About one or two percent (says Wikipedia) of fossil CO2 put into the air comes from airplanes. But new research says aviation may contribute twice that share to global warming. That’s because the high altitude haze left by contrails or so-called vapor trails contributes about as much as and maybe a bit more to trapping the sun’s heat than the CO2 does.
The news is in Nature Climate Change, by a team based in Germany. It received wide coverage – albeit in most cases via brief stories. That’s understandable. The irony and surprise of the finding does not take long to report, and to go into the atmospheric chemistry and solar forcing mechanisms is not, for most outlets, worth the space it would take. What few stories do is put the news in context. Aviation is a measurable source of greenhouse gases. It’s still fairly marginal compared to emissions from ground transportation and industry. It comes up mainly when climate contrarians accuse climate activists of hypocrisy if they took an airplane to an event to bemoan the failure of the world to reverse the rise in CO2 emissions. Doubling a small number still produces a pretty small number.
Of course, the CO2 will stay there for centuries while, if flying stops, the extra clouds will clear in almost no time. The impact on the sky was remarkable during the pause following the 9-11 attacks in the US. Not that an abandonment of the aviation industry, or of engines that leave contrails, is foreseeable.
Stories:
Reuters – Alister Doyle: Aircraft contrails stoke warming, cloud formation ; An odd and interesing idea is high in this story – that perhaps modified engines may shed much of the water from combustion as water drops, or form ice chunks, that would fall from the air. The copy I saw included a poor choice of illus. Those look like vortex condensations of vapor already in the atmosphere and momentarily generated by control surfaces, not the far more common and problematic contrails from engine exhaust.- New Scientist – Michael Marshall: Contrails warm the world more than aviation emissions;
- Ars Technica via Wired News – John Timmer : Contrails Worse for Climate Change than Planes’ Carbon Emissions ; Timmer or somebody found the best possible photo illus, a NASA satellite pic. Story does a commendable job distinguishing between the angle in Nature’s summary for reporters, and what the paper’s authors focussed on – which is the whole impact of aviation engine emissions including particulates, aerosols, oxides of nitrogen, etc.. The press release below, from the authors’ home institute, has both the research paper’s focus and that contrails currently have a greater warming effect than all the aviation carbon emissions built up in the atmosphere since the Wright Brothers made the first ones (hot air balloons too, I suppose).
- ABC (Australia) David Mark: Contrail effect greater than CO2: study; Mark reports that aviation CO2 accounts for 3 percent of all human-caused CO2 increases, a bit higher than this post reports at its top.
- LiveScience – Wynne Parry: Earth warmed by Trails of Clouds that Jets Leave Behind ; Ms. Parry or her editor are smart to link to a story on ship contrails. One wonders – if low altitude clouds cool the globe, while stratosphere ones warm it, to what extend do aviation and maritime traffics’ mists cancel?
Related News:
- Scripps Howard/ Chicago Sun Times (Mar 5) – Janet Zimmerman: Increased air traffic may be a factor in climate change;
Grist for the Mill: Institute for Physics (Germany) Press Release ;
– Charlie Petit
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