There are a lot of myths in aviation, but one that we've taken too much to heart is that airplanes are a blight upon the environment. The facts simply don't support this notion.
No matter how you cut it, the impact of a light airplane on the environment is not substantially different than that of a typical family vehicle, and by that I mean a surface-based vehicle, like a car or sport ute. And that impact is small. And I'm not just saying: I ran the numbers.
In a typical sport ute, I figured you're going to get around 16 mpg, which is optimistic under most actual conditions. In a year in which that vehicle is driven a high average of 12,000 miles, you're talking about pumping 750 gallons of gasoline into the tank, through the motor and into work, heat and exhaust. (Yeah, we all wish it were all work.) In my Cirrus at a high-average usage of 75 hours a year, I'm putting about 1200 gallons through the IO-550 and getting slightly more miles out of it than a Suburban or Expedition. In a Diamond DA40 or Skyhawk, the figures would compare even more favorably. We use a little more gas to fly rather than drive.
Relatively speaking, the number of airplanes is very small, probably around 250,000. According to DOT data, as of 2007 in the United States there were more than 250,000,000--that's 250 million!--registered cars on the roads. Non-registered vehicles like tractors and the like are excluded, as are motorcycles, but they would greatly increase that total. Even without them, that is more than a thousand times more wheeled vehicles than aircraft. One class of highway vehicles, big Class A motor homes (think coverted buses) hugely outnumber airplanes. Kevin Broom from the Recreational Vehicle Industry Association estimates that there are 1.2 million Class A motor homes in the United States, which is about five times as many of these big vehicles than there are airplanes. They are greatly outnumbered, I should point out, by SUVs. There are, in fact, more than 40 million sport utility vehicles alone. And that's not even bringing up the subject of power boats, nonroad motorized vehicles or gas powered tools. When it comes to green, our lawns are big culprits. There are more than 30 million gas powered lawn mowers out there. Spark combustion vehicles are everywhere. There are around as many forklifts in the United States as there are airplanes. Even given that around 20,000 of our airplanes are larger airplanes, specifically business jets and airliners, the truth is, our carbon footprint is absolutely minuscule.
Let's bear in mind, too, that other non-transportation sources are bigger polluters. The process of getting food to our tables, especially the emissions of the cattle used for beef and dairy production, makes the emissions of all transportation put together seem small. And then there are coal-fired powerplants. And don't get me started on volcanoes.
This is not to say that airplanes leave a wake of green in their paths. And there are problems, such as the lead in our 100LL avgas, but that problem, at least, will go away in the next 15 years or so, though not without some pain on the part of owners. And just as turbines have been getting cleaner and more efficient, so too will piston engines, as electronic ignition becomes the norm instead of the exception.
And let me point out that whereas people replace their cars on a frequent basis, airplanes have long lives. That in and of itself is green.
Then there's the subject of just how irreversible our carbon emissions problem is (if, indeed, it is a problem). As much as former Vice President and Nobel laureate Al Gore hates to admit it, there are a lot of very reputable scientists who believe that there is much we can do through geo-engineering, perhaps very inexpensively, to cool the earth to a more sustainable temperature. Some of them have even started working on fixes.
Regardless, the point is inescapable. Airplanes are not the anti-Prius. If indeed there is a problem, airplanes are a very tiny part of it. As we improve the efficiency of airplanes, we should continue to use and enjoy them, while we work toward larger, more realistic and more credible solutions to our environmental concerns.