A climatologist in the United States says the Arctic Circle should be a no-fly zone for major commercial flights.

In a new report, Mark Jacobson, a professor of civil engineering at Stanford University in California, says black soot from commercial jets is attracting heat from the sun.

Pilots have been flying over the pole for decades, but commercial flights began doing it more routinely in 1998, when Russia finally opened its airspace to other countries.

A climatologist in the U.S. says the Arctic Circle should be a no-fly zone for major commercial flights because they could be a cause of Arctic melting. (Jonathan Hayward/Canadian Press)

Now, more than 50,000 planes fly through the Arctic Circle every year. Jacobson says that could be a major cause of Arctic melting.

"One of the effects of the aircraft is they emit a lot of soot into the upper atmosphere and the sunlight is absorbed by that soot, and the air heats up, so you get this kind of elevated, heated air layer where the aircraft fly," Jacobson said.

However, if large planes flew outside of the Arctic Circle, they would burn more fuel. However, Jacobson argues the warming effect would not be as great.

The professor says he doesn't expect airlines to start rerouting flights around the Arctic Circle anytime soon: he said airlines save more than $100 million a year in fuel costs by using the Arctic Circle as a shortcut.