LOS ANGELES, Aug. 13 (Xinhua) -- Scientists at California Institute of Technology (Caltech) have found that leaks of natural gas used for heating homes and businesses are major contributors to methane in the atmosphere.

Researchers found that methane concentrations in the air above Los Angeles fluctuate in tandem with the seasons. In winter, when natural gas use is at its highest, methane concentrations are also highest. In summer, when natural gas use drops, so does the amount of methane in the air.

"Naturally, methane emissions should be pretty flat across the seasons, but maybe a little higher in the summer period because of a lot of things decompose from higher temperatures," said Liyin He, a graduate student in environmental science and engineering at Caltech. "But it seems that in the city, natural gas consumption is so high in the winter that a lot of it leaks into the atmosphere."

He conducted her research by using a device called a remote-sensing spectrometer atop Mt. Wilson, a mountain whose peak towers a mile above Los Angeles.

From its lofty perch, the spectrometer had a view of a wide swath of the urban area below. Methane is invisible to human eyes, but it is easily seen by the spectrometer because it strongly absorbs infrared light, the wavelength of light to which the spectrometer is sensitive.

Using this setup, the spectrometer was pointed at 33 surface sites around the region and collected methane measurements six to eight times a day for six years.

As methane is such a potent greenhouse gas, and is relatively short-lived in the atmosphere, identifying and reducing those natural gas leaks is one way humans might help reduce the effects of climate change, He said.