Greenhouse Gases, Global Warming, and Climate Change: Part One
What are greenhouse gases?
First of all, it’s necessary to understand that the term ‘greenhouse gas’ is improper. We’ll continue to use it, but keep that in mind. Greenhouse gases trap heat in the Earth’s atmosphere, but the mechanism involved is only vaguely analogous to the way in which greenhouses stay warm. The design of a greenhouse is such that the structure is optimized for capturing a lot of solar energy, which warms the ground inside and is transferred into the greenhouse ‘atmosphere’. But it is merely the structure of the greenhouse that keeps the warm air inside, through suppressing air convection. If you open a window in the greenhouse, the temperature will decrease. This is not how carbon dioxide works to trap heat in our atmosphere.
This picture is of Kuala Lumpur, Malaysia, while a huge fire was raging in the nearby forest. The haze is composed mainly of greenhouse gases, principally carbon dioxide and water vapor. Forest fires are one source of greenhouse gases; oil-burning factories and vehicles are others. Greenhouse emissions occur naturally, as part of a mechanism which keeps the temperature and composition of Earth’s atmosphere hovering within a delicate balance that is conducive to the needs of plant and animal life. This balance has persisted, with only minor fluctuations after the development of complex life, for at least three billion years. A caution: This does not make it an invincible balance. Longevity does not preclude fragility. Humankind has existed for about 200,000 years, and in the last one hundred and fifty years of our progress, populations across the globe have developed lifestyles which rely on the consumption of petrochemical fuel for energy and material needs.
The United States of America contains far less than one tenth of the world’s population [closer to 1/20] but consumes roughly one third of its petrochemical energy. The US Defense Department accounts for much of this, as it is the largest energy-consuming organization in the world. This is to be expected, since its annual budget is enough to feed, clothe, inoculate, and educate every needy child in the “third world”—you know, that other world. The one we’re defending ourselves from. China is also a particularly monstrous fossil fuel glutton, but only because there are more than a billion people there and because the government enjoys pursuing as many large-scale industrial projects as is simultaneously possible. Much of this activity is geared towards satisfying the extraneous imagined needs of the American market—in 2004, Wal-Mart alone was China’s eighth largest trading partner, ahead of the nations of Russia and Australia, and accounted for 10% of the US trade deficit with China. Even with thrice the population, China is not yet a serious competitor to US consumption—it is still in a production-intensive phase in its economy. That will soon change, and the balance of biopower will be altered, and what is unfolding in the Middle East is, quite clearly, in my view, much more of a strategic economic maneuver on the part of the West than some ideologically and morally centered campaign for democracy and human rights. Had the US, UK, France, and others fostered democratic and economic development through positive influences rather than the barrel of a gun—the latter having been chosen because it was never truly about democracy to begin with—much of the tragedy befalling the Middle East and our own country would have been averted. The Middle East was developing in its own way before the West got involved in the first place, which was approximately at the end of the Ottoman Empire brought about by the close of the First World War in 1918. This was just as it was becoming apparent that oil-burning engines would be the wave of the future. As Aldous Huxley would say, “Praise the Ford.”
A major byproduct of all this consumption—apart from hellish wars in the South and East and booming bank accounts in the North and West—is a quite substantial amount of manmade greenhouse gas emissions. Humans are putting too much carbon dioxide into the atmosphere. The balance may already have been fundamentally upset, and the failure to recognize and treat the issue may soon result in irreversible damages—this is according to NASA, not to Greenpeace. Greenhouse gases in our atmosphere are a lot like certain bacteria in our bodies in that, while it’s easy to think of them as completely icky all around, a certain amount of them is beneficial in carefully controlled moderation. The problem comes when humankind inadvertently tampers with this carefully controlled moderation in the course of its enlightened industrial progress, and then stubbornly refuses to acknowledge the importance of the problem and the utter, unyielding necessity of doing something about it as soon as is practiceable. That’s when the problem becomes an illness.
How do greenhouse gases regulate Earth’s temperature? Or: A Brief History of the Atmosphere
This is a molecule of carbon dioxide. The big guy in the middle is the carbon, and he’s just hangin’ out with his oxygen buddies. They probably met when something combusted, or maybe in some lungs somewhere, and now they’re drifting together through the atmosphere as one.
A water vapor molecule is built similarly, but with an oxygen atom in the middle, his arms wrapped around two hydrogen atoms. That, of course, is H2O.
Our atmosphere is composed, right about now, of 78% nitrogen, 21% percent oxygen, and 1-4% everything else. Most of that everything else is water vapor, the occurence of which is quite variable; and, right now, carbon dioxide accounts for about 0.0381 percent of the atmosphere. It’s not much on paper, but it’s by far the highest percentage of atmospheric CO2 the Earth has experienced in at least, quite conservatively, the last 100,000 years. Water vapor and carbon dioxide are the two most common greenhouse gases. If greenhouse gases only make up about 1% of our atmosphere, you might ask, how could they be so important in heating up the Earth? The answer ultimately lies in the structural and electrochemical qualities of the molecules, but let’s start with the Sun.
