For the first time in up to five million years, the concentration of carbon dioxide in our atmosphere is about to reach 400 parts per million (ppm). Former NASA scientist James Hansen warned that levels over 350ppm would destabilize the earth’s climate, but now we have far exceeded that figure with a record-breaking weekly average of 398.5ppm recorded on Monday, The Guardian reports. Researchers at the Earth Systems Research Laboratory in Hawaii expect we will hit the 400ppm milestone in May, 2013.
Levels of CO2 in the atmosphere have been steadily rising for 200 years. At the start of the industrial revolution, carbon emissions levels were at 280ppm. The CO2 level was recorded at 316ppm in 1958, when the Mauna Loa observatory started measurements.
Some experts say if levels exceed 350ppm, climate change will disrupt daily life on our planet. Much of the increase in carbon levels is tied to the burning of fossil fuels.
Although many industrialized nations have already reduced their carbon emissions, burning of fossil fuels still adds to the increase in atmospheric concentrations.
The last time CO2 levels were so high was likely in the Pliocene epoch, between 3.2m and 5m years ago, when Earth’s climate was significantly warmer than today.