The Earth reached a global warming milestone it may never recover from.
Climate scientists say carbon dioxide levels in the atmosphere surpassed 400 parts per million this month - 50 parts per million more than what most experts consider "safe."
And there's little hope that we will ever get our planet's levels back to that number again.
CO2 emissions have been a main source of climate change since the Industrial Revolution, causing Earth's temperature to rise 1.8 degrees Fahrenheit since then.
That's already led to record-breaking global temperatures, extreme weather and other effects.
Scientists are urging people to take this news as a wake-up call to get serious about reducing carbon emissions and fighting climate change.
