"The Arctic has lots of land at high latitudes, and the presence of land masses helps snow melt off more quickly," Steig said. "But there's not a lot of land to speak of in the high latitudes of the Southern Hemisphere," making the search for an explanation of what is going on here even more complicated.

The hypotheses scientists offer for the causes of glacier and ice shelf thinning in Antarctica are varied. Rising air, land and ocean temperatures or some combination have all been cited.

Some scientists have even proposed that a healing of the seasonal ozone hole over the South Pole and southernmost Chile, a phenomenon expected to take place in the next 50 years or so, could change the circulation of the atmosphere over the frozen continent in ways that could accelerate the thinning of Antarctic ice fields. But even without that, the situation developing in Antarctica is already sobering, glaciologists agree.

The data being collected in West Antarctica and on the peninsula farther north make that obvious, they say, though the degree to which that should be cause for concern around the rest of the planet will become clear only with more research.

"If Antarctica collapses, it will have a major effect on the whole globe," Rignot cautioned.

"Nature is playing a little experiment with us," he said, "showing us what could happen if the plug were to be removed."