There it is—the star of the show, quite literally. The Sun is the source of all energy on Earth. The energy we use puttering around in our automobiles didn’t come from BP-Amoco or Exxon-Mobil or Conoco-Philips or anything else hyphenated. It came from the Sun and, through natural processes, was stored deep within the ground many millions of years before we drilled and pumped it up to the surface and into our fuel tanks. The energy you’re using to read these words can be traced back to the Sun, in fact. There just aren’t any other comparable radiation sources around. Nobody does it like that lucky old Sun. Ommm. Ommm. All Hail Sun.
The Sun transmits energy at short wavelengths—it’s called shortwave radiation, or solar radiation. The shorter the wavelength of an energy wave, the more intense the energy. About half of the solar radiation Earth receives comes in the form of visible light. Most of the rest is in the near-infrared—we can’t see it with our eyes, but we feel it as heat.
About 3.5 billion years ago, a young, hot, totally available Earth had just cooled off enough to form a crust. But like a fresh-baked pie, things were still bubbling underneath the surface. The Earth was much more heavily populated with active volcanos than it is today, and life had not yet appeared. The atmosphere of Earth had been mostly hydrogen and helium, like that of present-day Jupiter or Saturn, but these light gases were dispersed by the Sun’s heat and by the Earth’s own longwave, weaker terrestrial radiation. The volcanos spewed up large amounts of water vapor, carbon dioxide, and other greenhouse gases—so they were the original greenhouse gas factories. There was still some hydrogen in the atmosphere, but freeroaming oxygen molecules were not yet common and there was much less nitrogen than there is today. The atmosphere then was about one hundred times thicker than today, and the miles and miles of cloud cover would have caused the Earth to freeze—especially since the Sun was much cooler then—had it not been for the radiative absorption of these greenhouse gases. Carbon dioxide and water vapor were much more prominent in the early atmosphere than they are today, so the greenhouse effect was likewise more prominent on Earth at this point in its history.
These greenhouse gas molecules have a funny shape. When radiation strikes oxygen or nitrogen, the atoms of these elements and molecules are not disturbed by the blow. Their structural solidity allows them to keep floating along as if nothing had happened, and the solar radiation simply bounces away at an angle. But carbon dioxide and water vapor molecules do not allow terrestrial longwave radiation to ricochet and keep going—they trap this balancing radiation and convert it into motion. Longwave radiation causes greenhouse gas molecules to vibrate faster, and this energy is radiated outwards in all directions through the intensified vibrations of these molecules. Greenhouse gases will emit about half of their captured radiation back towards space, but the other half is radiated down to Earth’s surface. Carbon dioxide and water vapor kept the Earth from freezing when the atmosphere was much thicker than it is today by trapping heat in this way.
Eventually, the temperature of the Earth rose to a point at which the water vapor began to condense and fall as rain. Oceans were formed, and about 50% of the atmospheric CO2 was absorbed into the ocean as gas bubbles. Some of the volcanos, now underwater, continued to spew out carbon dioxide, further charging the ocean with this greenhouse gas. Microbial life began to appear in the oceans at about this time, and early microorganisms converted much of this excess carbon dioxide into oxygen through photosynthesis. This is how oxygen came to be a major player in Earth’s atmosphere.
Time passed. Plant life evolved in the water and on the landmasses of Earth. Plants, in general, were much more efficient and effective at absorbing carbon dioxide and producing oxygen than microbes had been. This is mostly just a question of surface area. With no predators, plant life thrived and flourished until there was far too much oxygen in the atmosphere to support life as it had existed before. There were mass extinctions, but the increased oxygen levels allowed ozone to form a protective layer in the atmosphere which reflected much of the harmful ultraviolet radiation received from the Sun. This ultraviolet radiation had played a part in preventing the evolution of more complex organisms, organisms which produced relatively large amounts of nitrogenous waste. Since this time, many hundreds of millions of years ago, the composition of Earth’s atmosphere has remained relatively stable at the molecular ratios we listed above. There was a lot of initial turbulence, but the end result was a billion year-long—and counting—period of climate stability which provided a safe haven in which complex lifeforms like you and like me could come to be.
Why wouldn’t we want to protect that, at all costs? I’ll count to a billion while you think about it. ;-)
Back to carbon dioxide—today, as we said, there is far less CO2 and water vapor in our atmosphere than there once was. Whereas early microbial and plant life made good use of a lot of excessive greenhouse gas, the more complex lifeforms which followed later required much more stable temperature conditions in a narrower range. They also required freestanding oxygen, which tends to be displaced by carbon dioxide. This means that both CO2 and oxygen are required to be present in the atmosphere in order to support the full range of life on Earth, but they are not molecules which tend to remain in balance without an outside influence.
