Cause of Global Warming

Tendrils of condensation that mark the paths of high-flying jets sometimes form a loose lacework of man-made clouds in the upper atmosphere. The extra blanket of atmospheric insulation from these spreading contrails, as they are called, could accelerate global warming, studies have shown.

Now a group of researchers says something should be done. Their proposal would lengthen the typical airline flight.

High-altitude cirrus clouds, both natural and jet-induced, are unlike thicker low-altitude clouds, which block sunlight from reaching the surface. The thinner cirrus, which float in the sky at 20,000 feet or higher, act like a see-through blanket - letting sunlight pass in, while trapping reflected heat.

A rise in contrail formation -- and therefore blanketing -- is expected in the future, because air travel is growing at 3 percent to 5 percent a year, and cargo transportation by air is increasing by 7 percent a year and in order the toxic gasses will increase like carbon dioxide (CO2), nitrogen oxides, sulfur oxides, soot and water vapor.