We hop into the car, and head out to hunt, gather and forage for the next few meals. As we drive along, the odorless carbon dioxide (CO₂) invisibly disappears out the exhaust pipe. We give it narry a thought. It disperses quickly and goes…where? Glancing up we see plenty of space up in the sky, the “celestial dome” which includes everything above earth’s surface, including the atmosphere and outer space. Looks like CO₂ has plenty of room to roam.

We hear and read that CO₂ is warming things up too much and changing earth’s climate. How can that be? CO₂ has been vital to life on earth for millions of years. It causes the sun’s warmth to keep the oceans from freezing and it fosters a climate that makes life on land possible. It does that by comprising a very tiny fraction of the atmosphere, currently about 0.04%.

In this Part One article we will explore what’s happening. First, let’s define some terms:

* Greenhouse gases: carbon dioxide (CO₂), methane (CH₄), nitrogen oxides (NO₂, NO₃), Ozone (O₃), sulfur dioxide (SO₂), and the list goes on, at least 14, nearly all invisible. As they increase every year, the heat they trap in the lower atmosphere warms the air and the oceans, leading to…

* Global warming, which alters wind currents and storm tracks as the atmosphere warms, leading to…

*Climate Change worldwide, gradual in some areas, rapid in others (especially in polar regions),

leading to change in our …

*Weather, which is what we experience locally where we live, and sum of all weathers in large regions equals regional climates, and all of these together is our world-wide climate.

The atmosphere, our Aerial Ocean, is in constant motion, spreading its contents far and wide. It is mostly nitrogen (78%), oxygen (21%) , argon (0.9%). All other benign gases and bad pollutants plus water vapor together make up just 0.1%. This ocean of air surrounding earth can be compared to the outermost parchment of skin on an onion. It is this incredibly thin skin around earth that makes nearly all life on earth possible.

Our Aerial Ocean consists of four distinct parts:

1. The Troposphere: extending up to 7 miles (39,000′) at our latitudes (up to 11 miles at the equator, just 4 miles over the poles). For comparison, Mt. Everest summit is 29,029′. Distance from Panorama to downtown Olympia is 5 miles.
* Lots of vertical mixing of the air
* Contains 80% of all atmospheric gases
* The bottom third (to about 13,000′ to 15,000′) is the breathable part, depending on latitude
* Cools to -70 F at the its top

2. The Stratosphere: 7 to 30 miles (168,000′) at our latitude in Washington. For comparison, it’s 31 miles from Olympia to Tacoma.
* Distinctly layered in density and heat
* Ozone in higher altitudes protects life from most harsh UV rays
* Fierce winds
* Temperature goes from -70 F to 32 F at the top

3. The Mesosphere: 30 to 50 miles (280,000′). (It’s about 60 miles Lacey to downtown Seattle.)
* Very thin density, mostly dispersed light gases
* Temperature goes down to -130 F at the top

4. The Thermosphere: 50 to 300 miles. (It’s 225 miles to Eugene OR, 300 to Roseburg.)
* Temperature rises to 2000 degrees, but atmosphere is extremely thin, so very little “heat”
* Mostly hydrogen atoms, dispersing into space

Thus, the entire atmosphere stretches into the sky some 300 miles, about the distance from here to Roseburg on I-5, and then it’s just “space”. It’s the troposphere, the first 39,000′, that matters to life. This is where CO₂, water vapor and pollutants concentrate. All the gases are sorted by gravity, and CO₂ is one of the heaviest. It stays low in the troposphere. All pollutants are heavier than benign Nitrogen and Oxygen.

Now enter the sun’s rays, comprising the ElectroMagnetic Spectrum. The deadly short gamma rays and x-rays are diverted by earth’s magnetosphere. Some of the UV rays, all the light rays and the longer infrared rays, microwaves, TV and radio waves penetrate the atmosphere. These longer rays heat the earth and its troposphere.

At night earth radiates back into space 2/3 of all the daytime rays which reach the surface. Greenhouse gases in lower troposphere block 1/3 of the long wave heat energy from escaping into space, trapping heat close to earth surface. The longer heat waves trying to escape hit the layers of polluting gases and “bounce back”, staying in the lower troposphere. This works to our advantage as long as the CO₂ stays at low concentrations.

Over thousands of years CO₂ levels have been relatively low, in the area of 280 parts per million (ppm) of total atmosphere (as measured in ice cores). With the Industrial Revolution starting in the late 1700’s came coal burning. Since then the burning of all fossil fuels has escalated dramatically. CO₂ concentrations hit 400 ppm (0.04%) as recorded at the Mauna Loa measuring station early this year. That’s a whopping 42% increase. That degree of increase in so short a time has never occurred in over 800,000 years.

The average world wide air temperature at earth’s surface has been about 57 degrees for over 10,000 years, since the end of the last ice age. Volcanoes, forest fires, decomposition of organic matter etc. have put CO₂ and other pollutants into the air for centuries at the estimated rate of about 250 million tons per year. This compares with 29 billion tons for CO₂ now emitted by human activities. Without the natural CO₂ and other gases coming into the atmosphere each year, the average temperature on earth would be about -4 degrees. So CO₂ is a good thing for life, but within limits.

In PART TWO, we’ll look at the sources of CO₂ and other pollutants, how and why they have been increasing especially since the 1950’s, how long they stay in our precious Aerial Ocean, and what we can do about it.

Sources for this Part One:
The Weather Makers: How Man Is Changing the Climate and What It Means for Life on Earth, by Tim Flannery
Elemental Geosystems (a college textbook) by Robert Christopher
Carbon dioxide (Wikipedia reference)