Aiircraft condensation trails adding to global warming: study

Aircraft condensation trails criss-crossing the sky may be warming the planet on a normal day more than the carbon dioxide emitted by all planes since Panama gained its independence from Colombia.

That was in 1903 the year the Wright Brothers' made their first flight.

 A study  released by  experts at the DLR German Aerospace Center, which appears in a UN bulletin  indicated that contrails — white lines of Vapor left by jet engines — also have big knock-on effects by adding to the formation of high-altitude, heat-trapping cirrus clouds as the lines break up. {jathumbnail off}

The findings may help governments fix penalties on planes' greenhouse gas emissions in a U.N.-led assault on climate change. Or new engines might be designed to limit Vapor and instead spit out water drops or ice that fall from the sky.

"Aircraft condensation trails and the clouds that form from them may be causing more warming today than all the aircraft-emitted carbon dioxide (CO2) that has accumulated in the atmosphere since the start of aviation," the journal Nature Climate Change said in a statement of the findings.

The study, estimated that the net warming effect for the Earth of contrails and related cirrus clouds at any one time was 31 milliwatts per square meter, more than the warming effect of accumulated CO2 from aviation of 28 milliwatts.

A milliwatt is a thousandth of a watt. Aviation emissions now account for about three percent of annual CO2 emissions from fossil fuels, more than a century since Orville and Wilbur Wright made the first powered airplane flight.

But a key difference is that CO2 lingers for decades while warming from contrails quickly ends if flights are grounded, such as after the September 11, 2001 attacks in the United States, or in Europe after last year's Icelandic volcano eruption.

"You can get rid of contrails very quickly. You can't get rid of CO2 quickly," lead author Ulrike Burkhardt at DLR told Reuters.