Sea ice coverage as the opposite poles of the Earth stand in stark contrast, scientists report, as Antarctic sea ice has expanded to record high levels while Arctic sea ice is at its sixth lowest area ever recorded.

The yearly greatest extent of Antarctic sea ice normally is seen in September, as the winter in the Southern Hemisphere draws to a close, while Arctic sea ice typically shrinks to its yearly minimum as summer ends in the Northern Hemisphere.

"Antarctic sea ice is poised to set a record maximum this year, now at 7.6 million square miles and continuing to increase," the National Snow and Ice Data Center reported on its website.

The center has sea ice data dating to 1979, when satellites were first employed to measure coverage.

Sea-ice coverage extent is defined as the total area of the ocean where concentrations of ice are at least 15 percent in satellite measurements.

This is the third year in a row that Antarctic sea ice coverage has set a record, scientists note.

The same cannot be said for the continent's land ice, they say, as land-based ice sheets continue to melt.

Some of West Antarctica's glaciers are melting at rates from which they are unlikely to recover any time soon, studies earlier this year found.

At the other end of the world, Artic sea ice in 2014 has shrunk to 1.96 million square miles, considerably below the average recorded between 1979 and 2010 of about 2.37 million square miles.

That's about the same as was recoded in 2013.

"In the short term, it seems like there hasn't been much ice loss in the past couple of years, but I think it's still very much within the long-term trend of declining sea ice," says Axel Schweiger, head of the Polar Ice Science Center of the University of Washington. "One shouldn't necessarily expect every year to be a record low."

The steadily diminishing extent for Arctic ice has been blamed on man-made climate change that has seen rates of warming in the region exceed the global average for the last few decades, scientists say.

The added sea ice in Antarctica may somewhat slow global warming by reflecting sunlight back into space, but an overall trend of global shrinking will be unavoidable, says Jan Lieser of the Antarctic Climate and Ecosystems Cooperative Research Center in Tasmania.

"By 2100 we will see dramatic reductions," he says. "Once it goes belly-up it's not good for the rest of the world."