Back in 2013, scientists had announced that they had recorded the lowest temperatures on Earth’s surface: according to multiple satellite measurements, lows of -93°C (-135°F) were observed in several parts of the East Antarctic Plateau. This is already extraordinarily cold, but a new study – published in Geophysical Research Letters – has found that temperatures can drop even lower still.
A team, led by the National Snow and Ice Data Center (NSIDC) at the University of Colorado, Boulder, analyzed new data from several NASA and National Oceanic and Atmospheric Administration (NOAA) satellites. Between 2004 and 2016 during the winter months, they initially found temperatures matching that of the previous record low on the surface of the plateau.
As pointed out by this AGU blog post, the NASA satellite temperature data in this case is carefully calibrated using weather stations on the ground. NASA ended up recalibrating their measurements back in 2016, and a re-assessment of the data pushed the coldest temperatures on the East Antarctica Plateau down to -98°C (-144°F).
It’s difficult to imagine how utterly madcap this temperature reading is, but here’s one way of looking at it: this temperature is as cold as your boiling kettle is hot – so how exactly is it possibly quite so frigid down there?
Apart from the fact that its position on the globe means it gets very little direct sunlight, Antarctica is also incredibly high up. Parts of it are around 4,300 meters (about 14,000 feet) above sea level, which means you can find yourself down there on the frequently mountainous continent standing at the same height as those about to do a skydive from a plane elsewhere in the world.
The higher up you go, the lower the atmospheric pressure, and thermal energy becomes more diffuse – so it’s colder. It also helps that ice has a very high albedo, or reflectivity. Bouncing all that incoming solar radiation back upwards certainly makes Antarctica a fair bit colder than it otherwise would be.
The cold nature of the icy realm also means that there’s very little melting and evaporation going on there. That means you don’t have many clouds forming above it, which also means a layer of insulation present in much of the world also doesn’t exist.
There’s more: the topology of the landscape means that you often get cold, dense air rushing out from the flatter parts of the interior of the continent and down steep slopes to the coast. These so-called katabatic winds are pretty incredible; back in July 1972, record-breaking wind speeds of 327 kilometers (199 miles) per hour were recorded at Dumont d’Urville station.
Altogether, these factors guarantee that parts of Antarctica will be the coldest places on Earth. Plenty of these factors apply to the East Antarctic Plateau, a place that, unprotected, you'd perish in within just a few minutes.
This new study, however, brings with it an additional revelation.
The NSIDC team noticed that the new record-low surface temperatures were found in very small pits in the ice, right on the south side of the high ridges on the plateau, spread hundreds of kilometers apart. Incredibly cold and therefore dense air falls into these pits, gets stuck, and cools the air above it.
Not only that, but the air must be incredibly dry for several days. With no water vapor to trap any heat radiating out from the surface, things there cool further than elsewhere on Antarctica.
Unless the weather changes, the heat radiation from the cold air is pretty much the same as that escaping from the ground. Heat exchange is limited, and, hypothetically, no further surface cooling is possible.
Specialized instruments will be placed in the pits over the coming years to confirm this, but there’s a good chance that -98°C (-144°F) is the lower limit for temperatures on Earth’s surface.