The air above the South Pole is alive with highly reactive molecules that no-one knew were there. The discovery overturns the long-held assumption that the surface of the continent was almost chemically inert.
It will also mean some of the climate data extracted from Antarctic ice cores will need to be reassessed.
The results, which appear in the latest issue of the journal Geophysical Research Letters , have taken atmospheric scientists by surprise.
Douglas Davis and colleagues at Georgia Tech, in the United States, have measured levels of nitric oxide radicals up to 100m above the South Pole one or two orders of magnitude higher than expected.
Another team from the US National Center for Atmospheric Research in Boulder, Colorado, has found similarly high levels of the hydroxyl radical.
The levels of highly reactive free radicals are comparable to those found over the tropics.
Davis said: "People thought the South Pole was dead, but in fact there's a hell of a lot of chemistry going on. This is an incredible find."
The radicals are thought to be the product of 24-hour summer sunlight breaking down molecules in the snow. Their presence prompts the formation of ozone, just like city smogs.
The implications are still being explored, but Davis said there would be no impact on the ozone hole, many miles above in the atmosphere.
He said: "Some of these chemical species arriving at the South Pole may then undergo further chemistry and so perhaps some of our interpretation of these ice cores may have to be modified."