Greenland's ice sheets are melting faster than the natural process, according to NASA.

Two NASA satellites Terra and Aqua and Oceansat-2 satellite from the Indian Space Research Organization (ISRO) detected rapid melting of Greenland ice cover over four days.

While 40 percent of the ice sheet melted on July 8, researchers observed that nearly 97 percent of the ice sheet melted by July 12. The rate at which the ice sheet melted over a span of four years has baffled researchers and raised concerns about the impact of climate change in the future.

Melting of ice sheets on the edges or on the surface is a natural phenomenon during summer. As the ice sheet melts the water remains in place as it freezes again. While major portion of the water is retained by the ice sheet, some gets mixed with the ocean.

However, NASA researchers have observed an uncommon process of ice sheet melting at a faster rate. Last week, a massive ice sheet broke off from one of Greenland's largest glaciers, the Petermann Glacier.

"The Greenland ice sheet is a vast area with a varied history of change," Tom Wagner, NASA's cryosphere program manager in Washington told reporters. "This event, combined with other natural but uncommon phenomena, such as the large calving event last week on Petermann Glacier, are part of a complex story.

"Satellite observations are helping us understand how events like these may relate to one another as well as to the broader climate system."

According to NASA researchers, the surface melting process coincided with the time when an unusual heat dome is caused due to a high pressure system that develops in the atmosphere.

The melting ice sheets may lead to rise in sea levels. It will be a cause of concern if the melting events continue to emanate in Greenland. Earlier studies have shown evidently that Greenland is rising in some places around 1-inch per year due to ice sheet melting at an accelerated pace. Researchers believe that global warming is contributing to the accelerated rates.