(CNN) -- The thin wisps of condensation that trail jet airliners have a significant influence on the climate, according to scientists who studied U.S. skies during a rare interruption in national air traffic after the September 11 terrorist attacks.
During the three-day commercial flight hiatus, when the artificial clouds known as contrails all but disappeared, the variations in high and low temperatures increased by 1.1 degrees Celsius (2 degrees Fahrenheit) each day, said meteorological researchers.
While the temperature range is significant, whether the jet clouds have a net effect on global warming remains unknown.
"I think what we've shown are that contrails are capable of affecting temperatures," said lead scientist David Travis of the University of Wisconsin, Whitewater. "Which direction, in terms of net heating or cooling, is still up in the air."
Contrails Explainer: Long white wisps of artificial clouds high in the atmosphere, contrails are the condensation trails left behind by jet airplanes. Similar to human exhalation making a fog in chilly weather, contrails form when warm humid engine exhaust meets extremely cool air in the atmosphere. Air temperatures where contrails form are generally lower than minus 40 degrees Fahrenheit (minus 40 degrees Celsius). Like natural cirrus clouds, contrails insulate the planet, blocking out incoming solar energy from above and keeping in heat down below. Scientists estimate that contrails cover some 0.1 percent of the Earth's overall surface, with regional concentrations as high as 20 percent.
In many ways, contrails behave in the same manner as cirrus clouds, thin high-altitude floaters that block out solar energy from above and trap in heat below.
Now consider this - if three days without aircraft pollution can vary the temperature range across the US by 2 degrees F, are you trying to tell me that years of relentless pollution has no effect?????????????
CO2 is the indicator gas that is easily measured, not the sumtotal of pollutions. CO2 is only around 380 parts per million. The safe level in an office is considered to be 1000 parts per million.
Furthermore junk science predictions or disclaimers are just confusing the issue, serving the interests of polluters.
Foremost among the disclaimers with an ideological disbelief in manmade climate change are the god-botherers who believe little man could never effect what god has created so don't worry about it - god will look after it. Like hell.
