These conditions mean that in some parts of the United States, it’s actually colder than it is on Mars.
The latest weather data from the Curiosity rover on Mars recorded a peak temperature of -9 degrees Fahrenheit (-23 degrees Celsius) on the day of Sol 1910, which for us is December 20. The rover roams around Gale Crater, near the equator. There, the winter solstice has just passed and the cold season is getting started. Humans have yet to figure out if the red planet could be habitable, but right now it seems just as (in)hospitable as home, at least weather-wise. (Of course, Earth still has one thing that Mars doesn’t: breathable air.)
The comparison to Mars is indeed accurate, says Michael Mischna, a research scientist at NASA’s Jet Propulsion Laboratory in California where he studies the Martian climate—and where it will reach an enviable 80 degrees Fahrenheit (27 degrees Celsius) Friday. “Temperature is pretty much temperature wherever you are,” Mischna said.
There is one small difference. The atmosphere on Mars is about 100 times thinner than on Earth, which means a given air temperature—if you could stand outside on the planet, without a spacesuit—wouldn’t feel the same on both planets.
“If you were to jump into a pool that was 70 degrees, it would feel a lot colder to your body than standing in air at 70 degrees, and that’s because the water is able to suck the heat out of your body,” Mischna said. Like water molecules, air molecules can wick away warmth, but they’re much less efficient. On Mars, where there’s little water vapor and few air molecules, a person wouldn’t feel as cold. “Minus 100 degrees on Mars might only feel like minus 30,” he said.
There’s very little water on Mars, which means there’s no humidity; the heat is dry and the cold is bitter. Temperatures during summers on Mars, particularly at warmer regions like at the equator, can rise above freezing. At the height of the season, they can even reach 68 degrees Fahrenheit (20 degrees Celsius). Peak winter on Mars, however, is no match for the same season on Earth. Temperatures are -94 degrees Fahrenheit (-70 degrees Celsius) at the equator, and -200 degrees Fahrenheit (-130 degrees Celsius) at the poles.
Back on Earth, the American cold snap has prompted some doubters, including President Donald Trump, to surface their usual argument against climate change: that record-breaking, frigid temperatures are proof that human-driven climate change isn’t real.
The president is too eager to leap to conclusions: A single week of cold weather in one part of the world does not disprove that the world, overall, is warming. The Arctic’s current temperature is more than five degrees Fahrenheit above average, and 2017, as a whole, will be one of the warmest years ever recorded worldwide.
But this week’s Arctic blast may actually be a symptom of climate change, albeit an unusual one. In recent years, several studies have found that as the Arctic warms, it seems to destabilize other parts of the winter climate system, bringing frigid air down to the Midwest and Northeast. Scientists aren’t sure why this is happening yet—it may have to do with changes to the jet stream or the high-altitude vortex of air over the North Pole—but for now, it’s a well-documented aspect of our warming world. (Alas, these frigid winters don’t prevent the United States from suffering through scorching, climate-addled summers in the same year.)
Forecasters warn that this week’s temperatures could stretch through the New Year’s holiday. Here’s a disheartening map from the National Weather Service:
Maybe this holiday season will help prepare humanity for future New Years’ celebrations on Mars.