Data recently released by the National Oceanic and Atmospheric Administration (NOAA) shows that the concentration of global atmospheric carbon dioxide averaged 400.83 parts per million (ppm) in March, marking the first time the Earth has passed 400 ppm average for an entire month, ThinkProgress reported.

“It was only a matter of time that we would average 400 [ppm] globally, said NOAA scientist Pieter Tans in a statement, adding that it was a “significant milestone.”

“This marks the fact that humans burning fossil fuels have caused global carbon dioxide concentrations to rise more than 120 [ppm] since pre-industrial times. Half of that rise has occurred since 1980.”

co2_trend_glLast summer, “the NOAA’s Mauna Loa observatory in Hawaii averaged above 400 ppm for several months in a row, marking the longest time in recorded history that that much carbon dioxide had been in the atmosphere,” reported ThinkProgress. The global average last march, however, was 398.10 ppm.

“This event is a milestone on a road to unprecedented climate change for the human race,” University of Reading climate scientist Dr. Ed Hawkins told The Guardian. “The last time the Earth had this much carbon dioxide in the atmosphere was more than a million years ago, when modern humans hadn’t even evolved yet.”

Dr. Hawkins pointed out that the CO2 reaching this milestone comes just months before the United Nations Climate Change Summit in Paris. The NOAA’s data should help to prove to the world’s leaders that global warming is truly a global issue, and action needs to be taken as soon as possible.