They are now observing mainly thin, first-year ice floes which are extensively covered with melt ponds in the summer months where once metre-thick, multi-year ice used to float.
Melt water collects on the ice, forming melt ponds, permitting more sunlight and greater energy to penetrate the ice than is the case for white ice otherwise.
The ice absorbs more solar heat and is melting faster, said researchers from Alfred Wegener Institute (AWI) in Germany.
In recent years, Marcel Nicolaus, sea ice physicist and melt pond expert at the Alfred Wegener and his team have observed a strikingly large number of melt ponds during summer expeditions to the central Arctic.
Virtually half of the one-year ice was covered with melt ponds. Scientists attribute this observation to climate change.
"The ice cover of the Arctic Ocean has been undergoing fundamental change for some years. Thick, multi-year ice is virtually nowhere to be found any more," says Nicolaus, the journal Geophysical Research Letters reports.
"Instead, more than 50 percent of the ice cover now consists of thin one-year ice on which the melt water is particularly widespread.
"The decisive aspect here is the smoother surface of this young ice, permitting the melt water to spread over large areas and form a network of many individual melt ponds," said Nicolaus, according to an AWI statement.
The AWI sea ice physicists relied on a remotely operated underwater vehicle (ROV "Alfred") with radiation sensors and cameras, to figure out the extent of melting.
