporates, condenses, rains, soaks into the earth, seeps out in springs, flows to the sea, and then evaporates again.

There can be several cycles governing one particular species. Carbon dioxide, for example, is absorbed from the air by plants; the plants die; and decay releases the carbon dioxide back into the air. Another carbon dioxide cycle, bigger than that of plants, involves the emission of tons of carbon dioxide into the atmosphere in volcanic eruptions. The carbon dioxide is absorbed into the water of the oceans and then precipitates out or is absorbed by plankton, coral, etc. The resulting lime sinks to the bottom of the ocean, is carried below the surface at subduction zones where continental plates collide, and is blown back into the atmosphere by volcanoes.

What are the anthropogenic sources?

Now we are getting closer to global warming. For most of history, fuels were almost entirely made from things that grew, i.e. wood. This maintained a balance in the carbon dioxide in the atmosphere. Carbon dioxide that was released by burning wood was re-absorbed by the growing trees that became the next fire. It was not until we started using fossil fuels that the carbon dioxide began to increase in the atmosphere. Actually, if one takes a longer view, the fossil fuels were once plants and animals on the surface and contributed their carbon to the atmosphere. The Earth was a much warmer place then.

In the 1930’s (I think) a station was set up on Mauna Loa to measure atmospheric composition – as far as one could get from a major source of carbon dioxide. Since then, this station has measured a constantly increasing amount of carbon dioxide in the atmosphere. The rate of this increase has been accelerating, and actually shows fluctuations that correspond with events like recessions and the industrialization of China.

Methane is another greenhouse gas that has been increasing. It is more efficient as a greenhouse gas than is carbon dioxide. The main methane sources are the “belching cows and polluting trees” that President Reagan liked to make fun of. There have always been trees and cows, but there is getting to be more and more of the agricultural output that is fed to cattle. Beef has become the most popular food on the planet, with the result that there are more cattle than there have ever been.

What sources really matter?

So why isn’t this just a big chemistry problem? Why don’t the scientists just figure it out? The answer is that they are trying. It is a very complex and complicated problem with too many unknowns. Do we increase global warming by cutting down the rain forests, or do the weeds and grasses that take their place absorb more carbon dioxide than the trees did? Is the absorption of carbon dioxide by the oceans so great that the amount we are putting into the atmosphere doesn’t matter? Is warming bad? Will it bring rain to dry areas, or will it dry out wet areas? Some climate models predict that global warming will turn Europe into an ice box. Does it matter that most of the greenhouse gases are coming from a few very concentrated urban areas? Are the big urban centers affecting, and possibly invalidating, our measurements? Perhaps the hardest question of all is how the things we would have to do to reduce greenhouse gases would affect human prosperity – and which countries would have to make the most sacrifices?

What is, and what is not, global warming?

A hot summer or a mild winter is not the result of global warming. Since the build-up of greenhouse gases in the atmosphere is a gradual process, the increase in temperature is also a gradual process. Climate models show an increase of only a fraction of a degree per year as a result of global warming. If warming were all that happened, you probably wouldn’t even notice it.

The problem is that the global environment is a coupled system. That means that a change here may cause a bigger change there – or a smaller change. Everything is affected by everything else. An example is the climate of the southwest US. The Mojave Desert gets about the same annual rainfall as central Utah. The difference is that the Mojave gets it in the summer in the form of monsoon rains, while Utah gets it in the winter in the form of snow. Water in the Mojave either dries up or runs off, making a desert. Water in Utah is stored as snow in the mountains and is released gradually through the year. One result of global warming might be to move the weather patterns northward, making Utah like the Mojave.

Another example is the Gulf Stream. Heating of the water in the Gulf of Mexico and cooling near Greenland set up a circulation that brings warmed water to the north coast of Europe and keeps it warm. Some models indicate that the change in cooling if Greenland melts, or a change in the flow of the Nile River that hits the Gulf Stream outside the Straits of Gibraltar could change where the Gulf Stream flows and leave Europe with the same climate as Labrador (at the same latitude). The scary thing about the Gulf Stream models is that they predict that it will be a catastrophic event – there is a threshold at which the circulation pattern snaps to the new pattern.

A third example is the melting of the ice caps. Over the years the polar ice caps have reached equilibrium where the amount of ice that melts is balanced by the amount of new ice that formed. Part of this balance is maintained by the reflection of sunlight back out into space by the bright snow and ice at the polar caps. There is indication now that the polar caps are melting and the area covered by ice is shrinking. As the ice shrinks, less of the sunlight is reflected and more is absorbed by the blue water. The more that is absorbed the warmer it gets, the more ice melts, the less sunlight is reflected, and so on.

So do I believe in global warming? Of course I do! If there were no global warming we wouldn’t be able to live here. Venus, Earth and Mars receive roughly the same amount of energy from the sun. Venus’ atmosphere is thick carbon dioxide – and the temperature at the surface is about 800 degrees. Mars has an atmosphere that is too thin to act as a greenhouse – and the temperature at the surface is as cold as dry ice.

