Atmospheric CO2 Levels Likely To Break Historic Threshold In 2016

CO2 concentrations in the atmosphere
The level of CO2 in the atmosphere hasn’t been this high for over 3 million years. IM_photo/Shutterstock

For the first time in more than 3 million years, the level of carbon dioxide present in the atmosphere will breach the symbolic 400 parts per million level for the entire year. According to a new study released by the Met Office, it looks like it is now going to sit at this level for all of our lifetimes, as even if we reach the Paris climate agreement commitments, it is unlikely to have an effect in time to cut the CO2 concentration.  

The paper, published in Nature Climate Change, uses the data collected from the Mauna Loa Observatory in Hawaii, which maintains the benchmark for carbon dioxide concentrations. While the levels of the gas in the atmosphere typically fluctuate with the seasons, increasing in the winter before dropping in the summer when plant growth takes off, the Met Office predict that this will be the first year since the Pliocene when the atmospheric levels have not dipped below 400 ppm for the whole year.


“The atmospheric carbon dioxide concentration is rising year-on-year due to human emissions, but this year it is getting an extra boost due to the recent El Niño event – changes in the sea-surface temperature of the tropical Pacific Ocean,” explains Professor Richard Betts, from the Met Office and Exeter University, in a statement. “This warms and dries tropical ecosystems, reducing their uptake of carbon, and exacerbating forest fires.”

Last year's El Nino, potentially the largest one on record, has pushed CO2 levels up. NASA

Despite the news that 2015 saw the growth of CO2 emissions stall for the year, the prediction that it won’t hold looks like it will inevitably come to pass. Normally, the level of atmospheric CO2 has been steadily rising by around 2 ppm per year, but 2016 has seen a spike in this. The Met Office now think that in the year that has already smashed every temperature record so far, it will also smash the carbon dioxide concentration record as it increases by 3.15 ppm, plus or minus 0.53 ppm.

While it is only a prediction, the Met Office have been pretty spot on in past estimates. They predicted that the atmospheric CO2 levels would peak at 407.57 ppm in May this year, with official reading logging it at 407.7 ppm. It is unlikely to drop below the level of 400 ppm within the next generation, as the impact of El Nino is continuing to echo through the climate.


Carbon emissions have been steadily climbing, and show few signs of stopping. DyziO/Shutterstock 

The figure of 400 ppm is largely symbolic, with no significant impact on the climate system. But it does go to show the effect that humans are having on the environment. The last time it was at these levels was during the Pliocene, when global average temperatures were 3°C (5.4°F) higher than pre-Industrial times, and sea levels were 20 meters (66 feet) higher. It now seems that we are on the track to return to this past.


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  • climate change,

  • global warming,

  • CO2