Earth's Carbon Dioxide Levels Just Passed a Threshold Irrevocably

Some damages cannot be undone, and the planet just recorded one of them. This month, Earth officially recorded its atmospheric carbon dioxide moving beyond the 400 parts per million (ppm) mark - permanently.

According to a blog post from Scripps Institution of Oceanography from the University of California San Diego, September is a month that's supposed to log in a low number in the Mauna Loa CO2 curve due to the transition from summer to fall. Instead, weekly values throughout September have been consistently over 400 ppm, which means the monthly value will also be over the dreaded number.

"By November, we will be marching up the rising half of the cycle, pushing towards new highs and perhaps even breaking the 410 ppm barrier," Ralph Keeling, program director of Scripps CO2 Program and the author of the blog post on the website, wrote.

He added, "Brief excursions towards lower values are still possible but it already seems safe to conclude that we won't be seeing a monthly value below 400 ppm this year - or ever again for the indefinite future."

Although it's technically possible for the monthly value to dip lower in October, the blog revealed that even with a decrease, the number is almost certainly staying over 400 ppm.

Earlier this year, a report from 9news elaborated on the significance of passing the 400 ppm mark. CSIRO fellow Dr Paul Fraser called it a "psychological tipping point", but significant because once the values collected at the atmospheric measuring station in Cape Grim, Tasmania reaches 400 ppm, it's unlikely to drop less than the threshold again.

"In the days when I started measuring CO2 in the atmosphere in the 1970s all the texts would say that the CO2 concentration in the atmosphere was 300ppm or 0.03%, the concentration is now 0.04%," he explained. "It was rising at just over a part per million a year, it's now rising at about 3 parts per million a year. It's certainly going up quicker than we thought it would."

Fraser put the 400 ppm value in perspective by saying that standing in a highway with a constant stream of cars zipping past would likely hit the subject with about 500 ppm of CO2.