Global health. The current scenario and future perspectives

120 Figure 1. Diagram of the normal greenhouse effect (left) and the greenhouse effect with a higher concentration of GHGs in the atmosphere (right). Source: Own elaboration. For several decades, the concentration of greenhouse gases (GHGs) in the atmosphere has been increasing due to excessive use of fossil fuels, widespread agricultural practices and deforestation of forests that serve as CO 2 sinks . To accurately measure the concentration of certain gases, Charles Keeling began measuring atmospheric CO 2 concentration at the Mauna Loa Observatory in Hawaii in 1958, which showed a sustained increase over time (Figure 2) (Tans & Keeling, 2022). From 1750 to 2019, CO 2 has increased by approximately 47%, methane (CH 4 ) by 156%, and nitrous oxide (N 2 O) by 23% (IPCC, 2022).