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Monday, November 9, 2026Nov 9

Warming gas levels hit ‘troubling milestone’

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photo In this image released by NOAA, Chris Carparelli, adjusts a glass flask that line the walls of an air sample processing room at NOAA’s Earth System Research Laboratory in Boulder, Colo., Wednesday, May 30, 2012. Researchers at the lab measure the levels of carbon dioxide and other greenhouse gases in air sent in weekly from sites that are part of an international cooperative air sampling network. The world’s air has reached what scientists call a troubling new milestone for carbon dioxide, the main global warming pollution. Monitoring stations across the Arctic this spring are measuring more than 400 parts per million of the heat-trapping gas in the atmosphere. The number isn’t quite a surprise, because it’s been rising at an accelerating pace, having years ago blown by the 350 mark that many scientists say is the highest safe level for carbon dioxide. So far only the Arctic has reached that 400 level, but the rest of the world will soon follow. (AP Photo/NOAA, Will von Dauster)

SETH BORENSTEIN

WASHINGTON (AP) – The world’s air has reached what scientists call a troubling new milestone for carbon dioxide, the main global warming pollutant.

Monitoring stations across the Arctic this spring are measuring more than 400 parts per million of the heat-trapping gas in the atmosphere. The number isn’t quite a surprise, because it’s been rising at an accelerating pace. Years ago, it passed the 350 ppm mark that many scientists say is the highest safe level for carbon dioxide. It now stands globally at 395.

So far, only the Arctic has reached that 400 level, but the rest of the world will follow soon.

“The fact that it’s 400 is significant,” said Jim Butler, global monitoring director at the National Oceanic and Atmospheric Administration’s Earth System Research Lab in Boulder, Colo. “It’s just a reminder to everybody that we haven’t fixed this and we’re still in trouble.”