The authors of the new study, published in Geophysical Research Letters, found “approximately 100” sites that posted low temperatures of around minus 98 Celsius (minus 144 Fahrenheit) during the winters of 2004-2016. Most frequently, these temperatures, colder than the average temperature on Mars (around minus 60 Celsius), were observed in dips and hollows near the top of the East Antarctic Ice Sheet. They occurred at elevations of about 12,500 to 13,000 feet, mostly during July and August.
Before analysis of satellite data, the coldest temperature measured on Earth had been minus 89 Celsius, recorded on the East Antarctic Plateau at Russia’s Vostok Station in July 1983. The satellite data analysis published in 2013 analyzed 32 years’ worth of data to find that colder temperatures were present, closer to minus 93 Celsius. This latest study recalibrated satellite data using more up-to-date weather station data and concluded the coldest temperatures were 5 degrees lower than that.
The locations where the minus 98 air was analyzed shared similar characteristics. “[T]hey occurred in small hollows 2 to 3 meters (6 to 9 feet) deep in the surface of the ice, on the southern side of high ridges on the plateau,” the study’s news release explained.
Remarkably, the lowest temperatures observed at all of these hollows on the ice sheet was right around minus 98 Celsius, even though some of them were spaced tens of miles apart. In other words, the scientists found minus 98 Celsius seemed to represent the floor or the theoretical minimum for how cold it can get.
Such a frigid temperature reading is possible only occur under very specific weather conditions, the study found. The sky must be clear and winds calm to allow for any residual heat to radiate away from the Earth’s surface back into space. The air must also be as dry as possible, as water vapor, which is a greenhouse gas, can retain heat in the atmosphere.
If the air was extremely dry for a long period of time, it’s possible the temperature could go lower than 98 Celsius but not by much. “There’s a limit to how long the conditions persist to allow it to cool to these ultralow temperatures and a limit to how much heat you can actually get through the atmosphere, because water vapor has to be almost nonexistent in order to emit heat from the surface at these temperatures,” said Ted Scambos, a scientist at the National Snow and Ice Data Center and study lead author.
Will climate warming due to increasing concentrations of greenhouse gases in the atmosphere from human activity gradually raise the floor for this minimum temperature? Scambos says it’s possible.
“Going forward in time, I think we could see that the lower limit might slowly start to rise, as we put more carbon dioxide in the air, and water vapor in the stratosphere starts to increase,” he said.