For the first time in human history, the carbon dioxide (CO2) concentration in the atmosphere has passed the milestone level of 400 parts per million (ppm).
Two CO2 monitoring stations high on the Hawaiian volcano of Mauna Loa run by the US National Oceanic and Atmospheric Administration and the Scripps Institution of Oceanography, provide the global benchmark measurement., the data released on Friday shows that the daily average has passed 400ppm for the first time in its 50 years of recording, the Guardian reported.
Analysis of fossil air trapped in ancient ice and other data indicated that the level has not been seen on Earth for 3-5 million years, Pliocene period.
At that time, global average temperatures were 3 - 4C higher and up to 8C warmer at the poles.
At that time reef corals suffered a major extinction while forests grew up to the northern edge of the Arctic Ocean, a region which is today bare tundra, Arctic was ice-free, savannah spread across the Sahara desert and sea level was up to 40 metres higher.
These conditions could return in time, with bad consequences for civilisation, unless emissions of the gas from the burning of coal, gas and oil are curbed rapidly.
But despite warnings from scientists and a major economic recession, global emissions of CO2 have continued to soar unchecked.
Professor Ralph Keeling, who oversees the measurements on Mauna Loa, which were begun by his father in 1958, said that the landmark level is symbolic, it’s like turning 50: it’s a wake up call to what has been building up in front of people all along.
Prof Rajendra Pachauri, chair of the Intergovernmental Panel on Climate Change, which serves as science adviser to the world’s governments, said that the passing of this milestone is a significant reminder of the rapid rate and the extent to which people have increased the concentration of greenhouse gases in the atmosphere.
He said that at the beginning of industrialisation the concentration of CO2 was just 280ppm.