As the sea area freezes and melts each year, shrinking to its lowest extent ever recorded, Professor Peter Wadhams of Cambridge University called it a "global disaster" now unfolding in northern latitudes, the Guardian reported.
Wadhams has spent many years collecting ice thickness data from submarines passing below the arctic ocean.
He predicted the imminent break-up of sea ice in summer of 2007, when the previous lowest extent of 4.17 million square kilometres was set.
This year, it has unexpectedly plunged a further 5,00,000 sq km to less than 3.5 m sq km.
"I have been predicting [the collapse of sea ice in summer months] for many years. The main cause is simply global warming: as the climate has warmed there has been less ice growth during the winter and more ice melt during the summer," he said in an email to the paper.
"At first this didn't [get] noticed; the summer ice limits slowly shrank back, at a rate which suggested that the ice would last another 50 years or so. But in the end the summer melt overtook the winter growth such that the entire ice sheet melts or breaks up during the summer months," Wadhams said.
"This collapse, I predicted would occur in 2015-16 at which time the summer Arctic (August to September) would become ice-free. The final collapse towards that state is now happening and will probably be complete by those dates," he said.
"As the sea ice retreats in summer the ocean warms up (to 7C in 2011) and this warms the seabed too. The continental shelves of the Arctic are composed of offshore permafrost, frozen sediment left over from the last ice age," he said.
"As the water warms the permafrost melts and releases huge quantities of trapped methane, a very powerful greenhouse gas so this will give a big boost to global warming," Wadhams said.
He also called for "urgent" consideration of new ideas to reduce global temperatures.
"Climate change is no longer something we can aim to do something about in a few decades' time, and that we must not only urgently reduce CO2 emissions but must urgently examine other ways of slowing global warming, such as the various geoengineering ideas that have been put forward," he said.
These include reflecting the sun's rays back into space, making clouds whiter and seeding the ocean with minerals to absorb more CO2.