Carbon Dioxide Concentrations Will Reach A "Grim Milestone" In 2021
2) in the atmosphere reach levels 50 percent higher than those before the Industrial Revolution. The new forecast by the UK Met Office says that the concentrations of CO 2 will be around 2.29 parts per million (ppm) higher in 2021 than in 2020 at the Mauna Loa Observatory in Hawaii. This means atmospheric concentrations will exceed 417 ppm from April to June and be more than 50 percent higher than the level of 278 ppm seen in the late 18th century before the Industrial Revolution. The last time global carbon dioxide levels were consistently above 400 ppm was around 4 million years ago...
Source: iflscience.com