The record had stood for nearly 30 years: minus 128.6 degrees F (-89.2 ˚C), recorded a few meters above the ground at the Russian Vostok Research Station in East Antarctica. It was the coldest temperature ever sensed on Earth.

Not any more. Researchers from the National Snow and Ice Data Center in Boulder, Colo., announced a new record low today: -136 ˚F (-93.2 ˚C). The place: a small valley between two peaks on the East Antarctic Plateau.

The temperature actually occurred on Aug. 10, 2010, but researchers only discovered it recently after analyzing reams of data recorded by several Earth-sensing satellites. At first they were doubtful, but further analysis showed that temperatures very close to -136 ˚F also occurred dozens of times in other “pockets”—small, downslope valleys along a 620-mile-long ridge between Dome Argus and Dome Fuji.

The temperatures occurred on the surface, “as if you reached down and touched the snow,” explained Ted Scambos, lead scientist at the data center, speaking on Monday at the annual American Geophysical Union fall meeting in San Francisco. Not that you would want to do so. Scambos has been on the icy continent in conditions nearly as cold. In those situations, people must breath through a snorkel-like device worn inside their special jackets which warms the air before it enters the lungs, which would freeze if exposed. Even then, Scambos says, “it hurts to breath.” And walking on the surface, he says, “sounds like walking on crushed glass.”

Scambos and his colleagues think they have figured out why the temperature drops so low in the little valleys. When skies stay clear for several days, heat from below the surface of the high peaks radiates upward from the tops of the peaks. That creates a layer of super-chilled air just above the surface. That air is denser than the relatively warmer air right around it, so it sinks, and slides down the slope into the valley. There is can get stuck, motionless, cooling even further.

Data from the new Landsat 8 satellite, launched earlier this year, revealed four such pockets along the ridge on July 31 that were all about -135 ˚F, reassuring Scambos's team that their 2010 record was legitimate, and convincing them that temperatures almost that low occur regularly in various pockets.

For perspective, -136 ˚F is about as far below water’s freezing point as boiling is above that point. It’s also about 50 degrees colder than the coldest temperatures ever recorded in North America, including Alaska. “It’s more like what you’d find on Mars on a nice summer day, “Scambos says.

So how low can Earth’s temperature go? Scambos doesn’t expect it could drop much further. Some latent heat exists even a meter beneath the surface that radiates some “warmth” upward, and any kind of clouds, even thin ones, would help keep a bit of that heat in. “So it may be,” Scambos says, “that weather might not allow temperatures to go much lower.”

Image courtesy of Walta on WikimediaCommons