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Carbon dioxide passes symbolic mark Carbon dioxide passes symbolic mark
(35 minutes later)
The laboratory with the longest, continuous measure of the amount of carbon dioxide in the atmosphere has broken through a symbolic mark. The level of carbon dioxide in the atmosphere has risen above 400 parts per million for the first time in human history, US researchers say.
The "Keeling Lab" in Hawaii has seen the daily average concentration of the gas rise above 400 parts per million for the first time. The "Keeling Lab" in Hawaii has the longest continuous measurement of the greenhouse gas, which is a key driver of climate change.
Thursday's measurement, made atop the Mauna Loa volcano, registered 400.03.Thursday's measurement, made atop the Mauna Loa volcano, registered 400.03.
The last time CO2 was regularly above 400ppm was about 3-5 million years ago - before modern humans existed.The last time CO2 was regularly above 400ppm was about 3-5 million years ago - before modern humans existed.
The climate back then was also considerably warmer than it is today, according to scientists.The climate back then was also considerably warmer than it is today, according to scientists.
Carbon dioxide is described as the most important of the manmade greenhouse gases, produced principally through the burning of fossil fuels such as coal, oil and natural gas. The usual trend seen at the volcano is for the CO2 concentration to rise in winter months and then to fall back as the northern hemisphere growing season kicks in and pulls some of the gas out of the atmosphere. But the long-term trend is upwards.
When the late Charles Keeling began recording CO2 concentrations at the volcano in 1958, they were around 315 ppm (parts per million by volume - that is 315 molecules of CO2 for every one million molecules in the air). Every year since then, the curve has squiggled resolutely higher.
Keeling died in 2005, but his work is continued by his son Ralph, who is affiliated to the Scripps Institution of Oceanography in San Diego.
The monitoring station itself on Mauna Loa is run by the National Oceanic and Atmospheric Administration (Noaa)