It seems to confound logic – despite CO₂ emissions from fossil fuels and industry remaining at a constant level, the concentration of CO₂ in the atmosphere has experienced a record-breaking increase. This might lead you to believe that the measurement of CO₂ emissions is wrong or that the data is incorrect. But as Senior Researcher at Cicero, Glen Peters, has shown, the fact that CO₂ emissions have remained constant despite the increase in concentration is not actually an incongruity.
There are a number of factors that contribute to the overall CO₂ level in the atmosphere — the cycle of the seasons, volcanic activity, emissions, and the El Niño Southern Oscillation. In years where there is strong El Niño conditions there tends to be more droughts in important forested areas. This then reduces the productivity of the forests, which in turn affects their ability to absorb CO₂ from the atmosphere. With the conditions being so dry, it also runs the risk of wildfires in forests, emitting even more CO₂ into the atmosphere. In 2015/2016 there was a big El Niño, which lead to a year of record increase in CO₂ concentration.
To see the interplay between CO₂ Emissions, CO₂ Concentration and the El Niño Southern Oscillation, check out this great gif. It shows the three in action between 1980 and 2016.