There is a growing trend in social media in which people add to their bios text along the lines: “Born at xxx ppm.” But what does this mean? The number is the CO2 concentration in parts per million (ppm) in the atmosphere in the year you were born. This value has continuously increased since the Industrial Revolution. Carbon dioxide can retain heat, so the accumulation of this gas has increased temperature. Between 1880 and 1980, the temperature on Earth increased by 0.07oC every ten years. However, since 1981, this value has reached 0.18oC per decade. The consequences of this “global warming” can be felt already: the unprecedented heatwaves in the Pacific Northwest in 2021, London reaching 40oC for the first time in 2022, or the fact that July 2023 has been called the hottest month ever recorded on Earth.
CO2 is only one of the myriad of forms that carbon takes in nature. This element appears in different chemicals, and its cycle has struck a balance between biological and geological forms (carbon biogeochemical cycle). For example, processes such as volcano eruptions and wildfires would release this element into the atmosphere as carbon dioxide. Organisms such as algae, cyanobacteria, and plants would then fix this CO2 into their biomass using light as an energy source in photosynthesis. Other microorganisms could also generate organic matter using chemical energy instead of light (chemolithotrophy). Part of this organic matter would become carbon dioxide again, due to respiration, for example, but also, a large part of this organic matter would be buried due to geological processes, restarting the cycle.
However, human activity has disrupted this natural cycle by increasing the emission of greenhouse gases, including CO2. The carbon stored in non-renewable sources such as coal, oil, and wood is released into the atmosphere due to the combustion process to release energy. Up to the Industrial Revolution, nature was very efficient at balancing the concentration of greenhouse gases in the atmosphere. The ever-growing need for energy in industry and daily life has resulted in burning coal, petrol, and wood using combustion processes, thus delivering greenhouse gases into the atmosphere. Of this, 87% of the total amount is produced by burning fossil fuels, 9% is linked to the clearing of forests and land use changes, and industrial processes amount for the remaining 4%. Up to the Industrial Revolution, nature was very efficient at keeping balance in the concentration.