Global Warming – A Primer part 2

In part 1, we established the planet Earth is increasing in temperature.  One thing we didn’t specifically touch on, but should be obvious from looking at the charts is that the average global temperature is increasing faster than at any other point in time we are aware of.

Now, these are simple facts.  Sure, there’s some wiggle room in the data and some degree of uncertainty about the exact temperature in 1238.

However, (and this is something that a lot of non-scientists just don’t get) all of the data that we use for determining temperature point to the same range of temps at the same time.  Every way we have to tell the temperature all point to a global cooling event in the middle ages.  Every way we have to tell temperature all point to a warmer temperature before that.  All the trend lines of all the graphs are the same.

Simple, undisputed fact.  Even most of the “global warming deniers” accept this simple truth.

What many of them actually dispute is 1) Whether the massive warming trend that is going on right now is the result of human activity? 2) What should we do about it?

Now we need to talk a little about chemistry and physics.  I’ll try to make it painless, but this is really important.

The atmosphere is made up of a large variety of gases.  Most of these gases are totally neutral in effect and action.  Some are vitally important.  Some are toxic and dangerous.  Some can be both depending on where in the atmosphere it is.

The atmosphere is vitally important to us.  Here’s  little chart showing what it is made of.

Gas Percent Volume in Atmosphere
Nitrogen (N2) 78.084%
Oxygen (O2) 20.946%
Argon (Ar) 0.9340%
Carbon dioxide (CO2) 0.039%
Neon (Ne) 0.001818%
Helium (He) 0.000524%
Methane (CH4) 0.000179%
Krypton (Kr) 0.000114%
Hydrogen (H2) 0.000055%
Nitrous oxide (N2O) 0.00003%
Carbon monoxide (CO) 0.00001%
Xenon (Xe) 0.000009%
Ozone (O3) 0 to 7×10−6%
Nitrogen dioxide (NO2) 0.000002%
Iodine (I2) 0.000001%
Ammonia (NH3) trace
Not included in above dry atmosphere:
Water vapor (H2O) ~0.40% over full atmosphere, typically 1%-4% at surface

Now nitrogen isn’t that big a deal.  It’s nice and stable.  It doesn’t react with anything and it’s transparent to radiation.  It’s transparent to electromagnetic radiation (except ultraviolet) because of the shape of the N2 molecule.  Other molecules (notable CO2) are not transparent to radiation because they have a different shape [1].

As an interesting side note, nitrogen can become toxic at high pressures.  Really deep ocean breathing systems replace the nitrogen with helium.

Oxygen, of course, needs no introduction.  We have to have it to survive, even though it’s destroying us slowly.  But that’s a whole ‘nother post.

The one we’re really interested in is the 4th on the list, carbon dioxide.

This is another fact for your collection.  Carbon Dioxide (as well as water vapor, methane, nitrous oxide, and ozone) absorbs and emits infrared radiation (also known as heat).  This ability to absorb and emit infrared is a fundamental aspect of the arrangement of atoms and their electrons in the molecule.

Unlike what many people believe (and are led two by the common graphics), carbon dioxide does not reflect heat back to the Earth, but instead absorbs that heat (Infrared radiation) and then emits it back.  This prevents the heat energy from bleeding off into space like it normally does.

This is actually a good thing.  Without the CO2and other greenhouse gases in the atmosphere, the Earth would be very, very cold. The average global temperature was approximately 15.5°C (59.9°F).[2]

If there were no greenhouse gases, then the average temperature of the Earth would be close to zero degree Fahrenheit.  In fact, without greenhouse gases, the Earth would like a lot like one of our distant neighbors.

Mars

Mars is so cold, the ice caps are made of frozen carbon dioxide (and water).  At almost no point in the Martian year does ice ever melt into water.  Some of the frozen carbon dioxide (you may know it as dry ice) may sublime (change from solid to gas without becoming a liquid), but it will reform in the winter.

So, it’s a very good thing that we have those gases.

