According to a recent research taken out by a group of researchers from the University of Washington, it has been revealed that a decline in the level of isotope nitrogen-15 has been witnessed in Greenland's ice.

The study researchers have tested main samples of Greenland ice, and noticed a decline. It was said that it has happened due to the industrialization. But, now the study researchers have associated the decline with burning of fossil fuels.

Researcher Lei Geng said that they have been terming a different reason because they have seen a rise in acidity in the region. An easy way to detect acidity is to see the transformation of sulfur dioxide to sulfuric acid. "It changes the chemical properties of the lower troposphere, where we live, and that can have a lot of consequences", said Geng.

The findings of the study will be presented at American Geophysical Union meeting, which will take place in San Fransisco. Geng said that the built up of acidity has been taking place since many decades and at that time, no acid rain occurred.

Forest fire, car exhaust and lightening are some of the other reasons which are said to have increased the level of nitrogen-15.