Arctic ice could melt completely as early as summer 2040 due to global warming, experts said on Monday.

By 2040, only a small amount of perennial sea ice would remain along the north coasts of Greenland and Canada, while most of the Arctic basin would be ice-free in September, scientists say.

"We have already witnessed major losses in sea ice, but our research suggests that the decrease over the next few decades could be far more dramatic than anything that has happened so far," said lead researcher Marika Holland from the US National Centre for Atmospheric Research (NCAR). 

"These changes are surprisingly rapid," Holland added in a news release on Monday.

A slow, steady decline of Arctic ice is projected, as global warming continues, with a dramatic "tipping point" in about two decades, a study by a team of US and Canadian scientists shows.

The research by NCAR, the University of Washington and Montreal's McGill University, to be published by the scientific journal Geophysical Research Letters on Tuesday, found that the extent of sea ice each September could be reduced so abruptly that, within about 20 years, it may begin retreating four times faster than at any time in the observed record.

"As the ice retreats, the ocean transports more heat to the Arctic and the open water absorbs more sunlight, further accelerating the rate of warming and leading to the loss of more ice," Holland said.

"The ice is actually quite stable until 2025 and then boom, it goes," Holland earlier the fall meeting of the American Geophysical Union in San Francisco.

"The effects of greenhouse warming are starting to rear their ugly head," added Mark Serreze, a scientist at the National Snow and Ice Data Center at the University of Colorado in Boulder, as quoted by Reuters.