Lets’ Make This Clear
Contrails can persist for many minutes, even hours under the right conditions and in areas near large cities with busy airports the results can be striking to see. There’s more to this than meets the eye, however, because an abundance of clouds – artificial or not – over a prolonged period of time can’t help but have unnatural (and unwanted) effects on the people, animals and especially the plants that live on the ground.
An unplanned but literally enlightening experiment concerning the effects of contrails occurred over a three-day period following the September 11th, 2001 terror attacks in the United States. With all air traffic grounded by order of the FAA, climatologists were given a rare opportunity to note if and how the lack of contrails impacted on weather across the country.
The American Meteorological Society’s final report on the subject, published in March of 2004 and titled “Regional Variations in U.S. Diurnal Temperature Range for the 11–14 September 2001 Aircraft Groundings: Evidence of Jet Contrail Influence on Climate” indicated that over the three-day period the local diurnal temperature range (the difference between daily high and nightly low temperatures) was about 1°C (1.8°F) higher than the most recent such measurements taken before September 11th.
The obvious conclusion was that with the skies free from any and all contrails, more sunlight and associated heat was reaching the lowest layers of the atmosphere and the Earth’s surface just below. A couple of degrees may not sound like much but very small deviations from the normal over long periods of time can result in ice ages, flooding, droughts and global warming. It would seem that our modern, jet-set society has the unexpected side effect of cooling the planet during a widely-recognized warming phase. That’s good… on the other hand, contrails may be inadvertently masking the real pace of global warming.
