The year 2016 set yet another devastating record for global warming.

Carbon dioxide levels rose more than 2 parts per million (ppm) for the second year in a row, according to the National Oceanic and Atmospheric Administration.

Levels rose 3 ppm to 405.1 ppm in 2016, putting CO2 at its highest levels in over 10,000 years. This increase matched the record rise recorded in 2015, when CO2 levels officially passed 400 ppm, which climate scientists call the “point of no return.” After this mark, they claim, climate change is irreversible.

“This is a real shock to the atmosphere,” Peter Tans, lead scientist of NOAA’s Global Greenhouse Gas Reference Network, said in a statement. “The rate of CO2 growth over the last decade is 100 to 200 times faster than what the Earth experienced during the transition from the last Ice Age.”

The 400 ppm level, known as the “carbon threshold,” was long used by scientists as a warning that once we passed this mark, the climate cycle would be thrown into turmoil. From 10,000 years ago to the beginning of the Industrial Revolution in 1760, CO2 levels averaged around 280 ppm.

And we’ll probably never see levels drop below 400 ppm in our lifetime, according to Tans. If the world stopped burning fossil fuels right this second, the carbon dioxide would still be trapped in the atmosphere for the next few decades.

Additionally, 2016 was the hottest year ever recorded, since measurements began in 1880. And the record-breaking temperatures have continued into 2017, with February recording the month’s second-highest-ever temperatures across the globe.

“The need for concerted action on climate change has never been so stark nor the stakes so high,” David Reay, an emissions expert at the University of Edinburgh, told the Guardian.

On Tuesday, the World Meteorological Organization published its annual State of the Global Climate, noting that increasing temperatures have pushed Earth into “truly uncharted territory.”