Condensation Traps Heat In Earth's Atmosphere
Could there be some truth to speculation -- bandied about by
environmentalists for years -- that contrails from airliners could
contribute to global warming?
Well, the verdict is still out on that... but in a study
published Thursday in the journal Nature, scientists postulate
the visible streaks of condensation from high-flying airliners
could contribute to the greenhouse effect, by trapping heat in the
University of Reading meteorologist Nicola Stuber, the first
author of the study, suggests that contrails' overall impact on
climate change is similar in scope to that of carbon dioxide
emissions from all aircraft over a 100-year period... about 2 to 3
percent of all human CO2 emissions.
Contrails -- like other high, thin clouds -- reflect sunlight
back into space and cool the planet... but the study claims they
also trap energy in Earth's atmosphere and boost the warming
That warming effect is particularly evident at night, Stuber
"The solar cooling effect [in which contrails reflect solar rays
back into space] only happens during the day, when the sun is up,"
The study cites Britain's airline industry, where only one in
four flights is a night flight... but those flights, scientists
say, create some 60 percent of the warming attributed to
"The findings have implications beyond their pure scientific
value," said Stuber. "...they could be used if policy makers
decided to modify flight management systems in order to reduce the
climate impact of aviation."
Others scientists, however, questioned the study's findings.
"The jury is out on the impact of contrails," said Patrick
Minnis, an atmospheric scientist at NASA's Langley Research Center.
"Until we can measure it properly and extensively, and model it and
its interaction with cirrus clouds and contrails, we will continue
to have large uncertainties about the effect of contrails."