350 ppm

350 ppm (parts per million) refers to the concentration of carbon dioxide (CO₂) in the atmosphere. It means that for every one million molecules in the air, 350 are CO₂ molecules. This level is significant because scientists estimate that atmospheric CO₂ concentrations above 350 ppm contribute to dangerous climate change, leading to global warming and extreme weather. Currently, levels are higher, around 420 ppm, indicating increased greenhouse gases from fossil fuels and deforestation. Maintaining or reducing CO₂ levels to 350 ppm is seen as a goal to help stabilize the Earth's climate.