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“Hong’s work doesn’t prove that the contrails have no effect on temperature, just that they are unlikely to have a major role, says Ulrich Schumann, director of the Institute of Atmospheric Physics at the German Aerospace Center in Oberpfaffenhofen, near Munich.”
“Because Hong’s analysis studied high-level clouds in general-and not contrails in particular-Travis says that specific conclusions cannot be drawn about the role of contrails from the survey.”
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Nature 31 December 2008
doi:10.1038/news.2008.1335
Can aircraft trails affect climate?
Grounding planes after the 11 September attacks may not have caused unusual temperature effects.
Anna Barnett
When all commercial air traffic in the United States was grounded after the terrorist attacks of 11 September 2001, scientists got an unexpected opportunity to test ideas about the climate effects of the condensation trails left behind by jets.