As global warming intensifies, sea ice in the Arctic has shrunk to its smallest surface area since record-keeping began, US scientists have warned.
The National Snow and Ice Data Center (NSIDC) on Wednesday said satellite images showed the ice cap has melted to 3.4 million square kilometres as of September 16, the predicted lowest point for the year.
That is the smallest Arctic ice cover since record-keeping began in 1979.
"We are now in uncharted territory," NSIDC director Mark Serreze said in a statement. "While we've long known that as the planet warms up, changes would be seen first and be most pronounced in the Arctic, few of us were prepared for how rapidly the changes would actually occur."
This year's minimum followed a season already full of records for shrinking ice, with the lowest ever extents recorded on August 26 and again on September 4.