Carbon dioxide emissions

Several measuring stations around the world measure the concentration of CO₂ in the atmosphere. Most famous is the station at Mauna Loa [L24], Hawaii. This station is admittedly located near a volcano that releases CO₂, and when the wind blows from the volcano towards the measuring station the measurement results become incorrect. But the prevailing wind direction blows gases from the volcano away from the measuring station, and the errors that occur are easy to recognise and remove from the observation series [L25]. The figure below shows how the CO₂ concentration has developed at Mauna Loa:

A lesser-known series of measurements is from Barrow in northern Alaska [L26]:

The figures show a clear seasonal variation, with a higher concentration in spring than in autumn. This is because the vegetation loses leaves in the autumn. The leaves rot and emit CO₂. In spring and summer new leaves grow that use CO₂ in photosynthesis [L27].

In September 2018, the CO₂ concentration at Mauna Loa was 405 ppm (parts per million), and at Barrow 400 ppm. Studies of air bubbles in the Antarctic ice show the development of CO₂ concentration through many thousands of years. See for example [L28] showing that the concentration has been between 200 and 300 ppm during the last 400,000 years before 1950.

Once CO₂ has been released into the atmosphere, it is difficult to remove it again. Fortunately, a lot will be removed naturally by photosyntesis performed by vegetation and algae in the ocean. But photosyntesis will far from compensate for the increased CO₂ emissions. In the long run, CO₂ dissolves in the ocean and will eventually be converted to calcium carbonate, but this takes a very long time. Probably 20-50% of the carbon we release into the atmosphere during this century will still be there in the year 3000 [L29].

Latest update: 2021-07-13