Chelsea Bilskemper & John Leinbaugh's Atmospheric Learning Page
Natural Variability in the Earth's Climate

In the last 30 years, there has been greater interest in understanding what kinds of things are going on in the earth's atmosphere.  Most notably, many scientists have been trying to figure out the effects that humans have on the changing climate of our planet.  As we have gained more and more knowledge of how to build cars, factories, computers, buildings, and chemicals ~ we have also realized that some of these activities are increasing the amount of chemicals that we are putting into the air.  Lately, you may have heard of things like global warming, changing weather patterns, and the ozone hole.  Many scientists today think that the changes that the earth's climate is experiencing is directly related to the chemicals that we are releasing into the air.  Some of these chemicals can remain in the atmosphere for many, many years.  Some of them enhance the greenhouse effect, which would make temperatures warmer.  Other chemicals are suspected to be responsible  for destroying ozone molecules, which make up the ozone layer of the earth.  The ozone layer helps protect the earth from the rays of the sun which are harmful.

Here is the other part of the story, scientists have done tests (like analyzing ice cores, tree rings, and fossil records) to determine what the earth's climate was like for many thousands of years before us.  This graph shows what kind of results they have found.

                 Variation in Temperatures Over the Last 900,00 Years

    According to this graph, it shows that long
    before humans had the opportunity to put
    any chemicals into the air, the temperature
    of the earth was constantly changing.  It was
    moving up and down in a very similar pattern.
    These records show that before humans started
    burning lots of fossil fuels (oil, gas, coal) and
    creating chemicals that are harmful to things in
    our protective atmosphere, the climate was
    ALREADY going up and down all by itself.
 
 

This brings up two questions in my mind:

            1. Are the increasing global temperature that we are seeing coming from things we are doing or are they simply
                a part of the natural changes the earth has always experienced?

            2. If the climate of the earth was indeed changing like this before humans had the chance to become involved,
                WHAT was going on that caused the climate of the earth to move up and down all the time?

Answering these questions will lead to an investigation of the "natural variability" in the earth's climate system.  That is, if humans are not involved, what kinds of things "naturally" happen to make the climate of the earth move up and down?  This web page is going to try and explore these questions.  It will give you some background on what the earth's atmosphere is all about, what terms like climate, ozone layer, and greenhouse effect really mean, and how they affect your climate.  Ultimately, we will search out what causes the "natural variability" of the earth's climate.