Understanding Greenhouse Gases

In real estate, it’s all about location, location, location. With greenhouse gases, it’s all about location, location, location…and balance, as well.

Location and balance are key to understanding why we must reduce greenhouse gases in our atmosphere.

What are 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)
• sulphur hexafluoride (SF6)
• as well as two groups of gases know as hydrofluorocarbons (HFCs) and perfluorocarbons (PFCs).

Greenhouse gases share one important property: they all absorb and reflect infrared radiation. Just as a metal pot sitting on a stove stays hot after you turn off the flame, greenhouse gases trap and store 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.

Whether or not "greenhouse gas" is an appropriate term for these gases depends on how strictly you take your science. The overall effect is similar to what glass does in a greenhouse, letting energy pass through it on the way in, then trapping it on the way out, raising the temperature inside. The actual mechanism by which this happens is very different. So if you’re strict about your science, bear with us!

There is actually one greenhouse gas that we left off the list. In fact, it is the most common greenhouse gas of all. Can you guess what it is? We’ll give you the answer farther down the page.

The heat that greenhouse gasses absorb starts out as a different kind of energy: light from the sun. On this part of its journey, the light energy passes right through the greenhouse gases, because they are invisible, which is another way of saying they don’t react with light energy in the visible spectrum. The earth’s atmosphere allows about 94% of the the sun’s light reach the earth’s surface (some of it gets deflected by clouds and small particles of soot and debris, commonly known as smog), where it is absorbed and converted into heat energy. This is how the sun warms our planet.

An object that absorbs enough energy will eventually send some of it back. So the earth, as it warms, begins to emit energy back out into space. Just as it converted the energy from light to heat when it absorbed it, it now converts that energy back from heat to light. But this time, the light isn’t visible light; instead, it is infrared radiation.

If infrared radiation passed through the atmosphere at 94% efficiency, like visible light, everything would even out and we would have no reason to worry. This is, in fact, exactly what happens for the most common atmospheric gases like nitrogen and oxygen. But it’s a different story with greenhouse gases. They react to the infrared light, absorbing some of it and reflecting some of it back towards the earth’s surface. When they absorb the energy, they convert it into…you guesses it…heat.

You remember how we said, at the top of this page, that balance is a key to understanding global warming? It all comes down to the balance of greenhouse gases in the overall makeup of our atmosphere. When the balance is correct, everything is fine. 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 balance of greenhouse gases in earth’s atmosphere buffers the sun’s energy, and keeps the average temperature of our planet at a moderate 45°F. When the balance is skewed, things can get pretty extreme. On Venus, which has an atmosphere that is thick with heat-absorbing carbon dioxide, the average temperature is 850°F. And on Mercury, which has almost no atmosphere at all, temperatures can range from 870°F to -300°F.

Back on earth, greenhouse gases have historically been kept in balance by natural cycles. Water vapor cycles between the atmosphere and the surface through evaporation and condensation. Carbon dioxide cycles out of the atmosphere through photosynthesis by plants, then cycles back 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.

It is, however, a delicate balance. Change in the balance of greenhouse gases means change in the average temperature of our atmosphere, which also means change to the environment and, of particular concern, change to the highly complex patterns of the earth’s weather.

We know that the consequences can be catastrophic. We know that there were times in our past, for instance, 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 that in our posts on the History of Global Climate Change.

And it is increasingly clear that the balance of greenhouse gases is again in peril. Levels of virtually every greenhouse gas have risen steadily over the past two hundred years, and this change doesn’t fit the pattern of natural cycles. It does, however, fit the pattern of man’s use of fossil fuels. The weight of scientific evidence strongly suggests that our use of fossil fuels is changing the balance of greenhouse gases in ways that may have powerful consequences for human society.

How did we change the balance? By changing the location.

Fossil fuels spent millions of years locked in a location where they did no harm: buried deep below the ground in deposits of coal, oil and gas. But we have dug and drilled deep into the earth to pull them out, and then burned them to release them up into the atmosphere. This new location already had plenty of greenhouse gas. Each new emission has put the balance farther and farther out of true.

One way to reset the balance would be to move greenhouse gases OUT of the atmosphere and return them into the earth. The natural cycles do just this. But instead of doing this, we have compounded the problem by disrupting these natural cycles. We have chopped down forests, which pull carbon dioxide out of the air, and interfered with other systems that bring greenhouse gases back down to earth.

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 agricultural 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 plant species, unable to adapt to the new 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 back into our relationship with the earth. This means we must change the way we generate electricity, from burning coal, oil and gas to harnessing the wind and the sun and other renewable resources. And this change must start now.

How will RECs help this happen? Click this link to find out.