The BBC reports that scientists have been looking for a reason why the total amount of solar radiation reaching the earth’s surface has been increasing. A study suggests that part of the reason is that jet exhausts could be generating a layer of ice crystals that promotes a more diffuse type of light. This is why clear blue skies are getting more of a whitish tint. The scientists have been discussing their thinking at the American Geophysical Union meeting in San Francisco. Chuck Long, from the US National Oceanic and Atmospheric Administration (NOAA), said that if his thinking was correct then what is occurring is an example of “accidental geoengineering”.
“If you look up the definition of geoengineering, it includes large-scale manipulation of parts of the climate system or the environment, and I believe this ice haze from jet traffic does satisfy that requirement,” he told reporters.
Dr Long’s analysis suggests this “something” is high-altitude ice particles, and he links their production to the water and other emissions in aircraft contrails.
“You have to have a mechanism to generate the ice crystals and there is nothing in nature up there necessarily that we can identify that would consistently produce these ice particles, except the very well correlated and well documented increase in the commercial air traffic over the continental United States,” he told BBC News.