System in meltdown

Disruption to Antarctica’s freeze-thaw cycle will have existential ripple effects.

- Veronika Meduna

Year after year, the sub-zero waters around Antarctica go through Earth's biggest seasonal transformation. Around this time, they are usually freezing over, eventually almost doubling the continent's whiteness. In spring, much of the frozen ocean starts melting again, only to repeat the cycle from the end of summer.

But this year, Antarctica's icy fringe retreated further than during any late summer since satellite observations began in 1979. This record low followed a season that was "completely unprecedented since we've been able to see Antarctica's sea ice from space", says Niwa oceanographer Natalie Robinson.

Last October, Robinson embarked on her eighth Antarctic visit, but only after weeks of uncertainty whether there would be any sea ice thick enough to hold her team's field camp of several shipping containers. Southerly blizzards had been blasting the area, dragging any newly formed ice out to sea.