Effects of aircraft emissions studied

Published in The Hindu on December 24, 2009

cropped-cropped-new-image.jpgFirst ever analysis of emissions from aircraft have finally been made in the U.S., and they have been found responsible for 4 per cent to 8 per cent of surface global warming since surface air temperature records began in 1850.

This translates to a temperature increase of 0.03-0.06 degree C. Aircraft vapour trails have also been studied and they have been found responsible for 15-20 per cent warming in the Arctic.

The results of the study were presented recently by atmospheric scientists of Stanford University at the American Geophysical Union’s annual meeting in San Francisco, California.

According to Nature news, there are around 35 million commercial airline flights every year. Little wonder that they have come under great scrutiny in Europe as their combined contribution to warming is significant. Efforts are being taken to even levy carbon tax on aircraft emissions in Europe.

Though emissions from aircraft are well known to be one of the major sources of greenhouse gases, all earlier studies were based on estimates and not actual measurement. This study, which measured the emissions from 2004 to 2006, has addressed the lacuna.

The researchers have now been able to “develop 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,” notes Nature news.

Another significant outcome of the study has been its ability to clear the misconception that the impact of the emission is the same everywhere.

On the other hand, the fraction of cirrus clouds increased with emissions where vapour trails were abundant. In other locations it had an opposite effect.