Aviation's climate impact studied

WESSLING, Germany, March 29 (UPI) -- Aircraft contrails may be causing more warming now than all the aircraft emissions put into the atmosphere since the start of aviation, German researchers say.

In a paper published this week in the journal Nature Climate Change, Ulrike Burkhardt and Bernd Karcher describe using a climate model to quantify the impact of thin cirrus clouds that form as the condensation trails -- or 'contrails' -- created by aircraft spread out in the atmosphere.

Young line-shaped contrails and the clouds that form from them are the single largest climate-forcing agent associated with aviation, their study showed, presently causing more warming than all the previous carbon dioxide emitted by aircraft since they first took to the skies.

The findings are important, researchers say, as a basis for developing strategies to reduce the climate impacts of aviation, such as routing planes to avoid areas where contrails are likely to form and spread into cirrus clouds and developing aircraft engines that emit less water vapor into the atmosphere.