climate change: some general terms

A common question I get is "Is global warming real and/or are we causing it?" Well, all science is technically theory, but in my opinion (based on what I have read) the climate is certainly warming and we are impacting it as well.

I'm giving a presentation on climate change this week, so will be attempting to break it down over the next few posts. Hopefully it's not too intense - for my 3 followers haha. Also, please comment! I'm not saying I'm right and am always looking for ideas/inputs!
To start off, some wicked fun definitions!

1. global warming - refers to global temperature increases we have experienced since the mid 20th century. Thought to be caused by human activity.

2. climate change - any change in the statistical distribution of weather. Can be either a change in the average or a change in the order of events surrounding the average. Can occur once, or in a cyclical pattern, over decades to millions of years. ex: El Nino, glacial and interglacial periods (ice ages), the Dust Bowl, etc.

3. global weirding - I just heard this the other day. an increase in severe or unusual environmental activity. This speaks to the fact that the earth isn't getting warmer everywhere. Some places may get colder, some may experience monsoons, and some drought.

4. greenhouse effect - caused because of the gases present in our atmosphere that trap in heat almost like a blanket. Without the greenhouse effect the earth's average temperature would be approximately -20 degrees C (-4 F)!

5. greenhouse gas - are ranked in terms of how much they contribute to the greenhouse effect in terms of abundance and potency (for example, carbon dioxide is more abundant than methane, but methane is about 20X more potent of a greenhouse gas).
Anyway, the most abundant greenhouse gas is.... water vapor! which contributes 36-72%. Next up is carbon dioxide, 9-26%. Methane (farts! also carbon based) is 4-9%. And ozone is 3-7%. There are other greenhouse gases such as nitrous oxide and chlorofluorocarbons, but these 4 are the top contributors.