Commercial airline flights show that they are responsible for 4-8 percent of surface global warming, the first analysis of emissions since surface air temperature records began in 1850, which is equivalent to a temperature increase of 0.03 - 0.06 degree Celsius overall.
According to a report in Nature News, the analysis was done by atmospheric scientists at Stanford University in Palo Alto, California.
AdvertisementThe results of the analysis also show that in the Arctic, aircraft vapour trails produced 15-20 percent of warming.
"Previous studies have only estimated the impacts of commercial aviation, but this is the first use of actual emissions data - from 2004 and 2006 - to calculate warming from such flights," said Mark Jacobson, a Stanford engineer.
For the latest study, Jacobson and his team developed a model for aircraft emissions that accounts for atmospheric composition, cloudiness and the physical properties of emissions, particularly of black carbon - a major part of soot.
In his presentation, Jacobson explained how the model was applied to a nine-year simulation covering 2004 to 2013, after breaking up flight routes into 300-kilometre-square grids for analysis.
The model was able to calculate the characteristics of vapour trails based on the actual particulate size of emissions and their evolution over time.
Many previous studies have assumed that the impact of aircraft emissions was the same everywhere.
But, the new analysis reveals that aircraft emissions increased the fraction of cirrus clouds where vapour trails were most abundant, and actually decreased the cirrus fraction in several locations by increasing the temperatures in the lower atmosphere, reducing the relative humidity in such locations.
"If black-carbon emissions from aircraft could be reduced 20-fold, warming would be halted and a slight cooling would occur from plane-created vapour trails," Jacobson said.
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