Last week we passed an unfortunate marker when it comes to climate change: concentrations of carbon dioxide (CO2) in the atmosphere have hit 400 parts per million (ppm) near the Arctic.
What Does it Mean and Why Should We Care?
This level was discovered by scientists at the National Oceanic and Atmospheric Administration (NOAA), who have long measured CO2 concentrations at stations around the world through two ways: (1) volunteers collect air samples and send them to NOAA’s Earth System Research Laboratory in Colorado for analysis; and (2) half a dozen baseline observatories continuously monitor CO2 levels. One of these observatories is located in Barrow, Alaska. The observatory in Barrow, as well as air samples from several other northern locations including Canada, Finland, and Norway, show that 400 ppm was surpassed sometime this spring.