The Coastal Post - May, 1997

Jet Planes Pose Serious Environmental Threat; Can Anything Be Done About Contrails?

By Jim Scanlon

It is a criminal offense to mark or mar public or private property with chalk or paint or other material. This is understandable: what is hard to understand is the toleration afforded jet aircraft which leave long white streaks from one horizon to the other, some lasting for hours before turning slowly into thin gray clouds. This is not just a question of aesthetics, but of ever-increasing environmental degradation.

Just look up at any time, any clear day in winter or spring or fall and you will see a long white vapor trail following a barely visible jet, no doubt taking people like you and me someplace far away. Sometimes these lines braid and curl and wave slowly about before quickly disappearing. Sometimes they last longer, minutes, hours, maybe longer.

Sometimes no one on earth can see persistent contrails because lower level, natural clouds get in the way. But an endless queue of aircraft produce them in their wakes, seen or unseen, night and day, coming and going from airport to airport across the planet.

Whether or not one sees vapor trails, jet motors expel invisible oxides of nitrogen, carbon dioxide, carbon monoxide, soot and unburned hydrocarbon fuel besides the water which often condenses into the white lines we observe.

Simply burning fuel in the combustion chamber of a jet motor contributes toward "global warming" equally, in the same way as, say, power plants and buses, trucks, cars, etc. except that there are important differences-where the combustion products go, how long they stay and what their after effects are. A crude analogy might be that you can tolerate lots of dirt on your skin and some in your ears and mouth, but only a little in your eyes. It's not just how much, but where.

While taxiing on a runway, jet engines contribute significantly to urban smog just as other internal combustion engines---that is, unburnt fuel reacts with sunlight to produce ground level ozone, which is highly irritating to living things. Soot, in and of itself, is a irritant when breathed, but it also attracts acids which make it worse. This would continue during the initial stages of take off and steeply climbing to cruising altitude when the engines are going at full thrust. These effects are well known and usually accounted for in considering the environmental effects of civil aviation.

Once at cruising altitude in the upper troposphere (and often in the stratosphere) where the temperature is very low, very dry and relatively much cleaner than lower, closer to earth, the waste gases have different, sometimes very complicated effects---which are not accounted for.

The earth really isn't a sphere, it really isn't round and neither is the boundary between the highly changeable troposphere and the stable stratosphere. One bobs and ripples and intermingles on top the other

somewhat like a layer of oil on water. The stratosphere is warmer than the upper troposphere. There is a structure---a changing structure, but still a structure.

Warming a normally much colder part of the atmosphere breaks down this structure. Water is a very potent "greenhouse gas"---much more effective than carbon dioxide and other pollutants---and it is being

introduced in massive, ever increasing amounts just under, and just over, the defining boundary in the structure.

When the jet aircraft fly in the stratosphere the chemical reactions of exhaust gases reduce natural ozone, cooling the warmer air above the boundary, and allowing energetic ultra-violet radiation to penetrate lower where it warms the air and may even reach the surface of the earth.

Flying just below the boundary exhaust gases produce ozone and other heat-trapping gases which warm cold air, further distorting the boundary. With large numbers of aircraft flying fixed routes, the effects become more pronounced.

On April 13th, 14th and 15th the sky over Marin was clear and criss-crossed with particularly long lasting clouds from contrails. Thin straight lines that gradually spread out forming a hazy layer. Towards evening they were particularly visible, with three, thick blood-red lines forming over Mount Tam as the sun set. (I will have a small selection of these photos on display at Smiley's Schooner Saloon in Bolinas during the month of May).

How much do these clouds contribute towards changing the local climate, the regional climate and perhaps global climate?

It's hard to tell. The weather is very complicated and confusing although occasionally exceptional weather conditions produce conditions which allow for unmistakable signs of pollution from aircraft. A stagnant air mass which moved slowly across the Atlantic over Southern Europe a few years ago is a good example.

It has taken a half century for our government and the tobacco industry to officially come to the realization that cigarette smoking is unhealthy, addictive and has caused millions of early deaths.

Who wants to face the unpleasant possibility that a trillion dollar industry which provides millions of high paying, glamorous jobs and the magic carpets which carry us across continents in a few drowsy hours, might be highly dangerous to life on earth. Who wants to face it ?

The Federal Aviation Administration recently announced that domestic air passenger traffic will rise from 546.2 million in 1996 to 827.1 in by 2008. Aircraft are expected to get bigger. The average seat capacity

of planes flying Pacific Ocean routes will rise from 326 to 366 and might rise to 736. The market for "super jumbos" is estimated to be 1,400 planes in 20 years.

Civil air traffic is expected to increase 200 percent in 20 years. The effects of this traffic on the structure of the atmosphere are not being considered and it does not appear likely that they will.

It seems that this technology, as with others, has a life of its own, and is unreformable and irreversible. We are entering a new world.