shift the tundra landscape from being a temporary carbon sink to being a temporary carbon source.
“We’re over 400 and it’s not going back,” said Bryan Thomas, the station chief at the observatory. He remembers when 400 parts per million — a level first hit in 2012 — was considered the threshold that might shock people into climate action. Readings well above 400 have now become routine. “It keeps going up,” said Brian Vasel, director of operations at NOAA’s Global Monitoring Laboratory in Boulder, Colorado, who was in Utqiagvik for the opening celebration.
The observatories also measure chlorofluorocarbons, chemicals that eat away at the high-stratospheric ozone layer that protects the Earth and its inhabitants against solar radiation. A treaty signed in 1987, the Montreal Protocol, phased out and ultimately banned the ozone-depleting chemicals, and readings at the Barrow observatory and elsewhere tracked their decrease in the following years. But progress has not always been smooth.
“If we hadn’t been able to monitor that, we wouldn’t have been able to recover and get back on the trajectory,” Thomas said.