The Hot Air of Climate Change, Part 4

Does human activity contribute to global warming, and to what extent?

This is a multi-part series examining the current debate over "global warming", also known as "climate change".

As we examine the global warming arguments, we've found that it is extremely difficult if not impossible to accurately measure the global temperature over time; that there are a great many known climatic cycles which interact in extremely complex ways that have nothing to do with human activity; and that the Sun is known to have been getting warmer over the last few years, as seen by increasing temperatures on Mars.  But it doesn't seem completely unreasonable that we might be messing up the atmosphere, as anyone who has ever been to Los Angeles can attest.  So, our next question:

4. Does human activity contribute to global warming, and to what extent?

In 2004, it has been calculated that human activity released roughly 7910 million metric tons of carbon into the atmosphere - or, not quite 8 billion metric tons.  That is an almost unimaginably large number, and frequently you hear comparisons to an impossibly long coal-train that goes all the way around the world.  By human standards, it's a lot.

By the standards of the Earth, however, it's a drop in the bucket. Earth's atmosphere weighs 4.41 million billion tons.  Therefore, it's calculated that, each year, we are putting 6 ppm - that's parts per million - into the atmosphere.  In other words, out of every million pounds of atmosphere... we are adding 6 pounds of carbon.  That's .0006%.

Let's compare this to some other relevant percentages.  The FDA regulates how much rodent excrement, insect parts, mouse hairs, and other unpleasantness is permitted to be found in various foods.  Now, you might think they'd want to require its absolute absence, but that's not practical.  So, for example, we find that it is perfectly legal for peanut butter to contain an average of one rodent hair per 100 grams - that's about 7 tablespoons, or a bit less than half a cup.  In cornmeal, you're allowed one whole insect per 50 grams.

Not having a mouse conveniently to hand, we cannot determine what a single mouse hair generally weighs; but it is surely no less than 1/100 of a gram, which would make it twenty times as much, by percentage, as the carbon we're adding to the atmosphere.  And generally speaking, we don't consider our Skippy to be infested with mice.

You may be thinking, "It is unfair to compare the carbon we're adding to our atmosphere with mice in peanut butter!"  And you'd be absolutely right.  It's quite unfair - to the peanut butter.

Once the mouse hair is in the jar, it's not coming out until you spread it on your sandwich.  Not so with carbon in our atmosphere.

As attentive elementary students can relate, our planet has a fully functioning carbon cycle.  This means that, as we breathe oxygen and generate carbon dioxide, so do plants "breathe" carbon dioxide and release oxygen.  The more carbon dioxide there is in our atmosphere, the more lush we find plant growth becoming.

Of course, you can cast this in a very bad light - as witness this summer's rash of news articles about fast-growing, more potent poison ivy.  Nobody wants more poison ivy around, but it's absurd to emphasize the excessive growth of that one noxious weed, and completely ignore the exact same beneficial effect on the hundreds and hundreds of other useful, attractive, or edible plants that we are blessed with - all of which are working overtime to suck that CO2 out of the atmosphere just as fast as we can put it there.

Plants aren't the only natural action counteracting global warming.  Research shows that volcanoes have a tremendous effect too.  The 1991 eruption of Mt Pinatubo in the Philippines threw up to 26 million tonnes of sulfur dioxide into the stratosphere, where it became sulfuric acid aerosol - which causes coolingAccording to the Australian Commonwealth Scientific and Research Organization (CSIRO):

The climatic impact of the Pinatubo aerosol was stronger than the warming effects of either El NiƱo or human-induced greenhouse gas changes during 1991-93.

And that is just one volcano - admittedly a fairly large one.

Similarly, the destructive effects of Hurricane Katrina on the forests of the South - just one storm, albeit a big one - were enough to cancel out the carbon-sink effects of new forest growth in the entire rest of the country for the year.  And Al Gore aside, Hurricane Katrina cannot fairly be blamed on George W. Bush, or even Ronald Reagan.

The point here is not that human activity does nothing whatsoever.  It can certainly foul up a given locality - Cleveland is rightly infamous for its river that kept catching fire from all the nasty chemicals dumped into it, and anyone visiting a large city can clearly see the smog from vehicles.  It's a good idea to try to reduce that sort of filth, as Cleveland has done.

But in the grand scheme of things, when you are talking about the global climate, what we do has such a tiny effect, so easily overridden or counteracted by other natural processes, that we're barely even a rounding error.

And let's not forget the contribution to global warming made by belching cows and other ruminants.  It would appear that one single cow gives off more greenhouse gases per day than the average Land Rover, not exactly a fuel-efficient ride.

So, to the extent that there is any global warming going on, human activity is a vanishingly small part of it, overwhelmingly outclassed by volcanoes, energetic plants, and animals without table manners.  But that doesn't stop governments around the world from trying to legislate a solution to a non-problem.  Thus, we arrive at our next question:

5. If human activity is a significant cause, would specific proposed legislation have any positive effects, on balance?

To be continued...

Kermit Frosch is a guest writer for  Read other articles by Kermit Frosch or other articles on Environment.
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December 9, 2010 5:41 PM
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