Antarctic CO2 hits 400ppm for first time in 4m years

Climate Central: The last monitoring station in the world without a 400 parts per million reading has now reached it, NOAA confirms Carbon dioxide officially crossed the 400ppm threshold on 23 May at the South Pole Observatory. Photograph: Pool/Getty Images

We’re officially living in a new world.

Carbon dioxide has been steadily rising since the start of the Industrial Revolution, setting a new high year after year. There’s a notable new entry to the record books. The last station on Earth without a 400 parts per million (ppm) reading has reached it. Read more.