Blue-green algae in the oceans of Earth are vital in maintaining atmospheric oxygen levels. Carbon dioxide tends to build up in the atmosphere much more quickly than oxygen. But CO2 is also more easily absorbed into water than oxygen, and the presence of CO2 in ocean water stimulates the growth of algae which survive by consuming it and releasing oxygen back into the atmosphere. The algae acts as an intermediary which balances CO2 and O2 levels—the more CO2 it can consume, the more O2 it will release. The ocean cycles about 50% of Earth’s CO2, and the soil also aerates the gas. Our problem of balancing necessary oxygen with necessary CO2 is solved in this way—algae takes care of excess oceanic CO2, and complex plants take care of atmospheric and soil CO2. There are also other parts of the carbon cycle which contribute to the necessary equilibrium.
The Earth captures about 70% of the shortwave radiation it receives from the Sun. The remaining 30% is reflected back into space before reaching the surface. Because greenhouse gases absorb and redistribute that heat which remains within the atmosphere, an increase in their atmospheric presence will cause a rise in global temperature. To a certain degree, the bioprocesses of algae, more complex plants, and other parts of the carbon cycle are able to prevent greenhouse gas levels from getting out of hand, as we described above. Features of the Earth’s surface and atmosphere which reflect shortwave radiation are said to have high albedo—this means, more or less, that they are opaque and bright. Ice, snow-covered mountains, and clouds are all examples of reflective, high albedo surfaces. Albedo will reflect a certain amount of solar radiation, but greenhouse gases also work simultaneously to negate the net effect of these reflections as experienced at Earth’s surface.
As ice forms on the Earth’s surface, particularly at the poles, it traps little bubbles of atmosphere in much the same way as ice cubes in the freezer do. Scientists can examine the contents of ice samples deposited at different periods in history and can determine, from the chemical qualities of the trapped gases, what atmospheric conditions were like at a given time. These measurements can be taken with a high degree of accuracy and are not seriously disputed by any peer-reviewed publications in the climate sciences. The graph at right, courtesy of the US Oak Ridge National Laboratory, shows CO2 and mean temperature levels for the Northern Hemisphere as recorded in ice core samples dating back for 400,000 years. Do you notice a relationship between the CO2 level and the temperature level? When CO2 levels rise, there is a brief delay and then temperatures rise accordingly. When CO2 levels fall, the temperature drops soon after. The trend is uniform and without exception. It is cause, and effect. Other factors such as solar activity (flares/spots) and geothermal anomalies contribute to very minor fluctuations in temperature apart from greenhouse gas levels, but this data makes it very clear that greenhouse gases are the most direct influences on Earth’s temperature. They got the power, ladies and gentlemen.
There are two very disturbing things about this data. The first is that the directly measured CO2 level for 1994 is higher than any CO2 level recorded naturally at any prior point on the graph. The second is this: see the spike in the CO2 line leading up to the “pre-industrial” point? Now, see the spike in the yellow temperature line which is just now peaking a little later as a result? If the 1994 CO2 levels were that much higher than any levels observable since long before the dawn of humankind, how much higher do you think they will force the temperatures to rise in response? We haven’t seen that response yet, and our grandchildren might not even see it, but, unless you have the audacity to disbelieve 400,000 years’ worth of pristine data, you can bet that it is coming. In this graph, the yellow line has not yet had time to rise in response to the last alarming spike in the red line. That red spike, the ugly one right before the number ‘0,’ which represents the present, is the principal byproduct of man’s perpetually increasing consumption of fossil fuels since 1860. The levels are still rising as we debate what to do about this mess.
In Part Two, we’ll discuss the role of human industry in these escalating levels and we’ll investigate the “debate” about the reality of the threat of increasing greenhouse gas levels—a debate which is being waged almost entirely in Congress and in the press while the vast majority of the world’s respected climatological and ecological authorities look on in stupefaction and disbelief. We’ll see that, while George W., Tony Blair, Putin, and their many petrochemical energy industry goonies claim they just “ain’t too sure ’bout that there scientific evidence,” the overwhelming majority of credible, verifiable, and apolitical research on the subject continues to confirm and to augment its own findings over, and over, and over again with virtually no response from the world public and world governments.
In Part Three, we’ll talk about why the response has been so dismissive and about what we can do, through love, dedication, and diligence, to change attitudes and lifestyles for the better today, tomorrow, and for the rest of our lives. The idea is not to deny future generations of the right to live and breathe as we so thoughtlessly did. The idea is not to piss it all away for a paycheck and a sports car when a bite to eat and a nice brisk walk would do.
“You must be the change you wish to see in the world.” —Mohandas K. Mahatma Gandhi
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