In the past week, symbolic limits have been crossed. The carbon dioxide content in the atmosphere has exceeded 420 parts per million – which is about halfway to double compared to pre-industrial times.
As climate scientists previously predicted, last year’s bleak carbon dioxide record has now been broken. On April 8, the Mauna Loa Observatory in Hawaii reported a daily average of 421.36 parts per million (parts per million). The last year’s daily record, reported on May 1, was 418.03 ppm.
When measurements began in 1958, the level was just over 315 parts per million. The pre-industrial level, before humans began burning fossil fuels, was calculated to be less than 280 parts per million. Thus, the benchmark for this year means that the mileage has been crossed to a doubling of the CO2 content compared to the pre-industrial level.
At most in the spring
But these high levels are therefore daily average values, and it is no coincidence that record levels of carbon dioxide are reported in the spring. This occurs when the carbon dioxide content in the atmosphere is at its highest, before vegetation in the Northern Hemisphere – where most of the Earth’s mass is located – accelerates and begins to accumulate carbon dioxide through the process of leaf photosynthesis.
To get a clearer picture of evolution, the researchers start from the annual average relying on continuous measurements from stations around the world.
Although the closure
In 2020, the average carbon dioxide content was 412.5 parts per million, according to an aggregation from the US NOAA. This was an increase of about 2.6 parts per million compared to the previous year, and one of the five largest increases since the agency’s compilations began 63 years ago.
The increase occurred despite the fact that lockdowns during the pandemic resulted in a drop in global carbon dioxide emissions of about 7 percent, according to calculations by the National Oceanic and Atmospheric Administration (NOAA).
It could be the loudest
But the lower rate does not mean that the emissions have stopped. Net emissions of carbon dioxide into the atmosphere from fossil fuels continued, but somewhat slower than before.
“Had it not been for the economic slowdown, the increase in 2020 would have been the highest ever,” the authority wrote on its website.