"Near the moonscape summit of the Mauna Loa volcano in Hawaii, an infrared analyser will soon make history. Sometime in the next month, it is expected to record a daily concentration of carbon dioxide in the atmosphere of more than 400 parts per million (p.p.m.), a value not reached at this key surveillance point for a few million years," reports Richard Monastersky.
"There will be no balloons or noisemakers to celebrate the event. Researchers who monitor greenhouse gases will regard it more as a disturbing marker of humanity’s power to alter the chemistry of the atmosphere and by extension, the climate of the planet. At 400 p.p.m., nations will have a difficult time keeping global warming in check, says Corinne Le Quéré, a climate researcher at the University of East Anglia in Norwich, UK, who says that the impact 'is getting very dangerously close to reaching the 2 °C target that governments around the world have pledged not to exceed'."
When monitoring began at the station in 1958, 'the CO2level stood at 316 p.p.m., not much higher than the 280 p.p.m. that characterized conditions before the industrial revolution.'"