The last time Earth had a month of normal temperatures — compared to the 20th century — was in February 1985 . Lebron James was a crawling infant, just over a month old. Barack Obama was 24. Billie Eilish wouldn’t be born for another 16 years.

It’s now been 420 consecutive months that Earth, overall, has experienced temperatures above the 20th-century average, according to data collected from over 25,000 weather stations and scrutinized by the U.S. National Oceanic and Atmospheric Administration (NOAA).

On Thursday, the agency published data showing that December 2019 was the second hottest December in 140 years of modern record-keeping, and that the last six Decembers were the warmest six Decembers in recorded history.

The long-term trend is clear, beyond the cultural milestone of 420 straight months of above-normal temperatures:

2019 was the second hottest year on record.

19 of the last 20 years are now the warmest on record.

The ocean continues to accumulate heat and has warmed relentlessly since around 1990.

A routine climate science denialist argument — though willfully ignorant and increasingly pathetic — is that cold or low records were also broken in 2019. Of course, winter still arrives and daily weather will always fluctuate. But a critical point is with added background warming, high temperature records are fast outpacing low temperatures records. It's not even close.

As of mid-December, 364 all-time high temperatures were set in 2019, versus just 70 all-time lows.

"As the climate changes into a warmer climate we do expect to see more extreme warm temperatures," Ahira Sánchez-Lugo, a National Oceanic and Atmospheric Administration climatologist, told Mashable in December. "That’s what we’re seeing, and that’s what the data are showing."

Earths' global temperature anomolies. Notice anything? Image: noaa

2019 was the second hottest year on record, continuing a decades-long trend of warming. The last five years have been the five warmest since modern recordkeeping became possible 140 years ago. https://t.co/SdeVwaPM9r pic.twitter.com/1d4HIwudJY — NASA GISS (@NASAGISS) January 15, 2020

Meanwhile, Earth's atmospheric carbon dioxide emissions, a potent greenhouse gas, are now skyrocketing. CO2 levels haven't been this high in at least 800,000 years — though more likely millions of years. What's more, carbon levels are now rising at rates that are unprecedented in both the geologic and historic record.

These rapid and robust changes are unequivocally heating Earth and continually breaking daily, monthly, and annual records. "As we have shown in recent work, the record warm streaks we’ve seen in recent years simply cannot be explained without accounting for the profound impact we are having on the planet through the burning of fossil fuels and the resulting increase in atmospheric greenhouse gas concentrations," climate scientist Michael Mann, the director of the Earth System Science Center at Penn State University, told Mashable after Earth experienced its hottest ever month of June in 2019.

Earth will soon hit another 420 milestone, perhaps in 2021. Global atmospheric carbon dioxide concentrations nearly hit 415 parts per million, or ppm, in 2019.

But with ever-rising carbon-emissions, 420 ppm is a sure bet.