The most important gas in terms of keeping us warm is water vapor.  It contributes between 36-72% of the warming effect.  Carbon dioxide provides between 9-2% of the warming effect.  Methane, 4-9% and ozone 3-7%.

Physically, methane is a much more potent greenhouse gas.  On a molecule to molecule basis, methane contributes 72 times the warming that carbon dioxide does (over a 20-year period).  But if you look at the chart of atmosphere composition, there is almost 300 times the carbon dioxide in the atmosphere than there is methane.  So we have to take that into account.

A brief aside on methane.  A methane molecule will last in the atmosphere for about ten years.  It will break down (chemically) into carbon dioxide and water vapor (still greenhouse gases).  Three human based sources produce almost 40% of the methane in the atmosphere, energy production, landfills, and cattle.  Yep, cow farts (and zebra, musk ox, bison, etc) produce almost 17% of the methane in the atmosphere.  What’s even worse is that there is a lot of methane trapped in permafrost that is being released as the permafrost melts.  So, as the world gets warmer, more methane is released causing more warmth.  Yuch.

Carbon dioxide is the same way.  There is a very subtle clue that human produced carbon dioxide is a significant cause of global warming.

The black line represents the instrument record (i.e. we actually took those temperature readings).  Now, what happened about the time that the black line shows?

If you guessed a massive increase in the amount of carbon dioxide being pumped into the air, then you win a cookie.  The second industrial revolution began around 1850 with the introduction of steam ships, steam trains and later internal combustion systems and the need for industrial scale electricity production.

What could happen?  Well, we have another neighbor.

Don’t give me any crap about Venus being so hot only because it’s so much closer to the sun.  That massively thick bank of carbon dioxide and sulfur dioxide (also a greenhouse gas) clouds drive the surface temperature of Venus HIGHER than that of Mercury which is way closer to the sun than Venus and tidal locked so the same side of Mercury always faces the sun.  Wow.

Now, let’s finally talk a little about carbon dioxide.  We know it’s a greenhouse gas.  Only an idiot would tell you that humans aren’t dumping a lot of it into the atmosphere.  In fact, since 1960, humans have increased the amount of carbon dioxide in the atmosphere by over 20%.  Take a look.

This chart is not the result of volcanic emissions.

By 1960, Keeling and his group established the measurement record that was long enough to see not just the diurnal and seasonal variations, but also a year-on-year increase that roughly matched the amount of fossil fuels burned per year. In the article that made him famous, Keeling observed, “at the South Pole the observed rate of increase is nearly that to be expected from the combustion of fossil fuel.

The Keelings, the scientists (the father died in 2005 and his son is still performing the same work) who has been measuring this since the 1960s, takes reading to specifically avoid the volcano.

Since then, over 100 sites are taking CO2 readings as well and their data matches this.

So, what have we established.

1) Certain gases are known, due to their chemistry, to absorb and emit infrared radiation.  This is basic fundamental physics.  If anyone doubts this, then they are too stupid to argue with.

2) That the rate of carbon dioxide (a known greenhouse gas) has been increasing at a rate that is directly proportional to the amount of fossil fuels burned per year (over the last 50 years).

3) That the temperature (since the beginning of the industrial age) has been increasing at a rapid rate and is now, much higher than in any time in recorded history.

4) Of hottest years on record have all occurred in the last 15 years.

5) The inescapable conclusion is that man is directly affecting the atmosphere of the planet resulting in a massive increase in temperature.

Scientists have estimated that even if we stop all CO2 production right now, we are still committed to a 3-4 degree rise in global average temperature over the next 90 years (yes, many of us will be alive to deal with this then).  Any emissions that continue will only make it that much worse.

Fortunately, there are solutions.  We just have to have the moral courage to take them.  I’ll add, that even if global warming were not a concern, there are still many, many reasons to stop burning fossil fuels anyway.

______________________________________

1. It’s really not actually the shape, though that’s part of it.  There’s some complicated stuff about dipole moments and how the electrons are distributed.  But we won’t go there.

2. 20th Century Average.

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