Do I believe that global warming is increasing? I don’t think that can be denied either. If the concentration of greenhouse gases is greater than it used to be, the greenhouse heating has to be greater than it used to be.

Do I believe that global warming is dooming civilization? No. I think that in the long run mankind will adapt to new conditions. We always have. The problem is that there may be places or times where the adapting will not be pleasant. We don’t understand the global ecosystem well enough to predict who the winners and losers will be. If by “civilization” you mean the current standard of living and political stability in the United States, global warming may stress it, but there are a lot of other things going on in the world that worry me more.

What is the state of the politics?

Most of what I see in the popular press about global warming seems to me to be more politics than science. People who call themselves “liberals” say we are dooming the planet by continuing to produce greenhouse gases. People who call themselves “conservatives” say that global warming is a myth perpetuated by people committed to the overthrow of capitalism. To me, both are disingenuous. Evidences are Al Gore’s house and Rush Limbaugh’s refusal to listen to any scientific evidence. They remind me of the Book of Mormon’s definition of priestcraft.

Other countries, and many Americans, chastise the US for not signing the Kyoto treaty on global warming. It was not only rejected by President Bush. It was also rejected by congress. The main reason was that it would have required the US to make major reductions in carbon dioxide emissions (possible with our current technology only by shutting down industries), while not requiring the third-world countries like China and India to slow their industrialization. Industries in those countries and in Russia are extremely inefficient and are major polluters, but it was considered to be unfair to curtail their growth while they were still trying to catch up with the West.

What should be done – what matters, what doesn’t?

First, you can’t legislate your way out of global warming. This seems to be Al Gore’s solution. Requiring conservation without the technology is possible only by reducing capacity and lowering the standard of living. This does not affect the rich – like Al Gore – who can still afford to keep his standard of living when prices rise. It would have a profound effect on the poor who pay a high percentage of their income for necessities (gas, food, heat) that produce greenhouse gases. Legislating the way to science reminds me of the time when we had NSF money to build the “Polar Cap Observatory” on a Canadian island in the polar cap. Senator Stevens, who controlled the appropriations committee in the Senate, included in a bill that it had to be built in his state, Alaska – outside the polar cap.

Second, you can’t hide your head in the sand (Rush Limbaugh’s solution). If the catastrophic changes happen that some models predict, it would not be good to be surprised by them. Even if they don’t, we should be proactive about adjusting to global-scale changes in a way that will benefit all of us. If anthropomorphic global warming proves to be insignificant, we will be better off than if we didn’t understand global climate changes. If it proves to be significant, we don’t want to find out when it is too late for a good reaction.

Both approaches are having the result of isolating the scientific community from the mainstream. Both sides portray scientists who don’t agree with them as having a political agenda or of being paid or forced to falsify their results. The only “competent” scientists are the ones who agree with their viewpoint. My impression of scientists on both sides who populate the talk shows to advocate the “truth” about global warming have lost their objectivity – and hence their credibility as scientists. In the end, people in general lose their trust of science, and then even when something is learned it is rejected. The good scientists that I know are honest enough to change their minds if evidence doesn’t support their hypotheses. They are also honest enough to give anyone a hard time for shoddy science when they referee their publications, no matter which side of the argument is supported.

In the long run, the solution has to be a combination of common sense, good science, and sound proactive policies that encourage sustainable growth in living standards everywhere. An example of such an approach can be seen in the success of the effort to stop the depletion of the ozone layer. (In spite of what you hear on talk shows, this has nothing to do with global warming.) The scientists who documented the problem did so in peer-reviewed scientific journals. They made their case strongly enough that other scientists became involved. The scientific community debated for several years. A lot of money was put on the problem by governments around the world. Satellites were flown (including UARS, one that I worked on) to make critical measurements. Eventually the effect was understood and international treaties were signed to end the production of chlorofluorocarbons for refrigeration. Science responded with new substances that are as good for refrigerators and aerosol cans, but that don’t harm the environment.

Key in all of this is to restore science to a position of trust and to a popular career in society. Scientists in the global warming debate are portrayed as either government goons or left-wing radicals. The scientist in movies and on TV is either a naïve fool or an evil monster. Many of the brightest students who used to study science are going into the “glamour” fields like business, law and medicine (sorry Jared, Cory and Mike). Students smart enough to study science are smart enough to see that it is a long, hard program without a big payoff in either money or prestige. I know from experience that most people are uncomfortable talking about science with a scientist. Somehow we all took a load of guilt for not doing well away from our high school science classes instead of a load of excitement and curiosity.

The most important things we can do are to let our children have curiosity about the world around them and teach them that they can solve problems. We should speak up for real solutions, and recognize political solutions for what they are – sometimes necessary, but delaying the solution and not solving the problem. We should encourage the politics of common sense. Above all, we should believe that the earth was created with enough natural resources to last if we are good stewards and take care of the little patch that is ours.

Kent Miller

2006