Belated Science Saturday

Sorry for the absences, but I've been caught up with a few too many things the past two weeks.

I hope to make up for it by trying to talk about...global warming! Yay! A lot of this material is about one year late due to Al Gore's documentary and big oil's denial.

Before I jump into the proverbial swimming pool of double-edged razor blades, it'd be useful to talk about greenhouse gases. Greenhouse gases are special kinds of gaseous molecules. They are called greenhouse gases because they absorb energy from the sun and then reflect it in every direction - sometimes away from the earth, and something right into the earth.

Just like happenings in our bodies, processes in the atmosphere are governed by extremely delicate equilibriums. One of those equilibriums is the amount of radiation reaching the earth coming in from the sun. Greenhouse gases affect the amount of radiation reaching the earth.

How does this happen? First we need to see what makes a greenhouse gas. This is easy. Any molecule that is asymmetric will be a greenhouse gas to some degree. If a molecule displays any asymmetric nature, it will have something called an electric dipole, where the net number of electrons on one half of the molecule are different than the net number of electrons on another half of the molecule. If the molecule ever has a dipole, we call it "dipole active", and if it is dipole active, it will absorb energy and then radiate the energy out as infrared radiation.

If there are a lot of extra dipole active molecules in the air than the planet is used to, then there will be more greenhouse gases in the atmosphere emitting infrared radiation down to us. This will cause the planet's temperature to rise (but a big debate is to what degree will the temperature rise).

Here are the five main components of the earth's air:

(I know that if you add up all the percentages you will wind up with a number more than 100%. Thats because these compositions are all somewhat variable, with water vapor being the most variable depending on altitude, and proximity to bodies of liquid water.)

So lets learn about what we're breathing.

Nitrogen has a very strong 'triple-bond', and all of its electrons are are paired up into happy couples, so they are quite content being where they are. Because this molecule's electrons are so content, we usually call it "inert". Furthermore nitrogen is NOT a greenhouse gas because if we do a few tests on it (I'm going to call them the the stretch-test and the bend-test) the N-N molecule always will have an average number of electrons spread out in a symmetric manner. Nitrogen passes the stretch-test, and since it only has two atoms, it can't take the bend-test (we won't hold it against molecules that they can't take particular tests...)


Oxygen is a special molecule. Whereas nitrogen is very inert, oxygen has two electrons not paired up. Since two electrons are not paired up, this makes oxygen a very reactive molecule. (Reactive in the sense that it helps power our bodies, causes food to go bad, and helps makes metal rust.) Despite this great difference from nitrogen, oxygen is NOT a greenhouse gas. If you do the stretch-test on oxygen, you still have a very symmetric spreading of electrons around the whole molecule. Likewise, oxygen can't take the bend test. Oh well...

What about water? We all know about the importance of water to us and the planet. However, to determine if its dipole active, you should know that oxygen atoms hold many more electrons than hydrogen atoms. You don't even need to employ any test on water to see that there are more electrons on the left side of the molecule than on the right side, so water IS dipole active and IS a greenhouse gas. If anyone wonders why we don't talk about water as being something worth legislating, its because once water reaches high enough in the atmosphere it will cool and then condense to rain. The rain then falls to the ground and saps energy and heat to gain evaporate, thus cooling the earth. Basically, we consider the long-term effect of water as a greenhouse gas to be a wash (pun intended).

How about argon? Argon is a one of the "noble gases". That means it is a single atom, all of its electrons are paired up, and it is inert. If there was a single-atom equivalent to nitrogen gas, it would be a noble gas. Its just one atom, and for all intents and purposes, it is completely symmetric, so its not a greenhouse gas.

What about carbon dioxide? Well...its an interesting subject. Carbon dioxide is a natural byproduct of us breathing out. Likewise, plants and vegetation need it for photosynthesis so they can live. In that sense its "natural". Is carbon dioxide a greenhouse gas? It looks kind of like nitrogen and oxygen gases, and neither of those are greenhouse gases...but IT IS. Doing the stretch-test results in a still-symmetric molecules. However, the bend-test results in something looking bent like water. Oxygen atoms store more electrons than carbon atoms, so this molecule will be dipole active and will be a greenhouse gas...but only when it's bent.

Now, since carbon dioxide is only a greenhouse gas when it bends, its not necessarily as potent a greenhouse gas as water, which is always bent. (The dipole moment of water is also quite a bit stronger than the dipole moment of carbon dioxide.) Furthermore, there is about 25x as much water in the air as carbon dioxide, and its a natural molecule that plants and vegetation need in order to live. Thats enough data for some people to think that carbon dioxide isn't a pollutant.

The problem is, the reason why water isn't a serious greenhouse gas is not true in the case for carbon dioxide. Carbon dioxide doesn't condense as easily in the atmosphere and fall to the ground cooling the earth. When it goes up...it just stays up there. It would be one thing if there was a mechanism in place to reprocess the carbon dioxide (besides rainforests which are getting cut down for development purposes), but there isn't, and so we wind up seeing charts like this where carbon dioxide is never really decreasing:


It just happens that there are also charts that look like this:


Now from basic physical understanding, we know that carbon dioxide is a greenhouse gas. Its also not going away, and the more of it there is the warmer the planet will be. It also happens that there is data that seems to support temperatures started getting a little funky around the turn of the 20th century. Scientifically, there isn't a sound way to show this though.

Does anyone know for sure if this trend is because of carbon dioxide (or other greenhouse gases)? NO! A recurring spread by non-scientists and big oil conglomerates is the argument that weather patterns are cyclical, and thus we can't presume anything about our own impact. Thats kind of a creepy thought though especially since...can we be 100% certain that humans are contributing to global warming? YES!

We know that carbon dioxide is a greenhouse gas, we are producing more and more greenhouse gases that warm the earth, and so we are definitely causing an impact. We're seeing an impact now. We know what one of the causes of it is. So, it isn't so much that the 2nd chart is influenced by the 1st, its that the 1st chart alone is quite troubling. It's so troubling that some purveyors of crap (who are not surprisingly funded by big oil) do everything they can to muddle the picture. At least some people do their homework, here.

Maybe the solution is to just sue Al Gore. Sigh...