An anonymous reader quotes a report from New Scientist: The contrails left by airplanes last only hours. But they are now so widespread that their warming effect is greater than that of all the carbon dioxide emitted by airplanes that has accumulated in the atmosphere since the first flight of the Wright brothers. Worse still, this non-CO2 warming effect is set to triple by 2050, according to a study by Ulrike Burkhardt and colleagues at the Institute of Atmospheric Physics in Germany. Altogether, flying is responsible for around 5 percent of global warming, the team say, so this figure will soar even higher — and no meaningful actions are being taken to prevent this.
The researchers used a computer model of the atmosphere to estimate how much warming contrails caused in 2006 — the latest year for which a detailed air traffic inventory is available — and how much they will cause by 2050, when air traffic is expected to be four times higher. The model takes account of not only of the change in air traffic volume, but also the location and altitude of flights, along with the changing climate. The team conclude that the warming effect of contrails will rise from 50 milliwatts per square meter of the earth’s surface in 2006 to 160 mW/m^2 by 2050. In comparison, the warming due to CO2 from aviation will rise from 24 mW/m^2 to 84 mW/m^2 by 2050. If the airline industry improves fuel efficiency and reduces the number of soot particles by improving fuels and engines, the researchers say the warming from contrails by 2050 will be limited to 140 mW/m^2 and the warming from CO2 to 60 mW/m^2.
The study has been published in the journal Atmospheric Chemistry and Physics.