Relentless rise of carbon emissions
December 16, 2021 - Atmospheric carbon dioxide levels are 50% higher than when society began burning fossil fuels during the industrial revolution -- almost twice as large as the increase following the last ice age.
Measurements from the Mauna Loa Observatory in Hawaii show that on December 15, 2021, atmospheric carbon dioxide (CO2) levels reached more than 416 parts per million (ppm). Pre-industrial levels were about 277ppm.
Records derived from ice core measurements show that carbon dioxide levels in the atmosphere have remained between 180 and 300ppm for the past half a million years. Data also indicate that the average global CO2 concentration from 1750 to 1850 was around 278ppm to 284ppm.
Systematic long-term measurements of atmospheric CO2 were started in 1958 by Charles David Keeling at Mauna Loa. Since then, additional sites worldwide have enabled the global average CO2 concentration to be estimated. In combination with the ice core data, these records show three trends.
The annual average CO2 concentration increases year on year, mainly due to the burning of fossil fuels and deforestation.
Human-driven emissions are increasing, and the rise in CO2 has accelerated. It took 236 years to reach a 25% increase between 1750 and 1986, and by 2011 -- 25 years later -- it hit 40%. Now, a decade later, it has soared to 50.4%.
The Mauna Loa record shows a clear seasonal swing in atmospheric CO2 levels, peaking around May and a low point around September. The cycle is due to vegetation taking up CO2 in the growing season and releasing it in the autumn and winter.