Sunday, November 4, 2012

Anthropogenic Global Warming - Part 4 - Greenhouse Gasses


Chipmunk with back towards camera
I'm currently working on building an argument supporting Anthropogenic Global Warming, one chunk at a time.

Previous Parts:
Today's part is looking into what greenhouse gasses are, whether CO2 qualifies, and whether we can laboratory-test it.

Personal Commentary

In part 3, I was remarking on the issue of direct heat releasing through the burning of fossil fuels, and how that would be a detriment to my argument.

I thought of a decent way to explain it.

If it turns out that CO2 is not a greenhouse gas, it's hypothetically possible to see global warming that corresponds to the burning of fuels due to direct heating, without CO2 playing a role. Since CO2 is a byproduct of combustion, we would then see a CO2/Temperature correlation, even if it's not causation.

That's the quandary  That's actually a big part of what I'm trying to accomplish here. I'm attempting to establish causation.

Argument so far

Plants pull CO2 out of the atmosphere to build plant matter. 

Plant matter can die, be buried, and through a process called thermochemical conversion, turn into hydrocarbons, whether it's a liquid crude oil, natural gas or coal. This has been happening for at least 475 million years, with the amount of CO2 stored in the ground accumulating during that time.

The process of extracting fossil fuels and refining them produces a wide variety of types of hydrocarbons, all of which release CO2 into the atmosphere when burned, the amount of which varies depending on several factors, such as temperature and oxygen availability. The scientific community has done many studies about the CO2 (among other emissions) from internal combustion engines of various vehicles, in various scenarios. It's empirically demonstrable that our vehicles, among other sources, are emitting CO2.

Knowledge

The Earth is bombarded by electromagnetic energy from the sun. About a third of that energy is reflected into that space, but the other two-thirds are absorbed by the planet either directly (such as oceans), or through the greenhouse effect. Radiation emitted back by the planet often is done in lower-wavelengths, such as infrared, but that can be trapped/absorbed by gasses in the atmosphere - this is the greenhouse effect. Specifically, greenhouse gases are those that absorb energy from infrared wavelengths.[3][5] Different types of gasses have different levels of contribution to this effect. [1][5]

The greenhouse effect can be demonstrated in a few ways. 

The first is that the moon's temperature varies wildly from it's day-to-night cycles - from -110C to +130C. The moon is basically the same distance from the sun as the Earth is (within a very small fraction of difference), and yet Earth's daily temperature cycle varies to a much less degree. The atmosphere absorbs radiation during the day and retains it at night. Without the atmosphere absorbing and retaining heat, the Earth would be essentially uninhabitable. [2]

Second, the greenhouse effect of different gasses are laboratory-demonstrable. In fact, it's a common lab experiment for science class in schools across the lands. [4]

As previously mentioned, the greenhouse effect is that different gasses will absorb energy from infrared radiation, and heat up. The Earth radiates the electromagnetic radiation it receives in the infrared range.

A simple experiment can be set up to test whether this effect happens. It involves clear seal-able containers, such as soda bottles or glass containers. Place a thermometer into the container, and put the gas one is testing into the container (such that only that type of gas is present). Place it under a heat lamp, or another infrared source that has consistent output, and measure the temperature over time of the thermometer inside. One can test different types of gasses, such as nitrogen, oxygen, etc. As long as the experiment is properly controlled, and the test conditions are the same - such as the same type of containers, same volume, same IR/light levels, same laboratory equipment, etc - so that everything is the same from one test to another, except the gas being tested, one will find that different gases get warmer faster.

In more professional experimentation contexts, the warming potential for different gases are empirically measurable. Although CO2 has fairly low potential compared to some gasses, it's much higher than the bulk of the atmospheric makeup - oxygen and nitrogen. [1][6] Although methane (CH4) may be much higher in potential, if we output much more CO2 than CH4, it would make up the difference.

The bottom line is that the greenhouse effect, as well as CO2 being a greenhouse gas, is empirically confirmable, and confirmed.

How it ties into the argument

In part 3, I established that our combusting of fossil fuels outputs CO2. In this part, I'm establishing that the greenhouse effect exists, and that CO2 qualifies as a greenhouse gas. This is the next step in setting up the context for the problem.

Followup personal commentary

I went a bit further researching this one. I commented in a previous post that I was thinking that covering the rudimentary basics seemed like a waste of time - that I could have just skipped to whether we were outputting enough CO2 to be a problem. When I was researching and writing this up, I was thinking to myself that it was a safe assumption that everyone accepted that the greenhouse effect was real.

I was wrong.

Apparently that's one of the approaches people have towards denying anthropogenic global warming - denying that the greenhouse effect is a real thing - at all. I went into the research a bit more deep to establish this as true.

In fact, it's so easy to demonstrate as true that high school students can do the experiments

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