Understanding the Evidence for Climate Change
In rhythm with the recent upswing of political activity due to the presidential primaries, I have elected to write a piece on climate change. Climate change is a problem, and it is an issue that I wish was brought up more often in the debates for both parties. With this piece, I intend to enlighten individuals that may have the opinion that climate change is a “hoax” by presenting the evidence in an understandable and objective manner. I also want this to be a fun and informative experience for those who are simply interested in learning more about the issue of climate change.
Carbon Dioxide
First thing’s first, carbon dioxide is a chemical composed of one carbon atom, C, and two oxygen atoms, O2 for a molecular formula of CO2. Its structure is represented like this:
Where the black sphere represents the carbon atom and the two red spheres represent the oxygen atoms. Carbon dioxide is the largest contributor to global warming, and we will discuss why later. For now, we need to address how CO2 enters the atmosphere in the first place. One way in which CO2 enters the atmosphere is via our breath. Humans and all other land dwelling species breathe out CO2 as a part of our respiration (this is why scuba divers can’t just breathe in and out endlessly to and from their air supply). However, our breath is an extremely minimal factor in the scope of global climate alteration. The real contributor is the fossil fuel industry (gasoline and coal being the worst) because to run a car or produce electricity we must use energy. The most efficient means to obtain energy through fossil fuels is a chemical process known as combustion. Combustion has a general reaction pathway as follows:
Hydrocarbon + O2 → H2O + CO2 + Energy
A hydrocarbon is any substance that is made up primarily of carbon and hydrogen atoms, this includes gasoline and coal. O2 is oxygen from the air and we all know H2O and CO2. The rightwards arrow in this reaction equation points towards the products of the process, so when gasoline and oxygen are chemically combined by providing an initial spark of energy, we obtain water, carbon dioxide, and a substantial amount of energy in return. The takeaway message here is that humans have found a process that allows us to use our heavy machines by rearranging the chemical bonds from gasoline and coal into water and carbon dioxide. The chemical process gives us a lot of energy to use, but the yields for CO2 are incredibly high. So, CO2 enters our atmosphere via the combustion of fossil fuels, why is that so bad? It doesn’t mean we’re all going to heat up, does it? Let’s follow the CO2 and see where it takes us.
Is it Getting Hotter in Here or is it Just Quantum Mechanics?
Now that we know the most active source of introducing CO2 into our atmosphere, we need to understand how it interacts while it is way up above the clouds. The crazy thing about CO2 is that it is denser than air, which should mean that we would’ve all drowned in it by now, right? Luckily, Mother Nature has spared us from our own breath with wind currents that carry the carbon dioxide way up into the upper atmosphere. Don’t forget that the universe is a brutal uncaring beast, so carbon dioxide hasn’t given up on trying to kill us just because it was washed away into the atmosphere. It has a secret weapon called quantum mechanics on its side. Every molecule or compound in the universe has some set of natural vibrational frequencies. The bonds in carbon dioxide, for instance, will shorten and lengthen extremely rapidly. Everything around you has some vibration associated with it. Not a vibration you can feel, but every atom, even in the solids that comprise your computer screen vibrates ferociously on the subatomic scale. The energy of these vibrations can be calculated, and the energies for the different ways that CO2 vibrates are 1333 cm-1, 1333 cm-1, 667 cm-1, and 2349 cm-1. These numbers may appear meaningless to you, but if any one of these energies is matched by some form of light then the molecule will vibrate at higher energy than before (faster). The significance of the energies of carbon dioxide’s vibrations is that they fall within the same range as the middle region of infrared light (4,000 – 200 cm-1). Some middle range infrared light is reflected by the surface of Earth and begins to exit our atmosphere, but instead of being able to leave the atmosphere cleanly, carbon dioxide becomes excited into a vibrational state wherein it vibrates faster than before.
You can find examples of these vibrations for many molecules, including carbon dioxide, at this domain: http://chemwiki.ucdavis.edu/Physical_Chemistry/Spectroscopy/Vibrational_Spectroscopy/Vibrational_Modes
In quantum mechanics, the same fundamental principle applies as in classical physics, what goes up must come down. When I say excitation, or excited state, I am referring to an atom or molecule that has received energy from light. This excitation does not last forever, the atom or molecule soon dispatches that energy in either the same form (light) or other forms like heat. It’s analogous to throwing a baseball straight up into the air. When the baseball is in your hand, it is in a relaxed state, and when it is at its peak in the air it is in an excited state. When the ball claps down into your hand again, it releases energy in the form of sound *smack* and it is again in a relaxed state.
In our system, Earth, we will focus on the carbon dioxide molecules that are being exited by the infrared light that is reflected by Earth’s surface. The infrared light is providing the energy to “throw” our CO2 molecules into an excited state (the ball is up in the air after we provide the energy to get it there). The CO2 molecules then quickly relax (the ball comes back down into your hand) and when they relax, because of the relatively low amount of energy we need to input to cause the excitation of carbon dioxide, they emit heat instead of light (the ball emits sound as it smacks into your hand). This phenomenon is the Greenhouse Effect. By emitting CO2 into our atmosphere, we cause reflected sunlight to be absorbed and emitted as heat rather than allowing it clean passage out of our planet. We are knitting a chemical blanket that warms the entire world.
The Hard Truth
It is of my opinion that many people that deny the things that science claims do so simply because it is scary. The scientific method gives us the closest possible thing we have to an objective truth about our universe. It is not a method that allows for lies and politically or otherwise motivated schemes to seep through the cracks (thanks to peer review). As a result, science doesn’t come to happy and comfortable conclusions all of the time. This is something that you must live with and understand. Just because you want your entire life to be some sugar coated happy baby fun land it doesn’t mean that science owes it to you to come up with conclusions that say things like “the earth will last forever even while we do things to destroy it”. It is objective reality, and here is the unbiased evidence that human activity is what is leading us down this path.
The ice core data that you see is a measurement of carbonic acid content from deep cylindrical cutouts from glaciers (ice is wonderfully preserved ocean water from many thousands of years ago). Thanks to this process: CO2 + H2O → H2CO3 (carbonic acid), and the fact that we know the rate at which this process occurs, we can calculate the atmospheric content of CO2 by measuring the amount of carbonic acid that is found in deeper and deeper sections of glacial ice (ocean water that became frozen longer and longer ago). The measurements from Mauna Loa are direct measurements of CO2 content in the air high up in the atmosphere from a research center in Hawaii. To counter the “natural cycles” argument, you can plainly see a cycling in the ice core data. This is a natural cycle, the data since ~1800 (the industrial revolution) shows a clearly unnatural and unending spike in the quantity of atmospheric CO2. It is significant to note that this spike occurs right around the height of the industrial age because it is the era in which humans began burning fossil fuels to harness their energetic potential. We can conclude that it is extremely likely that humans have had influence in the emergence of climate change. Our focus was just on carbon dioxide in this discussion, but other gases that produce the same effects in the upper atmosphere are water and methane. Those gases are not the focus of this article because they are not increasing in quantity nearly as drastically as the upper atmospheric content of CO2.
References:
http://www.columbia.edu/~vjd1/carbon.htm
http://www.noaa.gov
http://webbook.nist.gov/cgi/cbook.cgi?ID=B4000020&Mask=800#Electronic-Spec