The average daily concentration of carbon dioxide (CO₂) in the atmosphere, measured at the Mauna Loa observatory (Hawaii, USA), a world reference station on this subject, reached the level of 424 parts per minute in May 2023. million (ppm). This concentration is the highest since the systematic, constant and detailed recording of this gas associated with the greenhouse effect and climate change began 63 years ago on this peak.
Various studies indicate that the current concentration of CO₂ in the Earth's atmosphere is the highest in the last 3 million years, although it has also been suggested that the record could reach up to 20 million years. Over the past 400,000 years, CO₂ concentrations have oscillated several times, from about 180 ppm during the great Holocene and Pleistocene ice ages to 280 ppm during interglacial periods.
To better understand the importance of this new record, it should be remembered that in the mid-18th century, at the start of the Industrial Revolution, there was only 280 ppm of CO₂ in the atmosphere. In 1959 the concentration of this gas in the atmosphere at the Mauna Loa observatory was 315 ppm, in 1990 it reached 354 ppm and in 2013 the level of 400 ppm was exceeded for the first time.
One of the most significant points in the data presented now is that the concentration of CO2 in the atmosphere increased by 3 ppm between May 2022 and May 2023, one of the highest figures recorded so far. When this type of observation began, in 1959, the increase was less than 1 ppm per year. The NOAA emphasizes in this sense that the rate of growth in the concentration of this gas in the atmosphere continues at a rate of decrease that is as high as it is worrying.
Rick Spinrad, NOAA administrator and internationally renowned physicist, commented on the new data from the Mauna Loa observatory, recalling that "for yet another year, we see carbon dioxide levels in our atmosphere increasing as a direct result of human activity." . Also constantly, "we see the impacts of climate change in heat waves, droughts, floods, forest fires and storms that occur around us," says this expert in a note released by the public institution he represents.
"It is clear that we will have to adapt to climate impacts that we cannot avoid, but we must put all our efforts to cut carbon pollution and safeguard this planet and our society."
The concentration of CO₂ in the atmosphere does not depend only on current annual emissions, but is largely determined by the total emissions that have been accumulating in the atmosphere in recent years and decades. As will be recalled, CO₂ is a gas that, once it reaches the atmosphere, tends to remain almost unchanged for tens of years, and it is estimated that it continues to warm the atmosphere (positive radiative forcing) for more than 100 years after its emission. Reducing CO₂ emissions is therefore necessary (if not essential if the climate is to be kept relatively stable) but its effects will only be truly noticeable in the medium and long term.
Pep Canadell, executive director of the Global Carbon Project, of the CSIRO (Australia's public scientific institution), in Canberra, explains in statements to La Vanguardia that, "during the last 200 years of burning fossil fuels, the concentration of CO₂ on the planet has only seen one direction: rising year after year, now being responsible for more heat waves, forest fires and floods, occurring with a frequency and intensity that past generations have never experienced." These trends, "will only stop becoming worse the day we stop using coal, oil and natural gas”.
“The last time planet Earth had such high concentrations of CO₂ in the atmosphere was more than 2 million years ago, when our ancestors were just walking upright and temperatures were much higher than they are today.” Canadell concludes that "unless CO₂ concentrations stop rising and then start to drop rapidly, temperatures will continue to rise, making parts of the planet uninhabitable by humans."
