Understanding Greenhouse Gases

Balance, proportion and location. These three words are key to understanding why we are trying to reduce greenhouse gases in our atmosphere.

What are the greenhouse gases? According to the Kyoto Protocol, the 1997 agreement sponsored by the United Nations Framework Convention on Climate Change (UNFCCC) to stabilize greenhouse gas concentrations in the atmosphere, the greenhouse gases are carbon dioxide (CO2), methane (CH4), nitrous oxide (N2), and sulphur hexafluoride (SF6), as well as two groups of gases know as hydrofluorocarbons (HFCs) and perfluorocarbons (PFCs). There is another greenhouse gas; in fact, it’s the most common greenhouse gas of all. Think about what it might be; we’ll give you the answer later on this page.

The greenhouse gases all share one important property: they absorb and reflect infrared radiation. You know how a pot on the stove stays hot after you turn off the flame? Greenhouse gases act the same way with the heat that is naturally emitted by the earth. Instead of letting it drift off into space, they hold onto it, and even send some of it back down to the surface.

That heat came originally from the sun, in the form of visible light. The earth’s atmosphere lets visible light pass through with very little energy lost (about 94% gets through). This includes the greenhouse gases; in the visible light spectrum, they’re invisible, and let the light energy pass through. While some of the sun’s light energy is deflected when it hits clouds in the lower atmosphere, most of it reaches the earth’s surface, where it is absorbed and converted into heat energy. This is how the sun warms our planet.

Any object that has absorbed enough energy will eventually send some of that energy back. This emitted energy may be in a different form from the energy it received. The earth, warmed by the visible light of the sun, releases some of that energy back into space. But this energy is no longer in the form of visible light; instead, it has been converted to infrared radiation.

If the atmosphere allowed infrared radiation to pass through it, just as it did for visible light, then everything would even out. And in fact, the most common atmospheric gases like nitrogen and oxygen act in exactly this way. But it’s a different story with greenhouse gases. They absorb some of that infrared energy, and reflect some of it back towards the earth’s surface. As greenhouse gas concentrations increase, absorption and reflection increase, and the overall temperature of the atmosphere goes up.

This is what we refer to when we talk about global warming.

Is global warming a problem? Not necessarily. Remember what we said back in the beginning: it’s all about balance and proportion. The cycle of energy, from the sun through the atmosphere to the earth, then from the earth through the atmosphere and back out into space, is a natural, eternal one. It occurs on every planet in the solar system. The atmosphere acts as a buffer between the sun’s energy and the planet. Planets with very little atmosphere have no buffer, and run to extremes of hot and cold. Planets with dense, opaque atmospheres have too much buffer, and never even feel the sun’s warmth.

In fact, were it not for greenhouse gases, and in particular water vapor (that’s the most common greenhouse gas), there would be no life on earth. The presence of greenhouse gases in our atmosphere is the reason the earth remains at a relatively consistent temperature (by the standards of the solar system, the earth is a very, very temperate place), which allows plants and animals to survive.

Balance and proportion of greenhouse gases have been maintained through the millennia by natural cycles. Water vapor cycles between the atmosphere and the earth through evaporation and condensation. Carbon dioxide cycles out of the atmosphere through photosynthesis by plants, and cycles back into the atmosphere through the decay of dying biomass and the exhaled breaths of animals. Life on earth has grown and evolved within these greenhouse gas cycles, as has human society.

But what happens if you change the balance and mess up the proportion? As greenhouse gas concentrations increase, the atmosphere absorbs more heat. Change in atmospheric temperature means changes to the environment, and of particular concern, changes to the highly complex patterns of the earth’s weather.

We know that these changes can be severe, and the results can be catasrophic, because we know that there were times in the past when great sheets of ice covered much of the earth. It was the study of these Ice Ages, in fact, that led to the discovery of greenhouse gases. You can read about this in the Histroy of Global Climate Change.

This is why the issue of greenhouse gases, and of global climate change, have become so important today. Because it is increasingly clear that the balance of greenhouse gases, particularly the greenhouse gases associated with the use of fossil fuels, is seriously out of whack. Levels of virtually every greenhouse gas have risen steadily over the past two hundred years, and these changes don’t fit the pattern of previous natural cycles. They do, however, fit the pattern of man’s use of fossil fuels.

The evidence points very strongly to the fact that our use of fossil fuels is changing the balance of greenhouse gases in ways that may have powerful consequences for human society.

You remember that we said, back at the beginning, that location was part of the problem? That’s how mankind has changed the natural balance of greenhouse gases. When we burn fossil fuels, we take greenhouse gases that had been locked miles below the surface of the earth in deep deposits of coal, oil and gas, and release them directly into the atmosphere.

This would not be problem is we balanced this release by cycling more greenhouse gases out of the atmosphere. Instead, we’ve done just the opposite, doing things like chopping down millions of square miles of forests.

What will be the end result of all this? No one knows for sure. The science of weather is bafflingly complex, involving a whole new branch of mathematics with the appropriate name of chaos theory, and we are only just beginning to understand it. But scientists are in agreement that global warming eventually leads to global climate change (these two terms are sometimes used interchangeably, though they refer to different things). They can only speculate on the consequences of global climate change, but many of the speculations are frightening. Sea levels could rise, forcing major cities to be abandoned and millions of people to migrate; changing patterns of rain and drought could turn major agriculatural centers into dust bowls; we could experience extended periods of high heat and extreme cold, with parts of the world in a new ice age; hurricanes could reach new levels of destructive power; important animal and species, adapted to the current global climate, could die out.

The goal of people who support renewable green energy is to change mankind’s impact on the greenhouse gas cycle, and to bring balance and proportion back into our relationship with the earth. This means we must change the way we generate electricity from burning coal, oil and gas to sources such as wind and solar, which produce no greenhouse gases, and boimass, which maintains a natural cycle by only burning a renewable, carbon offsetting source. And this change must start now.

How will RECs help this happen? Read on to find out.