By Duane Friend
We have been hearing about greenhouse gases, global warming, and climate change for years. If someone asked, could you explain what they really mean? This is the first of a series of articles where I want to focus on these processes, if they are affecting our climate, and if so how it can be managed.
The first thing to describe is the difference between weather and climate. Weather is the daily reading of temperature, precipitation, wind, etc. Climate looks at long term averages of those weather variables, typically over a minimum of 30 years.
Another thing to know is that earth’s climate has changed over time. If you would have been standing in what is now Jacksonville 18,000 years ago, you could have seen a giant sheet of ice off to the east. Ice ages have created glaciers that have advanced into Illinois multiple times over the last couple of million years. Three hundred million years ago, what is now Illinois was part of a vast tropical swamp near the equator. These changes in climate were caused by natural causes, such as changes in position of the earth to the sun and continental movement.
So now back to the terms. What are greenhouse gases, and why are they different than any other gas? To start, the atmosphere is made of mostly nitrogen and oxygen. These two gases alone make up 99 percent of all the gases present. Both of these are not greenhouse gases, but are very important for plants and animals to live. Nitrogen is important in protein and of course we need oxygen to breathe.
The remaining one percent of gases is made of many different substances, such as hydrogen, helium, neon and Superman’s nemesis krypton to name a few. Most of these just hang out, and don’t affect weather and climate. However, a select few such as carbon dioxide, methane, nitrous oxide and water vapor have the ability to take in and release certain wavelengths of energy (or heat). These are the greenhouse gases. Small amounts of these gases have been present in the atmosphere for millions of years.
As sunlight travels through the atmosphere and heats the earth’s surface, that heat escapes back to space. If the heat was kept forever, earth would have been toast long ago. However, some of this heat is intercepted by greenhouse gases as it is trying to escape.
If the heat is absorbed by a greenhouse gas, the heat is quickly released in all directions. A portion escapes to space, but some gets sent back to earth’s surface. The heat goes back and forth from earth to the atmosphere, losing a little to space every time. This is the greenhouse effect. It is a natural process, and keeps earth’s average temperature about 55 degrees warmer than it would be otherwise.
Well then if it’s a natural process, why are we talking about it? We talk about it because the concentration of greenhouse gases has increased over the past 150 years. With more of these gases in the atmosphere, the heat takes longer to escape to space. The enhanced greenhouse effect means the atmosphere is slowly getting warmer, hence the term global warming. Its cause and effect.
Why has greenhouse gases increased? There’s been a lot of research on this. Natural causes such as volcanic activity don’t explain it. According to the U.S. Geological Survey, average annual worldwide volcanic production of carbon dioxide is around 200 million tons. However, the amount of carbon dioxide produced by human activities averages over 20 Billion tons per year.
In the next article, I’ll talk about how climate models work, why they are much better today than they were 30 years ago, and why there are multiple models and not just one.